✎ resarch:nlpa:preethaprelims [Pollock Lab: Private Research Space]

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====== Preetha's Summer 2015 PhD Preliminary Research Project ======

**Problem Statement and Motivation:**
\\ Quorum is a new programming language designed specially for visually impaired individuals. Our research goal is to summarize
loops in Quorum, to identify the higher level abstraction of the action being performed by the loops.  Many algorithmic steps require more than one statement to implement, but not big enough to be a method. These steps are generally implemented by loops. Our idea is to mine loop characteristics of a given loop structure over the repository of the Quorum language source code, map it to a (already developed) action identification model, and thus identify the action performed by the specified loop. This might be very useful for human readers/coders, generating automatic comments for the loop structure(as very small percentage of code is well documented to help new users/coders), facilitate automatic code search tools, and help blind programmers grasp a quick high level view of code segments that otherwise are tedious and difficult to understand.

**Summary of background(from Xiaoran's paper):**
\\ Motivation for this project comes from a preexisting work by Xiaoran Wang, Dr. Lori Pollock and Dr. Vijay Shanker on "Developing a Model of Loop Actions by Mining Loop Characteristics from a Large Code Corpus". This project involved identifying the higher level abstraction of the action being performed by a particular loop structure in Java based on their structure, data flow and linguistic characteristics. They focused on loops that contain exactly one conditional statement(if-statement) and also the last lexical statement within the loop body; which they call a loop-if structure. The loop formats considered in Java were : for, enhanced-for, while or do-while(nested loops were not considered).
\\ Their approach was to first identify action units( a code block that consists of a sequence of consecutive statements that logically implement a high level action) that are implemented by loop structures. Then characterizing the loops as feature-value pairs to generate the loop feature vector and then develop a model(action identification model) that can associate actions with loops based on their loop feature vectors. 

**The problem with respect to the new language environment and motivation:**

Problems:
\\ 1. Loop structures in Quorum are different from that of Java - there is no for loop, instead in Quorum the loop structures are-
\\ repeat <expression> times
\\ repeat while <expression>
\\ repeat until <expression>
\\ \\ 2. As Quorum is a comparatively new programming language:
\\ a. Repository of source code for sample projects is very small. 
\\ b. Apart from the language compiler and standard library files, there is practically no source of complex codes to evaluate our tests.
\\ c. The language is written by very few(one or two) developers, thus we do not get to evaluate on different coding styles.
\\ d. Might not be able to find a lot of loop-ifs in the sample code.
\\ \\ 3. Identifying the language grammar and generating ASTs with ANTLR4 seems challenging.

Motivation:
\\ As we already have an action identification model developed for JAVA source code, it will be interesting to find out if we can implement the same on another programming language like Quorum.

**Proposed Ideas for addressing the problem(s) and justification:**
\\ 1. Mapping for loops(Java) to repeat loops in Quorum.
\\ 2. After successful implementation of the project, we would like to conduct a question-answer survey from different users/developers, to evaluate the correctness of our work. The question would consist of a piece of Quorum code containing loop-ifs, and the user have to select the correct action describing the code(according to him/her) out of the 4 available options provided to him. Thus the evaluation would not be biased.
\\ 3. Learn ANTLR4 to generate the ASTs, it might be useful as according to the last release, Quorum now uses ANTLR4 as back-end.

**The research activity list and order:**

1. Manually identify loop-if structures from sample Quorum code for at least 25-50 loops.
\\ 2. Manually extract the feature vectors for the identified loop-ifs.
\\ 3. Map the identified loop-ifs with the already developed action identification model.
\\ 4. Validate if the identified action is correct.
\\ 5. Identify the Quorum grammar.
\\ 6. Feed the grammar to Antlr4 to generate abstract syntax trees(ASTs).
\\ 7. Write program to automatically extract feature vectors from Quorum code using the already generated ASTs.
\\ 8. Use Xiaoran's code to map the feature vectors to the action identification model.
\\ 9. Identify the high level action implemented by a given loop.

**Work to discuss for meeting on Jun9,2015:**

**Short Introduction to Quorum syntax:**
\\ For more help on Quorum syntax refer to http://quorumlanguage.com/syntax.php

Data Types:
\\ 1. Integer
\\ 2. Number
\\ 3. Boolean
\\ 4. Text
\\ Type Casting: <type> <variable> = cast(<type to convert to>, <value to be converted>)

Arrays:
    use Libraries.Containers.Array
    Array<integer> a
    a:Set(0, 10) //put value=10 in the first slot in the array, which is named 0
    a:Get(1) //return value at index1
    a:SetSize(12) //setting the size of the array to 12, by default it is 10.
    
Loops(Repeats):

 1. repeat <expression> times

     integer a = complicatedMathAction()
     integer b = anotherComplexAction()
     repeat (b / a - (b + 5)) times
     end
\\ 2. repeat while <expression>

     integer a = 0
     repeat while a < 15
        a = a + 1
     end
     \\this syntax tells Quorum to continue executing as long as a happens to be smaller than 15.
\\ 3. repeat until <expression>
      integer a = 0
      repeat until a < 15
         a = a + 1
      end
      \\Since a is less than 15 this loop will execute 0 times. 

If Conditional:

    integer a = 1
    integer b = 1000
    integer c = 0
    if a > 100
     c = 1
    elseif b = 100
     c = 2
    else
     c = 3
    end

Methods(Actions):

    action main
      integer addedNumbers = add(5,10)
    end
    action add(integer a, integer b) returns integer
      return a + b
    end

Classes:
   class BankAccount
     integer money = 0
     action deposit(integer amount)
          money = money + amount
     end
     action withdraw(integer amount)
          money = money - amount
     end
   end
   
   use BankAccount
   class Main
     action Main
          BankAccount account
          account:deposit(10)
     end
   end

Inheritance:

   Class A
   Class B
   Class C is A,B
      action <name>
         parent:A.<method-name>(arguments)
         parent:B.<method-name>(arguments)
      end
   end
   
   class Main
      action main
         C <object name>
         <object name>:<action name>
      end
   end   

Generics:\\ In computer programming, we often want to create a class that generically specifies an algorithm. For example, we may want to create a list of objects, like a list of people in a phone book. Or, we may want to create a list of numbers, integers, or anything else. There are two ways we could accomplish this: 1) we could create separate implementations of our list for each data type (e.g., one for numbers, one for integers), or 2) we could create a "generic" class.

   class List<Type>
      action add(Type item)
      //add our list item
      end
   end
   List<integer> list
   list:add(1)
   list:add(2)
   list:add(3)
   //all of the following are fine
   List<string> list1
   List<Dog> list2 //assuming there is a Dog class somewhere
   List<boolean> list3

Autoboxing:
\\ Mutator function:
  Integer int
  int:SetValue(15)

Accessor Function:
   text t
   t = int:GetTextValue()

Comparison Function:
   Integer int1
   Integer int2
   int1:SetValue(5)
   int2:SetValue(7)
   integer lessThan = int1:CompareTo(int2)
   integer greaterThan = int2:CompareTo(int1)
   boolean equalTo = (int1:CompareTo(int2) = 0)

 After executing the above code:

    lessThan will equal -1, because 5 is less than 7,
    greaterThan will equal 1 because 7 is greater than 5, and
    equalTo will equal false because 5 is not equal to 7, and thus the result of the function is not 0.

Error Handling:
    use Libraries.Language.Errors.Error
    use Libraries.Language.Errors.DivideByZeroError
    class Main
      action Main
        number result = 0
        check
            text userInput = input("divide by?")
            integer divisor = cast(integer, userInput)
            result = 12/divisor
        detect e is Error or DivideByZeroError
            say e:GetErrorMessage()
            result = 12/1
        always
            say "calculating result"
        end
        say "The result is " + result
      end
    end


**Sample loop-ifs from Quorum Source Code:**

\\ Repo -> Quorum3 -> SourceCode -> Compiler.quorum
\\ 1. Line No: 486-496

       private action GetActionAtIndex(Class clazz, integer index) returns Action
           Action act = undefined
           File file = clazz:GetFile()
           text classPath = file:GetAbsolutePath()
           Iterator<Action> actions = clazz:GetActions()
           repeat while actions:HasNext()
                Action a = actions:Next()
                integer start = a:GetIndex()
                integer finish = a:GetIndexEnd()
                File f = a:GetFile()
                text actionPath = f:GetAbsolutePath()
                if index >= start and index <= finish and classPath = actionPath
                   act = a
                   return act
                end
           end
           return act
       end

Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:4, F6:0, F7:0, F8: 1,2
\\ Action Identified: find

\\ Repo → Quorum3 → SourceCode → Compiler.quorum 
\\ 2.Line No: 658-672

       private action AddSubpackagesAndClasses(CodeCompletionRequest request, CodeCompletionResult result, text name)
           //first find all of the packages/sub-packages 
           Iterator<text> packs = sandboxSymbolTable:GetSubpackageNames(name)
           repeat while packs:HasNext()
               text pack = packs:Next()
               integer size = name:GetSize() + 1
               text subpackName = pack:GetSubtext(0, size)
               text filteredName = subpackName + result:filter
               subpackName = pack:GetSubtext(size, pack:GetSize())
               if pack:StartsWith(filteredName)
                     CodeCompletionItem item = GetPackageCompletionItem(subpackName)
                     text filter = result:filter
                     integer size = filter:GetSize()
                     item:dotOffset = request:caretLocation - size
                     result:Add(item)
               end
           end

Feature Vector: F1:5, F2:2, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: add
**\\ According to Xiaoron's work: 
\\ Feature Vector: F1:5, F2:1, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: get
\\ Need to discuss if that is the correct action identified, according to me, it should be add**

**Questions for meeting on June 9,2015**
\\ 1. We should not consider nested loops right? Xiaoran's work did not include nested loops.
\\ 2. Xiaoran's Action Identification model contains entry for the most frequent 100 loops in Java source code. So there are some loop-ifs in Quorum for which I don't find the valid entry in the table.
\\ 3. Show Quorum grammar file and take feedback on how to proceed.
\\ 4. What if we don't find enough loop-ifs, how many should be sufficient for the project?

