decoded_sourcemap_from_generator() — svelte Function Reference

Architecture documentation for the decoded_sourcemap_from_generator() function in decode_sourcemap.js from the svelte codebase.

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Entity Profile

Compiler→ Transformer→ decoded_sourcemap_from_generator() — svelte Function Reference

Dependency Diagram

graph TD
  da8acc05_5b76_46d9_65c8_f41b23ed8dc3["decoded_sourcemap_from_generator()"]
  1351e89f_1c35_8e97_8067_5913392f2985["decode_sourcemap.js"]
  da8acc05_5b76_46d9_65c8_f41b23ed8dc3 -->|defined in| 1351e89f_1c35_8e97_8067_5913392f2985
  10d4a3f8_0b0d_01ad_be21_df83b1c0be75["decode_map()"]
  10d4a3f8_0b0d_01ad_be21_df83b1c0be75 -->|calls| da8acc05_5b76_46d9_65c8_f41b23ed8dc3
  style da8acc05_5b76_46d9_65c8_f41b23ed8dc3 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/svelte/src/compiler/preprocess/decode_sourcemap.js lines 11–81

function decoded_sourcemap_from_generator(generator) {
	let previous_generated_line = 1;
	/** @type {number[][][]} */
	const converted_mappings = [[]];
	let result_line = converted_mappings[0];
	let result_segment;
	let mapping;
	const source_idx = generator._sources
		.toArray()
		// @ts-ignore
		.reduce((acc, val, idx) => ((acc[val] = idx), acc), {});
	const name_idx = generator._names
		.toArray()
		// @ts-ignore
		.reduce((acc, val, idx) => ((acc[val] = idx), acc), {});
	const mappings = generator._mappings.toArray();
	for (let i = 0, len = mappings.length; i < len; i++) {
		mapping = mappings[i];
		if (mapping.generatedLine > previous_generated_line) {
			while (mapping.generatedLine > previous_generated_line) {
				converted_mappings.push([]);
				previous_generated_line++;
			}
			result_line = converted_mappings[mapping.generatedLine - 1]; // line is one-based
		} else if (i > 0) {
			const previous_mapping = mappings[i - 1];
			if (
				// sorted by selectivity
				mapping.generatedColumn === previous_mapping.generatedColumn &&
				mapping.originalColumn === previous_mapping.originalColumn &&
				mapping.name === previous_mapping.name &&
				mapping.generatedLine === previous_mapping.generatedLine &&
				mapping.originalLine === previous_mapping.originalLine &&
				mapping.source === previous_mapping.source
			) {
				continue;
			}
		}
		result_line.push([mapping.generatedColumn]);
		result_segment = result_line[result_line.length - 1];
		if (mapping.source != null) {
			result_segment.push(
				...[source_idx[mapping.source], mapping.originalLine - 1, mapping.originalColumn]
			);
			if (mapping.name != null) {
				result_segment.push(name_idx[mapping.name]);
			}
		}
	}

	/**
	 * @type {{
	 *  version: number;
	 * sources: string[];
	 * names: string[];
	 * mappings: number[][][];
	 * file?: string;
	 * }}
	 */
	const map = {
		version: generator._version,
		sources: generator._sources.toArray(),
		names: generator._names.toArray(),
		mappings: converted_mappings
	};
	if (generator._file != null) {
		map.file = generator._file;
	}
	// not needed: map.sourcesContent and map.sourceRoot
	return map;
}