Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1085 insertions, 0 deletions

diff --git a/widget/IMEData.h b/widget/IMEData.h
new file mode 100644
index 0000000000..188f973aca
--- /dev/null
+++ b/widget/IMEData.h
@@ -0,0 +1,1085 @@
+/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 mozilla_widget_IMEData_h_
+#define mozilla_widget_IMEData_h_
+
+#include "mozilla/CheckedInt.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/NativeKeyBindingsType.h"
+#include "mozilla/ToString.h"
+
+#include "nsCOMPtr.h"
+#include "nsIURI.h"
+#include "nsPoint.h"
+#include "nsRect.h"
+#include "nsString.h"
+#include "nsXULAppAPI.h"
+#include "Units.h"
+
+class nsIWidget;
+
+namespace mozilla {
+
+class ContentSelection;
+class WritingMode;
+
+template <class T>
+class Maybe;
+
+// Helper class to logging string which may contain various Unicode characters
+// and/or may be too long string for logging.
+class MOZ_STACK_CLASS PrintStringDetail : public nsAutoCString {
+ public:
+  static constexpr uint32_t kMaxLengthForCompositionString = 8;
+  static constexpr uint32_t kMaxLengthForSelectedString = 12;
+  static constexpr uint32_t kMaxLengthForEditor = 20;
+
+  PrintStringDetail() = delete;
+  explicit PrintStringDetail(const nsAString& aString,
+                             uint32_t aMaxLength = UINT32_MAX);
+  template <typename StringType>
+  explicit PrintStringDetail(const Maybe<StringType>& aMaybeString,
+                             uint32_t aMaxLength = UINT32_MAX);
+
+ private:
+  static nsCString PrintCharData(char32_t aChar);
+};
+
+// StartAndEndOffsets represents a range in flat-text.
+template <typename IntType>
+class StartAndEndOffsets {
+ protected:
+  static IntType MaxOffset() { return std::numeric_limits<IntType>::max(); }
+
+ public:
+  StartAndEndOffsets() = delete;
+  explicit StartAndEndOffsets(IntType aStartOffset, IntType aEndOffset)
+      : mStartOffset(aStartOffset),
+        mEndOffset(aStartOffset <= aEndOffset ? aEndOffset : aStartOffset) {
+    MOZ_ASSERT(aStartOffset <= mEndOffset);
+  }
+
+  IntType StartOffset() const { return mStartOffset; }
+  IntType Length() const { return mEndOffset - mStartOffset; }
+  IntType EndOffset() const { return mEndOffset; }
+
+  bool IsOffsetInRange(IntType aOffset) const {
+    return aOffset >= mStartOffset && aOffset < mEndOffset;
+  }
+  bool IsOffsetInRangeOrEndOffset(IntType aOffset) const {
+    return aOffset >= mStartOffset && aOffset <= mEndOffset;
+  }
+
+  void MoveTo(IntType aNewStartOffset) {
+    auto delta = static_cast<int64_t>(mStartOffset) - aNewStartOffset;
+    mStartOffset += delta;
+    mEndOffset += delta;
+  }
+  void SetOffsetAndLength(IntType aNewOffset, IntType aNewLength) {
+    mStartOffset = aNewOffset;
+    CheckedInt<IntType> endOffset(aNewOffset + aNewLength);
+    mEndOffset = endOffset.isValid() ? endOffset.value() : MaxOffset();
+  }
+  void SetEndOffset(IntType aEndOffset) {
+    MOZ_ASSERT(mStartOffset <= aEndOffset);
+    mEndOffset = std::max(aEndOffset, mStartOffset);
+  }
+  void SetStartAndEndOffsets(IntType aStartOffset, IntType aEndOffset) {
+    MOZ_ASSERT(aStartOffset <= aEndOffset);
+    mStartOffset = aStartOffset;
+    mEndOffset = aStartOffset <= aEndOffset ? aEndOffset : aStartOffset;
+  }
+  void SetLength(IntType aNewLength) {
+    CheckedInt<IntType> endOffset(mStartOffset + aNewLength);
+    mEndOffset = endOffset.isValid() ? endOffset.value() : MaxOffset();
+  }
+
+  friend std::ostream& operator<<(
+      std::ostream& aStream,
+      const StartAndEndOffsets<IntType>& aStartAndEndOffsets) {
+    aStream << "{ mStartOffset=" << aStartAndEndOffsets.mStartOffset
+            << ", mEndOffset=" << aStartAndEndOffsets.mEndOffset
+            << ", Length()=" << aStartAndEndOffsets.Length() << " }";
+    return aStream;
+  }
+
+ private:
+  IntType mStartOffset;
+  IntType mEndOffset;
+};
+
+// OffsetAndData class is designed for storing composition string and its
+// start offset.  Length() and EndOffset() return only valid length or
+// offset.  I.e., if the string is too long for inserting at the offset,
+// the length is shrunken.  However, the string itself is not shrunken.
