pegjs/test/unit/compiler/passes/report-infinite-repetition.spec.js

"use strict";

const chai = require( "chai" );
const helpers = require( "./helpers" );
const pass = require( "pegjs" ).compiler.passes.check.reportInfiniteRepetition;

chai.use( helpers );

const expect = chai.expect;

describe( "compiler pass |reportInfiniteRepetition|", function () {

    it( "reports infinite loops for zero_or_more", function () {

        expect( pass ).to.reportError( "start = ('')*", {
            message: "Possible infinite loop when parsing (repetition used with an expression that may not consume any input).",
            location: {
                start: { offset: 8, line: 1, column: 9 },
                end: { offset: 13, line: 1, column: 14 }
            }
        } );

    } );

    it( "reports infinite loops for one_or_more", function () {

        expect( pass ).to.reportError( "start = ('')+", {
            message: "Possible infinite loop when parsing (repetition used with an expression that may not consume any input).",
            location: {
                start: { offset: 8, line: 1, column: 9 },
                end: { offset: 13, line: 1, column: 14 }
            }
        } );

    } );

    it( "computes expressions that always consume input on success correctly", function () {

        expect( pass ).to.reportError( [
            "start = a*",
            "a 'a' = ''"
        ].join( "\n" ) );
        expect( pass ).to.not.reportError( [
            "start = a*",
            "a 'a' = 'a'"
        ].join( "\n" ) );

        expect( pass ).to.reportError( "start = ('' / 'a' / 'b')*" );
        expect( pass ).to.reportError( "start = ('a' / '' / 'b')*" );
        expect( pass ).to.reportError( "start = ('a' / 'b' / '')*" );
        expect( pass ).to.not.reportError( "start = ('a' / 'b' / 'c')*" );

        expect( pass ).to.reportError( "start = ('' { })*" );
        expect( pass ).to.not.reportError( "start = ('a' { })*" );

        expect( pass ).to.reportError( "start = ('' '' '')*" );
        expect( pass ).to.not.reportError( "start = ('a' '' '')*" );
        expect( pass ).to.not.reportError( "start = ('' 'a' '')*" );
        expect( pass ).to.not.reportError( "start = ('' '' 'a')*" );

        expect( pass ).to.reportError( "start = (a:'')*" );
        expect( pass ).to.not.reportError( "start = (a:'a')*" );

        expect( pass ).to.reportError( "start = ($'')*" );
        expect( pass ).to.not.reportError( "start = ($'a')*" );

        expect( pass ).to.reportError( "start = (&'')*" );
        expect( pass ).to.reportError( "start = (&'a')*" );

        expect( pass ).to.reportError( "start = (!'')*" );
        expect( pass ).to.reportError( "start = (!'a')*" );

        expect( pass ).to.reportError( "start = (''?)*" );
        expect( pass ).to.reportError( "start = ('a'?)*" );

        expect( pass ).to.reportError( "start = (''*)*" );
        expect( pass ).to.reportError( "start = ('a'*)*" );

        expect( pass ).to.reportError( "start = (''+)*" );
        expect( pass ).to.not.reportError( "start = ('a'+)*" );

        expect( pass ).to.reportError( "start = ('')*" );
        expect( pass ).to.not.reportError( "start = ('a')*" );

        expect( pass ).to.reportError( "start = (&{ })*" );

        expect( pass ).to.reportError( "start = (!{ })*" );

        expect( pass ).to.reportError( [
            "start = a*",
            "a = ''"
        ].join( "\n" ) );
        expect( pass ).to.not.reportError( [
            "start = a*",
            "a = 'a'"
        ].join( "\n" ) );

        expect( pass ).to.reportError( "start = ''*" );
        expect( pass ).to.not.reportError( "start = 'a'*" );

        expect( pass ).to.not.reportError( "start = [a-d]*" );

        expect( pass ).to.not.reportError( "start = .*" );

    } );

} );