File size: 2,163 Bytes
f0634fb | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | // src/parse.ts
//
// Public parse entry point. Runs the hand-written lexer + recursive-descent
// parser under a ParseBudget and returns the materialized syntax tree.
//
// Exit contract:
// - Budget exhaustion (time or node cap) → { ok: false, reason: 'aborted' }.
// `Aborted` never escapes.
// - Malformed input → { ok: true, hasError: true } with ERROR nodes and/or
// partial nodes where the parser recovered.
// - Any other parser-internal exception (a bug, not user input) is caught
// here as a last resort: the caller still gets a usable tree — a program
// root with a single ERROR child spanning the whole source and
// hasError: true — instead of an exception. Chosen over reporting
// 'aborted' because the parse did not hit its budget; downstream
// consumers keep working on a degraded tree and hasError signals the
// failure. (See the catch block below.)
import { Aborted, ParseBudget } from '#/budget';
import type { BudgetOptions } from '#/budget';
import { SyntaxNodeBuilder } from '#/node';
import type { SyntaxNode } from '#/node';
import { Parser, materialize } from '#/parser';
export type ParseResult =
| { ok: true; rootNode: SyntaxNode; hasError: boolean }
| { ok: false; reason: 'aborted' };
export type ParseOptions = BudgetOptions;
export function parse(source: string, options: ParseOptions = {}): ParseResult {
const budget = new ParseBudget(options);
try {
const parser = new Parser(source, budget);
const root = parser.parseProgram();
const rootNode = materialize(root, source);
return { ok: true, rootNode, hasError: parser.hasError };
} catch (error) {
if (error instanceof Aborted) return { ok: false, reason: 'aborted' };
// Last-resort guard for parser bugs: degrade to an ERROR root instead of
// throwing into the caller (see the file header for why).
const root = new SyntaxNodeBuilder({ type: 'program', source, startIndex: 0, endIndex: source.length });
root.addChild(new SyntaxNodeBuilder({ type: 'ERROR', source, startIndex: 0, endIndex: source.length }));
return { ok: true, rootNode: root, hasError: true };
}
}
|