+// Therefore, moving it to where all of the string can be contained,
+// they will return longer/bigger value.
+enum class OffsetAndDataFor {
+  CompositionString,
+  SelectedString,
+  EditorString,
+};
+template <typename IntType>
+class OffsetAndData {
+ protected:
+  static IntType MaxOffset() { return std::numeric_limits<IntType>::max(); }
+
+ public:
+  OffsetAndData() = delete;
+  explicit OffsetAndData(
+      IntType aStartOffset, const nsAString& aData,
+      OffsetAndDataFor aFor = OffsetAndDataFor::CompositionString)
+      : mData(aData), mOffset(aStartOffset), mFor(aFor) {}
+
+  bool IsValid() const {
+    CheckedInt<IntType> offset(mOffset);
+    offset += mData.Length();
+    return offset.isValid();
+  }
+  IntType StartOffset() const { return mOffset; }
+  IntType Length() const {
+    CheckedInt<IntType> endOffset(CheckedInt<IntType>(mOffset) +
+                                  mData.Length());
+    return endOffset.isValid() ? mData.Length() : MaxOffset() - mOffset;
+  }
+  IntType EndOffset() const { return mOffset + Length(); }
+  StartAndEndOffsets<IntType> CreateStartAndEndOffsets() const {
+    return StartAndEndOffsets<IntType>(StartOffset(), EndOffset());
+  }
+  const nsString& DataRef() const {
+    // In strictly speaking, we should return substring which may be shrunken
+    // for rounding to the max offset.  However, it's unrealistic edge case,
+    // and creating new string is not so cheap job in a hot path.  Therefore,
+    // this just returns the data as-is.
+    return mData;
+  }
+  bool IsDataEmpty() const { return mData.IsEmpty(); }
+
+  bool IsOffsetInRange(IntType aOffset) const {
+    return aOffset >= mOffset && aOffset < EndOffset();
+  }
+  bool IsOffsetInRangeOrEndOffset(IntType aOffset) const {
+    return aOffset >= mOffset && aOffset <= EndOffset();
+  }
+
+  void Collapse(IntType aOffset) {
+    mOffset = aOffset;
+    mData.Truncate();
+  }
+  void MoveTo(IntType aNewOffset) { mOffset = aNewOffset; }
+  void SetOffsetAndData(IntType aStartOffset, const nsAString& aData) {
+    mOffset = aStartOffset;
+    mData = aData;
+  }
+  void SetData(const nsAString& aData) { mData = aData; }
+  void TruncateData(uint32_t aLength = 0) { mData.Truncate(aLength); }
+  void ReplaceData(nsAString::size_type aCutStart,
+                   nsAString::size_type aCutLength,
+                   const nsAString& aNewString) {
+    mData.Replace(aCutStart, aCutLength, aNewString);
+  }
+
+  friend std::ostream& operator<<(
+      std::ostream& aStream, const OffsetAndData<IntType>& aOffsetAndData) {
+    const auto maxDataLength =
+        aOffsetAndData.mFor == OffsetAndDataFor::CompositionString
+            ? PrintStringDetail::kMaxLengthForCompositionString
+            : (aOffsetAndData.mFor == OffsetAndDataFor::SelectedString
+                   ? PrintStringDetail::kMaxLengthForSelectedString
+                   : PrintStringDetail::kMaxLengthForEditor);
+    aStream << "{ mOffset=" << aOffsetAndData.mOffset << ", mData="
+            << PrintStringDetail(aOffsetAndData.mData, maxDataLength).get()
+            << ", Length()=" << aOffsetAndData.Length()
+            << ", EndOffset()=" << aOffsetAndData.EndOffset() << " }";
+    return aStream;
+  }
+
+ private:
+  nsString mData;
+  IntType mOffset;
+  OffsetAndDataFor mFor;
+};
+
+namespace widget {
+
+/**
+ * Preference for receiving IME updates
+ *
+ * If mWantUpdates is not NOTIFY_NOTHING, nsTextStateManager will observe text
+ * change and/or selection change and call nsIWidget::NotifyIME() with
+ * NOTIFY_IME_OF_SELECTION_CHANGE and/or NOTIFY_IME_OF_TEXT_CHANGE.