**Meeting summary June9,2015**
\\ 1. We won't consider any kind of nested loops, only loop-ifs.
\\ 2. If we find loop-ifs that cannot be mapped to Xiaoran's action identification model, we have to leave that case. We cannot summarize such loops.
\\ 3. Only repository we have is the Quorum source code, so we have to work with less number of loop-ifs if we don't find many.We can automate the process to generate the feature vector from any Quorum code.
\\ 4. After manual extraction of feature vectors of 25-50 loop-ifs, prepare a test survey for validation.(possibly Xiaoran can help).
\\ 5. For generating AST, we might not need ANTLR4. First suggestion is to through the parser in Quorum and try to understand the code. There is a tree walker available in the code. We can use that and might not need to write one of our own.
We can try to stop the compiler execution after it generates the AST. It might not be visible or printed, it should be in the memory.
Now while running the tree walker, might print at nodes when we hit a loop,etc
\\ Parser:/Users/preethac/Desktop/Research/Summer Project 2015/stefika-quorum-language-25186e0d2fa6/plugins/ParserPlugin/src/plugins/quorum/Libraries/Language/Compile
\\ Compiler: /Users/preethac/Desktop/Research/Summer Project 2015/stefika-quorum-language-25186e0d2fa6/Quorum3/SourceCode

**Work to discuss-Meeting on June 17, 2015:**
\\ \\ **More Sample loop-ifs from Quorum Source Code:**
\\ Repo → Quorum3 → SourceCode → Compiler.quorum
\\ 3. Line No: 727-735 
    private action ReformPackage(Array<text> packs) returns text
        text result = ""
        integer i = 0
        repeat while i < packs:GetSize()
            text value = packs:Get(i)
            if i = 0
                result = result + value
            else
                result = result + value + "."
            end
            i = i + 1
        end
        return result
    end

Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: could not be identified(no entry in action identification table)
\\ very close to find, except that F5 is 0, not 1,2 or 4. 

\\ Repo → Quorum3 → SourceCode → Compiler.quorum
\\ 4. Line No: 1572-1580
      action TypeResolution(SymbolTable table, TypeChecker types, CompilerErrorManager errors)
        Iterator<Class> classes = table:GetClasses()
        repeat while classes:HasNext()
            Class next = classes:Next()
            next:ResolveUseStatements(table, errors)
        end
        classes = table:GetClasses()
        repeat while classes:HasNext()
            Class next = classes:Next()
            //because of the way the parent flattening algorithm works,
            //classes may already be resolved
            if not next:IsResolved()
                next:ResolveAllTypes(table, errors)
            end
        end
        classes = table:GetClasses()
        repeat while classes:HasNext()
            Class next = classes:Next()
            next:ComputeVirtualActionTable(errors)
            next:ComputeGenericsTables(errors)
            types:Add(next)
        end
    end

Feature Vector: F1:5, F2:ResolveAllTypes(), F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: not identified as method name not listed in action identification table

\\ Repo → Quorum3 → SourceCode → Compiler.quorum
\\ 5. Line No: 1784-1792
      private action ResolveQualifiedNames(
            SymbolTable table, 
            Iterator<QualifiedName> names, 
            HashTable<text, File> parsed,
            HashTable<text, File> unparsed, Class clazz)
        repeat while names:HasNext()
            QualifiedName qn = names:Next()
            if qn:IsAll()
                ResolveAllClassesInContainer(table, qn, parsed, unparsed, clazz)
            else
                text key = qn:GetStaticKey()
                ResolveClass(table, key, clazz, parsed, unparsed)
            end
        end
    end

Feature Vector: F1:4, F2:ResolveClass(), F3:0, F4:1, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: Not identified as method name not listed in action identification table
\\ Xiaoran's answer:
\\ vector: 4, method name, 0,1,0,0,0,2 action: not identified

\\ Repo → Quorum3 → SourceCode → Compiler.quorum
\\ 6. Line no: 1834-1841
      private action GetStandardLibraryFolderForPackage(text key) returns File
        if standardLibraryFolder = undefined
            File build
            build:SetPath(DEFAULT_STANDARD_LIBRARY_FOLDER)
            standardLibraryFolder = build
        end
        text loc = standardLibraryFolder:GetWorkingDirectory()
        text loc2 = standardLibraryFolder:GetAbsolutePath()
        File file
        file:SetWorkingDirectory(loc2)
        Array<text> values = key:Split("\.")
        text location = "/"
        Iterator<text> it = values:GetIterator()
        repeat while it:HasNext()
            text next = it:Next()
            location = location + next
            if it:HasNext()
                location = location + "/"
            end
        end
        file:SetPath(location)
        if file:Exists()
            return file
        end
        return undefined
    end

Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: Not identified(no entry in action identification table)
\\ Xiaoran's answer: 
\\ vector: 1,0,0,2,0,0,0,2 action: not identified

\\ Repo-> Quorum3 -> SourceCode -> Action.quorum
\\ 7. Line no.- 108-122
      action GetCodeCompletionItem(Variable variable) returns CodeCompletionItem
        ...
        text signature = GetStaticKey()        
        Iterator<Variable> variables = GetParameterIterator()
        text result = "("
        integer i = 0
        repeat while variables:HasNext()
            Variable param = variables:Next()
            Type type = param:GetType()
            text typeKey = ""
            text key = param:GetStaticKey()
            text name = param:GetName()
            typeKey = GetTypeName(type, variable)
            text value = typeKey + " " + name
            result = result + value
            if variables:HasNext()
                result = result + ", "
            end
            i = i + 1
        end
        result = result + ")"
        Type returnType = GetReturnType()
        //if the return type is void, ignore it. Otherwise, include it
        if not returnType:IsVoid()
            item:rightDisplayText = GetTypeName(returnType, variable)
        end
        ...
    end


Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: Not identified(no entry in action identification table)

\\ Repo-> Quorum3 -> SourceCode -> ActionOpcode.quorum
\\ 8. Line no.- 163-175 
      action WriteParameterDebuggingTable(JavaBytecodeLabel start, JavaBytecodeLabel finish)
        //now get all the variables in this block and write the debugging
        //table
        JavaBytecodeMethodWriter writer = GetMethodWriter()
        Iterator<Variable> variables = method:GetParameterIterator()
        repeat while variables:HasNext()
            Variable variable = variables:Next()
            if not variable:IsField() and variable:IsVisibleToDebugger()
                Type type = variable:GetType()
                text description = type:ConvertTypeToBytecodeSignatureInterface()
                text signature = type:ConvertTypeToBytecodeSignatureInterface()
                integer location = variable:GetBytecodeLocation()
                writer:VisitLocalVariable(variable:GetName(), description,
                    signature, start, finish, location)
            end
        end
        writer:VisitLocalVariable("this", clazz:ConvertStaticKeyToBytecodePathTypeName(),
                    clazz:ConvertStaticKeyToBytecodePathTypeName(), start, finish, 0)
    end

Feature Vector: F1:5, F2:VisitLocalVariable(), F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: Not identified(as method name not listed in action identification model)
\\ Question: Do we deal with loop-ifs like this where we have more than one ending statements of if block?
\\ Answer: We consider last statement.

\\ Repo-> Quorum3 -> SourceCode -> ActionOpcode.quorum
\\ 9. Line no.- 163-175 
      action WriteJavaScript returns text
        text result = "this." + method:ConvertActionToJavaScriptName() + " = function "  + "("
        Iterator<Variable> parameters = method:GetParameterIterator()
        integer position = 1
        repeat while parameters:HasNext()
            Variable param = parameters:Next()
            result = result + param:GetName()
            if parameters:HasNext()
                result = result + ", "
            end
        end
        result = result + ") {
"
        Iterator<QuorumOpcode> iterator = opcodeList:GetIterator()
        repeat while iterator:HasNext()
            QuorumOpcode opcode = iterator:Next()
            result = result + opcode:WriteJavaScript()
        end
        result = result + "};
"
        return result
    end

Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: Not identified(no entry in action identification table)

\\ Repo-> Quorum3 -> SourceCode -> Class.quorum
\\ 10. Line no.- 292-299
      action GetGenericList returns text
        text value = ""        
        i = 0
        repeat GetNumberGenerics() times
            if i = 0
                value = value + GetGeneric(i)
            else 
                value = value + ", " + GetGeneric(i)
            end
            i = i + 1
        end
        return value
      end

Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: Not identified (no entry in action identification table)
\\ Very close to find except that F5 is 0, not 1,2 or 4. 

\\ Repo-> Quorum3 -> SourceCode -> Class.quorum
\\ 11. Line no.- 850-870
      private action ResolveActions(SymbolTable table, CompilerErrorManager errors)
        Iterator<Action> actionIterator = me:GetActions()
        Array<Action> temp
        repeat while actionIterator:HasNext()
            Action next = actionIterator:Next()
            temp:Add(next)
            //first, we resolve the parameters
            Iterator<Variable> parameters = next:GetParameterIterator()
            repeat while parameters:HasNext()
                Variable param = parameters:Next()
                ResolveParameterType(param, param:GetType(), table, errors)
            end
            Type returnType = next:GetReturnType()
            if not returnType:IsVoid()
                ResolveParameterType(next, returnType, table, errors)
            end
            //next we resolve all of the variables in its blocks
            if next:GetBlock() not= undefined
                ResolveBlock(next:GetBlock(), table, errors)
            end
        end

Question: Do we consider repeat with multiple ifs inside and analyze the last if only?
\\ Answer: We only consider loops with one if and the if is also the last statement in the loop. 
\\ Loop discarded

\\ Repo-> Quorum3 -> SourceCode -> Class.quorum
\\ 12. Line no.- 883-889
      private action ResolveActions(SymbolTable table, CompilerErrorManager errors)
        Iterator<Action> actionIterator = me:GetActions()
        Array<Action> temp
        ...
        repeat while actionIterator:HasNext()
            Action next = actionIterator:Next()
            CompilerError error = Add(next)
            if error not= undefined
                errors:Add(error)
            end
        end
    end

Feature Vector: F1:5, F2:1, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: get
\\ Need to discuss if that is the correct action identified, according to me, it should be add if F2:2

\\ Repo-> Quorum3 -> SourceCode -> Class.quorum
\\ 13. Line no.- 894-900
      action ResolveFrames
        Iterator<Action> actionIterator = me:GetActions()
        repeat while actionIterator:HasNext()
            Action next = actionIterator:Next()
            if not next:IsSystem() and not next:IsBlueprint()
                Block b = next:GetBlock()
                b:AssignBytecodeLocations()
            end
        end
        if constructor not= undefined
            Block b = constructor:GetBlock()
            b:AssignBytecodeLocations()
        end
    end

Feature Vector: F1:5, F2:AssignBytecodeLocations(), F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: not identified
\\ Ques- multiple ending statements in if-block.
\\ Ans: We consider only the last statement.

\\ Repo-> Quorum3 -> SourceCode -> Class.quorum
\\ 14. Line no.- 1307-1314
      action ResolveParents(SymbolTable table, CompilerErrorManager errors)
        isResolvingParents = true
        Iterator<QualifiedName> names = GetUnresolvedParents()
        repeat while names:HasNext()
            QualifiedName name = names:Next()
            Class myParent = GetClass(name:GetStaticKey(), table, errors)
            if myParent not= undefined //if it is defined, add it as a valid parent
                parents:Add(myParent:GetStaticKey(), myParent)
            end //if it is not, ignore it, as an error has already been issued
        end
      ...
      end  

Feature Vector: F1:5, F2:1, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: get
\\ Need to discuss if that is the correct action identified, according to me, it should be add if F2:2
\\ Xiaoran's answer: 
\\ vector: 5,1,0,2,0,0,0,2 action: get

\\ Repo-> Quorum3 -> SourceCode -> Class.quorum
\\ 15. Line no.- 1789-1802
        Array<Action> finalMatches
        integer minPoints = 0
        minPoints = minPoints:GetMaximumValue()
        i = 0
        repeat matches:GetSize() times
            Action act = matches:Get(i)
            integer points = scores:Get(i)
            
            if points < minPoints
                minPoints = points
                finalMatches:Empty()
                finalMatches:Add(act)
            elseif points = minPoints
                finalMatches:Add(act)
            end
            i = i + 1
        end

Feature Vector: F1:5, F2:2, F3:0, F4:2, F5:0, F6:0, F7:0, F8:1 (as we consider only the if loop and it's last statement)
\\ Action Identified: add
\\ Xiaoran's answer:
\\ vector: 5,1,0,2,0,0,0,1 action: get
\\ Note: the last statement is i=i+1, not an if. It seems that this is the syntax of loop updater in Quorum.

