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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.
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/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Sergey Melyukov @smelukov
*/

"use strict";

const { UsageState } = require("../ExportsInfo");

/** @typedef {import("estree").Node} AnyNode */
/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../Module")} Module */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../ModuleGraphConnection")} ModuleGraphConnection */
/** @typedef {import("../ModuleGraphConnection").ConnectionState} ConnectionState */
/** @typedef {import("../Parser").ParserState} ParserState */
/** @typedef {import("../javascript/JavascriptParser")} JavascriptParser */
/** @typedef {import("../util/runtime").RuntimeSpec} RuntimeSpec */

/** @typedef {Map | true | undefined>} InnerGraph */
/** @typedef {function(boolean | Set | undefined): void} UsageCallback */

/**
 * @typedef {object} StateObject
 * @property {InnerGraph} innerGraph
 * @property {TopLevelSymbol=} currentTopLevelSymbol
 * @property {Map>} usageCallbackMap
 */

/** @typedef {false|StateObject} State */

/** @type {WeakMap} */
const parserStateMap = new WeakMap();
const topLevelSymbolTag = Symbol("top level symbol");

/**
 * @param {ParserState} parserState parser state
 * @returns {State | undefined} state
 */
function getState(parserState) {
	return parserStateMap.get(parserState);
}

/**
 * @param {ParserState} parserState parser state
 * @returns {void}
 */
exports.bailout = parserState => {
	parserStateMap.set(parserState, false);
};

/**
 * @param {ParserState} parserState parser state
 * @returns {void}
 */
exports.enable = parserState => {
	const state = parserStateMap.get(parserState);
	if (state === false) {
		return;
	}
	parserStateMap.set(parserState, {
		innerGraph: new Map(),
		currentTopLevelSymbol: undefined,
		usageCallbackMap: new Map()
	});
};

/**
 * @param {ParserState} parserState parser state
 * @returns {boolean} true, when enabled
 */
exports.isEnabled = parserState => {
	const state = parserStateMap.get(parserState);
	return !!state;
};

/**
 * @param {ParserState} state parser state
 * @param {TopLevelSymbol | null} symbol the symbol, or null for all symbols
 * @param {string | TopLevelSymbol | true} usage usage data
 * @returns {void}
 */
exports.addUsage = (state, symbol, usage) => {
	const innerGraphState = getState(state);

	if (innerGraphState) {
		const { innerGraph } = innerGraphState;
		const info = innerGraph.get(symbol);
		if (usage === true) {
			innerGraph.set(symbol, true);
		} else if (info === undefined) {
			innerGraph.set(symbol, new Set([usage]));
		} else if (info !== true) {
			info.add(usage);
		}
	}
};

/**
 * @param {JavascriptParser} parser the parser
 * @param {string} name name of variable
 * @param {string | TopLevelSymbol | true} usage usage data
 * @returns {void}
 */
exports.addVariableUsage = (parser, name, usage) => {
	const symbol =
		/** @type {TopLevelSymbol} */ (
			parser.getTagData(name, topLevelSymbolTag)
		) || exports.tagTopLevelSymbol(parser, name);
	if (symbol) {
		exports.addUsage(parser.state, symbol, usage);
	}
};

/**
 * @param {ParserState} state parser state
 * @returns {void}
 */
exports.inferDependencyUsage = state => {
	const innerGraphState = getState(state);

	if (!innerGraphState) {
		return;
	}

	const { innerGraph, usageCallbackMap } = innerGraphState;
	const processed = new Map();
	// flatten graph to terminal nodes (string, undefined or true)
	const nonTerminal = new Set(innerGraph.keys());
	while (nonTerminal.size > 0) {
		for (const key of nonTerminal) {
			/** @type {Set | true} */
			let newSet = new Set();
			let isTerminal = true;
			const value = innerGraph.get(key);
			let alreadyProcessed = processed.get(key);
			if (alreadyProcessed === undefined) {
				alreadyProcessed = new Set();
				processed.set(key, alreadyProcessed);
			}
			if (value !== true && value !== undefined) {
				for (const item of value) {
					alreadyProcessed.add(item);
				}
				for (const item of value) {
					if (typeof item === "string") {
						newSet.add(item);
					} else {
						const itemValue = innerGraph.get(item);
						if (itemValue === true) {
							newSet = true;
							break;
						}
						if (itemValue !== undefined) {
							for (const i of itemValue) {
								if (i === key) continue;
								if (alreadyProcessed.has(i)) continue;
								newSet.add(i);
								if (typeof i !== "string") {
									isTerminal = false;
								}
							}
						}
					}
				}
				if (newSet === true) {
					innerGraph.set(key, true);
				} else if (newSet.size === 0) {
					innerGraph.set(key, undefined);
				} else {
					innerGraph.set(key, newSet);
				}
			}
			if (isTerminal) {
				nonTerminal.delete(key);

