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import * as assert from 'assert';
import { Builder, LoopChecker } from '../src/builder';
describe('LLParse/LoopChecker', () => {
let b: Builder;
let lc: LoopChecker;
beforeEach(() => {
b = new Builder();
lc = new LoopChecker();
});
it('should detect shallow loops', () => {
const start = b.node('start');
start
.otherwise(start);
assert.throws(() => {
lc.check(start);
}, /Detected loop in "start".*"start"/);
});
it('should detect loops', () => {
const start = b.node('start');
const a = b.node('a');
const invoke = b.invoke(b.code.match('nop'), {
0: start,
}, b.error(1, 'error'));
start
.peek('a', a)
.otherwise(b.error(1, 'error'));
a.otherwise(invoke);
assert.throws(() => {
lc.check(start);
}, /Detected loop in "a".*"a" -> "invoke_nop"/);
});
it('should detect seemingly unreachable keys', () => {
const start = b.node('start');
const loop = b.node('loop');
start
.peek('a', loop)
.otherwise(b.error(1, 'error'));
loop
.match('a', loop)
.otherwise(loop);
assert.throws(() => {
lc.check(start);
}, /Detected loop in "loop" through.*"loop"/);
});
it('should ignore loops through `peek` to `match`', () => {
const start = b.node('start');
const a = b.node('a');
const invoke = b.invoke(b.code.match('nop'), {
0: start,
}, b.error(1, 'error'));
start
.peek('a', a)
.otherwise(b.error(1, 'error'));
a
.match('abc', invoke)
.otherwise(start);
assert.doesNotThrow(() => lc.check(start));
});
it('should ignore irrelevant `peek`s', () => {
const start = b.node('start');
const a = b.node('a');
start
.peek('a', a)
.otherwise(b.error(1, 'error'));
a
.peek('b', start)
.otherwise(b.error(1, 'error'));
assert.doesNotThrow(() => lc.check(start));
});
it('should ignore loops with multi `peek`/`match`', () => {
const start = b.node('start');
const another = b.node('another');
const NUM: ReadonlyArray<string> = [
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
];
const ALPHA: ReadonlyArray<string> = [
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
];
start
.match(ALPHA, start)
.peek(NUM, another)
.skipTo(start);
another
.match(NUM, another)
.otherwise(start);
assert.doesNotThrow(() => lc.check(start));
});
});
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