blob: 08a62d1b83de9eceaa43d1338d01869771d67e91 [file] [log] [blame]
/*
* Copyright (C) 2015, 2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
// https://whatwg.github.io/loader/#loader-object
// Module Loader has several hooks that can be customized by the platform.
// For example, the [[Fetch]] hook can be provided by the JavaScriptCore shell
// as fetching the payload from the local file system.
// Currently, there are 4 hooks.
// 1. Loader.resolve
// 2. Loader.fetch
@globalPrivate
function setStateToMax(entry, newState)
{
// https://whatwg.github.io/loader/#set-state-to-max
"use strict";
if (entry.state < newState)
entry.state = newState;
}
@globalPrivate
function newRegistryEntry(key)
{
// https://whatwg.github.io/loader/#registry
//
// Each registry entry becomes one of the 5 states.
// 1. Fetch
// Ready to fetch (or now fetching) the resource of this module.
// Typically, we fetch the source code over the network or from the file system.
// a. If the status is Fetch and there is no entry.fetch promise, the entry is ready to fetch.
// b. If the status is Fetch and there is the entry.fetch promise, the entry is just fetching the resource.
//
// 2. Instantiate (AnalyzeModule)
// Ready to instantiate (or now instantiating) the module record from the fetched
// source code.
// Typically, we parse the module code, extract the dependencies and binding information.
// a. If the status is Instantiate and there is no entry.instantiate promise, the entry is ready to instantiate.
// b. If the status is Instantiate and there is the entry.fetch promise, the entry is just instantiating
// the module record.
//
// 3. Satisfy
// Ready to request the dependent modules (or now requesting & resolving).
// Without this state, the current draft causes infinite recursion when there is circular dependency.
// a. If the status is Satisfy and there is no entry.satisfy promise, the entry is ready to resolve the dependencies.
// b. If the status is Satisfy and there is the entry.satisfy promise, the entry is just resolving
// the dependencies.
//
// 4. Link
// Ready to link the module with the other modules.
// Linking means that the module imports and exports the bindings from/to the other modules.
//
// 5. Ready
// The module is linked, so the module is ready to be executed.
//
// Each registry entry has the 4 promises; "fetch", "instantiate" and "satisfy".
// They are assigned when starting the each phase. And they are fulfilled when the each phase is completed.
//
// In the current module draft, linking will be performed after the whole modules are instantiated and the dependencies are resolved.
// And execution is also done after the all modules are linked.
//
// TODO: We need to exploit the way to execute the module while fetching non-related modules.
// One solution; introducing the ready promise chain to execute the modules concurrently while keeping
// the execution order.
"use strict";
return {
key: key,
state: @ModuleFetch,
fetch: @undefined,
instantiate: @undefined,
satisfy: @undefined,
dependencies: [], // To keep the module order, we store the module keys in the array.
module: @undefined, // JSModuleRecord
linkError: @undefined,
linkSucceeded: true,
evaluated: false,
};
}
function ensureRegistered(key)
{
// https://whatwg.github.io/loader/#ensure-registered
"use strict";
var entry = this.registry.@get(key);
if (entry)
return entry;
entry = @newRegistryEntry(key);
this.registry.@set(key, entry);
return entry;
}
function forceFulfillPromise(promise, value)
{
"use strict";
@assert(@isPromise(promise));
if ((@getPromiseInternalField(promise, @promiseFieldFlags) & @promiseStateMask) === @promiseStatePending)
@fulfillPromise(promise, value);
}
function fulfillFetch(entry, source)
{
// https://whatwg.github.io/loader/#fulfill-fetch
"use strict";
if (!entry.fetch)
entry.fetch = @newPromiseCapability(@InternalPromise).@promise;
this.forceFulfillPromise(entry.fetch, source);
@setStateToMax(entry, @ModuleInstantiate);
}
// Loader.
function requestFetch(entry, parameters, fetcher)
{
// https://whatwg.github.io/loader/#request-fetch
"use strict";
if (entry.fetch) {
var currentAttempt = entry.fetch;
if (entry.state !== @ModuleFetch)
return currentAttempt;
return currentAttempt.catch((error) => {
// Even if the existing fetching request failed, this attempt may succeed.
// For example, previous attempt used invalid integrity="" value. But this
// request could have the correct integrity="" value. In that case, we should
// retry fetching for this request.
// https://html.spec.whatwg.org/#fetch-a-single-module-script
if (currentAttempt === entry.fetch)
entry.fetch = @undefined;
return this.requestFetch(entry, parameters, fetcher);
});
}
// Hook point.
// 2. Loader.fetch
// https://whatwg.github.io/loader/#browser-fetch
// Take the key and fetch the resource actually.
// For example, JavaScriptCore shell can provide the hook fetching the resource
// from the local file system.
var fetchPromise = this.fetch(entry.key, parameters, fetcher).then((source) => {
@setStateToMax(entry, @ModuleInstantiate);
return source;
});
entry.fetch = fetchPromise;
return fetchPromise;
}
function requestInstantiate(entry, parameters, fetcher)
{
// https://whatwg.github.io/loader/#request-instantiate
"use strict";
// entry.instantiate is set if fetch succeeds.
if (entry.instantiate)
return entry.instantiate;
var instantiatePromise = (async () => {
var source = await this.requestFetch(entry, parameters, fetcher);
// https://html.spec.whatwg.org/#fetch-a-single-module-script
// Now fetching request succeeds. Then even if instantiation fails, we should cache it.