				// For the global key, merge with all other keys
				if (key === null) {
					const globalValue = innerGraph.get(null);
					if (globalValue) {
						for (const [key, value] of innerGraph) {
							if (key !== null && value !== true) {
								if (globalValue === true) {
									innerGraph.set(key, true);
								} else {
									const newSet = new Set(value);
									for (const item of globalValue) {
										newSet.add(item);
									}
									innerGraph.set(key, newSet);
								}
							}
						}
					}
				}
			}
		}
	}

	/** @type {Map>} */
	for (const [symbol, callbacks] of usageCallbackMap) {
		const usage = /** @type {true | Set | undefined} */ (
			innerGraph.get(symbol)
		);
		for (const callback of callbacks) {
			callback(usage === undefined ? false : usage);
		}
	}
};

/**
 * @param {ParserState} state parser state
 * @param {UsageCallback} onUsageCallback on usage callback
 */
exports.onUsage = (state, onUsageCallback) => {
	const innerGraphState = getState(state);

	if (innerGraphState) {
		const { usageCallbackMap, currentTopLevelSymbol } = innerGraphState;
		if (currentTopLevelSymbol) {
			let callbacks = usageCallbackMap.get(currentTopLevelSymbol);

			if (callbacks === undefined) {
				callbacks = new Set();
				usageCallbackMap.set(currentTopLevelSymbol, callbacks);
			}

			callbacks.add(onUsageCallback);
		} else {
			onUsageCallback(true);
		}
	} else {
		onUsageCallback(undefined);
	}
};

/**
 * @param {ParserState} state parser state
 * @param {TopLevelSymbol | undefined} symbol the symbol
 */
exports.setTopLevelSymbol = (state, symbol) => {
	const innerGraphState = getState(state);

	if (innerGraphState) {
		innerGraphState.currentTopLevelSymbol = symbol;
	}
};

/**
 * @param {ParserState} state parser state
 * @returns {TopLevelSymbol|void} usage data
 */
exports.getTopLevelSymbol = state => {
	const innerGraphState = getState(state);

	if (innerGraphState) {
		return innerGraphState.currentTopLevelSymbol;
	}
};

/**
 * @param {JavascriptParser} parser parser
 * @param {string} name name of variable
 * @returns {TopLevelSymbol | undefined} symbol
 */
exports.tagTopLevelSymbol = (parser, name) => {
	const innerGraphState = getState(parser.state);
	if (!innerGraphState) return;

	parser.defineVariable(name);

	const existingTag = /** @type {TopLevelSymbol} */ (
		parser.getTagData(name, topLevelSymbolTag)
	);
	if (existingTag) {
		return existingTag;
	}

	const fn = new TopLevelSymbol(name);
	parser.tagVariable(name, topLevelSymbolTag, fn);
	return fn;
};

/**
 * @param {Dependency} dependency the dependency
 * @param {Set | boolean} usedByExports usedByExports info
 * @param {ModuleGraph} moduleGraph moduleGraph
 * @param {RuntimeSpec} runtime runtime
 * @returns {boolean} false, when unused. Otherwise true
 */
exports.isDependencyUsedByExports = (
	dependency,
	usedByExports,
	moduleGraph,
	runtime
) => {
	if (usedByExports === false) return false;
	if (usedByExports !== true && usedByExports !== undefined) {
		const selfModule =
			/** @type {Module} */
			(moduleGraph.getParentModule(dependency));
		const exportsInfo = moduleGraph.getExportsInfo(selfModule);
		let used = false;
		for (const exportName of usedByExports) {
			if (exportsInfo.getUsed(exportName, runtime) !== UsageState.Unused)
				used = true;
		}
		if (!used) return false;
	}
	return true;
};

/**
 * @param {Dependency} dependency the dependency
 * @param {Set | boolean | undefined} usedByExports usedByExports info
 * @param {ModuleGraph} moduleGraph moduleGraph
 * @returns {null | false | function(ModuleGraphConnection, RuntimeSpec): ConnectionState} function to determine if the connection is active
 */
exports.getDependencyUsedByExportsCondition = (
	dependency,
	usedByExports,
	moduleGraph
) => {
	if (usedByExports === false) return false;
	if (usedByExports !== true && usedByExports !== undefined) {
		const selfModule =
			/** @type {Module} */
			(moduleGraph.getParentModule(dependency));
		const exportsInfo = moduleGraph.getExportsInfo(selfModule);
		return (connections, runtime) => {
			for (const exportName of usedByExports) {
				if (exportsInfo.getUsed(exportName, runtime) !== UsageState.Unused)
					return true;
			}
			return false;
		};
	}
	return null;
};

class TopLevelSymbol {
	/**
	 * @param {string} name name of the variable
	 */
	constructor(name) {
		this.name = name;
	}
}

exports.TopLevelSymbol = TopLevelSymbol;
exports.topLevelSymbolTag = topLevelSymbolTag;