\\ Repo-> Quorum3 -> SourceCode -> ClassOpcode.quorum
\\ 16. Line no.- 188-204
           Iterator<ActionOpcode> actionIterator = actions:GetIterator()
        repeat while actionIterator:HasNext()
            ActionOpcode act = actionIterator:Next()
            Action method = act:GetAction()
            act:Write()
            if not clazz:IsError()
                //write to the interface
                text name = method:GetName()
                text params = method:ConvertActionToBytecodeParameterInterfaceSignature()
                JavaBytecodeMethodWriter interfaceMethodWriter = 
                    interfaceWriter:VisitMethod(opcodes:GetPublic() + opcodes:GetAbstract(), 
                    name, params, null, undefined)
                interfaceMethodWriter:VisitEnd()
            end
        end

Feature Vector: F1:5, F2:VisitEnd(), F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: cannot be determined as method name not listed in action identification table

\\ Repo-> Quorum3 -> SourceCode -> ClassOpcode.quorum
\\ 17. Line no.- 207-213
           Iterator<Action> it = clazz:GetParentActions()
        repeat while it:HasNext()
            Action act = it:Next()
            Class parentOfMethod = act:GetParentClass()
            if not parentOfMethod:IsError() or clazz:GetStaticKey() = QUORUM_LIBRARY_LANGUAGE_ERRORS_ERROR
                WriteParentActionBytecode(act)
            end
        end


Feature Vector: F1:4, F2:WriteParentActionBytecode(), F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: cannot be determined as method name not listed in action identification table

\\ Repo-> Quorum3 -> SourceCode -> ClassOpcode.quorum
\\ 18. Line no.- 229-263
        private action WriteParentGetActions
        Iterator<Class> parents = clazz:GetParentClasses()
        text classBytecodeName = converter:ConvertStaticKeyToBytecodePath(staticKey)
        //initialize all of the parent objects as fields
        repeat while parents:HasNext()
            Class p = parents:Next()
            text parentKey = p:GetStaticKey()
            if parentKey not= QUORUM_LIBRARY_LANGUAGE_ERRORS_ERROR
                text parentName = p:ConvertStaticKeyToParentFieldName()
                text converted = p:ConvertStaticKeyToBytecodePath()
                text convertedParentNameType = p:ConvertStaticKeyToBytecodePathTypeName()
                text parentActionName = p:ConvertStaticKeyToParentActionName()
                text null = undefined
                JavaBytecodeMethodWriter parentWriter = classWriter:VisitMethod(opcodes:GetPublic(), 
                    parentActionName, "()" + p:ConvertStaticKeyToBytecodePathTypeName(), null, undefined)
                parentWriter:VisitCode()
                //load the ME pointer
                parentWriter:VisitVariable(opcodes:GetObjectLoad(), ME)
                //load the parent variable
                parentWriter:VisitField(opcodes:GetField(), 
                    clazz:ConvertStaticKeyToBytecodePath(),
                    p:ConvertStaticKeyToParentFieldName(),
                    p:ConvertStaticKeyToBytecodePathTypeName())
                //return the parent variable
                parentWriter:VisitInstruction(opcodes:GetObjectReturn())
                parentWriter:VisitMaxSize(0,0)
                parentWriter:VisitEnd()
                JavaBytecodeMethodWriter parentWriterInterface = interfaceWriter:VisitMethod(opcodes:GetPublic()+ opcodes:GetAbstract(), 
                    parentActionName, "()" + p:ConvertStaticKeyToBytecodePathTypeName(), null, undefined)
                    parentWriterInterface:VisitEnd()
            end
        end


Feature Vector: F1:5, F2:VisitEnd(), F3:0, F4:0, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: cannot be determined as method name not listed in action identification table


\\ Repo-> Quorum3 -> SourceCode -> ClassOpcode.quorum
\\ 19. Line no.- 674-697
       private action WriteParents(JavaBytecodeMethodWriter methodWriter)
        Iterator<Class> parents = clazz:GetParentClasses()
        text classBytecodeName = converter:ConvertStaticKeyToBytecodePath(staticKey)
        //initialize all of the parent objects as fields
        repeat while parents:HasNext()
            Class p = parents:Next()
            text parentKey = p:GetStaticKey()
            if parentKey not= QUORUM_LIBRARY_LANGUAGE_ERRORS_ERROR
                text parentName = p:ConvertStaticKeyToParentFieldName()
                text converted = p:ConvertStaticKeyToBytecodePath()
                text convertedParentNameType = p:ConvertStaticKeyToBytecodePathTypeName()
                methodWriter:VisitVariable(opcodes:GetObjectLoad(), ME)
                methodWriter:VisitType(opcodes:GetNew(), converted)
                methodWriter:VisitInstruction(opcodes:GetDuplicate())
                //push false on the parents and call a separate constructor
                methodWriter:VisitInstruction(opcodes:GetIntegerZero())
                methodWriter:VisitMethodInvoke(opcodes:GetInvokeSpecial(), converted, CONSTRUCTOR_JAVA_NAME, "(Z)V", false)
                methodWriter:VisitField(opcodes:GetPutField(), classBytecodeName, parentName, convertedParentNameType)
                text convertedHiddenType = p:ConvertStaticKeyToBytecodePathTypeNameInterface()
                methodWriter:VisitVariable(opcodes:GetObjectLoad(), ME)
                methodWriter:VisitField(opcodes:GetGetField(), clazz:ConvertStaticKeyToBytecodePath(), parentName, p:ConvertStaticKeyToBytecodePathTypeName())
                methodWriter:VisitVariable(opcodes:GetObjectLoad(), ME)
                methodWriter:VisitField(opcodes:GetPutField(), converted, p:GetHiddenVariableName(), convertedHiddenType)
            end
        end

Feature Vector: F1:5, F2: , F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: cannot be determined
\\ Question- Do we deal with nested method calls, like the method call as argument of another method call?What name of method call should we select in this case?
\\ Answer:If the parameter of a method invocation is another method invocation, we only consider the out-most level of method call. The verb is "visit" in this particular example. 

\\ Repo-> Quorum3 -> SourceCode -> CompilerProfiler.quorum
\\ 20. Line no.- 85-97
       action OutputTimes
        i = 0
        number start = 0
        number previous = 0
        repeat timing:GetSize() times
            number value = timing:Get(i)
            if i = 0
                output START_TIME_NAME + ": 0" 
                start = value
                previous = start
            else
                name = phaseHash:GetValue(i)
                output name + ": " + (value - previous)
                previous = value
            end
            i = i + 1
        end
    end

Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: not identified as corresponding entry not found in action identification table

\\ Repo-> Quorum3 -> SourceCode -> QualifiedName.quorum
\\ 21. Line no.- 61-68
        action GetStaticKey returns text
        key = ""
        i = 0
        repeat GetSize() times
            key = key + names:Get(i)
            if i < GetSize() - 1
                key = key + "."
            end
            i = i + 1
        end
        return key
    end

Feature Vector: F1:1, F2:0, F3:0, F4:0, F5:0, F6:0, F7:0, F8:1
\\ Action Identified: not identified
\\ Xiaoran's answer:
\\ vector: 1,0,0,2,0,0,0,1 action: not identified. This is very close to be action find, except that F5 is 0, not 1,2 or 4.

\\ Repo-> Quorum3 -> SourceCode -> QuorumByteCodeListener.quorum
\\ 22. Line no.- 1962-1974
       private action ComputeFinalParameters(Array<QuorumOpcode> parameterOpcodes, 
        Array<QuorumOpcode> conversions) returns Array<QuorumOpcode>
        //handle any casts, if there are any
        Array<QuorumOpcode> finalResolvedParameters
        integer next = 0
        repeat parameterOpcodes:GetSize() times
            QuorumOpcode previous = parameterOpcodes:Get(next)
            QuorumOpcode possibleCast = conversions:Get(next)
            if possibleCast not= undefined
                ExplicitCastOpcode caster = cast(ExplicitCastOpcode, possibleCast)
                caster:SetMethodWriter(methodWriter)
                caster:SetOpcodeToCast(previous)
                finalResolvedParameters:Add(caster)
            else //nothing to do with this opcode, just push it
                finalResolvedParameters:Add(previous)
            end
            next = next + 1
        end
        return finalResolvedParameters
    end

Feature Vector: F1:5, F2:2, F3:0, F4:2, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: add
\\ Xiaoran's answer: 
\\ vector: 5,1,0,2,0,0,0,2 action: get
\\ Completed looking for all loop-ifs in Repo-> Quorum3 -> SourceCode ->

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> Array.quorum
\\ 23. Line no.- 470-476
      action Has(Type value) returns boolean
        integer count = 0
        integer size = GetSize()
        repeat while count < size
            Type item = Get(count)
            if value:Equals(item)
                return true
            end
            count = count + 1
        end
        return false
    end

Feature Vector: F1:0, F2:0, F3:0, F4:0, F5:3, F6:0, F7:0, F8:2
\\ Action Identified: determine

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> Array.quorum
\\ 24. Line no.- 500-507
       action Remove(Type value) returns boolean
        integer count = 0
        integer size = GetSize()
        repeat while count < size
            Type item = Get(count)
            if value:Equals(item)
                RemoveAt(count)
                return true
            end
            count = count + 1
        end
        return false
    end

Feature Vector: F1:4, F2:5, F3:0, F4:1, F5:3, F6:0, F7:0, F8:2
\\ Action Identified: could not be identified
** \\ Note - This action should have been very easily identified as remove , need to discuss **
\\ Xiaoran's answer:
\\ action: 4,5,0,1,3,0,0,2 action: not identified
* we do not recognize cases when the last statement is method invocation.  

