Bug 1688879 - Part 3: Parse and register an import map. r=jonco,yulia

Implement
https://wicg.github.io/import-maps/#parse-an-import-map-string,
and
https://wicg.github.io/import-maps/#register-an-import-map

Differential Revision: https://phabricator.services.mozilla.com/D142071

dom/locales/en-US/chrome/dom/dom.properties

@@ -323,6 +323,13 @@ ScriptSourceNotAllowed=<script> source URI is not allowed in this document: “%
 ModuleSourceNotAllowed=Module source URI is not allowed in this document: “%S”.
 WebExtContentScriptModuleSourceNotAllowed=WebExtension content scripts may only load modules with moz-extension URLs and not: “%S”.
 ModuleResolveFailure=Error resolving module specifier “%S”. Relative module specifiers must start with “./”, “../” or “/”.
+ImportMapInvalidTopLevelKey=An invalid top-level key “%S” was present in the import map.
+ImportMapEmptySpecifierKeys=Specifier keys cannot be empty strings.
+ImportMapAddressesNotStrings=Addresses need to be strings.
+ImportMapInvalidAddress=Address “%S” was invalid.
+# %1$S is the specifier key, %2$S is the URL.
+ImportMapAddressNotEndsWithSlash=An invalid address was given for the specifier key “%1$S”; since “%1$S” ended in a slash, the address “%2$S” needs to as well.
+ImportMapScopePrefixNotParseable=The scope prefix URL “%S” was not parseable.
 # LOCALIZATION NOTE: %1$S is the invalid property value and %2$S is the property name.
 InvalidKeyframePropertyValue=Keyframe property value “%1$S” is invalid according to the syntax for “%2$S”.
 # LOCALIZATION NOTE: Do not translate "ReadableStream".

dom/script/ScriptLoader.cpp

@@ -822,7 +822,7 @@ already_AddRefed<ScriptLoadRequest> ScriptLoader::CreateLoadRequest(
       aCORSMode, aReferrerPolicy, aTriggeringPrincipal, domElement);
   RefPtr<ScriptLoadContext> context = new ScriptLoadContext();
 
-  if (aKind == ScriptKind::eClassic) {
+  if (aKind == ScriptKind::eClassic || aKind == ScriptKind::eImportMap) {
     RefPtr<ScriptLoadRequest> aRequest = new ScriptLoadRequest(
         aKind, aURI, fetchOptions, aIntegrity, referrer, context);
 
@@ -1166,6 +1166,29 @@ bool ScriptLoader::ProcessInlineScript(nsIScriptElement* aElement,
 
     return false;
   }
+
+  if (request->IsImportMapRequest()) {
+    UniquePtr<ImportMap> importMap = mModuleLoader->ParseImportMap(request);
+
+    // https://wicg.github.io/import-maps/#register-an-import-map
+    //
+    // Step 1. If element’s the script’s result is null, then fire an event
+    // named error at element, and return.
+    if (!importMap) {
+      NS_DispatchToCurrentThread(
+          NewRunnableMethod("nsIScriptElement::FireErrorEvent", aElement,
+                            &nsIScriptElement::FireErrorEvent));
+      return false;
+    }
+
+    // Step 3. Assert: element’s the script’s type is "importmap".
+    MOZ_ASSERT(aElement->GetScriptIsImportMap());
+
+    // Step 4 to step 9 is done in RegisterImportMap.
+    mModuleLoader->RegisterImportMap(std::move(importMap));
+    return false;
+  }
+
   request->mState = ScriptLoadRequest::State::Ready;
   if (aElement->GetParserCreated() == FROM_PARSER_XSLT &&
       (!ReadyToExecuteParserBlockingScripts() || !mXSLTRequests.isEmpty())) {
@@ -2994,6 +3017,19 @@ void ScriptLoader::ReportErrorToConsole(ScriptLoadRequest* aRequest,
                                   params, nullptr, u""_ns, lineNo, columnNo);
 }
 
