webpack/lib/asset/AssetSourceGenerator.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 Sergey Melyukov @smelukov
*/

"use strict";

const { RawSource } = require("webpack-sources");
const ConcatenationScope = require("../ConcatenationScope");
const Generator = require("../Generator");
const {
	NO_TYPES,
	CSS_URL_TYPES,
	JS_TYPES,
	JS_AND_CSS_URL_TYPES
} = require("../ModuleSourceTypesConstants");
const RuntimeGlobals = require("../RuntimeGlobals");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../Generator").GenerateContext} GenerateContext */
/** @typedef {import("../Module").ConcatenationBailoutReasonContext} ConcatenationBailoutReasonContext */
/** @typedef {import("../Module").SourceTypes} SourceTypes */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../NormalModule")} NormalModule */

class AssetSourceGenerator extends Generator {
	/**
	 * @param {ModuleGraph} moduleGraph the module graph
	 */
	constructor(moduleGraph) {
		super();

		this._moduleGraph = moduleGraph;
	}

	/**
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {GenerateContext} generateContext context for generate
	 * @returns {Source | null} generated code
	 */
	generate(
		module,
		{ type, concatenationScope, getData, runtimeTemplate, runtimeRequirements }
	) {
		const originalSource = module.originalSource();
		const data = getData ? getData() : undefined;

		switch (type) {
			case "javascript": {
				if (!originalSource) {
					return new RawSource("");
				}

				const content = originalSource.source();
				const encodedSource =
					typeof content === "string" ? content : content.toString("utf-8");

				let sourceContent;
				if (concatenationScope) {
					concatenationScope.registerNamespaceExport(
						ConcatenationScope.NAMESPACE_OBJECT_EXPORT
					);
					sourceContent = `${runtimeTemplate.supportsConst() ? "const" : "var"} ${
						ConcatenationScope.NAMESPACE_OBJECT_EXPORT
					} = ${JSON.stringify(encodedSource)};`;
				} else {
					runtimeRequirements.add(RuntimeGlobals.module);
					sourceContent = `${RuntimeGlobals.module}.exports = ${JSON.stringify(
						encodedSource
					)};`;
				}
				return new RawSource(sourceContent);
			}
			case "css-url": {
				if (!originalSource) {
					return null;
				}

				const content = originalSource.source();
				const encodedSource =
					typeof content === "string" ? content : content.toString("utf-8");

				if (data) {
					data.set("url", { [type]: encodedSource });
				}
				return null;
			}
			default:
				return null;
		}
	}

	/**
	 * @param {Error} error the error
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {GenerateContext} generateContext context for generate
	 * @returns {Source | null} generated code
	 */
	generateError(error, module, generateContext) {
		switch (generateContext.type) {
			case "javascript": {
				return new RawSource(
					`throw new Error(${JSON.stringify(error.message)});`
				);
			}
			default:
				return null;
		}
	}

	/**
	 * @param {NormalModule} module module for which the bailout reason should be determined
	 * @param {ConcatenationBailoutReasonContext} context context
	 * @returns {string | undefined} reason why this module can't be concatenated, undefined when it can be concatenated
	 */
	getConcatenationBailoutReason(module, context) {
		return undefined;
	}

	/**
	 * @param {NormalModule} module fresh module
	 * @returns {SourceTypes} available types (do not mutate)
	 */
	getTypes(module) {
		/** @type {Set<string>} */
		const sourceTypes = new Set();
		const connections = this._moduleGraph.getIncomingConnections(module);

		for (const connection of connections) {
			if (!connection.originModule) {
				continue;
			}

			sourceTypes.add(connection.originModule.type.split("/")[0]);
		}

		if (sourceTypes.size > 0) {
			if (sourceTypes.has("javascript") && sourceTypes.has("css")) {
				return JS_AND_CSS_URL_TYPES;
			} else if (sourceTypes.has("css")) {
				return CSS_URL_TYPES;
			}
			return JS_TYPES;
		}

		return NO_TYPES;
	}

	/**
	 * @param {NormalModule} module the module
	 * @param {string=} type source type
	 * @returns {number} estimate size of the module
	 */
	getSize(module, type) {
		const originalSource = module.originalSource();

		if (!originalSource) {
			return 0;
		}

		// Example: m.exports="abcd"
		return originalSource.size() + 12;
	}
}

module.exports = AssetSourceGenerator;