simple_arithmetic.g4

/*
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 Copyright (c) 2013, Tom Everett All rights reserved.
 
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grammar simple_arithmetic;

file_: assignment* EOF;

assignment: variable EQ expression;

expression:
	expression POW expression
	| expression (TIMES | DIV) expression
	| expression (PLUS | MINUS) expression
	| LPAREN expression RPAREN
	| (PLUS | MINUS)? atom;

atom: number | variable;

number: NUMBER;

variable: VARIABLE;

VARIABLE: VALID_ID_START VALID_ID_CHAR*;

fragment VALID_ID_START: 'a' .. 'z' | 'A' .. 'Z' | '_';

fragment VALID_ID_CHAR: VALID_ID_START | '0' .. '9';

//The NUMBER part gets its potential sign from "(PLUS | MINUS)* atom" in the expression rule
NUMBER: ('0' .. '9')+ ('.' ('0' .. '9')+)?;

fragment UNSIGNED_INTEGER: ('0' .. '9')+;

LPAREN: '(';

RPAREN: ')';

PLUS: '+';

MINUS: '-';

TIMES: '*';

DIV: '/';

EQ: '=';

POINT: '.';

POW: '^';

WS: [ \r\n\t]+ -> skip;