Method getIndexFromLoc

packages/plugin-kit/src/source-code.js:489–543

* Converts a `{ line: number, column: number }` pair into a source text index. * @param {Object} loc A line/column location. * @param {number} loc.line The line number of the location. (0 or 1-indexed based on language.) * @param {number} loc.column The column number of the location. (0 or 1-i

(loc)

	 * @public
	 */
	getIndexFromLoc(loc) {
		if (
			loc === null ||
			typeof loc !== "object" ||
			typeof loc.line !== "number" ||
			typeof loc.column !== "number"
		) {
			throw new TypeError(
				"Expected `loc` to be an object with numeric `line` and `column` properties.",
			);
		}

		const {
			start: { line: lineStart, column: columnStart },
			end: { line: lineEnd, column: columnEnd },
		} = this.getLoc(this.ast);

		if (loc.line < lineStart || lineEnd < loc.line) {
			throw new RangeError(
				`Line number out of range (line ${loc.line} requested). Valid range: ${lineStart}-${lineEnd}`,
			);
		}

		// If the loc is at the start, return the start index of the root node.
		if (loc.line === lineStart && loc.column === columnStart) {
			return 0;
		}

		// If the loc is at the end, return the index one "spot" past the last character of the file.
		if (loc.line === lineEnd && loc.column === columnEnd) {
			return this.text.length;
		}

		// Ensure `#lineStartIndices` are lazily calculated.
		this.#ensureLineStartIndicesFromLoc(loc, lineStart);

		const isLastLine = loc.line === lineEnd;
		const lineStartIndex = this.#lineStartIndices[loc.line - lineStart];
		const lineEndIndex = isLastLine
			? this.text.length
			: this.#lineStartIndices[loc.line - lineStart + 1];
		const positionIndex = lineStartIndex + loc.column - columnStart;

		if (
			loc.column < columnStart ||
			(isLastLine && positionIndex > lineEndIndex) ||
			(!isLastLine && positionIndex >= lineEndIndex)
		) {
			throw new RangeError(
				`Column number out of range (column ${loc.column} requested). Valid range for line ${loc.line}: ${columnStart}-${lineEndIndex - lineStartIndex + columnStart + (isLastLine ? 0 : -1)}`,
			);
		}

		return positionIndex;
	}

	/**
	 * Returns the range information for the given node or token.