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> Array.quorum
\\ 25. Line no.- 532-541
      action RemoveAll(Type value) returns boolean
        boolean hasRemoved = false
        integer count = 0
        integer size = GetSize()
        repeat while count < size
            Type item = Get(count)
            if value:Equals(item)
                RemoveAt(count)
                hasRemoved = true
                size = size - 1
            else
                count = count + 1
            end
        end
        return hasRemoved
    end

Feature Vector: F1:1, F2:0, F3:0, F4:1, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: could not be identified (Should have been identified as remove)

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> HashTable.quorum
\\ 26. Line no.- 82-87
        action GetValue(Key key) returns Value
        integer index = ComputeIndex(key)
        HashNode<Key, Value> node = array:Get(index)
        if node = undefined or key = undefined
            return undefined
        end 
        if key:Equals(node:key)
            return node:value
        end
        HashNode<Key, Value> temp = node:next
        repeat while temp not= undefined
            if key:Equals(temp:key)
                return temp:value
            end
            temp = temp:next
        end
        return undefined
    end

Feature Vector: F1:0, F2:0, F3:0, F4:1, F5:4, F6:0, F7:0, F8:2
\\ Action Identified: find

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> HashTable.quorum
\\ 27. Line no.- 490-495
       action HasKey(Key key) returns boolean
        integer index = ComputeIndex(key)
        HashNode<Key, Value> node = array:Get(index)
        if node = undefined or key = undefined
            return false
        end 
        if key:Equals(node:key)
            return true
        end
        HashNode<Key, Value> temp = node:next
        repeat while temp not= undefined
            if key:Equals(temp:key)
                return true
            end
            temp = temp:next
        end
        return false
    end


Feature Vector: F1:0, F2:0, F3:0, F4:0, F5:3, F6:0, F7:0, F8:2
\\ Action Identified: determine
\\ Xiaoran's answer:
\\ vector: 0,0,0,0,3,0,0,2 action: determine

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> List.quorum
\\ 28. Line no.- 254-263
        action GetFirstLocation(Type value) returns integer
        boolean found = false
        integer i = 0
        ListNode<Type> current = head
        repeat while current not= undefined
            Type type = current:value
            if value:Equals(type)
                current = undefined
                found = true
            else
                current = current:next
                i = i + 1
            end
        end
        if found
            return i
        else
            return invalidIndex
        end
    end

Feature Vector: F1:6, F2:0, F3:0, F4:0, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: determine

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> List.quorum
\\ 29. Line no.- 292-301
       action GetLastLocation(Type value) returns integer
        boolean found = false
        integer i = size - 1
        ListNode<Type> current = tail
        repeat while current not= undefined
            Type type = current:value
            if value:Equals(type)
                current = undefined
                found = true
            else
                current = current:previous
                i = i - 1
            end
        end
        if found 
            return i
        else
            return invalidIndex
        end
    end

Feature Vector: F1:6, F2:0, F3:0, F4:0, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: determine (Same as last one)

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> List.quorum
\\ 30. Line no.- 405-411
    action Has(Type value) returns boolean
        ListNode<Type> current = head
        repeat while current not= undefined
            Type type = current:value
            if value:Equals(type)
                return true
            end
            current = current:next
        end
        return false
    end

Feature Vector: F1:0, F2:0, F3:0, F4:0, F5:3, F6:0, F7:0, F8:2
\\ Action Identified: determine

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> List.quorum
\\ 31. Line no.- 448-455
        action Remove(Type value) returns boolean
        ListNode<Type> current = head
        repeat while current not= undefined
            Type type = current:value
            if value:Equals(type)
                RemoveNode(current)
                return true
            end
            current = current:next
        end
        return false
    end

Feature Vector: F1:5, F2:5, F3:0, F4:1, F5:3, F6:0, F7:0, F8:2
\\ Action Identified: not identified
** \\ Should have been identified as remove **
\\ Same for the following code:
       action RemoveAll(Type value) returns boolean
        ListNode<Type> current = head
        boolean wasRemoved = false
        repeat while current not= undefined
            Type type = current:value
            if value:Equals(type)
                RemoveNode(current)
                wasRemoved = true
            end
            current = current:next
        end
        return wasRemoved
    end

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> List.quorum
\\ 32. Line no.- 532-543
       private action GetFirstNode(Type value) returns ListNode<Type>
        boolean found = false
        integer i = 0
        ListNode<Type> current = head
        ListNode<Type> result = undefined
        repeat while current not= undefined
            Type type = current:value
            integer hash = type:GetHashCode()
            if value:GetHashCode() = hash
                result = current
                current = undefined
                found = true
            else
                current = current:next
                i = i + 1
            end
        end
        if found
            return result
        else
            return undefined
        end
    end

Feature Vector: F1:6, F2:0, F3:0, F4:0, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: determine

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> Support -> HashTableIterator.quorum
\\ 33. Line no.- 34-41
        private action GoToNextNode
        if node not= undefined
            node = node:next
        end
        if node not= undefined
            return now //we've found the next one
        else 
            position = position + 1
        end
        //the current one still needs to be found, it's currently undefined
        repeat while position < array:GetSize()
            HashNode<Key, Value> newNode = array:Get(position)
            if newNode not= undefined
                node = newNode
                return now //we're finished searching
            end
            position = position + 1
        end
    end


Feature Vector: F1:1, F2:0, F3:0, F4:2, F5:4, F6:0, F7:0, F8:2
\\ Action Identified: find
\\ Xiaoran's answer:
\\ vector: 1,0,0,2,4,0,0,2 action: find

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> Table.quorum
\\ 34. Line no.- 595-602
       action Has(Type value) returns boolean
        integer count = 0
        integer size = table:GetSize()
        repeat while count < size
            Array<Type> item = table:Get(count)
            if item:Has(value)
                return true
            end
            count = count + 1
        end
        return false
    end

Feature Vector: F1:0, F2:0, F3:0, F4:0, F5:3, F6:0, F7:0, F8:2
\\ Action Identified: determine


\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Containers -> Table.quorum
\\ 35. Line no.- 625-632
        action Remove(Type value) returns boolean
        integer count = 0
        integer size = table:GetSize()
        repeat while count < size
            Array<Type> item = table:Get(count)
            boolean removedItem = item:Remove(value)
            if removedItem
                return true
            end
            count = count + 1
        end
        return false
    end

Feature Vector: F1:0, F2:0, F3:0, F4:0, F5:3, F6:0, F7:0, F8:2
\\ Action Identified: determine
\\ Xiaoran's answer:
\\ vector: 0,0,0,0, 3,0,0,2 action: determine
\\ *the action is identified based on the model table. However, if we understand the code, the action is not correct. The reason the model can not get this action correct is that such situations in Java do not happen often. It may not occur often in Quorum either.

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Data -> Formats -> DocumentTypeDefinition.quorum
\\ 36. Line no.- 161-167
        public action GetEntityValue(text name) returns text
        Iterator<DocumentTypeDefinitionEntity> els = entities:GetIterator()
        DocumentTypeDefinitionEntity e
        repeat while els:HasNext()
            e = els:Next()
            entityName = e:GetName()
            if entityName:Equals(name)
                return e:GetValue()
            end
        end     
        return name
    end

Feature Vector: F1:5, F2:GetValue(), F3:0, F4:2, F5:4, F6:0, F7:0, F8:2
\\ Action Identified: not identified as method name not listed in action identification table.


\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Games -> Interface -> Panel.quorum
\\ 37. Line no.- 110-116
       action ItemAtPoint(number x, number y) returns Item
        integer index = items:GetSize() - 1
        Item temp = undefined
        repeat items:GetSize() times
            temp = items:Get(index)
            if temp:GetX() <= x and temp:GetX() + temp:GetWidth() >= x and temp:GetY() <= y and temp:GetY() + temp:GetHeight() >= y
                return temp
            end
            index = index - 1
        end
        return undefined
    end

Feature Vector: F1:0, F2:0, F3:0, F4:2, F5:4, F6:0, F7:1, F8:1
\\ Action Identified: find

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Games -> Keys.quorum
\\ 38. Line no.- 494-499
    action InitializeKeyNames
        integer index = 0
        repeat while index < 256
            text name = ToText(index)
            if name not= undefined
                keyNames:put(index, index)
            end
        end
    end

Feature Vector: F1:5, F2:3, F3:0, F4:1, F5:0, F6:0, F7:0, F8:2
\\ Action Identified: not identified
** Should be identified as something like add **
\\ Xiaoran's answer:
\\ vector: 5,3,0,1,0,0,0,2 action: not identified

** \\ Question to ask Xiaoran**- do we consider loops with both if and else, or only loops with single if(which is the also the last lexical statement of the block). If we consider loops with if and else, then which ending statement to consider- if's or else's?
\\ Answer: We consider loop-ifs with both if and else blocks, but to determine the action, we only consider the last statement in if block.

\\ Repo-> Quorum3 -> Library -> Standard -> Libraries-> Language -> Types -> Text.quorum
\\ 39. Line no.- 580-619
\\ Complex example, we can only take the last statement of if, but our model might not work too well.
     action Split(text delimiter) returns Array<text>
        // TODO: Rewrite this. it is horrid. There are much more clever ways to do this.
	Array<text> results
	integer pos = 0
	integer length = me:GetSize()
	Text delim
        delim:SetValue(delimiter)
	integer delimLength = delim:GetSize()
	text newString = ""
        boolean afterDelim = false
	repeat while pos < length
            // If this doesn't start the delimiter, add it to the new string.
            if me:GetCharacter(pos) not= delim:GetCharacter(0)
                newString = newString + me:GetCharacter(pos)
                pos = pos + 1
                afterDelim = false
            else
                // Matches start of delimiter. Keep track and bail if we don't match the delimiter
                text tmpString = ""
                integer delimPos = 0
                text currentChar = me:GetCharacter(pos)
                text currentDelimChar = delim:GetCharacter(0)
                // As long as the values read continue to match the delimiter...
                repeat while delimPos < delimLength and currentChar = currentDelimChar and pos < length
                    tmpString = tmpString + me:GetCharacter(pos)
                    delimPos = delimPos + 1 // keep going through delimiter
                    pos = pos + 1 // and keep moving ahead in main string                    
                    if pos < length
                        currentChar = me:GetCharacter(pos)
                    end
                    if delimPos < delimLength
                        currentDelimChar = delim:GetCharacter(delimPos)
                    end
                end
                if delimPos not= delimLength
                    // We didn't reach the end of the delimiter, so add this temporary string and keep moving.
                    tmpString = tmpString + newString
                    afterDelim = false
                else
                    // Delimiter hit. Store the result.
                    results:Add(newString)
                    newString = ""  
                    afterDelim = true
                end
            end
	end
  ...
  end

\\ Completed searching loop-ifs till Repo-> Quorum3 -> Library -> Standard -> Libraries
\\ Sent 10 loop-ifs to Xiaoran for evaluation.

