arithmetic.g4

/*
BSD License

Copyright (c) 2013, Tom Everett
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modification, are permitted provided that the following conditions
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   may be used to endorse or promote products derived from this software
   without specific prior written permission.

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*/

// $antlr-format alignTrailingComments true, columnLimit 150, minEmptyLines 1, maxEmptyLinesToKeep 1, reflowComments false, useTab false
// $antlr-format allowShortRulesOnASingleLine false, allowShortBlocksOnASingleLine true, alignSemicolons hanging, alignColons hanging

grammar arithmetic;

file_
    : equation* EOF
    ;

equation
    : expression relop expression
    ;

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

atom
    : scientific
    | variable
    ;

scientific
    : SCIENTIFIC_NUMBER
    ;

variable
    : VARIABLE
    ;

relop
    : EQ
    | GT
    | LT
    ;

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
SCIENTIFIC_NUMBER
    : NUMBER (E SIGN? UNSIGNED_INTEGER)?
    ;

fragment NUMBER
    : ('0' .. '9')+ ('.' ('0' .. '9')+)?
    ;

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

fragment E
    : 'E'
    | 'e'
    ;

fragment SIGN
    : '+'
    | '-'
    ;

LPAREN
    : '('
    ;

RPAREN
    : ')'
    ;

PLUS
    : '+'
    ;

MINUS
    : '-'
    ;

TIMES
    : '*'
    ;

DIV
    : '/'
    ;

GT
    : '>'
    ;

LT
    : '<'
    ;

EQ
    : '='
    ;

POINT
    : '.'
    ;

POW
    : '^'
    ;

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