// Instantiation won't be retried.
if (entry.instantiate)
return await entry.instantiate;
entry.instantiate = instantiatePromise;
var key = entry.key;
var moduleRecord = await this.parseModule(key, source);
var dependenciesMap = moduleRecord.dependenciesMap;
var requestedModules = this.requestedModules(moduleRecord);
var dependencies = @newArrayWithSize(requestedModules.length);
for (var i = 0, length = requestedModules.length; i < length; ++i) {
var depName = requestedModules[i];
var depKey = this.resolveSync(depName, key, fetcher);
var depEntry = this.ensureRegistered(depKey);
@putByValDirect(dependencies, i, depEntry);
dependenciesMap.@set(depName, depEntry);
}
entry.dependencies = dependencies;
entry.module = moduleRecord;
@setStateToMax(entry, @ModuleSatisfy);
return entry;
})();
return instantiatePromise;
}
function requestSatisfy(entry, parameters, fetcher, visited)
{
// https://html.spec.whatwg.org/#internal-module-script-graph-fetching-procedure
"use strict";
if (entry.satisfy)
return entry.satisfy;
visited.@add(entry);
var satisfyPromise = this.requestInstantiate(entry, parameters, fetcher).then((entry) => {
if (entry.satisfy)
return entry.satisfy;
var depLoads = @newArrayWithSize(entry.dependencies.length);
for (var i = 0, length = entry.dependencies.length; i < length; ++i) {
var depEntry = entry.dependencies[i];
var promise;
// Recursive resolving. The dependencies of this entry is being resolved or already resolved.
// Stop tracing the circular dependencies.
// But to retrieve the instantiated module record correctly,
// we need to wait for the instantiation for the dependent module.
// For example, reaching here, the module is starting resolving the dependencies.
// But the module may or may not reach the instantiation phase in the loader's pipeline.
// If we wait for the Satisfy for this module, it construct the circular promise chain and
// rejected by the Promises runtime. Since only we need is the instantiated module, instead of waiting
// the Satisfy for this module, we just wait Instantiate for this.
if (visited.@has(depEntry))
promise = this.requestInstantiate(depEntry, @undefined, fetcher);
else {
// Currently, module loader do not pass any information for non-top-level module fetching.
promise = this.requestSatisfy(depEntry, @undefined, fetcher, visited);
}
@putByValDirect(depLoads, i, promise);
}
return @InternalPromise.internalAll(depLoads).then((entries) => {
if (entry.satisfy)
return entry;
@setStateToMax(entry, @ModuleLink);
entry.satisfy = satisfyPromise;
return entry;
});
});
return satisfyPromise;
}
// Linking semantics.
function link(entry, fetcher)
{
// https://html.spec.whatwg.org/#fetch-the-descendants-of-and-instantiate-a-module-script
"use strict";
if (!entry.linkSucceeded)
throw entry.linkError;
if (entry.state === @ModuleReady)
return;
@setStateToMax(entry, @ModuleReady);
try {
// Since we already have the "dependencies" field,
// we can call moduleDeclarationInstantiation with the correct order
// without constructing the dependency graph by calling dependencyGraph.
var dependencies = entry.dependencies;
for (var i = 0, length = dependencies.length; i < length; ++i)
this.link(dependencies[i], fetcher);
this.moduleDeclarationInstantiation(entry.module, fetcher);
} catch (error) {
entry.linkSucceeded = false;
entry.linkError = error;
throw error;
}
}
// Module semantics.
function moduleEvaluation(entry, fetcher)
{
// http://www.ecma-international.org/ecma-262/6.0/#sec-moduleevaluation
"use strict";
if (entry.evaluated)
return;
entry.evaluated = true;
// The contents of the [[RequestedModules]] is cloned into entry.dependencies.
var dependencies = entry.dependencies;
for (var i = 0, length = dependencies.length; i < length; ++i)
this.moduleEvaluation(dependencies[i], fetcher);
this.evaluate(entry.key, entry.module, fetcher);
}
// APIs to control the module loader.
function provideFetch(key, value)
{
"use strict";
var entry = this.ensureRegistered(key);
if (entry.state > @ModuleFetch)
@throwTypeError("Requested module is already fetched.");
this.fulfillFetch(entry, value);
}
async function loadModule(moduleName, parameters, fetcher)
{
"use strict";
// Loader.resolve hook point.
// resolve: moduleName => Promise(moduleKey)
// Take the name and resolve it to the unique identifier for the resource location.
// For example, take the "jquery" and return the URL for the resource.
var key = await this.resolve(moduleName, @undefined, fetcher);
var entry = await this.requestSatisfy(this.ensureRegistered(key), parameters, fetcher, new @Set);
return entry.key;
}
function linkAndEvaluateModule(key, fetcher)
{
"use strict";
var entry = this.ensureRegistered(key);
if (entry.state < @ModuleLink)
@throwTypeError("Requested module is not instantiated yet.");
this.link(entry, fetcher);
return this.moduleEvaluation(entry, fetcher);
}
async function loadAndEvaluateModule(moduleName, parameters, fetcher)
{
"use strict";
var key = await this.loadModule(moduleName, parameters, fetcher);
return await this.linkAndEvaluateModule(key, fetcher);
}
async function requestImportModule(key, parameters, fetcher)
{
"use strict";
var entry = await this.requestSatisfy(this.ensureRegistered(key), parameters, fetcher, new @Set);
this.linkAndEvaluateModule(entry.key, fetcher);
return this.getModuleNamespaceObject(entry.module);
}
function dependencyKeysIfEvaluated(key)
{
"use strict";
var entry = this.registry.@get(key);
if (!entry || !entry.evaluated)
return null;
var dependencies = entry.dependencies;
var length = dependencies.length;
var result = new @Array(length);
for (var i = 0; i < length; ++i)
result[i] = dependencies[i].key;
return result;
}