webpack/lib/CodeGenerationResults.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

const { DEFAULTS } = require("./config/defaults");
const { getOrInsert } = require("./util/MapHelpers");
const { first } = require("./util/SetHelpers");
const createHash = require("./util/createHash");
const { RuntimeSpecMap, runtimeToString } = require("./util/runtime");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("./Module")} Module */
/** @typedef {import("./Module").SourceType} SourceType */
/** @typedef {import("./Module").CodeGenerationResult} CodeGenerationResult */
/** @typedef {import("./Module").CodeGenerationResultData} CodeGenerationResultData */
/** @typedef {import("./Module").ReadOnlyRuntimeRequirements} ReadOnlyRuntimeRequirements */
/** @typedef {import("./util/Hash").HashFunction} HashFunction */
/** @typedef {import("./util/runtime").RuntimeSpec} RuntimeSpec */

/**
 * Stores code generation results keyed by module and runtime so later stages
 * can retrieve emitted sources, metadata, and derived hashes.
 */
class CodeGenerationResults {
	/**
	 * Initializes an empty result store and remembers which hash function should
	 * be used when a result hash needs to be derived lazily.
	 * @param {HashFunction} hashFunction the hash function to use
	 */
	constructor(hashFunction = DEFAULTS.HASH_FUNCTION) {
		/** @type {Map<Module, RuntimeSpecMap<CodeGenerationResult>>} */
		this.map = new Map();
		/** @type {HashFunction} */
		this._hashFunction = hashFunction;
	}

	/**
	 * Returns the code generation result for a module/runtime pair, rejecting
	 * ambiguous lookups where no unique runtime-independent result exists.
	 * @param {Module} module the module
	 * @param {RuntimeSpec} runtime runtime(s)
	 * @returns {CodeGenerationResult} the CodeGenerationResult
	 */
	get(module, runtime) {
		const entry = this.map.get(module);
		if (entry === undefined) {
			throw new Error(
				`No code generation entry for ${module.identifier()} (existing entries: ${Array.from(
					this.map.keys(),
					(m) => m.identifier()
				).join(", ")})`
			);
		}
		if (runtime === undefined) {
			if (entry.size > 1) {
				const results = new Set(entry.values());
				if (results.size !== 1) {
					throw new Error(
						`No unique code generation entry for unspecified runtime for ${module.identifier()} (existing runtimes: ${Array.from(
							entry.keys(),
							(r) => runtimeToString(r)
						).join(", ")}).
Caller might not support runtime-dependent code generation (opt-out via optimization.usedExports: "global").`
					);
				}
				return /** @type {CodeGenerationResult} */ (first(results));
			}
			return /** @type {CodeGenerationResult} */ (entry.values().next().value);
		}
		const result = entry.get(runtime);
		if (result === undefined) {
			throw new Error(
				`No code generation entry for runtime ${runtimeToString(
					runtime
				)} for ${module.identifier()} (existing runtimes: ${Array.from(
					entry.keys(),
					(r) => runtimeToString(r)
				).join(", ")})`
			);
		}
		return result;
	}

	/**
	 * Reports whether a module has a stored result for the requested runtime, or
	 * a single unambiguous result when no runtime is specified.
	 * @param {Module} module the module
	 * @param {RuntimeSpec} runtime runtime(s)
	 * @returns {boolean} true, when we have data for this
	 */
	has(module, runtime) {
		const entry = this.map.get(module);
		if (entry === undefined) {
			return false;
		}
		if (runtime !== undefined) {
			return entry.has(runtime);
		} else if (entry.size > 1) {
			const results = new Set(entry.values());
			return results.size === 1;
		}
		return entry.size === 1;
	}

	/**
	 * Returns a generated source of the requested source type from a stored code
	 * generation result.
	 * @param {Module} module the module
	 * @param {RuntimeSpec} runtime runtime(s)
	 * @param {SourceType} sourceType the source type
	 * @returns {Source} a source
	 */
	getSource(module, runtime, sourceType) {
		return /** @type {Source} */ (
			this.get(module, runtime).sources.get(sourceType)
		);
	}

	/**
	 * Returns the runtime requirements captured during code generation for the
	 * requested module/runtime pair.
	 * @param {Module} module the module
	 * @param {RuntimeSpec} runtime runtime(s)
	 * @returns {ReadOnlyRuntimeRequirements | null} runtime requirements
	 */
	getRuntimeRequirements(module, runtime) {
		return this.get(module, runtime).runtimeRequirements;
	}

	/**
	 * Returns an arbitrary metadata entry recorded during code generation.
	 * @param {Module} module the module
	 * @param {RuntimeSpec} runtime runtime(s)
	 * @param {string} key data key
	 * @returns {ReturnType<CodeGenerationResultData["get"]>} data generated by code generation
	 */
	getData(module, runtime, key) {
		const data = this.get(module, runtime).data;
		return data === undefined ? undefined : data.get(key);
	}

	/**
	 * Returns a stable hash for the generated sources and runtime requirements,
	 * computing and caching it on first access.
	 * @param {Module} module the module
	 * @param {RuntimeSpec} runtime runtime(s)
	 * @returns {string} hash of the code generation
	 */
	getHash(module, runtime) {
		const info = this.get(module, runtime);
		if (info.hash !== undefined) return info.hash;
		const hash = createHash(this._hashFunction);
		for (const [type, source] of info.sources) {
			hash.update(type);
			source.updateHash(hash);
		}
		if (info.runtimeRequirements) {
			for (const rr of info.runtimeRequirements) hash.update(rr);
		}
		return (info.hash = hash.digest("hex"));
	}

	/**
	 * Stores a code generation result for a module/runtime pair, creating the
	 * per-module runtime map when needed.
	 * @param {Module} module the module
	 * @param {RuntimeSpec} runtime runtime(s)
	 * @param {CodeGenerationResult} result result from module
	 * @returns {void}
	 */
	add(module, runtime, result) {
		const map = getOrInsert(
			this.map,
			module,
			() =>
				/** @type {RuntimeSpecMap<CodeGenerationResult>} */
				new RuntimeSpecMap()
		);
		map.set(runtime, result);
	}
}

module.exports = CodeGenerationResults;