**Manual Loop Extraction Report**
\\ 1. Identified 37 loop-ifs from Quorum language repository.
\\ 2. Actions were identified for 17 loop-ifs, after mapping the feature vectors with the existent action identification model.
\\ 3. Details of actions identified: find(4 loop-ifs-Sample loop no.s - 1,26,33,37) + get(5 loop-ifs-Sample loop no.s - 2,12,14,15,22) + determine(8 loop-ifs-Sample loop no.s - 23,27,28,29,30,32,34,35). Only these 3 actions were identified.
\\ 4. 20 loop-ifs could not be identified: Could not be identified as no corresponding entry found in the action identification model(11 loop-ifs) + could not be identified as last statement of if block was method call, and the method name was not listed in the action identification model(9 loop-ifs-Sample loop no.s - 4,5,8,13,16,17,18,19,36).
\\ 5. Out of the 11 loop-ifs which could not be identified as no corresponding entry found in the action identification model - a few were very close to identifying action find(Sample loop no.s - 3,10,21)
\\ 6. Out of the 17 loop-ifs identified action, one is identified wrong(Loop no-35), it should have been action remove.
\\ 7. Also, one of the issues which I think is very important, is that, all the loop-ifs which should be identified as add, are getting identified as get(Sample loop no- 2,12,14,15,22). This is because, according to Xiaoran this loops should have F2=1 , whereas I thought it should be F2=2. Had it been identified as F2=2, then the feature vector corresponds to the correct action(add) from the action identification model.
\\ Spoke to Xiaoran, he says it is just the label, get-actually means add.(Previously get and add were named as add1 and add2, later to avoid confusion one is labelled as get)
**Not sure how to handle this. Should I just consider those as get(s) and move on? Need your input.Please let me know if you need further details about manual extraction process**
\\ Note: Loop no.s sent to Xiaoran for evaluation - 5,6,14,15,21,22,24,27,33,35,38. All details of his comments and mine are documented above for reference.

** COMPILER AND AST **
\\ Reply of Dr. Stefik on Quorum Compiler in a private list(Google group):
\\ The compiler has changed a lot in the last year and we haven't posted documentation on how to use it yet, largely because our  official release date isn't until June 30th (12 days).
That said, since this is a private list, here's the easiest way to build it (I am writing the instructions soon anyway):
\\ 1. Download NetBeans 8.02 or later from Oracle and the latest of JDK 8
\\ 2. Go to Tools -> Plugins. Under settings, add the following as an update center:
http://quorumlanguage.com/updates/quorum/updates.xml 
\\ 3. This will give you access to two plugins, Quorum 3 and Accessibility. 
\\ 4. Restart NetBeans and you should be able to open/create Quorum projects. 

The compiler is in a separate project, not the standard library, but can be found here: https://bitbucket.org/stefika/quorum-language under the folder Quorum3.
\\ 5. If you grabbed the compiler, you should be able to click Build and it will work as expected. 
\\ Now, if you have the compiler, you can use the Compiler class to build source, or you can make your own QuorumSourceListener subclass and then do what you want in processing source. Finally, if you just can't get any of that to work, you can always copy the Antlr grammar for Quorum directly and then tweak it to your heart's content. That is located here: 
\\ https://bitbucket.org/stefika/quorum-language/src/269c256f6cd4f8b85d1c850d0f3098a10335fe62/plugins/ParserPlugin/src/plugins/quorum/Libraries/Language/Compile/Quorum.g4?at=master

HTH,
Stefik

\\ My updates on compiler and AST:
\\ Successfully followed steps 1-5.
\\ Compiler class is to be found at(no idea how to build source with it) : 
/Users/preethac/Desktop/Research/Summer Project 2015/Quorum_Repo_New/Quorum3/Build/quorum/Libraries/Language/ and not visible from Sodbeans(IDE for Quorum).
\\ Class QuorumSourceListener is to be found in file "QuorumSourceListener.quorum"
\\ Also no clear instructions given on how to run Quorum from cmd(tried installing but failed), so trying to run the whole compiler project from Sodbeans only and figure out the flow(working on it now). Quorum3 folder is the whole compiler project.

\\ Preethas-MacBook-Pro:SourceCode preethac$ grep "class QuorumSourceListener" *.quorum
\\ QuorumSourceListener.quorum:class QuorumSourceListener
\\ \\ Preethas-MacBook-Pro:SourceCode preethac$ grep QuorumSourceListener *.quorum
\\ Compiler.quorum:    private action ParseSandbox(text source, QuorumSourceListener listener, SymbolTable table, CompilerErrorManager errors,
\\ Compiler.quorum:    action Parse(File file, QuorumSourceListener listener)
\\ Compiler.quorum:    private system action ParseNative(File file, QuorumSourceListener listener)
\\ Compiler.quorum:    action Parse(text source, QuorumSourceListener listener)
\\ Compiler.quorum:    private system action ParseNative(text source, QuorumSourceListener listener)
\\ Parser.quorum:class Parser is QuorumSourceListener
\\ QuorumBytecodeListener.quorum:class QuorumBytecodeListener is QuorumSourceListener 
\\ QuorumJavascriptListener.quorum:class QuorumJavascriptListener is QuorumSourceListener
\\ QuorumSourceListener.quorum:class QuorumSourceListener
\\ TypeCheckListener.quorum:class TypeCheckListener is QuorumSourceListener

Examining useful(what I think) pieces of code:
\\ Compiler.quorum(line no-2121-2139) at https://bitbucket.org/stefika/quorum-language/src/caf90e22e4f17863ee3d4a6a0aa9a2f669856bef/Quorum3/SourceCode/Compiler.quorum?at=master:
      action Parse(File file, QuorumSourceListener listener)
        listener:SetSymbolTable(symbolTable)
        listener:SetCompilerErrorManager(compilerErrorManager)
        listener:SetFile(file)
        listener:SetTypeChecker(checker)
        ParseNative(file, listener)
    end

    private system action ParseNative(File file, QuorumSourceListener listener)


    action Parse(text source, QuorumSourceListener listener)
        listener:SetSymbolTable(symbolTable)
        listener:SetCompilerErrorManager(compilerErrorManager)
        listener:SetTypeChecker(checker)
        ParseNative(source, listener)
    end

    private system action ParseNative(text source, QuorumSourceListener listener)

QuorumSourceListener.quorum at https://bitbucket.org/stefika/quorum-language/src/caf90e22e4f17863ee3d4a6a0aa9a2f669856bef/Quorum3/SourceCode/QuorumSourceListener.quorum?at=master

Parser.quorum at https://bitbucket.org/stefika/quorum-language/src/caf90e22e4f17863ee3d4a6a0aa9a2f669856bef/Quorum3/SourceCode/Parser.quorum?at=master

Parser related .class files at : /Users/preethac/Desktop/Research/Summer Project 2015/Quorum_Repo_New/Quorum3/Library/Standard/Plugins/org/antlr/v4 (for my reference)
\\ or, in general at: https://bitbucket.org/stefika/quorum-language/src/caf90e22e4f17863ee3d4a6a0aa9a2f669856bef/Quorum3/Library/Standard/Plugins/org/antlr/v4/runtime/?at=master

\\ Antlr grammar for Quorum :
\\ https://bitbucket.org/stefika/quorum-language/src/269c256f6cd4f8b85d1c850d0f3098a10335fe62/plugins/ParserPlugin/src/plugins/quorum/Libraries/Language/Compile/Quorum.g4?at=master

\\ When tried running this grammar in Antlr, got the following errors(not able to figure out the errors yet):
   Preethas-MacBook-Pro:tmp preethac$ antlr4 Quorum.g4
   warning(155): Quorum.g4:317:32: rule NEWLINE contains a lexer command with an unrecognized constant value; lexer interpreter may  produce incorrect output
   warning(155): Quorum.g4:318:38: rule WS contains a lexer command with an unrecognized constant value; lexer interpreters may produce incorrect output
   warning(155): Quorum.g4:322:34: rule COMMENTS contains a lexer command with an unrecognized constant value; lexer interpreters may produce incorrect output
   Preethas-MacBook-Pro:tmp preethac$ javac Quorum*.java
   QuorumParser.java:1002: error: package quorum.Libraries.Language.Compile.Context does not exist
		public quorum.Libraries.Language.Compile.Context.ActionContext actionContext;
		                                                ^
   QuorumParser.java:1150: error: package quorum.Libraries.Language.Compile does not exist
		public quorum.Libraries.Language.Compile.QualifiedName qualifiedName;
		                                        ^
   QuorumParser.java:2242: error: package quorum.Libraries.Language.Compile.Symbol does not exist
		public quorum.Libraries.Language.Compile.Symbol.Type type;
		                                               ^
   3 errors
   
   Identified these errors are results of the following lines of code in the grammar file.
   Line no:63-66
   method_shared returns [quorum.Libraries.Language.Compile.Context.ActionContext actionContext]
        :
        ACTION ID (LEFT_PAREN (formal_parameter (COMMA formal_parameter)*)? RIGHT_PAREN)? (RETURNS return_type = assignment_declaration )?
        ;

   Line no:72-76
   qualified_name returns [quorum.Libraries.Language.Compile.QualifiedName qualifiedName]
	:	ids+=ID (PERIOD ids+=ID)* 
	;
   block 	:	statement*
	;

   Line no:150-156
   assignment_declaration returns [quorum.Libraries.Language.Compile.Symbol.Type type]
	:	qualified_name generic_statement?   #GenericAssignmentDeclaration
	|	INTEGER_KEYWORD                     #IntegerAssignmentDeclaration
	|	NUMBER_KEYWORD                      #NumberAssignmentDeclaration
	|	TEXT                                #TextAssignmentDeclaration
	|	BOOLEAN_KEYWORD                     #BooleanAssignmentDeclaration
        ;

     
   Directory to be searched for the location is: 
   1.
   Desktop/Research/Summer Project 2015/Quorum_Latest/quorum/plugins/quorum/Libraries/Language/Compile/
   Tried running antlr4 from the above path, shows same error.
   Copied All directories of "quorum/Libraries/Language/Compile/..." to local directory and also Quorum.g4 in the same directory, still gives the same error.
   2.
   Desktop/Research/Summer Project 2015/Quorum_Latest/plugins/ParserPlugin/src/plugins/quorum/Libraries/Language/Compile
   Same results as above

   What does return mean in ANTLR grammar?
   Reference : http://bkiers.blogspot.com/2011/03/2-introduction-to-antlr.html
   <rule> returns [<datatype> <variablename>]
     ; ...
     ;

   Temporarily works if following changes made in grammar file(but supposedly not correct)
   method_shared returns [quorum.Libraries.Language.Compile.Context.ActionContext actionContext] made to:
   method_shared returns [ActionContext actionContext]
   
   qualified_name returns [quorum.Libraries.Language.Compile.QualifiedName qualifiedName] made to:
   qualified_name returns [String qualifiedName] 
   (as QualifiedName qualifiedName doesn't work)
   
   assignment_declaration returns [quorum.Libraries.Language.Compile.Symbol.Type type] made to:
   assignment_declaration returns [String type]
   (as Type type doesn't work)
   
   Currently experimenting on /Users/preethac/Desktop/Research/Summer Project 2015/Antlr/quorum/plugins/Quorum.g4
   
