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pegjs/test/api/generated-parser-api.spec.js

217 lines
6.6 KiB
JavaScript

"use strict";
const chai = require( "chai" );
const peg = require( "pegjs" );
const sinon = require( "sinon" );
const expect = chai.expect;
describe( "generated parser API", function () {
describe( "parse", function () {
it( "parses input", function () {
const parser = peg.generate( "start = 'a'" );
expect( parser.parse( "a" ) ).to.equal( "a" );
} );
it( "throws an exception on syntax error", function () {
const parser = peg.generate( "start = 'a'" );
expect( () => {
parser.parse( "b" );
} ).to.throw();
} );
describe( "start rule", function () {
const parser = peg.generate( `
a = 'x' { return 'a'; }
b = 'x' { return 'b'; }
c = 'x' { return 'c'; }
`, { allowedStartRules: [ "b", "c" ] } );
describe( "when |startRule| is not set", function () {
it( "starts parsing from the first allowed rule", function () {
expect( parser.parse( "x" ) ).to.equal( "b" );
} );
} );
describe( "when |startRule| is set to an allowed rule", function () {
it( "starts parsing from specified rule", function () {
expect( parser.parse( "x", { startRule: "b" } ) ).to.equal( "b" );
expect( parser.parse( "x", { startRule: "c" } ) ).to.equal( "c" );
} );
} );
describe( "when |startRule| is set to a disallowed start rule", function () {
it( "throws an exception", function () {
expect( () => {
parser.parse( "x", { startRule: "a" } );
} ).to.throw();
} );
} );
} );
describe( "tracing", function () {
const parser = peg.generate( `
start = a / b
a = 'a'
b = 'b'
`, { trace: true } );
describe( "default tracer", function () {
it( "traces using console.log (if console is defined)", function () {
const messages = [
"1:1-1:1 rule.enter start",
"1:1-1:1 rule.enter a",
"1:1-1:1 rule.fail a",
"1:1-1:1 rule.enter b",
"1:1-1:2 rule.match b",
"1:1-1:2 rule.match start"
];
if ( typeof console === "object" ) sinon.stub( console, "log" );
try {
parser.parse( "b" );
if ( typeof console === "object" ) {
expect( console.log.callCount ).to.equal( messages.length );
messages.forEach( ( message, index ) => {
const call = console.log.getCall( index );
expect( call.calledWithExactly( message ) ).to.equal( true );
} );
}
} finally {
if ( typeof console === "object" ) console.log.restore();
}
} );
} );
describe( "custom tracers", function () {
describe( "trace", function () {
it( "receives tracing events", function () {
const events = [
{
type: "rule.enter",
rule: "start",
location: {
start: { offset: 0, line: 1, column: 1 },
end: { offset: 0, line: 1, column: 1 }
}
},
{
type: "rule.enter",
rule: "a",
location: {
start: { offset: 0, line: 1, column: 1 },
end: { offset: 0, line: 1, column: 1 }
}
},
{
type: "rule.fail",
rule: "a",
location: {
start: { offset: 0, line: 1, column: 1 },
end: { offset: 0, line: 1, column: 1 }
}
},
{
type: "rule.enter",
rule: "b",
location: {
start: { offset: 0, line: 1, column: 1 },
end: { offset: 0, line: 1, column: 1 }
}
},
{
type: "rule.match",
rule: "b",
result: "b",
location: {
start: { offset: 0, line: 1, column: 1 },
end: { offset: 1, line: 1, column: 2 }
}
},
{
type: "rule.match",
rule: "start",
result: "b",
location: {
start: { offset: 0, line: 1, column: 1 },
end: { offset: 1, line: 1, column: 2 }
}
}
];
const tracer = { trace: sinon.spy() };
parser.parse( "b", { tracer: tracer } );
expect( tracer.trace.callCount ).to.equal( events.length );
events.forEach( ( event, index ) => {
const call = tracer.trace.getCall( index );
expect( call.calledWithExactly( event ) ).to.equal( true );
} );
} );
} );
} );
} );
it( "accepts custom options", function () {
const parser = peg.generate( "start = 'a'" );
parser.parse( "a", { foo: 42 } );
} );
} );
} );