@stackpress/idea-parser/esm/Lexer.js

Parses ideas to AST and readable JSON.

import Exception from './Exception.js';
export default class Lexer {
    _code = '';
    _index = 0;
    _dictionary = {};
    get dictionary() {
        return { ...this._dictionary };
    }
    get index() {
        return this._index;
    }
    clone() {
        const lexer = new Lexer();
        lexer.load(this._code, this._index);
        for (const key in this._dictionary) {
            lexer.define(key, this._dictionary[key].reader);
        }
        return lexer;
    }
    define(key, reader) {
        this._dictionary[key] = { key, reader };
    }
    expect(keys) {
        if (!Array.isArray(keys)) {
            keys = [keys];
        }
        const definitions = keys.map(key => {
            const reader = this.get(key);
            if (!reader) {
                throw Exception.for('Unknown definition %s', key);
            }
            return reader;
        }).filter(Boolean);
        if (!definitions.length) {
            throw Exception.for('Unknown definitions %s', keys.join(', '));
        }
        const match = this.match(this._code, this._index, keys);
        if (!match) {
            if (this._code[this._index + 10]) {
                throw Exception.for('Unexpected %s ... expecting %s', this._code
                    .substring(this._index, this._index + 10)
                    .replace(/[\n\r]/g, ' ')
                    .trim(), keys.join(' or ')).withPosition(this._index, this.nextSpace());
            }
            else {
                throw Exception.for('Unexpected %s expecting %s', this._code.substring(this._index, this._index + 10), keys.join(' or ')).withPosition(this._index, this.nextSpace());
            }
        }
        this._index = match.end;
        return match;
    }
    get(key) {
        return this._dictionary[key];
    }
    load(code, index = 0) {
        this._code = code;
        this._index = index;
        return this;
    }
    match(code, start, keys) {
        keys = keys || Object.keys(this._dictionary);
        for (let i = 0; i < keys.length; i++) {
            if (!this._dictionary[keys[i]]) {
                throw Exception.for('Unknown definition %s', keys[i]);
            }
            const results = this._dictionary[keys[i]].reader(code, start, this);
            if (results && results.end > start) {
                return results;
            }
        }
        return null;
    }
    next(names) {
        const start = this._index;
        try {
            this.expect(names);
            this._index = start;
            return true;
        }
        catch (error) {
            this._index = start;
            return false;
        }
    }
    optional(names) {
        const start = this._index;
        try {
            return this.expect(names);
        }
        catch (error) {
            this._index = start;
            return undefined;
        }
    }
    read() {
        return this.optional(Object.keys(this.dictionary));
    }
    substring(start, end) {
        return this._code.substring(start, end);
    }
    nextSpace() {
        const index = this._code.indexOf(' ', this._index);
        return index === -1 ? this._code.length : index;
    }
}