PythonParser.g4

/*
Python grammar
The MIT License (MIT)
Copyright (c) 2021 Robert Einhorn

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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The above copyright notice and this permission notice shall be included in
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THE SOFTWARE.
 */

 /*
 * Project      : an ANTLR4 parser grammar based on the official Python 3.8.17 grammar
 *                https://github.com/RobEin/tiny-python
 * Developed by : Robert Einhorn
 */


parser grammar PythonParser; // Tiny Python based on: https://docs.python.org/3.8/reference/grammar.html
options { tokenVocab=PythonLexer; }

// ANTLR4 grammar for a tiny Python

file_input: (NEWLINE | stmt)* EOF; // start rule

stmt: simple_stmt | compound_stmt;

simple_stmt: small_stmt NEWLINE;
small_stmt: expr_stmt | flow_stmt | print_stmt;
expr_stmt: NAME '=' expr;
flow_stmt: break_stmt | continue_stmt;
break_stmt: 'break';
continue_stmt: 'continue';

compound_stmt: if_stmt | while_stmt;
if_stmt: 'if' namedexpr_test ':' suite ('elif' namedexpr_test ':' suite)* ('else' ':' suite)?;
while_stmt: 'while' namedexpr_test ':' suite;
suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT;

namedexpr_test: test;
test : comparison;
comparison: expr (comp_op expr)*;

comp_op: '<'|'>'|'=='|'>='|'<='|'!=';

expr: expr (( '+' | '-' ) expr)+
   | NAME
   | NUMBER
   | STRING+
   | input_func
   | '(' expr ')'
   ;

//*** the following rules are for demonstration only ****
input_func: INPUT '(' arg ')'; // "input" is not a reserved keyword in Python 3
print_stmt: PRINT '(' arg ')'; // "print" is not a reserved keyword in Python 3
arg : NAME | STRING+ | NUMBER | expr;