Parser Project
Compiler Project
COP-5621

1. Overview
2. Instructions

1. Overview

In this project you will implement a pretty printer using the ANTLR visitor of the While grammar from the Lexer project.

The only rules are that nested conditional blocks should be indented. The choice of whitespace and other constructs is up to you.

2. Instructions

Create a python program called

~/cop5621spring25/compiler/compiler/Parser.py

Here is a template base visitor to start from:

2.1. Template code

import sys
from antlr4 import *
sys.path.append('./')  # if you want to avoid PYTHONPATH
from grammar.WhileLexer import WhileLexer
from grammar.WhileParser import WhileParser
from grammar.WhileVisitor import WhileVisitor
import logging
from textwrap import indent, dedent

class Printer(WhileVisitor):
    # Visit a parse tree produced by WhileParser#Assignment.
    def visitAssignment(self, ctx:WhileParser.AssignmentContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#Skip.
    def visitSkip(self, ctx:WhileParser.SkipContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#If.
    def visitIf(self, ctx:WhileParser.IfContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#While.
    def visitWhile(self, ctx:WhileParser.WhileContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#Compound.
    def visitCompound(self, ctx:WhileParser.CompoundContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#Not.
    def visitNot(self, ctx:WhileParser.NotContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#ROp.
    def visitROp(self, ctx:WhileParser.ROpContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#Or.
    def visitOr(self, ctx:WhileParser.OrContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#And.
    def visitAnd(self, ctx:WhileParser.AndContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#True.
    def visitTrue(self, ctx:WhileParser.TrueContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#False.
    def visitFalse(self, ctx:WhileParser.FalseContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#BParen.
    def visitBParen(self, ctx:WhileParser.BParenContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#AOp.
    def visitAOp(self, ctx:WhileParser.AOpContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#Var.
    def visitVar(self, ctx:WhileParser.VarContext):
        print(ctx.ID())
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#Num.
    def visitNum(self, ctx:WhileParser.NumContext):
        return self.visitChildren(ctx)


    # Visit a parse tree produced by WhileParser#AParen.
    def visitAParen(self, ctx:WhileParser.AParenContext):
        return self.visitChildren(ctx)

input_stream = StdinStream()
lexer = WhileLexer(input_stream)
stream = CommonTokenStream(lexer)
parser = WhileParser(stream)
tree = parser.s()
if parser.getNumberOfSyntaxErrors() > 0:
  print("syntax errors")
  exit(1)
printer = Printer()
printer.visit(tree)

Parser Project Compiler Project COP-5621

Table of Contents

1. Overview

2. Instructions

2.1. Template code

Parser Project
Compiler Project
COP-5621