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/* 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
const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
setTimeout: "resource://gre/modules/Timer.sys.mjs",
clearTimeout: "resource://gre/modules/Timer.sys.mjs",
});
ChromeUtils.defineLazyGetter(lazy, "console", () => {
return console.createInstance({
maxLogLevelPref: "browser.translations.logLevel",
prefix: "Translations",
});
});
/**
* Map the NodeFilter enums that are used by the TreeWalker into enums that make
* sense for determining the status of the nodes for the TranslationsDocument process.
* This aligns the meanings of the filtering for the translations process.
*/
const NodeStatus = {
// This node is ready to translate as is.
READY_TO_TRANSLATE: NodeFilter.FILTER_ACCEPT,
// This node is a shadow host and needs to be subdivided further.
SHADOW_HOST: NodeFilter.FILTER_ACCEPT,
// This node contains too many block elements and needs to be subdivided further.
SUBDIVIDE_FURTHER: NodeFilter.FILTER_SKIP,
// This node should not be considered for translation.
NOT_TRANSLATABLE: NodeFilter.FILTER_REJECT,
};
/**
* @typedef {import("../translations").NodeVisibility} NodeVisibility
* @typedef {(message: string) => Promise<string>} TranslationFunction
*/
/**
* Create a translation cache with a limit. It implements a "least recently used" strategy
* to remove old translations. After `#cacheExpirationMS` the cache will be emptied.
* This cache is owned statically by the TranslationsChild. This means that it will be
* re-used on page reloads if the origin of the site does not change.
*/
export class LRUCache {
/** @type {Map<string, string>} */
#htmlCache = new Map();
/** @type {Map<string, string>} */
#textCache = new Map();
/** @type {string} */
#fromLanguage;
/** @type {string} */
#toLanguage;
/**
* This limit is used twice, once for Text translations, and once for HTML translations.
*/
#cacheLimit = 5_000;
/**
* This cache will self-destruct after 10 minutes.
*/
#cacheExpirationMS = 10 * 60_000;
/**
* @param {string} fromLanguage
* @param {string} toLanguage
*/
constructor(fromLanguage, toLanguage) {
this.#fromLanguage = fromLanguage;
this.#toLanguage = toLanguage;
}
/**
* @param {boolean} isHTML
* @returns {boolean}
*/
#getCache(isHTML) {
return isHTML ? this.#htmlCache : this.#textCache;
}
/**
* Get a translation if it exists from the cache, and move it to the end of the cache
* to keep it alive longer.
*
* @param {string} sourceString
* @param {boolean} isHTML
* @returns {string}
*/
get(sourceString, isHTML) {
const cache = this.#getCache(isHTML);
const targetString = cache.get(sourceString);
if (targetString === undefined) {
return undefined;
}
// Maps are ordered, move this item to the end of the list so it will stay
// alive longer.
cache.delete(sourceString);
cache.set(sourceString, targetString);
this.keepAlive();
return targetString;
}
/**
* @param {string} sourceString
* @param {string} targetString
* @param {boolean} isHTML
*/
set(sourceString, targetString, isHTML) {
const cache = this.#getCache(isHTML);
if (cache.size === this.#cacheLimit) {
// If the cache is at the limit, get the least recently used translation and
// remove it. This works since Maps have keys ordered by insertion order.
const key = cache.keys().next().value;
cache.delete(key);
}
cache.set(sourceString, targetString);
this.keepAlive();
}
/**
* @param {string} fromLanguage
* @param {string} toLanguage
*/
matches(fromLanguage, toLanguage) {
return (
this.#fromLanguage === fromLanguage && this.#toLanguage === toLanguage
);
}
/**
* @type {number}
*/
#timeoutId = 0;
#pendingKeepAlive = false;
/**
* Clear out the cache on a timer.
*/
keepAlive() {
if (this.#timeoutId) {
lazy.clearTimeout(this.#timeoutId);
}
if (!this.#pendingKeepAlive) {
// Rather than continuously creating new functions in a tight loop, only schedule
// one keepAlive timeout on the next tick.
this.#pendingKeepAlive = true;
lazy.setTimeout(() => {
this.#pendingKeepAlive = false;
this.#timeoutId = lazy.setTimeout(() => {
this.#htmlCache = new Map();
this.#textCache = new Map();
}, this.#cacheExpirationMS);
}, 0);
}
}
}
/**
* How often the DOM is updated with translations, in milliseconds.
*/
const DOM_UPDATE_INTERVAL_MS = 50;
/**
* These tags are excluded from translation.
*/
const EXCLUDED_TAGS = new Set([
// The following are elements that semantically should not be translated.
"CODE",
"KBD",
"SAMP",
"VAR",
"ACRONYM",
// The following are deprecated tags.
"DIR",
"APPLET",
// The following are embedded elements, and are not supported (yet).
"MATH",
"EMBED",
"OBJECT",
"IFRAME",
// This is an SVG tag that can contain arbitrary XML, ignore it.
"METADATA",
// These are elements that are treated as opaque by Firefox which causes their
// innerHTML property to be just the raw text node behind it. Any text that is sent as
// HTML must be valid, and there is no guarantee that the innerHTML is valid.
"NOSCRIPT",
"NOEMBED",
"NOFRAMES",
// The title is handled separately, and a HEAD tag should not be considered.
"HEAD",
// These are not user-visible tags.
"STYLE",
"SCRIPT",
"TEMPLATE",
// Textarea elements contain user content, which should not be translated.
"TEXTAREA",
]);
/**
* Attributes to be translated
*/
const TRANSLATABLE_ATTRIBUTES = ["title", "placeholder"];
/**
* Selector to get all the attributes
* ["[attribute1]", "[attribute2]", ...];
*/
const TRANSLATABLE_ATTRIBUTES_SELECTOR = TRANSLATABLE_ATTRIBUTES.map(
attribute => "[" + attribute + "]"
);
/**
* Options used by the mutation observer
*/
const MUTATION_OBSERVER_OPTIONS = {
characterData: true,
childList: true,
subtree: true,
attributes: true,
attributeFilter: TRANSLATABLE_ATTRIBUTES,
};
/**
* This class manages the process of translating the DOM from one language to another.
* A translateHTML and a translateText function are injected into the constructor. This
* class is responsible for subdividing a Node into small enough pieces to where it
* contains a reasonable amount of text and inline elements for the translations engine
* to translate. Once a node has been identified as a small enough chunk, its innerHTML
* is read, and sent for translation. The async translation result comes back as an HTML
* string. The DOM node is updated with the new text and potentially changed DOM ordering.
*
* This class also handles mutations of the DOM and will translate nodes as they are added
* to the page, or the when the node's text is changed by content scripts.
*/
export class TranslationsDocument {
/**
* The BCP 47 language tag that is used on the page.
*
@type {string} */
documentLanguage;
/**
* The timeout between the first translation received and the call to update the DOM
* with translations.
*/
#updateTimeout = null;
#attributeUpdateTimeout = null;
/**
* The nodes that need translations. They are queued when the document tree is walked,
* and then they are dispatched for translation based on their visibility. The viewport
* nodes are given the highest priority.
*
* @type {Map<Node, NodeVisibility>}
*/
#queuedNodes = new Map();
/**
* The nodes that need Attribute translations. They are queued when the document tree is walked,
* and then they are dispatched for translation based on their visibility. The viewport
* nodes are given the highest priority.
*
* @type {Map<Node, { attributeList: string[], visibility: NodeVisibility }>}
*/
#queuedAttributeNodes = new Map();
/**
* The count of how many pending translations have been sent to the translations
* engine.
*/
#pendingTranslationsCount = 0;
/**
* The list of nodes that need updating with the translated HTML. These are batched
* into an update.
*
* @type {Set<{ node: Node, translatedHTML: string }>}
*/
#nodesWithTranslatedHTML = new Set();
/**
* The list of nodes that need updating with the translated Attribute HTML. These are batched
* into an update.
*
* @type {Set<{ node: Node, translation: string, attribute: string }>}
*/
#nodesWithTranslatedAttributes = new Set();
/**
* The set of nodes that have been subdivided and processed for translation. They
* should not be submitted again unless their contents have been changed.
*
* @type {WeakSet<Node>}
*/
#processedNodes = new WeakSet();
/**
* All root elements we're trying to translate. This should be the `document.body`
* and the the `title` element.
*
* @type {Set<Node>}
*/
#rootNodes = new Set();
/**
* This promise gets resolved when the initial viewport translations are done.
* This is a key user-visible performance metric. It represents what the user
* actually sees.
*
* @type {Promise<void> | null}
*/
viewportTranslated = null;
isDestroyed = false;
/**
* This boolean indicates whether the first visible DOM translation change is about to occur.
*
* @type {boolean}
*/
hasFirstVisibleChange = false;
/**
* Construct a new TranslationsDocument. It is tied to a specific Document and cannot
* be re-used. The translation functions are injected since this class shouldn't
* manage the life cycle of the translations engines.
*
* @param {Document} document
* @param {string} documentLanguage - The BCP 47 tag of the source language.
* @param {string} toLanguage - The BCP 47 tag of the destination language.
* @param {number} innerWindowId - This is used for better profiler marker reporting.
* @param {MessagePort} port - The port to the translations engine.
* @param {() => void} requestNewPort - Used when an engine times out and a new
* translation request comes in.
* @param {() => void} reportVisibleChange - Used to report to the actor that the first visible change
* for a translation is about to occur.
* @param {number} translationsStart
* @param {() => number} now
* @param {LRUCache} translationsCache
*/
constructor(
document,
documentLanguage,
toLanguage,
innerWindowId,
port,
requestNewPort,
reportVisibleChange,
translationsStart,
now,
translationsCache
) {
/**
* The language of the document. If elements are found that do not match this language,
* then they are skipped.
*
* @type {string}
*/
this.documentLanguage = documentLanguage;
if (documentLanguage.length !== 2) {
throw new Error(
"Expected the document language to be a valid 2 letter BCP 47 language tag: " +
documentLanguage
);
}
if (toLanguage.length !== 2) {
throw new Error(
"Expected the destination language to be a valid 2 letter BCP 47 language tag: " +
toLanguage
);
}
/** @type {QueuedTranslator} */
this.translator = new QueuedTranslator(
port,
requestNewPort,
reportVisibleChange
);
/** @type {number} */
this.innerWindowId = innerWindowId;
/** @type {DOMParser} */
this.domParser = new document.ownerGlobal.DOMParser();
/** @type {Document} */
this.document = document;
/** @type {LRUCache} */
this.translationsCache = translationsCache;
/** @type {() => void} */
this.actorReportFirstVisibleChange = reportVisibleChange;
/**
* This selector runs to find child nodes that should be excluded. It should be
* basically the same implementation of `isExcludedNode`, but as a selector.
*
* @type {string}
*/
this.excludedNodeSelector = [
// Use: [lang|=value] to match language codes.
//
//
// The elements with an attribute name of attr whose value can be exactly
// value or can begin with value immediately followed by a hyphen, - (U+002D).
// It is often used for language subcode matches.
`[lang]:not([lang|="${this.documentLanguage}"])`,
`[translate=no]`,
`.notranslate`,
`[contenteditable="true"]`,
`[contenteditable=""]`,
[...EXCLUDED_TAGS].join(","),
].join(",");
this.observer = new document.ownerGlobal.MutationObserver(mutationsList => {
for (const mutation of mutationsList) {
switch (mutation.type) {
case "childList":
for (const node of mutation.addedNodes) {
this.#processedNodes.delete(node);
this.subdivideNodeForTranslations(node);
if (node.nodeType === Node.ELEMENT_NODE) {
this.translateAttributes(node);
}
}
break;
case "characterData":
this.#processedNodes.delete(mutation);
this.subdivideNodeForTranslations(mutation.target);
break;
case "attributes":
this.queueAttributeNodeForTranslation(mutation.target, [
mutation.attributeName,
]);
this.dispatchQueuedAttributeTranslations();
break;
default:
break;
}
}
});
this.document.addEventListener(
"visibilitychange",
this.handleVisibilityChange
);
const addRootElements = () => {
this.addRootElement(document.querySelector("title"));
this.addRootElement(document.body, true /* reportWordsInViewport */);
};
if (document.body) {
addRootElements();
} else {
// The TranslationsDocument was invoked before the DOM was ready, wait for
// it to be loaded.
document.addEventListener("DOMContentLoaded", addRootElements);
}
this.viewportTranslated?.then(() => {
ChromeUtils.addProfilerMarker(
"TranslationsChild",
{ innerWindowId, startTime: now() },
"Viewport translations"
);
ChromeUtils.addProfilerMarker(
"TranslationsChild",
{ innerWindowId, startTime: translationsStart },
"Time to first translation"
);
});
document.documentElement.lang = toLanguage;
lazy.console.log(
"Beginning to translate.",
// The defaultView may not be there on tests.
document.defaultView?.location.href
);
}
/**
* Queue a node for translation of attributes.
*
* @param {Node} node
* @param {Array<string>} attributeList
*/
queueAttributeNodeForTranslation(node, attributeList) {
/** @type {NodeVisibility} */
let visibility = "out-of-viewport";
if (isNodeHidden(node)) {
visibility = "hidden";
} else if (isNodeInViewport(node)) {
visibility = "in-viewport";
}
this.#queuedAttributeNodes.set(node, { attributeList, visibility });
}
/**
* Start and stop the translator as the page is shown. For instance, this will
* transition into "hidden" when the user tabs away from a document.
*/
handleVisibilityChange = () => {
if (this.document.visibilityState === "visible") {
this.translator.showPage();
} else {
ChromeUtils.addProfilerMarker(
"Translations",
{ innerWindowId: this.innerWindowId },
"Pausing translations and discarding the port"
);
this.translator.hidePage();
}
};
/**
* Remove any dangling event handlers.
*/
destroy() {
this.isDestroyed = true;
this.translator.destroy();
this.stopMutationObserver();
this.document.removeEventListener(
"visibilitychange",
this.handleVisibilityChange
);
}
/**
* Helper function for adding a new root to the mutation
* observer.
*
* @param {Node} root
*/
observeNewRoot(root) {
this.#rootNodes.add(root);
this.observer.observe(root, MUTATION_OBSERVER_OPTIONS);
}
/**
* This function finds all sub shadow trees of node and
* add the ShadowRoot of those subtrees to the mutation
* observer.
*/
addShadowRootsToObserver(node) {
const nodeIterator = node.ownerDocument.createTreeWalker(
node,
NodeFilter.SHOW_ELEMENT,
function (node) {
return node.openOrClosedShadowRoot
? NodeFilter.FILTER_ACCEPT
: NodeFilter.FILTER_SKIP;
}
);
let currentNode;
while ((currentNode = nodeIterator.nextNode())) {
// Only shadow hosts are accepted nodes
const shadowRoot = currentNode.openOrClosedShadowRoot;
this.observeNewRoot(shadowRoot);
this.addShadowRootsToObserver(shadowRoot);
}
}
/**
* Add a new element to start translating. This root is tracked for mutations and
* kept up to date with translations. This will be the body element and title tag
* for the document.
*
* @param {Element} [node]
*/
addRootElement(node) {
if (!node) {
return;
}
if (node.nodeType !== Node.ELEMENT_NODE) {
// This node is not an element, do not add it.
return;
}
if (this.#rootNodes.has(node)) {
// Exclude nodes that are already targetted.
return;
}
this.#rootNodes.add(node);
let viewportNodeTranslations = this.subdivideNodeForTranslations(node);
let viewportAttributeTranslations = this.translateAttributes(node);
if (!this.viewportTranslated) {
this.viewportTranslated = Promise.allSettled([
...(viewportNodeTranslations ?? []),
...(viewportAttributeTranslations ?? []),
]);
}
this.observer.observe(node, MUTATION_OBSERVER_OPTIONS);
this.addShadowRootsToObserver(node);
}
/**
* Add qualified nodes to queueNodeForTranslation by recursively walk
* through the DOM tree of node, including elements in Shadow DOM.
*
* @param {Element} [node]
*/
processSubdivide(node) {
const nodeIterator = node.ownerDocument.createTreeWalker(
node,
NodeFilter.SHOW_ELEMENT | NodeFilter.SHOW_TEXT,
this.determineTranslationStatusForUnprocessedNodes
);
// This iterator will contain each node that has been subdivided enough to
// be translated.
let currentNode;
while ((currentNode = nodeIterator.nextNode())) {
const shadowRoot = currentNode.openOrClosedShadowRoot;
if (shadowRoot) {
this.processSubdivide(shadowRoot);
} else {
this.queueNodeForTranslation(currentNode);
}
}
}
/**
* Start walking down through a node's subtree and decide which nodes to queue for
* translation. This first node could be the root nodes of the DOM, such as the
* document body, or the title element, or it could be a mutation target.
*
* The nodes go through a process of subdivision until an appropriate sized chunk
* of inline text can be found.
*
* @param {Node} node
*/
subdivideNodeForTranslations(node) {
if (!this.#rootNodes.has(node)) {
// This is a non-root node, which means it came from a mutation observer.
// This new node could be a host element for shadow tree
const shadowRoot = node.openOrClosedShadowRoot;
if (shadowRoot && !this.#rootNodes.has(shadowRoot)) {
this.observeNewRoot(shadowRoot);
} else {
// Ensure that it is a valid node to translate by checking all of its ancestors.
for (let parent of getAncestorsIterator(node)) {
// Parent is ShadowRoot. We can stop here since this is
// the top ancestor of the shadow tree.
if (parent.containingShadowRoot == parent) {
break;
}
if (
this.determineTranslationStatus(parent) ===
NodeStatus.NOT_TRANSLATABLE
) {
return;
}
}
}
}
switch (this.determineTranslationStatusForUnprocessedNodes(node)) {
case NodeStatus.NOT_TRANSLATABLE:
// This node is rejected as it shouldn't be translated.
return;
// SHADOW_HOST and READY_TO_TRANSLATE both map to FILTER_ACCEPT
case NodeStatus.SHADOW_HOST:
case NodeStatus.READY_TO_TRANSLATE:
const shadowRoot = node.openOrClosedShadowRoot;
if (shadowRoot) {
this.processSubdivide(shadowRoot);
} else {
// This node is ready for translating, and doesn't need to be subdivided. There
// is no reason to run the TreeWalker, it can be directly submitted for
// translation.
this.queueNodeForTranslation(node);
}
break;
case NodeStatus.SUBDIVIDE_FURTHER:
// This node may be translatable, but it needs to be subdivided into smaller
// pieces. Create a TreeWalker to walk the subtree, and find the subtrees/nodes
// that contain enough inline elements to send to be translated.
this.processSubdivide(node);
break;
}
if (node.nodeName === "BODY") {
this.reportWordsInViewport();
}
this.dispatchQueuedTranslations();
}
/**
* Get all the nodes which have selected attributes
* from the node/document and queue them.
* Call the translate function on these nodes
*
* @param {Node} node
* @returns {Array<Promise<void>> | null}
*/
translateAttributes(node) {
const attributeList = getTranslatableAttributes(node);
if (attributeList.length) {
// Queue the root node if it has any attributes
// Because querySelectorAll searches only child nodes.
this.queueAttributeNodeForTranslation(node, attributeList);
}
// Get all attributes in child nodes at once
const nodesWithTranslatableAttributes = node.querySelectorAll(
TRANSLATABLE_ATTRIBUTES_SELECTOR
);
for (const node of nodesWithTranslatableAttributes) {
const attributeList = getTranslatableAttributes(node);
this.queueAttributeNodeForTranslation(node, attributeList);
}
return this.dispatchQueuedAttributeTranslations();
}
/**
* Test whether this is an element we do not want to translate. These are things like
* <code> elements, elements with a different "lang" attribute, and elements that
* have a `translate=no` attribute.
*
* @param {Node} node
*/
isExcludedNode(node) {
// Property access be expensive, so destructure required properties so they are
// not accessed multiple times.
const { nodeType } = node;
if (nodeType === Node.TEXT_NODE) {
// Text nodes are never excluded.
return false;
}
if (nodeType !== Node.ELEMENT_NODE) {
// Only elements and and text nodes should be considered.
return true;
}
const { nodeName } = node;
if (
EXCLUDED_TAGS.has(
// SVG tags can be lowercased, so ensure everything is uppercased.
nodeName.toUpperCase()
)
) {
// This is an excluded tag.
return true;
}
if (!this.matchesDocumentLanguage(node)) {
// Exclude nodes that don't match the fromLanguage.
return true;
}
if (node.getAttribute("translate") === "no") {
// This element has a translate="no" attribute.
return true;
}
if (node.classList.contains("notranslate")) {
// Google Translate skips translations if the classList contains "notranslate"
return true;
}
if (node.isContentEditable) {
// This field is editable, and so exclude it similar to the way that form input
// fields are excluded.
return true;
}
return false;
}
/**
* Runs `determineTranslationStatus`, but only on unprocessed nodes.
*
* @param {Node} node
* @returns {number} - One of the NodeStatus values.
*/
determineTranslationStatusForUnprocessedNodes = node => {
if (this.#processedNodes.has(node)) {
// Skip nodes that have already been processed.
return NodeStatus.NOT_TRANSLATABLE;
}
return this.determineTranslationStatus(node);
};
/**
* Determines if a node should be submitted for translation, not translatable, or if
* it should be subdivided further. It doesn't check if the node has already been
* processed.
*
* The return result works as a TreeWalker NodeFilter as well.
*
* @param {Node} node
* @returns {number} - One of the `NodeStatus` values. See that object
* for documentation. These values match the filters for the TreeWalker.
* These values also work as a `NodeFilter` value.
*/
determineTranslationStatus(node) {
if (node.openOrClosedShadowRoot) {
return NodeStatus.SHADOW_HOST;
}
if (isNodeQueued(node, this.#queuedNodes)) {
// This node or its parent was already queued, reject it.
return NodeStatus.NOT_TRANSLATABLE;
}
if (this.isExcludedNode(node)) {
// This is an explicitly excluded node.
return NodeStatus.NOT_TRANSLATABLE;
}
if (node.textContent.trim().length === 0) {
// Do not use subtrees that are empty of text. This textContent call is fairly
// expensive.
return !node.hasChildNodes()
? NodeStatus.NOT_TRANSLATABLE
: NodeStatus.SUBDIVIDE_FURTHER;
}
if (nodeNeedsSubdividing(node)) {
// Skip this node, and dig deeper into its tree to cut off smaller pieces
// to translate. It is presumed to be a wrapper of block elements.
return NodeStatus.SUBDIVIDE_FURTHER;
}
if (
containsExcludedNode(node, this.excludedNodeSelector) &&
!hasTextNodes(node)
) {
// Skip this node, and dig deeper into its tree to cut off smaller pieces
// to translate.
return NodeStatus.SUBDIVIDE_FURTHER;
}
// This node can be treated as entire block to submit for translation.
return NodeStatus.READY_TO_TRANSLATE;
}
/**
* Queue a node for translation.
*
* @param {Node} node
*/
queueNodeForTranslation(node) {
/** @type {NodeVisibility} */
let visibility = "out-of-viewport";
if (isNodeHidden(node)) {
visibility = "hidden";
} else if (isNodeInViewport(node)) {
visibility = "in-viewport";
}
this.#queuedNodes.set(node, visibility);
}
/**
* Submit the translations giving priority to nodes in the viewport.
*
* @returns {Array<Promise<void>> | null}
*/
dispatchQueuedTranslations() {
let inViewportCounts = 0;
let outOfViewportCounts = 0;
let hiddenCounts = 0;
let inViewportTranslations = null;
if (!this.viewportTranslated) {
inViewportTranslations = [];
}
for (const [node, visibility] of this.#queuedNodes) {
if (visibility === "in-viewport") {
inViewportCounts++;
const promise = this.submitTranslation(node);
if (inViewportTranslations) {
inViewportTranslations.push(promise);
}
}
}
for (const [node, visibility] of this.#queuedNodes) {
if (visibility === "out-of-viewport") {
outOfViewportCounts++;
this.submitTranslation(node);
}
}
for (const [node, visibility] of this.#queuedNodes) {
if (visibility === "hidden") {
hiddenCounts++;
this.submitTranslation(node);
}
}
ChromeUtils.addProfilerMarker(
"Translations",
{ innerWindowId: this.innerWindowId },
`Translate ${this.#queuedNodes.size} nodes.\n\n` +
`In viewport: ${inViewportCounts}\n` +
`Out of viewport: ${outOfViewportCounts}\n` +
`Hidden: ${hiddenCounts}\n`
);
this.#queuedNodes.clear();
return inViewportTranslations;
}
/**
* Submit the Attribute translations giving priority to nodes in the viewport.
*
* @returns {Array<Promise<void>> | null}
*/
dispatchQueuedAttributeTranslations() {
let inViewportCounts = 0;
let outOfViewportCounts = 0;
let hiddenCounts = 0;
let inViewportTranslations = null;
if (!this.viewportTranslated) {
inViewportTranslations = [];
}
// Submit the nodes with attrbutes to be translated.
for (const [node, { attributeList, visibility }] of this
.#queuedAttributeNodes) {
if (visibility === "in-viewport") {
inViewportCounts++;
const promise = this.submitAttributeTranslation(node, attributeList);
if (inViewportTranslations) {
inViewportTranslations.push(promise);
}
}
}
for (const [node, { attributeList, visibility }] of this
.#queuedAttributeNodes) {
if (visibility === "out-of-viewport") {
outOfViewportCounts++;
this.submitAttributeTranslation(node, attributeList);
}
}
for (const [node, { attributeList, visibility }] of this
.#queuedAttributeNodes) {
if (visibility === "hidden") {
hiddenCounts++;
this.submitAttributeTranslation(node, attributeList);
}
}
ChromeUtils.addProfilerMarker(
"Attribute Translations",
{ innerWindowId: this.innerWindowId },
`Attribute Translate ${this.#queuedAttributeNodes.size} nodes.\n\n` +
`In viewport: ${inViewportCounts}\n` +
`Out of viewport: ${outOfViewportCounts}\n` +
`Hidden: ${hiddenCounts}\n`
);
this.#queuedAttributeNodes.clear();
return inViewportTranslations;
}
/**
* Submit a node for Attribute translation to the translations engine.
*
* @param {Node} node
* @returns {Promise<void>}
*/
async submitAttributeTranslation(node, attributeList) {
if (node.nodeType === Node.ELEMENT_NODE) {
for (const attribute of attributeList) {
const text = node.getAttribute(attribute);
if (text.trim().length === 0) {
continue;
}
const translation = await this.maybeTranslate(
node,
text,
false /*isHTML*/
);
if (translation != null) {
this.scheduleNodeUpdateWithTranslationAttribute(
node,
translation,
attribute
);
}
}
}
}
/**
* Schedule a node to be updated with a translation.
*
* @param {Node} node
* @param {string} translation
*/
scheduleNodeUpdateWithTranslationAttribute(node, translation, attribute) {
// Add the nodes to be populated with the next translation update.
this.#nodesWithTranslatedAttributes.add({
node,
translation,
attribute,
});
if (this.#pendingTranslationsCount === 0) {
// No translations are pending, update the node.
this.updateNodesWithTranslationsAttributes();
} else if (!this.#attributeUpdateTimeout) {
// Schedule an update.
this.#attributeUpdateTimeout = lazy.setTimeout(
this.updateNodesWithTranslationsAttributes.bind(this),
DOM_UPDATE_INTERVAL_MS
);
} else {
// An update has been previously scheduled, do nothing here.
}
}
/**
* This is called every `DOM_UPDATE_INTERVAL_MS` ms with translations
* for attributes in the nodes.
*
* This function is called asynchronously, so nodes may already be dead. Before
* accessing a node make sure and run `Cu.isDeadWrapper` to check that it is alive.
*/
updateNodesWithTranslationsAttributes() {
// Stop the mutations so that the updates won't trigger observations.
this.pauseMutationObserverAndRun(() => {
for (const { node, translation, attribute } of this
.#nodesWithTranslatedAttributes) {
if (Cu.isDeadWrapper(node)) {
// The node is no longer alive.
ChromeUtils.addProfilerMarker(
"Translations",
{ innerWindowId: this.innerWindowId },
"Node is no long alive."
);
continue;
}
// Update the attribute of the node with translated attribute
if (attribute) {
node.setAttribute(attribute, translation);
}
}
this.#nodesWithTranslatedAttributes.clear();
this.#attributeUpdateTimeout = null;
});
}
/**
* Record how many words were in the viewport, as this is the most important
* user-visible translation content.
*/
reportWordsInViewport() {
if (
// This promise gets created for the first dispatchQueuedTranslations
this.viewportTranslated ||
this.#queuedNodes.size === 0
) {
return;
}
// This requires a segmenter for a proper implementation.
const whitespace = /\s+/;
let wordCount = 0;
for (const [node, visibility] of this.#queuedNodes) {
if (visibility === "in-viewport") {
wordCount += node.textContent.trim().split(whitespace).length;
}
}
const message = wordCount + " words are in the viewport.";
lazy.console.log(message);
ChromeUtils.addProfilerMarker(
"Translations",
{ innerWindowId: this.innerWindowId },
message
);
}
/**
* Submit a node for translation to the translations engine.
*
* @param {Node} node
* @returns {Promise<void>}
*/
async submitTranslation(node) {
// Give each element an id that gets passed through the translation so it can be
// reunited later on.
if (node.nodeType === Node.ELEMENT_NODE) {
node.querySelectorAll("*").forEach((el, i) => {
el.dataset.mozTranslationsId = i;
});
}
/** @type {string} */
let text;
/** @type {boolean} */
let isHTML;
if (node.nodeType === Node.ELEMENT_NODE) {
text = node.innerHTML;
isHTML = true;
} else {
text = node.textContent;
isHTML = false;
}
if (text.trim().length === 0) {
return;
}
// Mark this node as not to be translated again unless the contents are changed
// (which the observer will pick up on)
this.#processedNodes.add(node);
const translatedHTML = await this.maybeTranslate(node, text, isHTML);
if (translatedHTML != null) {
this.scheduleNodeUpdateWithTranslation(node, translatedHTML);
}
}
/**
* A single function to update pendingTranslationsCount while
* calling the translate function
*
* @param {Node} node
* @param {string} text
* @property {boolean} isHTML
* @returns {Promise<string | null>}
*/
async maybeTranslate(node, text, isHTML) {
this.#pendingTranslationsCount++;
try {
let translation = this.translationsCache.get(text, isHTML);
if (translation === undefined) {
translation = await this.translator.translate(node, text, isHTML);
this.translationsCache.set(text, translation, isHTML);
} else if (!this.hasFirstVisibleChange) {
this.hasFirstVisibleChange = true;
this.actorReportFirstVisibleChange();
}
return translation;
} catch (error) {
lazy.console.log("Translation failed", error);
} finally {
this.#pendingTranslationsCount--;
}
return null;
}
/**
* Start the mutation observer, for instance after applying the translations to the DOM.
*/
startMutationObserver() {
if (Cu.isDeadWrapper(this.observer)) {
// This observer is no longer alive.
return;
}
for (const node of this.#rootNodes) {
if (Cu.isDeadWrapper(node)) {
// This node is no longer alive.
continue;
}
this.observer.observe(node, MUTATION_OBSERVER_OPTIONS);
}
}
/**
* Stop the mutation observer, for instance to apply the translations to the DOM.
*/
stopMutationObserver() {
// Was the window already destroyed?
if (!Cu.isDeadWrapper(this.observer)) {
this.observer.disconnect();
}
}
/**
* This is called every `DOM_UPDATE_INTERVAL_MS` ms with translations for nodes.
*
* This function is called asynchronously, so nodes may already be dead. Before
* accessing a node make sure and run `Cu.isDeadWrapper` to check that it is alive.
*/
updateNodesWithTranslations() {
// Stop the mutations so that the updates won't trigger observations.
this.pauseMutationObserverAndRun(() => {
for (const { node, translatedHTML } of this.#nodesWithTranslatedHTML) {
if (Cu.isDeadWrapper(node)) {
// The node is no longer alive.
ChromeUtils.addProfilerMarker(
"Translations",
{ innerWindowId: this.innerWindowId },
"Node is no long alive."
);
continue;
}
switch (node.nodeType) {
case Node.TEXT_NODE: {
if (translatedHTML.trim().length !== 0) {
// Only update the node if there is new text.
node.textContent = translatedHTML;
}
break;
}
case Node.ELEMENT_NODE: {
// in the addon which set the innerHTML directly. We can't set the innerHTML
// here, but perhaps there is another way to get back some of the performance.
const translationsDocument = this.domParser.parseFromString(
`<!DOCTYPE html><div>${translatedHTML}</div>`,
"text/html"
);
updateElement(translationsDocument, node);
break;
}
}
}
this.#nodesWithTranslatedHTML.clear();
this.#updateTimeout = null;
});
}
/**
* Stop the mutations so that the updates of the translations
* in the nodes won't trigger observations.
*
* @param {Function} run The function to update translations
*/
pauseMutationObserverAndRun(run) {
this.stopMutationObserver();
run();
this.startMutationObserver();
}
/**
* Schedule a node to be updated with a translation.
*
* @param {Node} node
* @param {string} translatedHTML
*/
scheduleNodeUpdateWithTranslation(node, translatedHTML) {
// Add the nodes to be populated with the next translation update.
this.#nodesWithTranslatedHTML.add({ node, translatedHTML });
if (this.#pendingTranslationsCount === 0) {
// No translations are pending, update the node.
this.updateNodesWithTranslations();
} else if (!this.#updateTimeout) {
// Schedule an update.
this.#updateTimeout = lazy.setTimeout(
this.updateNodesWithTranslations.bind(this),
DOM_UPDATE_INTERVAL_MS
);
} else {
// An update has been previously scheduled, do nothing here.
}
}
/**
* Check to see if a language matches the document language.
*
* @param {Node} node
*/
matchesDocumentLanguage(node) {
if (!node.lang) {
// No `lang` was present, so assume it matches the language.
return true;
}
// First, cheaply check if language tags match, without canonicalizing.
if (langTagsMatch(this.documentLanguage, node.lang)) {
return true;
}
try {
// Make sure the local is in the canonical form, and check again. This function
// throws, so don't trust that the language tags are formatting correctly.
const [language] = Intl.getCanonicalLocales(node.lang);
return langTagsMatch(this.documentLanguage, language);
} catch (_error) {
return false;
}
}
}
/**
* Get the list of attributes that need to be translated
* in a given node.
*
* @returns {Array<string>}
*/
function getTranslatableAttributes(node) {
if (node.nodeType !== Node.ELEMENT_NODE) {
return [];
}
return TRANSLATABLE_ATTRIBUTES.filter(attribute =>
node.hasAttribute(attribute)
);
}
/**
* This function needs to be fairly fast since it's used on many nodes when iterating
* over the DOM to find nodes to translate.
*
* @param {Text | HTMLElement} node
*/
function isNodeHidden(node) {
/** @type {HTMLElement} */
const element = getElementForStyle(node);
if (!element) {
throw new Error("Unable to find the Element to compute the style for node");
}
// This flushes the style, which is a performance cost.
const style = element.ownerGlobal.getComputedStyle(element);
return style.display === "none" || style.visibility === "hidden";
}
/**
* This function cheaply checks that language tags match.
*
* @param {string} knownLanguage
* @param {string} otherLanguage
*/
function langTagsMatch(knownLanguage, otherLanguage) {
if (knownLanguage === otherLanguage) {
// A simple direct match.
return true;
}
if (knownLanguage.length !== 2) {
throw new Error("Expected the knownLanguage to be of length 2.");
}
// Check if the language tags part match, e.g. "en" and "en-US".
return (
knownLanguage[0] === otherLanguage[0] &&
knownLanguage[1] === otherLanguage[1] &&
otherLanguage[2] === "-"
);
}
/**
* This function returns the correct element to determine the
* style of node.
*
* @param {Node} node
@returns {HTMLElement} */
function getElementForStyle(node) {
if (node.nodeType != Node.TEXT_NODE) {
return node;
}
if (node.parentElement) {
return node.parentElement;
}
// For cases like text node where its parent is ShadowRoot,
// we'd like to use flattenedTreeParentNode
if (node.flattenedTreeParentNode) {
return node.flattenedTreeParentNode;
}
// If the text node is not connected or doesn't have a frame.
return null;
}
/**
* This function runs when walking the DOM, which means it is a hot function. It runs
* fairly fast even though it is computing the bounding box. This is all done in a tight
* loop, and it is done on mutations. Care should be taken with reflows caused by
* getBoundingClientRect, as this is a common performance issue.
*
* The following are the counts of how often this is run on a news site:
*
* Given:
* 1573 DOM nodes
* 504 Text nodes
* 1069 Elements
*
* There were:
* 209 calls to get this funcion.
*
* @param {Node} node
*/
function isNodeInViewport(node) {
const window = node.ownerGlobal;
const document = node.ownerDocument;
/** @type {HTMLElement} */
const element = getElementForStyle(node);
if (!element) {
throw new Error("Unable to find the Element to compute the style for node");
}
const rect = element.getBoundingClientRect();
return (
rect.top >= 0 &&
rect.left >= 0 &&
rect.bottom <=
(window.innerHeight || document.documentElement.clientHeight) &&
rect.right <= (window.innerWidth || document.documentElement.clientWidth)
);
}
/**
* Actually perform the update of the element with the translated node. This step
* will detach all of the "live" nodes, and match them up in the correct order as provided
* by the translations engine.
*
* @param {Document} translationsDocument
* @param {Element} element
* @returns {void}
*/
function updateElement(translationsDocument, element) {
// This text should have the same layout as the target, but it's not completely
// guaranteed since the content page could change at any time, and the translation process is async.
//
// The document has the following structure:
//
// <html>
// <head>
// <body>{translated content}</body>
// </html>
const originalHTML = element.innerHTML;
/**
* The Set of translation IDs for nodes that have been cloned.
*
* @type {Set<number>}
*/
const clonedNodes = new Set();
merge(element, translationsDocument.body.firstChild);
/**
* Merge the live tree with the translated tree by re-using elements from the live tree.
*
* @param {Node} liveTree
* @param {Node} translatedTree
*/
function merge(liveTree, translatedTree) {
/** @type {Map<number, Element>} */
const liveElementsById = new Map();
/** @type {Array<Text>} */
const liveTextNodes = [];
// Remove all the nodes from the liveTree, and categorize them by Text node or
// Element node.
let node;
while ((node = liveTree.firstChild)) {
node.remove();
if (node.nodeType === Node.ELEMENT_NODE) {
liveElementsById.set(node.dataset.mozTranslationsId, node);
} else if (node.nodeType === Node.TEXT_NODE) {
liveTextNodes.push(node);
}
}
// The translated tree dictates the order.
const translatedNodes = [...translatedTree.childNodes];
for (
let translatedIndex = 0;
translatedIndex < translatedNodes.length;
translatedIndex++
) {
const translatedNode = translatedNodes[translatedIndex];
if (translatedNode.nodeType === Node.TEXT_NODE) {
// Copy the translated text to the original Text node and re-append it.
let liveTextNode = liveTextNodes.shift();
if (liveTextNode) {
liveTextNode.data = translatedNode.data;
} else {
liveTextNode = translatedNode;
}
liveTree.appendChild(liveTextNode);
} else if (translatedNode.nodeType === Node.ELEMENT_NODE) {
const translationsId = translatedNode.dataset.mozTranslationsId;
// Element nodes try to use the already existing DOM nodes.
// Find the element in the live tree that matches the one in the translated tree.
let liveElement = liveElementsById.get(translationsId);
if (!liveElement) {
lazy.console.warn("Could not find a corresponding live element", {
path: createNodePath(translatedNode, translationsDocument.body),
translationsId,
liveElementsById,
translatedNode,
});
continue;
}
// Has this element already been added to the list? Then duplicate it and re-add
// it as a clone. The Translations Engine can sometimes duplicate HTML.
if (liveElement.parentNode) {
liveElement = liveElement.cloneNode(true /* deep clone */);
clonedNodes.add(translationsId);
lazy.console.warn(
"Cloning a node because it was already inserted earlier",
{
path: createNodePath(translatedNode, translationsDocument.body),
translatedNode,
liveElement,
}
);
}
if (isNodeTextEmpty(translatedNode)) {
// The original node had text, but the one that came out of translation
// didn't have any text. This scenario might be caused by one of two causes:
//
// 1) The element was duplicated by translation but then not given text
// content. This happens on Wikipedia articles for example.
//
// 2) The translator messed up and could not translate the text. This
// happens on YouTube in the language selector. In that case, having the
// original text is much better than no text at all.
//
// To make sure it is case 1 and not case 2 check whether this is the only occurrence.
for (let i = 0; i < translatedNodes.length; i++) {
if (translatedIndex === i) {
// This is the current node, not a sibling.
continue;
}
const sibling = translatedNodes[i];
if (
// Only consider other element nodes.
sibling.nodeType === Node.ELEMENT_NODE &&
// If the sibling's translationsId matches, then use the sibling's
// node instead.
translationsId === sibling.dataset.mozTranslationsId
) {
// This is case 1 from above. Remove this element's original text nodes,
// since a sibling text node now has all of the text nodes.
removeTextNodes(liveElement);
}
}
// Report this issue to the console.
lazy.console.warn(
"The translated element has no text even though the original did.",
{
path: createNodePath(translatedNode, translationsDocument.body),
translatedNode,
liveElement,
}
);
} else if (!isNodeTextEmpty(liveElement)) {
// There are still text nodes to find and update, recursively merge.
merge(liveElement, translatedNode);
}
// Put the live node back in the live branch. But now t has been synced with the
// translated text and order.
liveTree.appendChild(liveElement);
}
}
const unhandledElements = [...liveElementsById].filter(
([, element]) => !element.parentNode
);
for (node of liveTree.querySelectorAll("*")) {
// Clean-up the translation ids.
delete node.dataset.mozTranslationsId;
}
if (unhandledElements.length) {
lazy.console.warn(
`${createNodePath(
translatedTree,
translationsDocument.body
)} Not all nodes unified`,
{
unhandledElements,
clonedNodes,
originalHTML,
translatedHTML: translationsDocument.body.innerHTML,
liveTree: liveTree.outerHTML,
translatedTree: translatedTree.outerHTML,
}
);
}
}
}
/**
* For debug purposes, compute a string path to an element.
*
* e.g. "div/div#header/p.bold.string/a"
*
* @param {Node} node
* @param {Node | null} root
*/
function createNodePath(node, root) {
if (root === null) {
root = node.ownerDocument.body;
}
let path =
node.parentNode && node.parentNode !== root
? createNodePath(node.parentNode)
: "";
path += `/${node.nodeName}`;
if (node.id) {
path += `#${node.id}`;
} else if (node.className) {
for (const className of node.classList) {
path += "." + className;
}
}
return path;
}
/**
* @param {Node} node
* @returns {boolean}
*/
function isNodeTextEmpty(node) {
if ("innerText" in node) {
return node.innerText.trim().length === 0;
}
if (node.nodeType === Node.TEXT_NODE && node.nodeValue) {
return node.nodeValue.trim().length === 0;
}
return true;
}
/**
* @param {Node} node
*/
function removeTextNodes(node) {
for (const child of node.childNodes) {
switch (child.nodeType) {
case Node.TEXT_NODE:
node.removeChild(child);
break;
case Node.ELEMENT_NODE:
removeTextNodes(child);
break;
default:
break;
}
}
}
/**
* Test whether any of the direct child text nodes of are non-whitespace
* text nodes.
*
* For example:
* - `<p>test</p>`: yes
* - `<p> </p>`: no
* - `<p><b>test</b></p>`: no
*
* @param {Node} node
* @returns {boolean}
*/
function hasTextNodes(node) {
if (node.nodeType !== Node.ELEMENT_NODE) {
// Only check element nodes.
return false;
}
for (const child of node.childNodes) {
if (child.nodeType === Node.TEXT_NODE) {
if (child.textContent.trim() === "") {
// This is just whitespace.
continue;
}
// A text node with content was found.
return true;
}
}
// No text nodes were found.
return false;
}
/**
* Like `isExcludedNode` but looks at the full subtree. Used to see whether
* we can submit a subtree, or whether we should split it into smaller
* branches first to try to exclude more of the non-translatable content.
*
* @param {Node} node
* @param {string} excludedNodeSelector
* @returns {boolean}
*/
function containsExcludedNode(node, excludedNodeSelector) {
return (
node.nodeType === Node.ELEMENT_NODE &&
node.querySelector(excludedNodeSelector)
);
}
/**
* Check if this node has already been queued to be translated. This can be because
* the node is itself is queued, or its parent node is queued.
*
* @param {Node} node
* @param {Map<Node, any>} queuedNodes
* @returns {boolean}
*/
function isNodeQueued(node, queuedNodes) {
if (queuedNodes.has(node)) {
return true;
}
// If the immediate parent is the body, it is allowed.
if (node.parentNode === node.ownerDocument.body) {
return false;
}
// Accessing the parentNode is expensive here according to performance profilling. This
// is due to XrayWrappers. Minimize reading attributes by storing a reference to the
// `parentNode` in a named variable, rather than re-accessing it.
let parentNode;
let lastNode = node;
while ((parentNode = lastNode.parentNode)) {
if (queuedNodes.has(parentNode)) {
return parentNode;
}
lastNode = parentNode;
}
return false;
}
/**
* Reads the elements computed style and determines if the element is a block-like
* element or not. Every element that lays out like a block should be sent in as one
* cohesive unit to be translated.
*
* @param {Element} element
*/
function getIsBlockLike(element) {
const win = element.ownerGlobal;
// SVG elements will report as inline, but there is no block layout in SVG.
// Treat every SVG element as being block so that every node will be subdivided.
return true;
}
const { display } = win.getComputedStyle(element);
return display !== "inline" && display !== "none";
}
/**
* Determine if this element is an inline element or a block element. Inline elements
* should be sent as a contiguous chunk of text, while block elements should be further
* subdivided before sending them in for translation.
*
* @param {Node} node
* @returns {boolean}
*/
function nodeNeedsSubdividing(node) {
if (node.nodeType === Node.TEXT_NODE) {
// Text nodes are fully subdivided.
return false;
}
if (!getIsBlockLike(node)) {
// This element is inline, or not displayed.
return false;
}
for (let child of node.childNodes) {
switch (child.nodeType) {
case Node.TEXT_NODE:
// Keep checking for more inline or text nodes.
continue;
case Node.ELEMENT_NODE: {
if (getIsBlockLike(child)) {
// This node is a block node, so it needs further subdividing.
return true;
}
// Keep checking for more inline or text nodes.
continue;
}
default:
return true;
}
}
return false;
}
/**
* Returns an iterator of a node's ancestors.
*
* @param {Node} node
* @returns {Generator<ParentNode>}
*/
function* getAncestorsIterator(node) {
const document = node.ownerDocument;
for (
let parent = node.parentNode;
parent && parent !== document.documentElement;
parent = parent.parentNode
) {
yield parent;
}
}
/**
* This contains all of the information needed to perform a translation request.
*
* @typedef {object} TranslationRequest
* @property {Node} node
* @property {string} sourceText
* @property {boolean} isHTML
* @property {Function} resolve
* @property {Function} reject
*/
/**
* When a page is hidden, mutations may occur in the DOM. It doesn't make sense to
* translate those elements while the page is hidden, especially as it may bring
* a translations engine back to life, which can be quite expensive. Queue those
* messages here.
*/
class QueuedTranslator {
/**
* @type {MessagePort | null}
*/
#port = null;
/**
* @type {() => void}
*/
#actorRequestNewPort;
/**
* Send a message to the actor that the first visible DOM translation change is about to occur.
*
* @type {() => void}
*/
#actorReportFirstVisibleChange;
/**
* An id for each message sent. This is used to match up the request and response.
*/
#nextMessageId = 0;
/**
* Tie together a message id to a resolved response.
*
* @type {Map<number, TranslationRequest>}
*/
#requests = new Map();
/**
* If the translations are paused, they are queued here. This Map is ordered by
* from oldest to newest requests with stale requests being removed.
*
* @type {Map<Node, TranslationRequest>}
*/
#queue = new Map();
/**
* @type {"uninitialized" | "ready" | "error" | "closed"}
*/
engineStatus = "uninitialized";
/**
* @param {MessagePort} port
* @param {() => void} actorRequestNewPort
* @param {() => void} actorReportFirstVisibleChange
*/
constructor(port, actorRequestNewPort, actorReportFirstVisibleChange) {
this.#actorRequestNewPort = actorRequestNewPort;
this.#actorReportFirstVisibleChange = actorReportFirstVisibleChange;
this.acquirePort(port);
}
/**
* When an engine gets closed while still in use, a new one will need to be requested.
*
* @type {{ promise: Promise<void>, resolve: Function, reject: Function } | null}
*/
#portRequest = null;
/**
* Keep track if the page is shown or hidden. When the page is hidden, no translations
* will be posted to the translations engine.
*/
#isPageShown = true;
/**
* Note when a new port is being requested so we don't re-request it.
*/
showPage() {
this.#isPageShown = true;
if (this.#port) {
throw new Error(
"Attempting to show the page when there is already port available"
);
}
if (this.#queue.size) {
// There are queued translations, request a new port. After the port is retrieved
// the pending queue will be processed.
this.#requestNewPort();
}
}
/**
* Hide the page, and move any outstanding translation requests to a queue.
*/
hidePage() {
this.#isPageShown = false;
this.discardPort();
if (this.#requests.size) {
lazy.console.log(
"Pausing translations with pending translation requests."
);
}
this.#moveRequestsToQueue();
}
/**
* Request a new port. The port will come in via `acquirePort`, and then resolved
* through the `this.#portRequest.resolve`.
*
* @returns {Promise<void>}
*/
#requestNewPort() {
if (this.#portRequest) {
// A port was already requested.
return this.#portRequest.promise;
}
const portRequest = { promise: null, resolve: null, reject: null };
portRequest.promise = new Promise((resolve, reject) => {
portRequest.resolve = resolve;
portRequest.reject = reject;
});
this.#portRequest = portRequest;
// Send a request through the actor for a new port. The request response will
// trigger the method `QueuedTranslator.prototype.acquirePort`
this.#actorRequestNewPort();
this.#portRequest.promise
.then(
() => {
this.#portRequest = null;
// Resume the queued translations.
if (this.#queue.size) {
lazy.console.log(
`Resuming ${
this.#queue.size
} translations from the pending translation queue.`
);
const oldQueue = this.#queue;
this.#queue = new Map();
this.#repostTranslations(oldQueue);
}
},
error => {
lazy.console.error(error);
}
)
.finally(() => {
this.#portRequest = null;
});
return portRequest.promise;
}
/**
* Send a request to translate text to the Translations Engine. If it returns `null`
* then the request is stale. A rejection means there was an error in the translation.
* This request may be queued.
*
* @param {Node} node
* @param {string} sourceText
* @param {boolean} isHTML
*/
async translate(node, sourceText, isHTML) {
if (this.#isPageShown && !this.#port) {
try {
await this.#requestNewPort();
} catch {}
}
// At this point we don't know if the page is still shown, or if the attempt
// to get a port was successful so check again.
if (!this.#isPageShown || !this.#port) {
// Queue the request while the page isn't shown.
return new Promise((resolve, reject) => {
const previousRequest = this.#queue.get(node);
if (previousRequest) {
// Previous requests get resolved as null, as this new one will replace it.
previousRequest.resolve(null);
// Delete the entry so that the order of the queue is maintained. The
// new request will be put on the end.
this.#queue.delete(node);
}
// This Promises's resolve and reject will be chained after the translation
// request. For now add it to the queue along with the other arguments.
this.#queue.set(node, { node, sourceText, isHTML, resolve, reject });
});
}
return this.#postTranslationRequest(node, sourceText, isHTML);
}
/**
* Posts the translation to the translations engine through the MessagePort.
*
* @param {Node} node
* @param {string} sourceText
* @param {boolean} isHTML
* @returns {{ translateText: TranslationFunction, translateHTML: TranslationFunction}}
*/
#postTranslationRequest(node, sourceText, isHTML) {
return new Promise((resolve, reject) => {
const messageId = this.#nextMessageId++;
// Store the "resolve" for the promise. It will be matched back up with the
// `messageId` in #handlePortMessage.
this.#requests.set(messageId, {
node,
sourceText,
isHTML,
resolve,
reject,
});
this.#port.postMessage({
type: "TranslationsPort:TranslationRequest",
messageId,
sourceText,
isHTML,
});
});
}
/**
* Close the port and move any pending translations onto a queue.
*/
discardPort() {
if (this.#port) {
this.#port.postMessage({ type: "TranslationsPort:DiscardTranslations" });
this.#port.close();
this.#port = null;
}
this.#moveRequestsToQueue();
this.engineStatus = "uninitialized";
}
/**
* Move any unfulfilled requests to the queue so they can be sent again when
* the page is active again.
*/
#moveRequestsToQueue() {
if (this.#requests.size) {
for (const request of this.#requests.values()) {
this.#queue.set(request.node, request);
}
this.#requests = new Map();
}
}
/**
* Acquires a port, checks on the engine status, and then starts or resumes
* translations.
*
* @param {MessagePort} port
*/
acquirePort(port) {
if (this.#port) {
if (this.engineStatus === "ready") {
lazy.console.error(
"Received a new translation port while one already existed."
);
}
this.discardPort();
}
this.#port = port;
const portRequest = this.#portRequest;
// Match up a response on the port to message that was sent.
port.onmessage = ({ data }) => {
switch (data.type) {
case "TranslationsPort:TranslationResponse": {
if (!this.hasFirstVisibleChange) {
this.hasFirstVisibleChange = true;
this.#actorReportFirstVisibleChange();
}
const { targetText, messageId } = data;
// A request may not match match a messageId if there is a race during the pausing
// and discarding of the queue.
this.#requests.get(messageId)?.resolve(targetText);
this.#requests.delete(messageId);
break;
}
case "TranslationsPort:GetEngineStatusResponse": {
if (portRequest) {
const { resolve, reject } = portRequest;
if (data.status === "ready") {
resolve();
} else {
reject(new Error("The engine failed to load."));
}
}
this.engineStatus = data.status;
break;
}
case "TranslationsPort:EngineTerminated": {
// The engine was terminated, and if a translation is needed a new port
// will need to be requested.
this.engineStatus = "closed";
this.discardPort();
if (this.#queue.size && this.#isPageShown) {
this.#requestNewPort();
}
break;
}
default:
lazy.console.error("Unknown translations port message: " + data.type);
break;
}
};
port.postMessage({ type: "TranslationsPort:GetEngineStatusRequest" });
}
/**
* Re-send a list of translation requests.
*
* @param {Map<any, TranslationRequest>} mappedRequests
* This is either the this.#queue or this.#requests.
*/
#repostTranslations(mappedRequests) {
for (const value of mappedRequests.values()) {
const { node, sourceText, isHTML, resolve, reject } = value;
if (Cu.isDeadWrapper(node)) {
// If the node is dead, resolve without any text. Do not reject as that
// will be treated as an error.
resolve(null);
} else {
this.#postTranslationRequest(node, sourceText, isHTML).then(
resolve,
reject
);
}
}
}
/**
* Close the port and remove any pending or queued requests.
*/
destroy() {
this.#port.close();
this.#requests = new Map();
this.#queue = new Map();
}
}