boolean-expressions
Version:
Boolean expression parser and evaluator. Makes use of the Ohm grammar package with grammar rules found [here](https://github.com/avadavat/boolean-expressions/blob/master/src/grammar/grammarRules.ts).
83 lines (82 loc) • 3.06 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
/**
* Creates a semantics object with our truth grammar for the given query
* parameters.
*
* Returns a function to evaluate the semantics for the given match result
* with the given variables set to true, and the omitted variables set to false.
* This takes advantage of closures to allow us to re-use the same semantics object.
*
* The semantics API doesn't allow us to accept parameters to the evaluate
* function so this is how we get around it.
*/
function createSemantics(truthGrammar, matchResult) {
var trueVariables;
var semantics = truthGrammar.createSemantics().addOperation("evaluate", {
Exp: function (e) {
return e.evaluate();
},
PriExp: function (e) {
return e.evaluate();
},
NotExp: function (_op, exp) {
return !exp.evaluate();
},
OrExp_or: function (left, _op, right) {
return left.evaluate() || right.evaluate();
},
NorExp_nor: function (left, _op, right) {
return !(left.evaluate() || right.evaluate());
},
AndExp_and: function (left, _op, right) {
return left.evaluate() && right.evaluate();
},
NandExp_nand: function (left, _op, right) {
return !(left.evaluate() && right.evaluate());
},
XorExp_xor: function (left, _op, right) {
return left.evaluate() !== right.evaluate();
},
XnorExp_xnor: function (left, _op, right) {
return left.evaluate() === right.evaluate();
},
IfExp_arrow: function (left, _op, right) {
return !left.evaluate() || right.evaluate();
},
IfExp_ifThen: function (_if, left, _then, right) {
return !left.evaluate() || right.evaluate();
},
ConverseExp_arrow: function (left, _op, right) {
return left.evaluate() || !right.evaluate();
},
NimplyExp_nimply: function (left, _op, right) {
return left.evaluate() && !right.evaluate();
},
ConverseNimplyExp_converseNimply: function (left, _op, right) {
return !left.evaluate() && right.evaluate();
},
BiconditionalExp_biconditional: function (left, _op, right) {
return left.evaluate() === right.evaluate();
},
ParenExp: function (_open, exp, _close) {
return exp.evaluate();
},
ident: function (first, remaining) {
var variableName = first.sourceString + remaining.sourceString;
return trueVariables.indexOf(variableName) >= 0;
},
True: function (_) {
return true;
},
False: function (_) {
return false;
}
})(matchResult);
function evaluateWithTrueVariables(variables) {
trueVariables = variables;
return semantics.evaluate();
}
return evaluateWithTrueVariables;
}
exports.default = createSemantics;