expression-evaluation/dst/ParserFrame.js

Expression Evaluation

export class ParserFrame {
    _expr;
    _start;
    _end;
    constructor(_expr, _start = 0, _end = 0) {
        this._expr = _expr;
        this._start = _start;
        this._end = _end;
    }
    get expr() {
        return this._expr;
    }
    get start() {
        return this._start;
    }
    get end() {
        return this._end;
    }
    starts(start) {
        this._start = start;
        return this;
    }
    ends(end) {
        this._end = end;
        return this;
    }
    frame(token) {
        return token
            ? new ParserFrame(this._expr, this._expr.indexOf(token), this._expr.indexOf(token) + token.length)
            : new ParserFrame(this._expr, this._start, this._end);
    }
    throwError(message) {
        const offset = this._start < 32 ? 0 : this._start - 32;
        const length = this._end < this._start ? 0 : this._end - this._start - 1;
        throw new Error(`error: ${message} at position ${this._start}:\n${this._expr.substring(offset, offset + 60)}\n` +
            `${' '.repeat(this._expr.substring(offset, this._start).length)}^${'\''.repeat(length)}`);
    }
}