+void ScriptLoader::ReportWarningToConsole(
+    ScriptLoadRequest* aRequest, const char* aMessageName,
+    const nsTArray<nsString>& aParams) const {
+  nsIScriptElement* element =
+      aRequest->GetScriptLoadContext()->GetScriptElement();
+  uint32_t lineNo = element ? element->GetScriptLineNumber() : 0;
+  uint32_t columnNo = element ? element->GetScriptColumnNumber() : 0;
+  nsContentUtils::ReportToConsole(nsIScriptError::warningFlag,
+                                  "Script Loader"_ns, mDocument,
+                                  nsContentUtils::eDOM_PROPERTIES, aMessageName,
+                                  aParams, nullptr, u""_ns, lineNo, columnNo);
+}
+
 void ScriptLoader::ReportPreloadErrorsToConsole(ScriptLoadRequest* aRequest) {
   if (NS_FAILED(aRequest->GetScriptLoadContext()->mUnreportedPreloadError)) {
     ReportErrorToConsole(

dom/script/ScriptLoader.h

@@ -551,6 +551,11 @@ class ScriptLoader final : public JS::loader::ScriptLoaderInterface {
 
   void ReportErrorToConsole(ScriptLoadRequest* aRequest,
                             nsresult aResult) const override;
+
+  void ReportWarningToConsole(
+      ScriptLoadRequest* aRequest, const char* aMessageName,
+      const nsTArray<nsString>& aParams = nsTArray<nsString>()) const override;
+
   void ReportPreloadErrorsToConsole(ScriptLoadRequest* aRequest);
 
   nsresult AttemptAsyncScriptCompile(ScriptLoadRequest* aRequest,

js/loader/ImportMap.cpp

@@ -0,0 +1,441 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ImportMap.h"
+
+#include "js/Array.h"                 // IsArrayObject
+#include "js/friend/ErrorMessages.h"  // js::GetErrorMessage, JSMSG_*
+#include "js/JSON.h"                  // JS_ParseJSON
+#include "ModuleLoaderBase.h"         // ScriptLoaderInterface
+#include "nsContentUtils.h"
+#include "nsIScriptElement.h"
+#include "nsIScriptError.h"
+#include "nsJSUtils.h"  // nsAutoJSString
+#include "nsNetUtil.h"  // NS_NewURI
+#include "ScriptLoadRequest.h"
+
+using JS::SourceText;
+using mozilla::LazyLogModule;
+using mozilla::MakeUnique;
+using mozilla::UniquePtr;
+
+namespace JS::loader {
+
+LazyLogModule ImportMap::gImportMapLog("ImportMap");
+
+#undef LOG
+#define LOG(args) \
+  MOZ_LOG(ImportMap::gImportMapLog, mozilla::LogLevel::Debug, args)
+
+#define LOG_ENABLED() \
+  MOZ_LOG_TEST(ImportMap::gImportMapLog, mozilla::LogLevel::Debug)
+
+void ReportWarningHelper::Report(const char* aMessageName,
+                                 const nsTArray<nsString>& aParams) const {
+  mLoader->ReportWarningToConsole(mRequest, aMessageName, aParams);
+}
+
+// https://wicg.github.io/import-maps/#parse-a-url-like-import-specifier
+static already_AddRefed<nsIURI> ParseURLLikeImportSpecifier(
+    const nsAString& aSpecifier, nsIURI* aBaseURL) {
+  nsCOMPtr<nsIURI> uri;
+  nsresult rv;
+
+  // Step 1. If specifier starts with "/", "./", or "../", then:
+  if (StringBeginsWith(aSpecifier, u"/"_ns) ||
+      StringBeginsWith(aSpecifier, u"./"_ns) ||
+      StringBeginsWith(aSpecifier, u"../"_ns)) {
+    // Step 1.1. Let url be the result of parsing specifier with baseURL as the
+    // base URL.
+    rv = NS_NewURI(getter_AddRefs(uri), aSpecifier, nullptr, aBaseURL);
+    // Step 1.2. If url is failure, then return null.
+    if (NS_FAILED(rv)) {
+      return nullptr;
+    }
+
+    // Step 1.3. Return url.
+    return uri.forget();
+  }
+
+  // Step 2. Let url be the result of parsing specifier (with no base URL).
+  rv = NS_NewURI(getter_AddRefs(uri), aSpecifier);
+  // Step 3. If url is failure, then return null.
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  // Step 4. Return url.
+  return uri.forget();
+}
+
+// https://wicg.github.io/import-maps/#normalize-a-specifier-key
+static void NormalizeSpecifierKey(const nsAString& aSpecifierKey,
+                                  nsIURI* aBaseURL,
+                                  const ReportWarningHelper& aWarning,
+                                  nsAString& aRetVal) {
+  // Step 1. If specifierKey is the empty string, then:
+  if (aSpecifierKey.IsEmpty()) {
+    // Step 1.1. Report a warning to the console that specifier keys cannot be
+    // the empty string.
+    aWarning.Report("ImportMapEmptySpecifierKeys");
+
+    // Step 1.2. Return null.
+    aRetVal = EmptyString();
+    return;
+  }
+
+  // Step 2. Let url be the result of parsing a URL-like import specifier, given
+  // specifierKey and baseURL.
+  nsCOMPtr<nsIURI> url = ParseURLLikeImportSpecifier(aSpecifierKey, aBaseURL);
+
+  // Step 3. If url is not null, then return the serialization of url.
+  if (url) {
+    aRetVal = NS_ConvertUTF8toUTF16(url->GetSpecOrDefault());
+    return;
+  }
+
+  // Step 4. Return specifierKey.
+  aRetVal = aSpecifierKey;
+}
+
+// https://wicg.github.io/import-maps/#sort-and-normalize-a-specifier-map
+static UniquePtr<SpecifierMap> SortAndNormalizeSpecifierMap(
+    JSContext* aCx, JS::HandleObject aOriginalMap, nsIURI* aBaseURL,
+    const ReportWarningHelper& aWarning) {
+  // Step 1. Let normalized be an empty map.
+  UniquePtr<SpecifierMap> normalized = MakeUnique<SpecifierMap>();
+
+  JS::Rooted<JS::IdVector> specifierKeys(aCx, JS::IdVector(aCx));
+  if (!JS_Enumerate(aCx, aOriginalMap, &specifierKeys)) {
+    return nullptr;
+  }
+
+  // Step 2. For each specifierKey → value of originalMap,
+  for (size_t i = 0; i < specifierKeys.length(); i++) {
+    const JS::RootedId specifierId(aCx, specifierKeys[i]);
+    nsAutoJSString specifierKey;
+    NS_ENSURE_TRUE(specifierKey.init(aCx, specifierId), nullptr);
+
+    // Step 2.1. Let normalizedSpecifierKey be the result of normalizing a
+    // specifier key given specifierKey and baseURL.
+    nsString normalizedSpecifierKey;
+    NormalizeSpecifierKey(specifierKey, aBaseURL, aWarning,
+                          normalizedSpecifierKey);
+
+    // Step 2.2. If normalizedSpecifierKey is null, then continue.
+    if (normalizedSpecifierKey.IsEmpty()) {
+      continue;
+    }
+
+    JS::RootedValue idVal(aCx);
+    NS_ENSURE_TRUE(JS_GetPropertyById(aCx, aOriginalMap, specifierId, &idVal),
+                   nullptr);
+    // Step 2.3. If value is not a string, then:
+    if (!idVal.isString()) {
+      // Step 2.3.1. Report a warning to the console that addresses need to
+      // be strings.
+      aWarning.Report("ImportMapAddressesNotStrings");
+
+      // Step 2.3.2. Set normalized[normalizedSpecifierKey] to null.
+      normalized->insert_or_assign(normalizedSpecifierKey, nullptr);
+
+      // Step 2.3.3. Continue.
+      continue;
+    }
+
+    nsAutoJSString value;
+    NS_ENSURE_TRUE(value.init(aCx, idVal), nullptr);
+
+    // Step 2.4. Let addressURL be the result of parsing a URL-like import
+    // specifier given value and baseURL.
+    nsCOMPtr<nsIURI> addressURL = ParseURLLikeImportSpecifier(value, aBaseURL);
+
+    // Step 2.5. If addressURL is null, then:
+    if (!addressURL) {
+      // Step 2.5.1. Report a warning to the console that the address was
+      // invalid.
+      AutoTArray<nsString, 1> params;
+      params.AppendElement(value);
+      aWarning.Report("ImportMapInvalidAddress", params);
+
+      // Step 2.5.2. Set normalized[normalizedSpecifierKey] to null.
+      normalized->insert_or_assign(normalizedSpecifierKey, nullptr);
+
+      // Step 2.5.3. Continue.
+      continue;
+    }
+
+    nsCString address = addressURL->GetSpecOrDefault();
+    // Step 2.6. If specifierKey ends with U+002F (/), and the serialization
+    // of addressURL does not end with U+002F (/), then:
+    if (StringEndsWith(specifierKey, u"/"_ns) &&
+        !StringEndsWith(address, "/"_ns)) {
+      // Step 2.6.1. Report a warning to the console that an invalid address
+      // was given for the specifier key specifierKey; since specifierKey
+      // ended in a slash, the address needs to as well.
+      AutoTArray<nsString, 2> params;
+      params.AppendElement(specifierKey);
+      params.AppendElement(NS_ConvertUTF8toUTF16(address));
+      aWarning.Report("ImportMapAddressNotEndsWithSlash", params);
+
+      // Step 2.6.2. Set normalized[normalizedSpecifierKey] to null.
+      normalized->insert_or_assign(normalizedSpecifierKey, nullptr);
+
+      // Step 2.6.3. Continue.
+      continue;
+    }
+
+    LOG(("ImportMap::SortAndNormalizeSpecifierMap {%s, %s}",
+         NS_ConvertUTF16toUTF8(normalizedSpecifierKey).get(),
+         addressURL->GetSpecOrDefault().get()));
+
+    // Step 2.7. Set normalized[normalizedSpecifierKey] to addressURL.
+    normalized->insert_or_assign(normalizedSpecifierKey, addressURL);
+  }
+
+  // Step 3: Return the result of sorting normalized, with an entry a being
+  // less than an entry b if b’s key is code unit less than a’s key.
+  //
+  // Impl note: The sorting is done when inserting the entry.
+  return normalized;
+}
+
+// Check if it's a map defined in
+// https://infra.spec.whatwg.org/#ordered-map
+//
+// If it is, *aIsMap will be set to true.
+static bool IsMapObject(JSContext* aCx, JS::HandleValue aMapVal, bool* aIsMap) {
+  MOZ_ASSERT(aIsMap);
+
+  *aIsMap = false;
+  if (!aMapVal.isObject()) {
+    return true;
+  }
+
+  bool isArray;
+  if (!IsArrayObject(aCx, aMapVal, &isArray)) {
+    return false;
+  }
+
+  *aIsMap = !isArray;
+  return true;
+}
+
+// https://wicg.github.io/import-maps/#sort-and-normalize-scopes
+static UniquePtr<ScopeMap> SortAndNormalizeScopes(
+    JSContext* aCx, JS::HandleObject aOriginalMap, nsIURI* aBaseURL,
+    const ReportWarningHelper& aWarning) {
+  JS::Rooted<JS::IdVector> scopeKeys(aCx, JS::IdVector(aCx));
+  if (!JS_Enumerate(aCx, aOriginalMap, &scopeKeys)) {
+    return nullptr;
+  }
+
+  // Step 1. Let normalized be an empty map.
+  UniquePtr<ScopeMap> normalized = MakeUnique<ScopeMap>();
+
+  // Step 2. For each scopePrefix → potentialSpecifierMap of originalMap,
+  for (size_t i = 0; i < scopeKeys.length(); i++) {
+    const JS::RootedId scopeKey(aCx, scopeKeys[i]);
+    nsAutoJSString scopePrefix;
+    NS_ENSURE_TRUE(scopePrefix.init(aCx, scopeKey), nullptr);
+
+    // Step 2.1. If potentialSpecifierMap is not a map, then throw a TypeError
+    // indicating that the value of the scope with prefix scopePrefix needs to
+    // be a JSON object.
+    JS::RootedValue mapVal(aCx);
+    NS_ENSURE_TRUE(JS_GetPropertyById(aCx, aOriginalMap, scopeKey, &mapVal),
+                   nullptr);
+
+    bool isMap;
+    if (!IsMapObject(aCx, mapVal, &isMap)) {
+      return nullptr;
+    }
+    if (!isMap) {
+      const char16_t* scope = scopePrefix.get();
+      JS_ReportErrorNumberUC(aCx, js::GetErrorMessage, nullptr,
+                             JSMSG_IMPORT_MAPS_SCOPE_VALUE_NOT_A_MAP, scope);
+      return nullptr;
+    }
+
+    // Step 2.2. Let scopePrefixURL be the result of parsing scopePrefix with
+    // baseURL as the base URL.
+    nsCOMPtr<nsIURI> scopePrefixURL;
+    nsresult rv = NS_NewURI(getter_AddRefs(scopePrefixURL), scopePrefix,
+                            nullptr, aBaseURL);
+
+    // Step 2.3. If scopePrefixURL is failure, then:
+    if (NS_FAILED(rv)) {
+      // Step 2.3.1. Report a warning to the console that the scope prefix URL
+      // was not parseable.
+      AutoTArray<nsString, 1> params;
+      params.AppendElement(scopePrefix);
+      aWarning.Report("ImportMapScopePrefixNotParseable", params);
+
+      // Step 2.3.2. Continue.
+      continue;
+    }
+
+    // Step 2.4. Let normalizedScopePrefix be the serialization of
+    // scopePrefixURL.
+    nsCString normalizedScopePrefix = scopePrefixURL->GetSpecOrDefault();
+
+    // Step 2.5. Set normalized[normalizedScopePrefix] to the result of sorting
+    // and normalizing a specifier map given potentialSpecifierMap and baseURL.
+    JS::RootedObject potentialSpecifierMap(aCx, &mapVal.toObject());
+    UniquePtr<SpecifierMap> specifierMap = SortAndNormalizeSpecifierMap(
+        aCx, potentialSpecifierMap, aBaseURL, aWarning);
+    if (!specifierMap) {
+      return nullptr;
+    }
+
+    normalized->insert_or_assign(normalizedScopePrefix,
+                                 std::move(specifierMap));
+  }
+
+  // Step 3. Return the result of sorting normalized, with an entry a being less
+  // than an entry b if b’s key is code unit less than a’s key.
+  //
+  // Impl note: The sorting is done when inserting the entry.
+  return normalized;
+}
+
+// https://wicg.github.io/import-maps/#parse-an-import-map-string
+// static
+UniquePtr<ImportMap> ImportMap::ParseString(
+    JSContext* aCx, SourceText<char16_t>& aInput, nsIURI* aBaseURL,
+    const ReportWarningHelper& aWarning) {
+  // Step 1. Let parsed be the result of parsing JSON into Infra values given
+  // input.
+  JS::Rooted<JS::Value> parsedVal(aCx);
+  if (!JS_ParseJSON(aCx, aInput.get(), aInput.length(), &parsedVal)) {
+    // If JS_ParseJSON fail it will throw SyntaxError.
+    NS_WARNING("Parsing Import map string failed");
+    return nullptr;
+  }
+
+  // Step 2. If parsed is not a map, then throw a TypeError indicating that
+  // the top-level value needs to be a JSON object.
+  bool isMap;
+  if (!IsMapObject(aCx, parsedVal, &isMap)) {
+    return nullptr;
+  }
+  if (!isMap) {
+    JS_ReportErrorNumberASCII(aCx, js::GetErrorMessage, nullptr,
+                              JSMSG_IMPORT_MAPS_NOT_A_MAP);
+    return nullptr;
+  }
+
+  JS::RootedObject parsedObj(aCx, &parsedVal.toObject());
+  JS::RootedValue importsVal(aCx);
+  if (!JS_GetProperty(aCx, parsedObj, "imports", &importsVal)) {
+    return nullptr;
+  }
+
+  // Step 3. Let sortedAndNormalizedImports be an empty map.
+  //
+  // Impl note: If parsed["imports"] doesn't exist, we will allocate
+  // sortedAndNormalizedImports to an empty map in Step 8 below.
+  UniquePtr<SpecifierMap> sortedAndNormalizedImports = nullptr;
+
+  // Step 4. If parsed["imports"] exists, then:
+  if (!importsVal.isUndefined()) {
+    // Step 4.1. If parsed["imports"] is not a map, then throw a TypeError
+    // indicating that the "imports" top-level key needs to be a JSON object.
+    bool isMap;
+    if (!IsMapObject(aCx, importsVal, &isMap)) {
+      return nullptr;
+    }
+    if (!isMap) {
+      JS_ReportErrorNumberASCII(aCx, js::GetErrorMessage, nullptr,
+                                JSMSG_IMPORT_MAPS_IMPORTS_NOT_A_MAP);
+      return nullptr;
+    }
+
+    // Step 4.2. Set sortedAndNormalizedImports to the result of sorting and
+    // normalizing a specifier map given parsed["imports"] and baseURL.
+    JS::RootedObject importsObj(aCx, &importsVal.toObject());
+    sortedAndNormalizedImports =
+        SortAndNormalizeSpecifierMap(aCx, importsObj, aBaseURL, aWarning);
+    if (!sortedAndNormalizedImports) {
+      return nullptr;
+    }
+  }
+
+  JS::RootedValue scopesVal(aCx);
+  if (!JS_GetProperty(aCx, parsedObj, "scopes", &scopesVal)) {
+    return nullptr;
+  }
+
+  // Step 5. Let sortedAndNormalizedScopes be an empty map.
+  //
+  // Impl note: If parsed["scopes"] doesn't exist, we will allocate
+  // sortedAndNormalizedScopes to an empty map in Step 8 below.
+  UniquePtr<ScopeMap> sortedAndNormalizedScopes = nullptr;
+
+  // Step 6. If parsed["scopes"] exists, then:
+  if (!scopesVal.isUndefined()) {
+    // Step 6.1. If parsed["scopes"] is not a map, then throw a TypeError
+    // indicating that the "scopes" top-level key needs to be a JSON object.
+    bool isMap;
+    if (!IsMapObject(aCx, scopesVal, &isMap)) {
+      return nullptr;
+    }
+    if (!isMap) {
+      JS_ReportErrorNumberASCII(aCx, js::GetErrorMessage, nullptr,
+                                JSMSG_IMPORT_MAPS_SCOPES_NOT_A_MAP);
+      return nullptr;
+    }
+
+    // Step 6.2. Set sortedAndNormalizedScopes to the result of sorting and
+    // normalizing scopes given parsed["scopes"] and baseURL.
+    JS::RootedObject scopesObj(aCx, &scopesVal.toObject());
+    sortedAndNormalizedScopes =
+        SortAndNormalizeScopes(aCx, scopesObj, aBaseURL, aWarning);
+    if (!sortedAndNormalizedScopes) {
+      return nullptr;
+    }
+  }
+
+  // Step 7. If parsed’s keys contains any items besides "imports" or
+  // "scopes", report a warning to the console that an invalid top-level key
+  // was present in the import map.
+  JS::Rooted<JS::IdVector> keys(aCx, JS::IdVector(aCx));
+  if (!JS_Enumerate(aCx, parsedObj, &keys)) {
+    return nullptr;
+  }
+
+  for (size_t i = 0; i < keys.length(); i++) {
+    const JS::RootedId key(aCx, keys[i]);
+    nsAutoJSString val;
+    NS_ENSURE_TRUE(val.init(aCx, key), nullptr);
+    if (val.EqualsLiteral("imports") || val.EqualsLiteral("scopes")) {
+      continue;
+    }
+
+    AutoTArray<nsString, 1> params;
+    params.AppendElement(val);
+    aWarning.Report("ImportMapInvalidTopLevelKey", params);
+  }
+
+  // Impl note: Create empty maps for sortedAndNormalizedImports and
+  // sortedAndNormalizedImports if they aren't allocated.
+  if (!sortedAndNormalizedImports) {
+    sortedAndNormalizedImports = MakeUnique<SpecifierMap>();
+  }
+  if (!sortedAndNormalizedScopes) {
+    sortedAndNormalizedScopes = MakeUnique<ScopeMap>();
+  }
+
+  // Step 8. Return the import map whose imports are
+  // sortedAndNormalizedImports and whose scopes scopes are
+  // sortedAndNormalizedScopes.
+  return MakeUnique<ImportMap>(std::move(sortedAndNormalizedImports),
+                               std::move(sortedAndNormalizedScopes));
+}
+
+#undef LOG
+#undef LOG_ENABLED
+}  // namespace JS::loader

js/loader/ImportMap.h

@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef js_loader_ImportMap_h
+#define js_loader_ImportMap_h
+
+#include <functional>
+#include <map>
+
+#include "js/SourceText.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Logging.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/UniquePtr.h"
+#include "nsStringFwd.h"
+#include "nsTArray.h"
+
+struct JSContext;
+class nsIScriptElement;
+class nsIURI;
+
+namespace JS::loader {
+class LoadedScript;
+class ScriptLoaderInterface;
+class ScriptLoadRequest;
+
+/**
+ * A helper class to report warning to ScriptLoaderInterface.
+ */
+class ReportWarningHelper {
+ public:
+  ReportWarningHelper(ScriptLoaderInterface* aLoader,
+                      ScriptLoadRequest* aRequest)
+      : mLoader(aLoader), mRequest(aRequest) {}
+
+  void Report(const char* aMessageName,
+              const nsTArray<nsString>& aParams = nsTArray<nsString>()) const;
+
+ private:
+  RefPtr<ScriptLoaderInterface> mLoader;
+  ScriptLoadRequest* mRequest;
+};
+
+// Specifier map from import maps.
+// https://wicg.github.io/import-maps/#specifier-map
+using SpecifierMap =
+    std::map<nsString, nsCOMPtr<nsIURI>, std::greater<nsString>>;
+
+// Scope map from import maps.
+// https://wicg.github.io/import-maps/#import-map-scopes
+using ScopeMap = std::map<nsCString, mozilla::UniquePtr<SpecifierMap>,
+                          std::greater<nsCString>>;
+
+/**
+ * Implementation of Import maps.
+ * https://wicg.github.io/import-maps
+ */
+class ImportMap {
+ public:
+  ImportMap(mozilla::UniquePtr<SpecifierMap> aImports,
+            mozilla::UniquePtr<ScopeMap> aScopes)
+      : mImports(std::move(aImports)), mScopes(std::move(aScopes)) {}
+
+  /**
+   * Parse the JSON string from the Import map script.
+   * This function will throw TypeError if there's any invalid key or value in
+   * the JSON text according to the spec.
+   *
+   * See https://wicg.github.io/import-maps/#parse-an-import-map-string
+   */
+  static mozilla::UniquePtr<ImportMap> ParseString(
+      JSContext* aCx, JS::SourceText<char16_t>& aInput, nsIURI* aBaseURL,
+      const ReportWarningHelper& aWarning);
+
+  // Logging
+  static mozilla::LazyLogModule gImportMapLog;
+
+ private:
+  /**
+   * https://wicg.github.io/import-maps/#import-map
+   *
+   * A import map is a struct with two items:
+   * 1. imports, a specifier map, and
+   * 2. scopes, an ordered map of URLs to specifier maps.
+   */
+  mozilla::UniquePtr<SpecifierMap> mImports;
+  mozilla::UniquePtr<ScopeMap> mScopes;
+};
+
+}  // namespace JS::loader
+
+#endif  // js_loader_ImportMap_h

js/loader/ModuleLoaderBase.cpp

@@ -8,6 +8,7 @@
 #include "LoadedScript.h"
 #include "ModuleLoadRequest.h"
 #include "ScriptLoadRequest.h"
+#include "mozilla/dom/ScriptSettings.h"  // AutoJSAPI
 #include "mozilla/dom/ScriptTrace.h"
 
 #include "js/Array.h"  // JS::GetArrayLength
@@ -31,6 +32,7 @@
 
 using mozilla::GetMainThreadSerialEventTarget;
 using mozilla::Preferences;
+using mozilla::UniquePtr;
 using mozilla::dom::AutoJSAPI;
 
 namespace JS::loader {
@@ -1099,6 +1101,50 @@ void ModuleLoaderBase::CancelAndClearDynamicImports() {
   mDynamicImportRequests.CancelRequestsAndClear();
 }
 
+UniquePtr<ImportMap> ModuleLoaderBase::ParseImportMap(
+    ScriptLoadRequest* aRequest) {
+  AutoJSAPI jsapi;
+  if (!jsapi.Init(GetGlobalObject())) {
+    return nullptr;
+  }
+
+  MOZ_ASSERT(aRequest->IsTextSource());
+  MaybeSourceText maybeSource;
+  nsresult rv = aRequest->GetScriptSource(jsapi.cx(), &maybeSource);
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  JS::SourceText<char16_t>& text = maybeSource.ref<SourceText<char16_t>>();
+  ReportWarningHelper warning{mLoader, aRequest};
+
+  // https://html.spec.whatwg.org/multipage/scripting.html#prepare-a-script
+  // https://wicg.github.io/import-maps/#integration-prepare-a-script
+  // Insert the following case to prepare a script step 25.2:
+  // (Impl Note: the latest html spec is step 27.2)
+  // Switch on the script's type:
+  // "importmap"
+  // Step 1. Let import map parse result be the result of create an import map
+  // parse result, given source text, base URL and settings object.
+  //
+  // Impl note: According to the spec, ImportMap::ParseString will throw a
+  // TypeError if there's any invalid key/value in the text. After the parsing
+  // is done, we should report the error if there's any, this is done in
+  // ~AutoJSAPI.
+  //
+  // See https://wicg.github.io/import-maps/#register-an-import-map, step 7.
+  return ImportMap::ParseString(jsapi.cx(), text, aRequest->mBaseURL, warning);
+}
+
+void ModuleLoaderBase::RegisterImportMap(UniquePtr<ImportMap> aImportMap) {
+  // Check for aImportMap is done in ScriptLoader.
+  MOZ_ASSERT(aImportMap);
+
+  // Step 8. Set element’s node document's import map to import map parse
+  // result’s import map.
+  mImportMap = std::move(aImportMap);
+}
+
 #undef LOG
 #undef LOG_ENABLED
 

js/loader/ModuleLoaderBase.h

@@ -10,6 +10,7 @@
 #include "LoadedScript.h"
 #include "ScriptLoadRequest.h"
 
+#include "ImportMap.h"
 #include "js/TypeDecls.h"  // JS::MutableHandle, JS::Handle, JS::Root
 #include "js/Modules.h"
 #include "nsRefPtrHashtable.h"
@@ -22,6 +23,7 @@
 #include "mozilla/dom/JSExecutionContext.h"
 #include "mozilla/MaybeOneOf.h"
 #include "mozilla/MozPromise.h"
+#include "mozilla/UniquePtr.h"
 
 class nsIURI;
 
@@ -60,6 +62,10 @@ class ScriptLoaderInterface : public nsISupports {
   virtual void ReportErrorToConsole(ScriptLoadRequest* aRequest,
                                     nsresult aResult) const = 0;
 
+  virtual void ReportWarningToConsole(
+      ScriptLoadRequest* aRequest, const char* aMessageName,
+      const nsTArray<nsString>& aParams = nsTArray<nsString>()) const = 0;
+
   // Fill in CompileOptions, as well as produce the introducer script for
   // subsequent calls to UpdateDebuggerMetadata
   virtual nsresult FillCompileOptionsForRequest(
@@ -147,6 +153,8 @@ class ModuleLoaderBase : public nsISupports {
  protected:
   RefPtr<ScriptLoaderInterface> mLoader;
 
+  mozilla::UniquePtr<ImportMap> mImportMap;
+
   virtual ~ModuleLoaderBase();
 
  public:
@@ -227,6 +235,12 @@ class ModuleLoaderBase : public nsISupports {
   void ProcessDynamicImport(ModuleLoadRequest* aRequest);
   void CancelAndClearDynamicImports();
 
+  // Process <script type="importmap">
+  mozilla::UniquePtr<ImportMap> ParseImportMap(ScriptLoadRequest* aRequest);
+
+  // Implements https://wicg.github.io/import-maps/#register-an-import-map
+  void RegisterImportMap(mozilla::UniquePtr<ImportMap> aImportMap);
+
   // Internal methods.
 
  private:

js/loader/ScriptLoadRequest.h

@@ -181,6 +181,7 @@ class ScriptLoadRequest
       mozilla::MaybeOneOf<JS::SourceText<char16_t>, JS::SourceText<Utf8Unit>>;
 
   bool IsModuleRequest() const { return mKind == ScriptKind::eModule; }
+  bool IsImportMapRequest() const { return mKind == ScriptKind::eImportMap; }
 
   ModuleLoadRequest* AsModuleRequest();
   const ModuleLoadRequest* AsModuleRequest() const;

js/loader/moz.build

@@ -5,6 +5,7 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 EXPORTS.js.loader += [
+    "ImportMap.h",
     "LoadContextBase.h",
     "LoadedScript.h",
     "ModuleLoaderBase.h",
@@ -14,6 +15,7 @@ EXPORTS.js.loader += [
 ]
 
 UNIFIED_SOURCES += [
+    "ImportMap.cpp",
     "LoadContextBase.cpp",
     "LoadedScript.cpp",
     "ModuleLoaderBase.cpp",

js/public/friend/ErrorNumbers.msg

@@ -727,6 +727,12 @@ MSG_DEF(JSMSG_MISSING_EXPORT,            1, JSEXN_SYNTAXERR, "local binding for
 MSG_DEF(JSMSG_BAD_MODULE_STATUS,         0, JSEXN_INTERNALERR, "module record has unexpected status")
 MSG_DEF(JSMSG_DYNAMIC_IMPORT_FAILED,     0, JSEXN_TYPEERR, "error loading dynamically imported module")
 
+// Import maps
+MSG_DEF(JSMSG_IMPORT_MAPS_NOT_A_MAP, 0, JSEXN_TYPEERR, "the top-level value needs to be a JSON object")
+MSG_DEF(JSMSG_IMPORT_MAPS_IMPORTS_NOT_A_MAP, 0, JSEXN_TYPEERR, "the imports top-level key needs to be a JSON object")
+MSG_DEF(JSMSG_IMPORT_MAPS_SCOPES_NOT_A_MAP, 0, JSEXN_TYPEERR, "the scopes top-level key needs to be a JSON object")
+MSG_DEF(JSMSG_IMPORT_MAPS_SCOPE_VALUE_NOT_A_MAP, 1, JSEXN_TYPEERR, "the value of the scope with prefix '{0}' needs to be a JSON object")
+
 // Promise
 MSG_DEF(JSMSG_CANNOT_RESOLVE_PROMISE_WITH_ITSELF,       0, JSEXN_TYPEERR, "A promise cannot be resolved with itself.")
 MSG_DEF(JSMSG_PROMISE_CAPABILITY_HAS_SOMETHING_ALREADY, 0, JSEXN_TYPEERR, "GetCapabilitiesExecutor function already invoked with non-undefined values.")