+ * Please note that the text change observing cost is very expensive especially
+ * on an HTML editor has focus.
+ * If the IME implementation on a particular platform doesn't care about
+ * NOTIFY_IME_OF_SELECTION_CHANGE and/or NOTIFY_IME_OF_TEXT_CHANGE,
+ * they should set mWantUpdates to NOTIFY_NOTHING to avoid the cost.
+ * If the IME implementation needs notifications even while our process is
+ * deactive, it should also set NOTIFY_DURING_DEACTIVE.
+ */
+struct IMENotificationRequests final {
+  typedef uint8_t Notifications;
+
+  enum : Notifications {
+    NOTIFY_NOTHING = 0,
+    NOTIFY_TEXT_CHANGE = 1 << 1,
+    NOTIFY_POSITION_CHANGE = 1 << 2,
+    // NOTIFY_MOUSE_BUTTON_EVENT_ON_CHAR is used when mouse button is pressed
+    // or released on a character in the focused editor.  The notification is
+    // notified to IME as a mouse event.  If it's consumed by IME, NotifyIME()
+    // returns NS_SUCCESS_EVENT_CONSUMED.  Otherwise, it returns NS_OK if it's
+    // handled without any error.
+    NOTIFY_MOUSE_BUTTON_EVENT_ON_CHAR = 1 << 3,
+    // NOTE: NOTIFY_DURING_DEACTIVE isn't supported in environments where two
+    //       or more compositions are possible.  E.g., Mac and Linux (GTK).
+    NOTIFY_DURING_DEACTIVE = 1 << 7,
+
+    NOTIFY_ALL = NOTIFY_TEXT_CHANGE | NOTIFY_POSITION_CHANGE |
+                 NOTIFY_MOUSE_BUTTON_EVENT_ON_CHAR,
+  };
+
+  IMENotificationRequests() : mWantUpdates(NOTIFY_NOTHING) {}
+
+  explicit IMENotificationRequests(Notifications aWantUpdates)
+      : mWantUpdates(aWantUpdates) {}
+
+  IMENotificationRequests operator|(
+      const IMENotificationRequests& aOther) const {
+    return IMENotificationRequests(aOther.mWantUpdates | mWantUpdates);
+  }
+  IMENotificationRequests& operator|=(const IMENotificationRequests& aOther) {
+    mWantUpdates |= aOther.mWantUpdates;
+    return *this;
+  }
+  bool operator==(const IMENotificationRequests& aOther) const {
+    return mWantUpdates == aOther.mWantUpdates;
+  }
+
+  bool WantTextChange() const { return !!(mWantUpdates & NOTIFY_TEXT_CHANGE); }
+
+  bool WantPositionChanged() const {
+    return !!(mWantUpdates & NOTIFY_POSITION_CHANGE);
+  }
+
+  bool WantChanges() const { return WantTextChange(); }
+
+  bool WantMouseButtonEventOnChar() const {
+    return !!(mWantUpdates & NOTIFY_MOUSE_BUTTON_EVENT_ON_CHAR);
+  }
+
+  bool WantDuringDeactive() const {
+    return !!(mWantUpdates & NOTIFY_DURING_DEACTIVE);
+  }
+
+  Notifications mWantUpdates;
+};
+
+/**
+ * IME enabled states.
+ *
+ * WARNING: If you change these values, you also need to edit:
+ *   nsIDOMWindowUtils.idl
+ */
+enum class IMEEnabled {
+  /**
+   * 'Disabled' means the user cannot use IME. So, the IME open state should
+   * be 'closed' during 'disabled'.
+   */
+  Disabled,
+  /**
+   * 'Enabled' means the user can use IME.
+   */
+  Enabled,
+  /**
+   * 'Password' state is a special case for the password editors.
+   * E.g., on mac, the password editors should disable the non-Roman
+   * keyboard layouts at getting focus. Thus, the password editor may have
+   * special rules on some platforms.
+   */
+  Password,
+  /**
+   * 'Unknown' is useful when you cache this enum.  So, this shouldn't be
+   * used with nsIWidget::SetInputContext().
+   */
+  Unknown,
+};
+
+/**
+ * Contains IMEStatus plus information about the current
+ * input context that the IME can use as hints if desired.
+ */
+
+struct IMEState final {
+  IMEEnabled mEnabled;
+
+  /**
+   * IME open states the mOpen value of SetInputContext() should be one value of
+   * OPEN, CLOSE or DONT_CHANGE_OPEN_STATE.  GetInputContext() should return
+   * OPEN, CLOSE or OPEN_STATE_NOT_SUPPORTED.
+   */
+  enum Open {
+    /**
+     * 'Unsupported' means the platform cannot return actual IME open state.
+     * This value is used only by GetInputContext().
+     */
+    OPEN_STATE_NOT_SUPPORTED,
+    /**
+     * 'Don't change' means the widget shouldn't change IME open state when
+     * SetInputContext() is called.
+     */
+    DONT_CHANGE_OPEN_STATE = OPEN_STATE_NOT_SUPPORTED,
+    /**
+     * 'Open' means that IME should compose in its primary language (or latest
+     * input mode except direct ASCII character input mode).  Even if IME is
+     * opened by this value, users should be able to close IME by theirselves.
+     * Web contents can specify this value by |ime-mode: active;|.
+     */
+    OPEN,
+    /**
+     * 'Closed' means that IME shouldn't handle key events (or should handle
+     * as ASCII character inputs on mobile device).  Even if IME is closed by
+     * this value, users should be able to open IME by theirselves.
+     * Web contents can specify this value by |ime-mode: inactive;|.
+     */
+    CLOSED
+  };
+  Open mOpen;
+
+  IMEState() : mEnabled(IMEEnabled::Enabled), mOpen(DONT_CHANGE_OPEN_STATE) {}
+
+  explicit IMEState(IMEEnabled aEnabled, Open aOpen = DONT_CHANGE_OPEN_STATE)
+      : mEnabled(aEnabled), mOpen(aOpen) {}
+
+  // Returns true if the user can input characters.
+  // This means that a plain text editor, an HTML editor, a password editor or
+  // a plain text editor whose ime-mode is "disabled".
+  bool IsEditable() const {
+    return mEnabled == IMEEnabled::Enabled || mEnabled == IMEEnabled::Password;
+  }
+};
+
+// NS_ONLY_ONE_NATIVE_IME_CONTEXT is a special value of native IME context.
+// If there can be only one IME composition in a process, this can be used.
+#define NS_ONLY_ONE_NATIVE_IME_CONTEXT \
+  (reinterpret_cast<void*>(static_cast<intptr_t>(-1)))
+
+struct NativeIMEContext final {
+  // Pointer to native IME context.  Typically this is the result of
+  // nsIWidget::GetNativeData(NS_RAW_NATIVE_IME_CONTEXT) in the parent process.
+  // See also NS_ONLY_ONE_NATIVE_IME_CONTEXT.
+  uintptr_t mRawNativeIMEContext;
+  // Process ID of the origin of mNativeIMEContext.
+  uint64_t mOriginProcessID;
+
+  NativeIMEContext() : mRawNativeIMEContext(0), mOriginProcessID(0) {
+    Init(nullptr);
+  }
+
+  explicit NativeIMEContext(nsIWidget* aWidget)
+      : mRawNativeIMEContext(0), mOriginProcessID(0) {
+    Init(aWidget);
+  }
+
+  bool IsValid() const {
+    return mRawNativeIMEContext &&
+           mOriginProcessID != static_cast<uintptr_t>(-1);
+  }
+
+  void Init(nsIWidget* aWidget);
+  void InitWithRawNativeIMEContext(const void* aRawNativeIMEContext) {
+    InitWithRawNativeIMEContext(const_cast<void*>(aRawNativeIMEContext));
+  }
+  void InitWithRawNativeIMEContext(void* aRawNativeIMEContext);
+
+  bool operator==(const NativeIMEContext& aOther) const {
+    return mRawNativeIMEContext == aOther.mRawNativeIMEContext &&
+           mOriginProcessID == aOther.mOriginProcessID;
+  }
+  bool operator!=(const NativeIMEContext& aOther) const {
+    return !(*this == aOther);
+  }
+};
+
+struct InputContext final {
+  InputContext()
+      : mOrigin(XRE_IsParentProcess() ? ORIGIN_MAIN : ORIGIN_CONTENT),
+        mMayBeIMEUnaware(false),
+        mHasHandledUserInput(false),
+        mInPrivateBrowsing(false) {}
+
+  // If InputContext instance is a static variable, any heap allocated stuff
+  // of its members need to be deleted at XPCOM shutdown.  Otherwise, it's
+  // detected as memory leak.
+  void ShutDown() {
+    mURI = nullptr;
+    mHTMLInputType.Truncate();
+    mHTMLInputMode.Truncate();
+    mActionHint.Truncate();
+    mAutocapitalize.Truncate();
+  }
+
+  bool IsPasswordEditor() const {
+    return mHTMLInputType.LowerCaseEqualsLiteral("password");
+  }
+
+  NativeKeyBindingsType GetNativeKeyBindingsType() const {
+    MOZ_DIAGNOSTIC_ASSERT(mIMEState.IsEditable());
+    // See GetInputType in IMEStateManager.cpp
+    if (mHTMLInputType.IsEmpty()) {
+      return NativeKeyBindingsType::RichTextEditor;
+    }
+    return mHTMLInputType.EqualsLiteral("textarea")
+               ? NativeKeyBindingsType::MultiLineEditor
+               : NativeKeyBindingsType::SingleLineEditor;
+  }
+
+  // https://html.spec.whatwg.org/dev/interaction.html#autocapitalization
+  bool IsAutocapitalizeSupported() const {
+    return !mHTMLInputType.EqualsLiteral("password") &&
+           !mHTMLInputType.EqualsLiteral("url") &&
+           !mHTMLInputType.EqualsLiteral("email");
+  }
+
+  bool IsInputAttributeChanged(const InputContext& aOldContext) const {
+    return mIMEState.mEnabled != aOldContext.mIMEState.mEnabled ||
+#if defined(ANDROID) || defined(MOZ_WIDGET_GTK) || defined(XP_WIN)
+           // input type and inputmode are supported by Windows IME API, GTK
+           // IME API and Android IME API
+           mHTMLInputType != aOldContext.mHTMLInputType ||
+           mHTMLInputMode != aOldContext.mHTMLInputMode ||
+#endif
+#if defined(ANDROID) || defined(MOZ_WIDGET_GTK)
+           // autocapitalize is supported by Android IME API and GTK IME API
+           mAutocapitalize != aOldContext.mAutocapitalize ||
+#endif
+#if defined(ANDROID)
+           // enterkeyhint is only supported by Android IME API.
+           mActionHint != aOldContext.mActionHint ||
+#endif
+           false;
+  }
+
+  IMEState mIMEState;
+
+  // The URI of the document which has the editable element.
+  nsCOMPtr<nsIURI> mURI;
+
+  /* The type of the input if the input is a html input field */
+  nsString mHTMLInputType;
+
+  // The value of the inputmode
+  nsString mHTMLInputMode;
+
+  /* A hint for the action that is performed when the input is submitted */
+  nsString mActionHint;
+
+  /* A hint for autocapitalize */
+  nsString mAutocapitalize;
+
+  /**
+   * mOrigin indicates whether this focus event refers to main or remote
+   * content.
+   */
+  enum Origin {
+    // Adjusting focus of content on the main process
+    ORIGIN_MAIN,
+    // Adjusting focus of content in a remote process
+    ORIGIN_CONTENT
+  };
+  Origin mOrigin;
+
+  /* True if the webapp may be unaware of IME events such as input event or
+   * composiion events. This enables a key-events-only mode on Android for
+   * compatibility with webapps relying on key listeners. */
+  bool mMayBeIMEUnaware;
+
+  /**
+   * True if the document has ever received user input
+   */
+  bool mHasHandledUserInput;
+
+  /* Whether the owning document of the input element has been loaded
+   * in private browsing mode. */
+  bool mInPrivateBrowsing;
+
+  bool IsOriginMainProcess() const { return mOrigin == ORIGIN_MAIN; }
+
+  bool IsOriginContentProcess() const { return mOrigin == ORIGIN_CONTENT; }
+
+  bool IsOriginCurrentProcess() const {
+    if (XRE_IsParentProcess()) {
+      return IsOriginMainProcess();
+    }
+    return IsOriginContentProcess();
+  }
+};
+
+// FYI: Implemented in nsBaseWidget.cpp
+const char* ToChar(InputContext::Origin aOrigin);
+
+struct InputContextAction final {
+  /**
+   * mCause indicates what action causes calling nsIWidget::SetInputContext().
+   * It must be one of following values.
+   */
+  enum Cause {
+    // The cause is unknown but originated from content. Focus might have been
+    // changed by content script.
+    CAUSE_UNKNOWN,
+    // The cause is unknown but originated from chrome. Focus might have been
+    // changed by chrome script.
+    CAUSE_UNKNOWN_CHROME,
+    // The cause is user's keyboard operation.
+    CAUSE_KEY,
+    // The cause is user's mouse operation.
+    CAUSE_MOUSE,
+    // The cause is user's touch operation (implies mouse)
+    CAUSE_TOUCH,
+    // The cause is users' long press operation.
+    CAUSE_LONGPRESS,
+    // The cause is unknown but it occurs during user input except keyboard
+    // input.  E.g., an event handler of a user input event moves focus.
+    CAUSE_UNKNOWN_DURING_NON_KEYBOARD_INPUT,
+    // The cause is unknown but it occurs during keyboard input.
+    CAUSE_UNKNOWN_DURING_KEYBOARD_INPUT,
+  };
+  Cause mCause;
+
+  /**
+   * mFocusChange indicates what happened for focus.
+   */
+  enum FocusChange {
+    FOCUS_NOT_CHANGED,
+    // A content got focus.
+    GOT_FOCUS,
+    // Focused content lost focus.
+    LOST_FOCUS,
+    // Menu got pseudo focus that means focused content isn't changed but
+    // keyboard events will be handled by menu.
+    MENU_GOT_PSEUDO_FOCUS,
+    // Menu lost pseudo focus that means focused content will handle keyboard
+    // events.
+    MENU_LOST_PSEUDO_FOCUS,
+    // The widget is created.  When a widget is crated, it may need to notify
+    // IME module to initialize its native IME context.  In such case, this is
+    // used.  I.e., this isn't used by IMEStateManager.
+    WIDGET_CREATED
+  };
+  FocusChange mFocusChange;
+
+  bool ContentGotFocusByTrustedCause() const {
+    return (mFocusChange == GOT_FOCUS && mCause != CAUSE_UNKNOWN);
+  }
+
+  bool UserMightRequestOpenVKB() const {
+    // If focus is changed, user must not request to open VKB.
+    if (mFocusChange != FOCUS_NOT_CHANGED) {
+      return false;
+    }
+    switch (mCause) {
+      // If user clicks or touches focused editor, user must request to open
+      // VKB.
+      case CAUSE_MOUSE:
+      case CAUSE_TOUCH:
+      // If script does something during a user input and that causes changing
+      // input context, user might request to open VKB.  E.g., user clicks
+      // dummy editor and JS moves focus to an actual editable node.  However,
+      // this should return false if the user input is a keyboard event since
+      // physical keyboard operation shouldn't cause opening VKB.
+      case CAUSE_UNKNOWN_DURING_NON_KEYBOARD_INPUT:
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  /**
+   * IsHandlingUserInput() returns true if it's caused by a user action directly
+   * or it's caused by script or something but it occurred while we're handling
+   * a user action.  E.g., when it's caused by Element.focus() in an event
+   * handler of a user input, this returns true.
+   */
+  static bool IsHandlingUserInput(Cause aCause) {
+    switch (aCause) {
+      case CAUSE_KEY:
+      case CAUSE_MOUSE:
+      case CAUSE_TOUCH:
+      case CAUSE_LONGPRESS:
+      case CAUSE_UNKNOWN_DURING_NON_KEYBOARD_INPUT:
+      case CAUSE_UNKNOWN_DURING_KEYBOARD_INPUT:
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  bool IsHandlingUserInput() const { return IsHandlingUserInput(mCause); }
+
+  InputContextAction()
+      : mCause(CAUSE_UNKNOWN), mFocusChange(FOCUS_NOT_CHANGED) {}
+
+  explicit InputContextAction(Cause aCause,
+                              FocusChange aFocusChange = FOCUS_NOT_CHANGED)
+      : mCause(aCause), mFocusChange(aFocusChange) {}
+};
+
+// IMEMessage is shared by IMEStateManager and TextComposition.
+// Update values in GeckoEditable.java if you make changes here.
+// XXX Negative values are used in Android...
+typedef int8_t IMEMessageType;
+enum IMEMessage : IMEMessageType {
+  // This is used by IMENotification internally.  This means that the instance
+  // hasn't been initialized yet.
+  NOTIFY_IME_OF_NOTHING,
+  // An editable content is getting focus
+  NOTIFY_IME_OF_FOCUS,
+  // An editable content is losing focus
+  NOTIFY_IME_OF_BLUR,
+  // Selection in the focused editable content is changed
+  NOTIFY_IME_OF_SELECTION_CHANGE,
+  // Text in the focused editable content is changed
+  NOTIFY_IME_OF_TEXT_CHANGE,
+  // Notified when a dispatched composition event is handled by the
+  // contents.  This must be notified after the other notifications.
+  // Note that if a remote process has focus, this is notified only once when
+  // all dispatched events are handled completely.  So, the receiver shouldn't
+  // count number of received this notification for comparing with the number
+  // of dispatched events.
+  // NOTE: If a composition event causes moving focus from the focused editor,
+  //       this notification may not be notified as usual.  Even in such case,
+  //       NOTIFY_IME_OF_BLUR is always sent.  So, notification listeners
+  //       should tread the blur notification as including this if there is
+  //       pending composition events.
+  NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED,
+  // Position or size of focused element may be changed.
+  NOTIFY_IME_OF_POSITION_CHANGE,
+  // Mouse button event is fired on a character in focused editor
+  NOTIFY_IME_OF_MOUSE_BUTTON_EVENT,
+  // Request to commit current composition to IME
+  // (some platforms may not support)
+  REQUEST_TO_COMMIT_COMPOSITION,
+  // Request to cancel current composition to IME
+  // (some platforms may not support)
+  REQUEST_TO_CANCEL_COMPOSITION
+};
+
+// FYI: Implemented in nsBaseWidget.cpp
+const char* ToChar(IMEMessage aIMEMessage);
+
+struct IMENotification final {
+  IMENotification() : mMessage(NOTIFY_IME_OF_NOTHING), mSelectionChangeData() {}
+
+  IMENotification(const IMENotification& aOther)
+      : mMessage(NOTIFY_IME_OF_NOTHING) {
+    Assign(aOther);
+  }
+
+  ~IMENotification() { Clear(); }
+
+  MOZ_IMPLICIT IMENotification(IMEMessage aMessage)
+      : mMessage(aMessage), mSelectionChangeData() {
+    switch (aMessage) {
+      case NOTIFY_IME_OF_SELECTION_CHANGE:
+        mSelectionChangeData.mString = new nsString();
+        mSelectionChangeData.Clear();
+        break;
+      case NOTIFY_IME_OF_TEXT_CHANGE:
+        mTextChangeData.Clear();
+        break;
+      case NOTIFY_IME_OF_MOUSE_BUTTON_EVENT:
+        mMouseButtonEventData.mEventMessage = eVoidEvent;
+        mMouseButtonEventData.mOffset = UINT32_MAX;
+        mMouseButtonEventData.mCursorPos.MoveTo(0, 0);
+        mMouseButtonEventData.mCharRect.SetRect(0, 0, 0, 0);
+        mMouseButtonEventData.mButton = -1;
+        mMouseButtonEventData.mButtons = 0;
+        mMouseButtonEventData.mModifiers = 0;
+        break;
+      default:
+        break;
+    }
+  }
+
+  void Assign(const IMENotification& aOther) {
+    bool changingMessage = mMessage != aOther.mMessage;
+    if (changingMessage) {
+      Clear();
+      mMessage = aOther.mMessage;
+    }
+    switch (mMessage) {
+      case NOTIFY_IME_OF_SELECTION_CHANGE:
+        if (changingMessage) {
+          mSelectionChangeData.mString = new nsString();
+        }
+        mSelectionChangeData.Assign(aOther.mSelectionChangeData);
+        break;
+      case NOTIFY_IME_OF_TEXT_CHANGE:
+        mTextChangeData = aOther.mTextChangeData;
+        break;
+      case NOTIFY_IME_OF_MOUSE_BUTTON_EVENT:
+        mMouseButtonEventData = aOther.mMouseButtonEventData;
+        break;
+      default:
+        break;
+    }
+  }
+
+  IMENotification& operator=(const IMENotification& aOther) {
+    Assign(aOther);
+    return *this;
+  }
+
+  void Clear() {