   Preethas-MacBook-Pro:plugins preethac$ grun Quorum statement -tree
   if a > 100
    c = 1
   elseif b = 100
   c = 2
   else
   c = 3
   end
   (statement (if_statement if (expression (expression (action_call a)) > (expression 100)) (block (statement (assignment_statement c = (expression 1)))) elseif (expression (expression (action_call b)) = (expression 100)) (block (statement (assignment_statement c = (expression 2)))) else (block (statement (assignment_statement c = (expression 3)))) end))
   
   Preethas-MacBook-Pro:plugins preethac$ grun Quorum loop_statement -tree
   repeat until a < 15
       a = a + 1
    end
   (loop_statement repeat until (expression (expression (action_call a)) < (expression 15)) (block (statement (assignment_statement a = (expression (expression (action_call a)) + (expression 1))))) end)
   
   Preethas-MacBook-Pro:plugins preethac$ grun Quorum statement -tree
      repeat while index < 256
          text name = ToText(index)
          if name not= undefined
              keyNames:put(index, index)
          end
      end
(statement (loop_statement repeat while (expression (expression (action_call index)) < (expression 256)) (block (statement (assignment_statement (assignment_declaration text) name = (expression (action_call ToText ( (function_expression_list (expression (action_call index))) ))))) (statement (if_statement if (expression (expression (action_call name)) not= (expression undefined)) (block (statement (solo_method_call (qualified_name keyNames) : put ( (expression (action_call index)) , (expression (action_call index)) )))) end))) end))

** Running Quorum from Console**
\\  /Users/preethac/Desktop/Research/Summer Project 2015/Quorum_Console/Quorum3
    Preethas-MacBook-Pro:Quorum3 preethac$ ls -lrt
    total 4336
    -rwxr-xr-x@ 1 preethac  staff  2212531 Jun 30 11:18 Quorum.jar
    drwxr-xr-x@ 5 preethac  staff      170 Jul  4 19:55 Library 
    -rw-r--r--  1 preethac  staff       15 Jul  6 22:27 Hello.quorum
    drwxr-xr-x  3 preethac  staff      102 Jul  6 22:28 Run
    drwxr-xr-x  3 preethac  staff      102 Jul  6 22:28 Build
    
    Preethas-MacBook-Pro:Quorum3 preethac$ java -jar Quorum.jar -name MyProgram -compile Hello.quorum
    Quorum 3.0
    Build Successful
    
    Preethas-MacBook-Pro:Run preethac$ pwd
    /Users/preethac/Desktop/Research/Summer Project 2015/Quorum_Console/Quorum3/Run
    
    Preethas-MacBook-Pro:Run preethac$ java -jar MyProgram.jar 
    Hello
    
**Running with -help**
    Preethas-MacBook-Pro:Quorum3 preethac$ java -jar Quorum.jar -help
    Quorum Quorum 3.0

    Quorum is a computer programming language, which you can use either from the console using flags (the program you just ran) or from a development environment (like NetBeans). For this version, the commands that Quorum knows take the following format:

    java -jar Quorum.jar (-flag value*)*

    What this means is that you can pass a flag to Quorum combined with any number of values. The legal flags are listed as follows:
    -name This flag tells Quorum to change the name the file is outputs.

    -compile This flag tells Quorum to compile a set of files.

    -test This flag tells Quorum to run its test suite on itself.

    -help This flag tells Quorum to output this help screen. 


    Here are a few examples of how you can use this program:
        java -jar Quorum.jar Hello.quorum 

    This would request that Quorum compiles the source file Hello.quorum.

        java -jar Quorum.jar -compile Hello.quorum

        java -jar Quorum.jar -name MyProgram -compile Hello.quorum

    This would cause Quorum to compile Hello.quorum and name the output MyProgram.

        java -jar Quorum.jar Hello.quorum Goodbye.quorum

    This would cause Quorum to Compile two source code files. The first file must have a Main action.

    For more information on writing programs in Quorum, visit www.quorumlanguage.com.

**Build.sh**
\\ Creates a temporary directory, copies into it the source code for compiler(all files in source code), the library files and the files under Run. Compiles all latest(Quorum3) compiler files in Quorum2(using Default.jar) and creates Quorum.jar. Using this jar file re-compiles Quorum3 in Quorum3. Creates a folder Quorum, copies into the final Quorum.jar and Library files. Runs all the test suite(library files) on Quorum.jar. This Quorum.jar is the actual compiler, using which we can now compile our quorum programs.
   wifi-roaming-128-4-156-36:Quorum preethac$ java -jar Quorum.jar Hello.quorum 
   Quorum 3.0
   Build Successful
   wifi-roaming-128-4-156-36:Quorum preethac$ ls -lrt
   total 3592
   -rw-r--r--  1 preethac  staff  1833024 Jul  7 16:36 Quorum.jar
   drwxr-xr-x@ 4 preethac  staff      136 Jul  7 16:37 Library
   -rw-r--r--  1 preethac  staff       15 Jul  7 16:42 Hello.quorum
   drwxr-xr-x  3 preethac  staff      102 Jul  7 16:42 Run
   drwxr-xr-x  3 preethac  staff      102 Jul  7 16:42 Build
   wifi-roaming-128-4-156-36:Quorum preethac$ cd Run/
   wifi-roaming-128-4-156-36:Run preethac$ ls -lrt
   total 512
   -rw-r--r--  1 preethac  staff  258607 Jul  7 16:42 Default.jar
   wifi-roaming-128-4-156-36:Run preethac$ java -jar Default.jar 
   Hello

**Antlr Error**
\\ Couldn't fix the error. Refer https://github.com/antlr/antlr4/issues/497 and http://stackoverflow.com/questions/22027175/why-am-i-getting-an-error-when-assigning-tokens-to-a-channel. But could not figure out the causes-not sure if we need to edit the grammar file to run Antlr. Compared the Quorum.tokens file generated by Antlr after running Antlr4 Quorum.g4, and the given Quorum.token file, looks like it is similar.

**.class files in library**
Eg:parser.java, lexer.java, Token.java, AbstractParseTreeVisitor.java, SyntaxTree.java,etc. Decoded the .class files to .java files with Sodbeans.Not able to understand the compiled-code sections in it.Clueless.

**ANTLR Notes**
\\ \\ **Running ANTLR**
\\ Add antlr-4.5-complete.jar to your CLASSPATH:
  $ export CLASSPATH=".:/usr/local/lib/antlr-4.5-complete.jar:$CLASSPATH"
It's also a good idea to put this in your .bash_profile or whatever your startup script is.

Create aliases for the ANTLR Tool, and TestRig.
  $ alias antlr4='java -Xmx500M -cp "/usr/local/lib/antlr-4.5-complete.jar:$CLASSPATH" org.antlr.v4.Tool'
  $ alias grun='java org.antlr.v4.runtime.misc.TestRig'
  
  ANTLR provides a flexible testing tool in the runtime library called TestRig. 
  It can display lots of information about how a recognizer matches input from a file or standard input. 
  TestRig uses Java reflection to invoke compiled recognizers. 
  The test rig takes a grammar name, a starting rule name kind of like a main() method, and various options that dictate the output we want.
  Let’s say we’d like to print the tokens created during recognition. 
  Tokens are vocabulary symbols like keyword hello and identifier parrt.

  grammar Hello; // Define a grammar called Hello
  r : 'hello' ID ; // match keyword hello followed by an identifier
  ID : [a-z]+ ; // match lower-case identifiers
  WS : [ \t\r\n]+ -> skip ; // skip spaces, tabs, newlines, \r (Windows)
  
  $ antlr4 Hello.g4 
  # Generate parser and lexer using antlr4 alias from before 
  $ ls
  Hello.g4 
  HelloLexer.java 
  HelloParser.java 
  Hello.tokens 
  HelloLexer.tokens
  HelloBaseListener.java 
  HelloListener.java
  $ javac *.java # Compile ANTLR-generated code
  
  $ grun Hello r -tokens # start the TestRig on grammar Hello at rule r
  ➾ hello parrt # input for the recognizer that you type
  ➾ EOF # type ctrl-D on Unix or Ctrl+Z on Windows
  
   ❮ [@0,0:4='hello',<1>,1:0] # these three lines are output from grun 
   [@1,6:10='parrt',<2>,1:6]
   [@2,12:11='<EOF>',<-1>,2:0]
   
   ➾ $ grun Hello r -tree
   ➾ hello parrt ➾EOF
   ❮ (r hello parrt)
   
   grun Hello r -trace
   hello parrt
   enter   r, LT(1)=hello
   consume [@0,0:4='hello',<1>,1:0] rule r
   consume [@1,6:10='parrt',<2>,1:6] rule r
   exit    r, LT(1)=<EOF>
   
   $ grun
   java org.antlr.v4.runtime.misc.TestRig GrammarName startRuleName
     [-tokens] [-tree] [-gui] [-ps file.ps] [-encoding encodingname]
     [-trace] [-diagnostics] [-SLL]
     [input-filename(s)]
   Use startRuleName='tokens' if GrammarName is a lexer grammar.
   Omitting input-filename makes rig read from stdin.

   -tokens prints out the token stream.
   -tree prints out the parse tree in LISP form.
   -gui displays the parse tree visually in a dialog box.
   -ps file.ps generates a visual representation of the parse tree in PostScript and stores it in file.ps. The parse tree figures in this chapter were generated with -ps.
   -encoding encodingname specifies the test rig input file encoding if the current locale would not read the input properly. For example, we need this option to parse a Japanese-encoded XML file in Section 12.4, Parsing and Lexing XML, on page 224.
   -trace prints the rule name and current token upon rule entry and exit. -diagnostics turns on diagnostic messages during parsing. This generates messages only for unusual situations such as ambiguous input phrases.
   -SLL uses a faster but slightly weaker parsing strategy.

**ANTLR Parsing**
\\ The process of grouping characters into words or symbols (tokens) is called lexical analysis or simply tokenizing. We call a program that tokenizes the input a lexer. The lexer can group related tokens into token classes, or token types, such as INT (integers), ID (identifiers), FLOAT (floating-point numbers), and so on. The lexer groups vocabulary symbols into types when the parser cares only about the type, not the individual symbols. Tokens consist of at least two pieces of information: the token type (identifying the lexical structure) and the text matched for that token by the lexer.
The second stage is the actual parser and feeds off of these tokens to recognize the sentence structure, in this case an assignment statement. By default, ANTLR generated parsers build a data structure called a parse tree or syntax tree that records how the parser recognized the structure of the input sentence and its component phrases.
\\ Lexers process characters and pass tokens to the parser, which in turn checks syntax and creates a parse tree. The correspond- ing ANTLR classes are CharStream, Lexer, Token, Parser, and ParseTree. The “pipe” connecting the lexer and parser is called a TokenStream.
\\ ParseTree subclasses RuleNode and TerminalNode that correspond to subtree roots and leaf nodes. RuleNode has familiar methods such as getChild() and getParent(), but RuleNode isn’t specific to a particular grammar. To better support access to the elements within specific nodes, ANTLR generates a RuleNode subclass for each rule.
\\ ANTLR generates tree walking mechanisms automatically.
\\ By default, ANTLR generates a parse-tree listener interface that responds to events triggered by the built-in tree walker. To walk a tree and trigger calls into a listener, ANTLR’s runtime provides class ParseTreeWalker. To make a language application, we build a ParseTreeListener implementation containing application-specific code that typically calls into a larger surrounding application.
ANTLR generates a ParseTreeListener subclass specific to each grammar with enter and exit methods for each rule.
\\ Option -visitor asks ANTLR to generate a visitor interface from a grammar with a visit method per rule. 
  ParseTree tree = ... ; // tree is result of parsing 
  MyVisitor v = new MyVisitor();
  v.visit(tree);

\\ There are two key ANTLR components: the ANTLR tool itself and the ANTLR runtime (parse-time) API. When we say “run ANTLR on a grammar,” we’re talking about running the ANTLR tool, class org.antlr.v4.Tool. Running ANTLR generates code (a parser and a lexer) that recognizes sentences in the language described by the grammar. A lexer breaks up an input stream of characters into tokens and passes them to a parser that checks the syntax. The runtime is a library of classes and methods needed by that generated code such as Parser, Lexer, and Token. First we run ANTLR on a grammar and then compile the generated code against the runtime classes in the jar. Ultimately, the compiled application runs in conjunction with the runtime classes.

