Created
June 2, 2015 04:00
-
-
Save anujku/562967bfe41759ac5a05 to your computer and use it in GitHub Desktop.
Simple Arithmetics Grammar
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
/* | |
* Simple Arithmetics Grammar | |
* ========================== | |
* | |
* Accepts expressions like "2 * (3 + 4)" and computes their value. | |
*/ | |
{ | |
function combine(first, rest, combiners) { | |
var result = first, i; | |
for (i = 0; i < rest.length; i++) { | |
result = combiners[rest[i][1]](result, rest[i][3]); | |
} | |
return result; | |
} | |
} | |
Expression | |
= first:Term rest:(_ ("+" / "-") _ Term)* { | |
return combine(first, rest, { | |
"+": function(left, right) { return left + right; }, | |
"-": function(left, right) { return left - right; } | |
}); | |
} | |
Term | |
= first:Factor rest:(_ ("*" / "/") _ Factor)* { | |
return combine(first, rest, { | |
"*": function(left, right) { return left * right; }, | |
"/": function(left, right) { return left / right; } | |
}); | |
} | |
Factor | |
= "(" _ expr:Expression _ ")" { return expr; } | |
/ Integer | |
Integer "integer" | |
= [0-9]+ { return parseInt(text(), 10); } | |
_ "whitespace" | |
= [ \t\n\r]* |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment