loader-runner
Version:
Runs (webpack) loaders
544 lines (486 loc) • 14.1 kB
JavaScript
/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
;
const { readFile } = require("fs");
const loadLoader = require("./loadLoader");
const HASH_ESCAPE_REGEXP = /#/g;
// UTF-8 encoding of the BOM: EF BB BF
const UTF8_BOM_0 = 0xef;
const UTF8_BOM_1 = 0xbb;
const UTF8_BOM_2 = 0xbf;
function utf8BufferToString(buf) {
// Detect and skip the BOM at the buffer level to avoid materializing the
// prefix as JS string and then re-slicing it.
if (
buf.length >= 3 &&
buf[0] === UTF8_BOM_0 &&
buf[1] === UTF8_BOM_1 &&
buf[2] === UTF8_BOM_2
) {
return buf.toString("utf8", 3);
}
return buf.toString("utf8");
}
/**
* Escape `#` characters with a preceding `\0` byte. Short-circuits when the input contains no `#`, avoiding the regex scan for the common case.
* @param {string} str input string
* @returns {string} escaped string
*/
function escapeHash(str) {
return str.includes("#") ? str.replace(HASH_ESCAPE_REGEXP, "\0#") : str;
}
const PATH_QUERY_FRAGMENT_REGEXP =
/^((?:\0.|[^?#\0])*)(\?(?:\0.|[^#\0])*)?(#.*)?$/;
const ZERO_ESCAPE_REGEXP = /\0(.)/g;
/**
* @param {string} identifier identifier
* @returns {[string, string, string]} parsed identifier
*/
function parseIdentifier(identifier) {
// Fast path for inputs that don't use \0 escaping.
const firstEscape = identifier.indexOf("\0");
if (firstEscape < 0) {
const queryStart = identifier.indexOf("?");
const fragmentStart = identifier.indexOf("#");
if (fragmentStart < 0) {
if (queryStart < 0) {
// No fragment, no query
return [identifier, "", ""];
}
// Query, no fragment
return [
identifier.slice(0, queryStart),
identifier.slice(queryStart),
"",
];
}
if (queryStart < 0 || fragmentStart < queryStart) {
// Fragment, no query
return [
identifier.slice(0, fragmentStart),
"",
identifier.slice(fragmentStart),
];
}
// Query and fragment
return [
identifier.slice(0, queryStart),
identifier.slice(queryStart, fragmentStart),
identifier.slice(fragmentStart),
];
}
const match = PATH_QUERY_FRAGMENT_REGEXP.exec(identifier);
return [
match[1].replace(ZERO_ESCAPE_REGEXP, "$1"),
match[2] ? match[2].replace(ZERO_ESCAPE_REGEXP, "$1") : "",
match[3] || "",
];
}
function dirname(path) {
if (path === "/") return "/";
const i = path.lastIndexOf("/");
const j = path.lastIndexOf("\\");
const i2 = path.indexOf("/");
const j2 = path.indexOf("\\");
const idx = i > j ? i : j;
const idx2 = i > j ? i2 : j2;
if (idx < 0) return path;
if (idx === idx2) return path.slice(0, idx + 1);
return path.slice(0, idx);
}
function createLoaderObject(loader) {
const obj = {
path: null,
query: null,
fragment: null,
options: null,
ident: null,
normal: null,
pitch: null,
raw: null,
data: null,
pitchExecuted: false,
normalExecuted: false,
};
Object.defineProperty(obj, "request", {
enumerable: true,
get() {
return escapeHash(obj.path) + escapeHash(obj.query) + obj.fragment;
},
set(value) {
if (typeof value === "string") {
const [path, query, fragment] = parseIdentifier(value);
obj.path = path;
obj.query = query;
obj.fragment = fragment;
obj.options = undefined;
obj.ident = undefined;
return;
}
if (!value.loader) {
throw new Error(
`request should be a string or object with loader and options (${JSON.stringify(
value
)})`
);
}
const { loader: path, fragment, type, options, ident } = value;
obj.path = path;
obj.fragment = fragment || "";
obj.type = type;
obj.options = options;
obj.ident = ident;
if (options === null || options === undefined) {
obj.query = "";
} else if (typeof options === "string") {
obj.query = `?${options}`;
} else if (ident) {
obj.query = `??${ident}`;
} else if (typeof options === "object" && options.ident) {
obj.query = `??${options.ident}`;
} else {
obj.query = `?${JSON.stringify(options)}`;
}
},
});
obj.request = loader;
if (Object.preventExtensions) {
Object.preventExtensions(obj);
}
return obj;
}
function runSyncOrAsync(fn, context, args, callback) {
let isSync = true;
let isDone = false;
let isError = false; // internal error
let reportedError = false;
// eslint-disable-next-line func-name-matching
const innerCallback = (context.callback = function innerCallback(
...callbackArgs
) {
if (isDone) {
if (reportedError) return; // ignore
throw new Error("callback(): The callback was already called.");
}
isDone = true;
isSync = false;
try {
callback(...callbackArgs);
} catch (err) {
isError = true;
throw err;
}
});
context.async = function async() {
if (isDone) {
if (reportedError) return; // ignore
throw new Error("async(): The callback was already called.");
}
isSync = false;
return innerCallback;
};
try {
const result = (function LOADER_EXECUTION() {
return fn.apply(context, args);
})();
if (isSync) {
isDone = true;
if (result === undefined) return callback();
if (
result &&
typeof result === "object" &&
typeof result.then === "function"
) {
return result.then((r) => {
callback(null, r);
}, callback);
}
return callback(null, result);
}
} catch (err) {
if (isError) throw err;
if (isDone) {
// loader is already "done", so we cannot use the callback function
// for better debugging we print the error on the console
if (typeof err === "object" && err.stack) {
// eslint-disable-next-line no-console
console.error(err.stack);
} else {
// eslint-disable-next-line no-console
console.error(err);
}
return;
}
isDone = true;
reportedError = true;
callback(err);
}
}
function convertArgs(args, raw) {
if (!raw && Buffer.isBuffer(args[0])) {
args[0] = utf8BufferToString(args[0]);
} else if (raw && typeof args[0] === "string") {
args[0] = Buffer.from(args[0], "utf8");
}
}
function iterateNormalLoaders(options, loaderContext, args, callback) {
while (loaderContext.loaderIndex >= 0) {
const currentLoaderObject =
loaderContext.loaders[loaderContext.loaderIndex];
if (currentLoaderObject.normalExecuted) {
loaderContext.loaderIndex--;
continue;
}
const fn = currentLoaderObject.normal;
currentLoaderObject.normalExecuted = true;
if (!fn) continue;
convertArgs(args, currentLoaderObject.raw);
return runSyncOrAsync(fn, loaderContext, args, (err, ...nextArgs) => {
if (err) return callback(err);
iterateNormalLoaders(options, loaderContext, nextArgs, callback);
});
}
return callback(null, args);
}
function processResource(options, loaderContext, callback) {
// set loader index to last loader
loaderContext.loaderIndex = loaderContext.loaders.length - 1;
const { resourcePath } = loaderContext;
if (!resourcePath) {
return iterateNormalLoaders(options, loaderContext, [null], callback);
}
options.processResource(loaderContext, resourcePath, (err, ...args) => {
if (err) return callback(err);
// eslint-disable-next-line prefer-destructuring
options.resourceBuffer = args[0];
iterateNormalLoaders(options, loaderContext, args, callback);
});
}
function iteratePitchingLoaders(options, loaderContext, callback) {
// Iterative walk over already-pitched loaders without recursion.
while (loaderContext.loaderIndex < loaderContext.loaders.length) {
const currentLoaderObject =
loaderContext.loaders[loaderContext.loaderIndex];
if (currentLoaderObject.pitchExecuted) {
loaderContext.loaderIndex++;
continue;
}
return loadLoader(currentLoaderObject, (err) => {
if (err) {
loaderContext.cacheable(false);
return callback(err);
}
const fn = currentLoaderObject.pitch;
currentLoaderObject.pitchExecuted = true;
if (!fn) return iteratePitchingLoaders(options, loaderContext, callback);
runSyncOrAsync(
fn,
loaderContext,
[
loaderContext.remainingRequest,
loaderContext.previousRequest,
(currentLoaderObject.data = {}),
],
(pitchErr, ...args) => {
if (pitchErr) return callback(pitchErr);
// Determine whether to continue the pitching process based on
// argument values (as opposed to argument presence) in order
// to support synchronous and asynchronous usages. Inline loop
// avoids allocating a predicate closure per pitched loader.
let hasArg = false;
for (let i = 0; i < args.length; i++) {
if (args[i] !== undefined) {
hasArg = true;
break;
}
}
if (hasArg) {
loaderContext.loaderIndex--;
iterateNormalLoaders(options, loaderContext, args, callback);
} else {
iteratePitchingLoaders(options, loaderContext, callback);
}
}
);
});
}
// Reached the end: move on to processing the resource itself.
return processResource(options, loaderContext, callback);
}
/**
* Join loader requests into a single `!`-separated string for a range of loader indices.
* @param {object[]} loaders loader objects
* @param {number} start inclusive start index
* @param {number} end exclusive end index
* @param {string} resource resource string
* @returns {string} joined request
*/
function joinRequests(loaders, start, end, resource) {
let result = "";
for (let i = start; i < end; i++) {
result += `${loaders[i].request}!`;
}
return result + resource;
}
module.exports.getContext = function getContext(resource) {
const [path] = parseIdentifier(resource);
return dirname(path);
};
module.exports.runLoaders = function runLoaders(options, callback) {
// read options
const resource = options.resource || "";
const loaderContext = options.context || {};
const processResourceFn =
options.processResource ||
((readResource, context, res, cb) => {
context.addDependency(res);
readResource(res, cb);
}).bind(null, options.readResource || readFile);
const splittedResource = resource && parseIdentifier(resource);
const resourcePath = splittedResource ? splittedResource[0] : "";
const resourceQuery = splittedResource ? splittedResource[1] : "";
const resourceFragment = splittedResource ? splittedResource[2] : "";
const contextDirectory = resourcePath ? dirname(resourcePath) : null;
// execution state
let requestCacheable = true;
const fileDependencies = [];
const contextDependencies = [];
const missingDependencies = [];
// prepare loader objects
const loaders = (options.loaders || []).map(createLoaderObject);
loaderContext.context = contextDirectory;
loaderContext.loaderIndex = 0;
loaderContext.loaders = loaders;
loaderContext.resourcePath = resourcePath;
loaderContext.resourceQuery = resourceQuery;
loaderContext.resourceFragment = resourceFragment;
loaderContext.async = null;
loaderContext.callback = null;
loaderContext.cacheable = (flag) => {
if (flag === false) {
requestCacheable = false;
}
};
loaderContext.dependency = loaderContext.addDependency = (file) => {
fileDependencies.push(file);
};
loaderContext.addContextDependency = (context) => {
contextDependencies.push(context);
};
loaderContext.addMissingDependency = (context) => {
missingDependencies.push(context);
};
loaderContext.getDependencies = () => fileDependencies.slice();
loaderContext.getContextDependencies = () => contextDependencies.slice();
loaderContext.getMissingDependencies = () => missingDependencies.slice();
loaderContext.clearDependencies = () => {
fileDependencies.length = 0;
contextDependencies.length = 0;
missingDependencies.length = 0;
requestCacheable = true;
};
Object.defineProperty(loaderContext, "resource", {
enumerable: true,
get() {
return (
escapeHash(loaderContext.resourcePath) +
escapeHash(loaderContext.resourceQuery) +
loaderContext.resourceFragment
);
},
set(value) {
const splitted = value && parseIdentifier(value);
loaderContext.resourcePath = splitted ? splitted[0] : "";
loaderContext.resourceQuery = splitted ? splitted[1] : "";
loaderContext.resourceFragment = splitted ? splitted[2] : "";
},
});
Object.defineProperty(loaderContext, "request", {
enumerable: true,
get() {
return joinRequests(
loaders,
0,
loaders.length,
loaderContext.resource || ""
);
},
});
Object.defineProperty(loaderContext, "remainingRequest", {
enumerable: true,
get() {
return joinRequests(
loaders,
loaderContext.loaderIndex + 1,
loaders.length,
loaderContext.resource
);
},
});
Object.defineProperty(loaderContext, "currentRequest", {
enumerable: true,
get() {
return joinRequests(
loaders,
loaderContext.loaderIndex,
loaders.length,
loaderContext.resource
);
},
});
Object.defineProperty(loaderContext, "previousRequest", {
enumerable: true,
get() {
const end = loaderContext.loaderIndex;
if (end === 0) return "";
let result = loaders[0].request;
for (let i = 1; i < end; i++) {
result += `!${loaders[i].request}`;
}
return result;
},
});
Object.defineProperty(loaderContext, "query", {
enumerable: true,
get() {
const entry = loaders[loaderContext.loaderIndex];
return entry.options && typeof entry.options === "object"
? entry.options
: entry.query;
},
});
Object.defineProperty(loaderContext, "data", {
enumerable: true,
get() {
return loaders[loaderContext.loaderIndex].data;
},
});
// finish loader context
if (Object.preventExtensions) {
Object.preventExtensions(loaderContext);
}
const processOptions = {
resourceBuffer: null,
processResource: processResourceFn,
};
iteratePitchingLoaders(processOptions, loaderContext, (err, result) => {
if (err) {
return callback(err, {
cacheable: requestCacheable,
fileDependencies,
contextDependencies,
missingDependencies,
});
}
callback(null, {
result,
resourceBuffer: processOptions.resourceBuffer,
cacheable: requestCacheable,
fileDependencies,
contextDependencies,
missingDependencies,
});
});
};