  /** Grammars always start with a grammar header. This grammar is called
   *  ArrayInit and must match the filename: ArrayInit.g4
  */
  grammar ArrayInit;
  /** A rule called init that matches comma-separated values between {...}. */
  
  init : '{' value (',' value)* '}' ; // must match at least one value
      /** A value can be either a nested array/struct or a simple integer (INT) */
      
  value : init 
        | INT
        ;
  // parser rules start with lowercase letters, lexer rules with uppercase 
  INT : [0-9]+ ; // Define token INT as one or more digits
  WS : [ \t\r\n]+ -> skip ; // Define whitespace rule, toss it out

**ArrayInitParser.java** This file contains the parser class definition specific to grammar ArrayInit that recognizes our array language syntax.
public class ArrayInitParser extends Parser { ... }
It contains a method for each rule in the grammar as well as some support
code.

**ArrayInitLexer.java** ANTLR automatically extracts a separate parser and lexer specification from our grammar. This file contains the lexer class definition, which ANTLR generated by analyzing the lexical rules INT and WS as well as the grammar literals '{', ',', and '}'. Recall that the lexer tokenizes the input, breaking it up into vocabulary symbols. Here’s the class outline:
public class ArrayInitLexer extends Lexer { ... }

**ArrayInit.tokens** ANTLR assigns a token type number to each token we define and stores these values in this file. It’s needed when we split a large grammar into multiple smaller grammars so that ANTLR can synchronize all the token type numbers. See Importing Grammars, on page 36.

**ArrayInitListener.java, ArrayInitBaseListener.java** By default, ANTLR parsers build a tree from the input. By walking that tree, a tree walker can fire “events” (callbacks) to a listener object that we provide. ArrayInitListener is the interface that describes the callbacks we can implement. ArrayInitBaseListener is a set of empty default implementations. This class makes it easy for us to override just the callbacks we’re interested in. ANTLR can alsogenerate tree visitors for us with the -visitor command-line option.

**Integrating a Generated Parser into a Java Program**
  // import ANTLR's runtime libraries
  import org.antlr.v4.runtime.*; import org.antlr.v4.runtime.tree.*;
  public class Test {
  public static void main(String[] args) throws Exception {
              
  // create a CharStream that reads from standard input
  ANTLRInputStream input = new ANTLRInputStream(System.in); 
  
  // create a lexer that feeds off of input CharStream
  ArrayInitLexer lexer = new ArrayInitLexer(input); 
  
  // create a buffer of tokens pulled from the lexer
  CommonTokenStream tokens = new CommonTokenStream(lexer); 
  
  // create a parser that feeds off the tokens buffer
  ArrayInitParser parser = new ArrayInitParser(tokens);
  
  ParseTree tree = parser.init(); // begin parsing at init rule
  System.out.println(tree.toStringTree(parser)); // print LISP-style tree 
  
  // Create a generic parse tree walker that can trigger callbacks
  ParseTreeWalker walker = new ParseTreeWalker();
  // Walk the tree created during the parse, trigger callbacks 
  walker.walk(new ShortToUnicodeString(), tree); 
  System.out.println(); // print a \n after translation
   }
  }

  ➾ $ javac ArrayInit*.java Test.java
  ➾ $ java Test
  ➾ {1,{2,3},4} ➾EOF
  ❮ (init { (value 1) , (value (init { (value 2) , (value 3) })) , (value 4) }) 

We can split a large grammar file into logical chunks, such as, parser rules and lexical rules, and one can import the other.
\\ ANTLR parsers automatically generate visitor interfaces and blank method implementations
\\ Modifications to the grammar - need to label the alternatives of the rules. (The labels can be any identifier that doesn’t collide with a rule name.) Without labels on the alternatives, ANTLR generates only one visitor method per rule.
  
  LabeledExpr.g4
  stat:   expr NEWLINE         # printExpr
      | ID '=' expr NEWLINE    # assign
      | NEWLINE ;              # blank
  expr: expr op=('*'|'/') expr # MulDiv
      | expr op=('+'|'-') expr # AddSub 
      | INT                    # int
      | ID                     #id
      | '(' expr ')'           # parens 
      ;
  MUL :'*' ; // assigns token name to '*' used above in grammar 
  DIV :'/' ;
  ADD :'+' ;
  SUB :'-' ;

**ANTLR Visitor**
  ➾ $ antlr4 -no-listener -visitor LabeledExpr.g4
  First, ANTLR generates a visitor interface with a method for each labeled alternative name.
  
  public interface LabeledExprVisitor<T> 
  {
  T visitId(LabeledExprParser.IdContext ctx); # from label id
  T visitAssign(LabeledExprParser.AssignContext ctx); # from label assign 
  T visitMulDiv(LabeledExprParser.MulDivContext ctx); # from label MulDiv ...
  }
  
ANTLR also generates a default visitor implementation called LabeledExprBaseVisitor that we can subclass.

**ANTLR Listener**
\\ The key “interface” between the grammar and our listener object is called JavaListener, and ANTLR automatically generates it for us. It defines all of the methods that class ParseTreeWalker from ANTLR’s runtime can trigger as it traverses the parse tree.  
\\ The biggest difference between the listener and visitor mechanisms is that listener methods are called by the ANTLR-provided walker object, whereas visitor methods must walk their children with explicit visit calls. Forgetting to invoke visit() on a node’s children means those subtrees don’t get visited. ANTLR generates a default implementation called JavaBaseListener. Our interface extractor can then subclass JavaBaseListener and override the methods of interest.

**ANTLR Grammar**
\\ **Channels**-The secret to preserving but ignoring comments and whitespace is to send those tokens to the parser on a “hidden channel.” The parser tunes to only a single channel and so we can pass anything we want on the other channels.  
\\ ANTLR generates a function for each rule in your grammar.
\\ \\ Introduction to grammar:
\\ Grammars consist of a header that names the grammar and a set of rules that can invoke each other.
  grammar MyG;
  rule1 : «stuff» ; 
  rule2 : «more stuff» ; ...
The nouns on the right side are typically references to either tokens or yet-to-be-defined rules. 
\\ \\ Pattern: Sequence
\\ In a grammar for eg. the retrieve command is a keyword followed by an integer followed by a newline token. To specify such a sequence in a grammar, we simply list the elements in order. In ANTLR notation, the retrieve command is just sequence 'RETR' INT '\n', where INT represents the integer token type.
\\ retr : 'RETR' INT '\n' ; (match keyword integer newline sequence).
\\ We are labeling the RETR sequence as the retr rule. Elsewhere in the grammar, we can refer to the RETR sequence with the rule name as a shorthand.
\\ To encode a sequence of one or more elements, we use the + subrule operator. Eg: INT+
\\ To specify that a list can be empty, we use the zero-or-more * operator: INT*
   match 'rule-name :' followed by at least one alternative followed by zero 
   or more alternatives separated by '|' symbols followed by ';' 
   rule : ID ':' alternative ('|' alternative )* ';' ;

Pattern: Choice
\\ To express the notion of choice in a language, we use | as the “or” operator in ANTLR rules to separate grammatical choices called alternatives or produc- tions. Grammars are full of choices.
   stmt: node_stmt 
       | edge_stmt 
       | attr_stmt 
       | id '=' id
       | subgraph 
       ;
Pattern: Token Dependency
  object
      : '{' pair (',' pair)* '}' 
      | '{' '}' // empty object 
      ;
  pair: STRING ':' value ;
Pattern: Nested Phrase
\\ If the pseudocode for a rule references itself, we are going to need a recursive (self-referencing) rule.
Let’s see how nesting works for code blocks. A while statement is the keyword while followed by a condition expression in parentheses followed by a statement. We can also treat multiple statements as a single block statement by wrapping them in curly braces. Expressing that grammatically looks like this:
  stat: 'while' '(' expr ')' stat // match WHILE statement
      | '{' stat* '}' // match block of statements in curlies
      ... // and other kinds of statements 
      ;
Antlr grammar resolved operator precedence by the alternative given first
    expr : expr '^'<assoc=right> expr // ^ operator is right associative 
         | expr '*' expr // match subexpressions joined with '*' operator 
         | expr '+' expr // match subexpressions joined with '+' operator 
         | INT // matches simple integer atom
         ;
Highest priority to ^, then * and so forth. By default, ANTLR associates operators left to right as we’d expect for * and +. Some operators like exponentiation group right to left, though, so we have to manually specify the associativity on the operator token using option assoc.
\\ In grammar pseudo code, a string is a sequence of any characters between double quotes.
\\ STRING : '"' .*? '"' ;  match anything in "...",as a pattern for matching stuff inside quotes or other delimiters.
\\ When a lexer matches the tokens we’ve defined so far, it emits them via the token stream to the parser. The parser then checks the grammatical structure of the stream. 
   Token Category  Description and Examples
   Punctuation     The easiest way to handle operators and punctuation is to directly reference them in parser rules.
                   call : ID '(' exprList ')' ;
                   Some programmers prefer to define token labels such as LP (left parenthesis) instead.
                   call : ID LP exprList RP ;
                   LP : '(' ;
                   RP : ')' ;
   Keywords        Keywords are reserved identifiers, and we can either reference them directly or define token types for them.
                   returnStat : 'return' expr ';'
   Identifiers     Identifiers look almost the same in every language, with some variation about what the first character can be and whether Unicode characters are allowed.
                   ID : ID_LETTER (ID_LETTER | DIGIT)* ; // From C language 
                   fragment ID_LETTER : 'a'..'z'|'A'..'Z'|'_' ;
                   fragment DIGIT : '0'..'9' ;
   Numbers         These are definitions for integers and simple floating-point numbers.
                   INT : DIGIT+ ;
                   FLOAT
                       : DIGIT+ '.' DIGIT* 
                       | '.' DIGIT+
                       ;
   Strings        Match double-quoted strings.
                  STRING: '"'(ESC|.)*?'"';
                  fragment ESC : '\\' [btnr"\\] ; // \b, \t, \n etc...
   Comments       Match and discard comments.
                  LINE_COMMENT : '//' .*? '\n' -> skip ; 
                  COMMENT : '/*' .*? '*/' -> skip ;
   Whitespace     Match and discard comments.
                  WS : [ \t\n\r]+ -> skip ;

**ANTLR Listeners and Visitors**
\\ A listener is an object that responds to rule entry and exit events (phrase recognition events) triggered by a parse-tree walker as it discovers and finishes nodes. To support situations where an application must control how a tree is walked, ANTLR-generated parse trees also support the well-known tree visitor pattern.
The biggest difference between listeners and visitors is that listener methods aren’t responsible for explicitly calling methods to walk their children. Visitors, on the other hand, must explicitly trigger visits to child nodes to keep the tree traversal going. Visitors get to control the order of traversal and how much of the tree gets visited because of these explicit calls to visit children.

