A simple business rules language based on JISON

rule.jison

/* description: Parses end executes mathematical expressions. */

/* lexical grammar */
%lex
%%

\s+                   /* skip whitespace */
[0-9]+("."[0-9]+)?\b  return 'NUMBER'
"true"                return 'TRUE'
"false"               return 'FALSE'
"not"                 return 'NOT'
"and"                 return 'AND'
"or"                  return 'OR'
"%"                   return '%'
"="                   return '='
"!="                  return '='
"*"                   return '*'
"/"                   return '/'
"-"                   return '-'
"+"                   return '+'
">"                   return '>'
"<"                   return '<'
">="                  return '>='
"<="                  return '<='
"^"                   return '^'
"("                   return '('
")"                   return ')'
"PI"                  return 'PI'
"E"                   return 'E'
\"(?:\"\"|[^"])*\"   return 'STRING'
([\[\]a-zA-Z0-9._$^\!@\(]+)  return 'IDENT'
<<EOF>>               return 'EOF'
.                     return 'INVALID'

/lex

/* operator associations and precedence */


%left '%'
%left '+' '-'
%left '*' '/'
%left '^'
%left '>' '<' '>=' '<='
%left 'NOT'
%left 'AND' 'OR' 
%left '=' '<>'
%left UMINUS

%start expressions

%% /* language grammar */

expressions
    : e EOF
        {return $1;}
    ;

e
    : e '+' e
        {$$ = $1+$3;}
    | 'NOT' e
        {$$ = !$2;}
    | e 'OR' e
        {$$ = $1 || $3;}
    | e 'AND' e
        {$$ = $1 && $3;}
    | e '=' e
        {$$ = $1 == $3;}
    | e '<>' e
        {$$ = $1 != $3;}
    | e '-' e
        {$$ = $1-$3;}
    | e '*' e
        {$$ = $1*$3;}
    | e '/' e
        {$$ = $1/$3;}
    | e '>' e
        {$$ = $1>$3;}
    | e '<' e
        {$$ = $1<$3;}
    | e '>=' e
        {$$ = $1>=$3;}
    | e '<=' e
        {$$ = $1<=$3;}
    | e '^' e
        {$$ = Math.pow($1, $3);}
    | '-' e %prec UMINUS
        {$$ = -$2;}
    | '(' e ')'
        {$$ = $2;}
    | e '%'
        {$$ = $1 / 100;}
    | TRUE
        {$$ = true;}
    | FALSE
        {$$ = false;}
    | NUMBER
        {$$ = Number(yytext);}
    | STRING
        {$$ = $1.substring(1, $1.length-1);}
    | IDENT
        {$$ = __data__[$1];}
    | E
        {$$ = Math.E;}
    | PI
        {$$ = Math.PI;}
    ;