\\ From the grammar, ANTLR generates <filename>Parser, which automatically builds the parse tree.
\\ Once we have a parse tree, we can use ParseTreeWalker to visit all of the nodes, triggering enter and exit methods.
ANTLR’s ParseTreeWalker triggers enter and exit methods for each rule subtree as it discovers and finishes nodes, respectively. 

**Listener**
\\ ANTLR generates a <filename>Listener from the grammar file.
\\ ANTLR also generates class PropertyFileBaseListener with default implementations which implements the PropertyFileListener.

    Propertyfile.g4
    file : prop+ ;
    prop : ID '=' STRING '\n' ;
    ID   : [a-z]+ ;
    STRING : '"' .*? '"' ;
    
    t.properties
    user="parrt"
    machine="maniac"
    
    **PropertyFileListener.java**
    import org.antlr.v4.runtime.tree.*; 
    import org.antlr.v4.runtime.Token;
    public interface PropertyFileListener extends ParseTreeListener 
    { 
    void enterFile(PropertyFileParser.FileContext ctx);
    void exitFile(PropertyFileParser.FileContext ctx);
    void enterProp(PropertyFileParser.PropContext ctx);
    void exitProp(PropertyFileParser.PropContext ctx);
    }

Because there are only two parser rules in grammar PropertyFile, there are four methods in the interface.

  TestPropertyFile.java
  import org.antlr.v4.misc.OrderedHashMap;
  import org.antlr.v4.runtime.*;
  import org.antlr.v4.runtime.tree.*;
  import java.io.*;
  import java.util.Map;

  public class TestPropertyFile {
    public static class PropertyFileLoader extends PropertyFileBaseListener {
        Map<String,String> props = new OrderedHashMap<String, String>();
        public void exitProp(PropertyFileParser.PropContext ctx) {
            String id = ctx.ID().getText(); // prop : ID '=' STRING '\n' ;
            String value = ctx.STRING().getText();
            props.put(id, value);
        }
    }

    public static void main(String[] args) throws Exception {
        String inputFile = null;
        if ( args.length>0 ) inputFile = args[0];
        InputStream is = System.in;
        if ( inputFile!=null ) {
            is = new FileInputStream(inputFile);
        }
        ANTLRInputStream input = new ANTLRInputStream(is);
        PropertyFileLexer lexer = new PropertyFileLexer(input);
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        PropertyFileParser parser = new PropertyFileParser(tokens);
        ParseTree tree = parser.file();

        // create a standard ANTLR parse tree walker
        ParseTreeWalker walker = new ParseTreeWalker();
        // create listener then feed to walker
        PropertyFileLoader loader = new PropertyFileLoader();
        walker.walk(loader, tree);        // walk parse tree
        System.out.println(loader.props); // print results
    }
  }
Interface ParseTreeListener is in the ANTLR runtime library and dictates that every listener respond to events visitTerminal(), enterEveryRule(), exitEveryRule(), and (upon syntax errors) visitErrorNode(). ANTLR generates interface PropertyFileListener from grammar PropertyFile and default implementations for all methods in class PropertyFileBaseListener. The only thing that we’re building is the PropertyFileLoader, which inherits all of the blank functionality from PropertyFileBaseListener.
Method exitProp() has access to the rule context object, PropContext, associated with rule prop. That context object has methods for each of the elements mentioned in rule prop (ID and STRING). Because those elements are token ref- erences in the grammar, the methods return TerminalNode parse-tree nodes. We can either directly access the text of the token payload via getText(), as we’ve done here, or get the Token payload first via getSymbol().
   
   $ antlr4 PropertyFile.g4
   $ ls PropertyFile*.java
   PropertyFileBaseListener.java PropertyFileListener.java PropertyFileLexer.java PropertyFileParser.java
   $ javac TestPropertyFile.java PropertyFile*.java
   $ cat t.properties
   user="parrt"
   machine="maniac"
   $ java TestPropertyFile t.properties
   {user="parrt", machine="maniac"}

Our test program successfully reconstitutes the property assignments from the file into a map data structure in memory.

**Visitor**
\\ To use a visitor instead of a listener, we ask ANTLR to generate a visitor interface, implement that interface, and then create a test rig that calls visit() on the parse tree. 
When we use the -visitor option on the command line, ANTLR generates interface PropertyFileVisitor and class PropertyFileBaseVisitor, which has the following default implementations:

   public class PropertyFileBaseVisitor<T> extends AbstractParseTreeVisitor<T> implements PropertyFileVisitor<T>
   {
    @Override public T visitFile(PropertyFileParser.FileContext ctx) { ... } 
    @Override public T visitProp(PropertyFileParser.PropContext ctx) { ... }
   }

   TestPropertyFileVisitor.java
   import org.antlr.v4.misc.OrderedHashMap;
   import org.antlr.v4.runtime.*;
   import org.antlr.v4.runtime.tree.*;
   import java.io.*;
   import java.util.Map;

   public class TestPropertyFileVisitor {
    public static class PropertyFileVisitor extends
        PropertyFileBaseVisitor<Void>
    {
        Map<String,String> props = new OrderedHashMap<String, String>();
        public Void visitProp(PropertyFileParser.PropContext ctx) {
            String id = ctx.ID().getText(); // prop : ID '=' STRING '\n' ;
            String value = ctx.STRING().getText();
            props.put(id, value);
            return null; // Java says must return something even when Void
        }
    }

    public static void main(String[] args) throws Exception {
        String inputFile = null;
        if ( args.length>0 ) inputFile = args[0];
        InputStream is = System.in;
        if ( inputFile!=null ) {
            is = new FileInputStream(inputFile);
        }
        ANTLRInputStream input = new ANTLRInputStream(is);
        PropertyFileLexer lexer = new PropertyFileLexer(input);
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        PropertyFileParser parser = new PropertyFileParser(tokens);
        ParseTree tree = parser.file();

        PropertyFileVisitor loader = new PropertyFileVisitor();
        loader.visit(tree);
        System.out.println(loader.props); // print results
    }
  }

Visitors walk parse trees by explicitly calling interface ParseTreeVisitor’s visit() method on child nodes. That method is implemented in AbstractParseTreeVisitor. In this case, the nodes created for prop invocations don’t have children, so visitProp() doesn’t have to call visit().
\\ The biggest difference between a visitor and listener test rig (such as TestPropertyFile) is that visitor test rigs don’t need a ParseTreeWalker. They just ask the visitor to visit the tree created by the parser.

**Questions about Proposal Writing**
\\ 1.Do I need to include all the citations that Xiaoran used in his paper? No, only 6,4,26,27,quorum website, stefik’s paper, probably 12 or 13 in total.
\\ 2.Cited Xiaoran's paper, hope that is alright.
\\ 3.What do I need to cite in reference to Quorum?Any paper, their website,etc?
\\ 4.Cited ANTLR4 book, hope that is okay.
\\ 5.To describe the project outline, can I include a sample Quorum code snippet and explain the corresponding feature vector identified for that loop?
\\ 6.Do I include the challenges and motivation with respect to new environment and how to deal with that?
\\ 7.What else do I need to add? Should I add the feature vector table from Xiaoran's paper, or should I explain little about the work related to Quorum compilers? 

\\ Margin should be 1 inch on left and right -done
\\ Change verbs in project steps - done
\\ after first line cite quorum website, say how many blind prog are there(to be found somewhere in his website), refer to his paper.
\\ at the end, before the reference, present a summary of results , how it would help programmers,etc

**Application on Quorum**
  TestQuorum.java
  
  // import ANTLR's runtime libraries
  import org.antlr.v4.runtime.*; 
  import org.antlr.v4.runtime.tree.*;

  public class TestQuorum {
	public static void main(String[] args) throws Exception {
              	// create a CharStream that reads from standard input
		ANTLRInputStream input = new ANTLRInputStream(System.in);	
		// create a lexer that feeds off of input CharStream
		QuorumLexer lexer = new QuorumLexer(input);
		 // create a buffer of tokens pulled from the lexer
		CommonTokenStream tokens = new CommonTokenStream(lexer);
		 // create a parser that feeds off the tokens buffer
		QuorumParser parser = new QuorumParser(tokens);
		ParseTree tree = parser.start(); // begin parsing at start rule
               //ParseTree tree = parser.statement(); //begin parsing at statement rule   
		System.out.println(tree.toStringTree(parser));
		 // print LISP-style tree 
		}
	}

   This file works with a sample loop-if in Quorum to print out the tree.
   With parser.start()
   
   Preethas-MacBook-Pro:Antlr preethac$ java TestQuorum
   repeat while index < 256
        text name = ToText(index)
        if name not= undefined
            keyNames:put(index, index)
        end
    end
   (start (class_declaration (no_class_stmnts (statement (loop_statement repeat while (expression (expression (action_call index)) < (expression 256)) (block (statement (assignment_statement (assignment_declaration text) name = (expression (action_call ToText ( (function_expression_list (expression (action_call index))) ))))) (statement (if_statement if (expression (expression (action_call name)) not= (expression undefined)) (block (statement (solo_method_call keyNames : (solo_method_required_method_part put ( (function_expression_list (expression (action_call index)) , (expression (action_call index))) ))))) end))) end)))) <EOF>)
   
   with parser.statement()
   Preethas-MacBook-Pro:Antlr preethac$ java TestQuorum
   repeat while index < 256
      text name = ToText(index)
      if name not= undefined
          keyNames:put(index, index)
      end
   end
   (statement (loop_statement repeat while (expression (expression (action_call index)) < (expression 256)) (block (statement (assignment_statement (assignment_declaration text) name = (expression (action_call ToText ( (function_expression_list (expression (action_call index))) ))))) (statement (if_statement if (expression (expression (action_call name)) not= (expression undefined)) (block (statement (solo_method_call keyNames : (solo_method_required_method_part put ( (function_expression_list (expression (action_call index)) , (expression (action_call index))) ))))) end))) end))