+    if (mMessage == NOTIFY_IME_OF_SELECTION_CHANGE) {
+      MOZ_ASSERT(mSelectionChangeData.mString);
+      delete mSelectionChangeData.mString;
+      mSelectionChangeData.mString = nullptr;
+    }
+    mMessage = NOTIFY_IME_OF_NOTHING;
+  }
+
+  bool HasNotification() const { return mMessage != NOTIFY_IME_OF_NOTHING; }
+
+  void MergeWith(const IMENotification& aNotification) {
+    switch (mMessage) {
+      case NOTIFY_IME_OF_NOTHING:
+        MOZ_ASSERT(aNotification.mMessage != NOTIFY_IME_OF_NOTHING);
+        Assign(aNotification);
+        break;
+      case NOTIFY_IME_OF_SELECTION_CHANGE:
+        MOZ_ASSERT(aNotification.mMessage == NOTIFY_IME_OF_SELECTION_CHANGE);
+        mSelectionChangeData.Assign(aNotification.mSelectionChangeData);
+        break;
+      case NOTIFY_IME_OF_TEXT_CHANGE:
+        MOZ_ASSERT(aNotification.mMessage == NOTIFY_IME_OF_TEXT_CHANGE);
+        mTextChangeData += aNotification.mTextChangeData;
+        break;
+      case NOTIFY_IME_OF_POSITION_CHANGE:
+      case NOTIFY_IME_OF_COMPOSITION_EVENT_HANDLED:
+        MOZ_ASSERT(aNotification.mMessage == mMessage);
+        break;
+      default:
+        MOZ_CRASH("Merging notification isn't supported");
+        break;
+    }
+  }
+
+  IMEMessage mMessage;
+
+  // NOTIFY_IME_OF_SELECTION_CHANGE specific data
+  struct SelectionChangeDataBase {
+    // Selection range.
+    uint32_t mOffset;
+
+    // Selected string
+    nsString* mString;
+
+    // Writing mode at the selection.
+    uint8_t mWritingModeBits;
+
+    bool mIsInitialized;
+    bool mHasRange;
+    bool mReversed;
+    bool mCausedByComposition;
+    bool mCausedBySelectionEvent;
+    bool mOccurredDuringComposition;
+
+    // FYI: Cannot we make these methods inline because of an include hell of
+    //      RawServoAnimationValueMap
+    void SetWritingMode(const WritingMode& aWritingMode);
+    WritingMode GetWritingMode() const;
+
+    uint32_t StartOffset() const {
+      MOZ_ASSERT(mHasRange);
+      return mOffset;
+    }
+    uint32_t EndOffset() const {
+      MOZ_ASSERT(mHasRange);
+      return mOffset + Length();
+    }
+    uint32_t AnchorOffset() const {
+      MOZ_ASSERT(mHasRange);
+      return mOffset + (mReversed ? Length() : 0);
+    }
+    uint32_t FocusOffset() const {
+      MOZ_ASSERT(mHasRange);
+      return mOffset + (mReversed ? 0 : Length());
+    }
+    const nsString& String() const {
+      MOZ_ASSERT(mHasRange);
+      return *mString;
+    }
+    uint32_t Length() const {
+      MOZ_ASSERT(mHasRange);
+      return mString->Length();
+    }
+    bool IsInInt32Range() const {
+      return mHasRange && mOffset <= INT32_MAX && Length() <= INT32_MAX &&
+             mOffset + Length() <= INT32_MAX;
+    }
+    bool HasRange() const { return mIsInitialized && mHasRange; }
+    bool IsCollapsed() const { return !mHasRange || mString->IsEmpty(); }
+    void ClearSelectionData() {
+      mIsInitialized = false;
+      mHasRange = false;
+      mOffset = UINT32_MAX;
+      mString->Truncate();
+      mWritingModeBits = 0;
+      mReversed = false;
+    }
+    void Clear() {
+      ClearSelectionData();
+      mCausedByComposition = false;
+      mCausedBySelectionEvent = false;
+      mOccurredDuringComposition = false;
+    }
+    bool IsInitialized() const { return mIsInitialized; }
+    void Assign(const SelectionChangeDataBase& aOther) {
+      mIsInitialized = aOther.mIsInitialized;
+      mHasRange = aOther.mHasRange;
+      if (mIsInitialized && mHasRange) {
+        mOffset = aOther.mOffset;
+        *mString = aOther.String();
+        mReversed = aOther.mReversed;
+        mWritingModeBits = aOther.mWritingModeBits;
+      } else {
+        mOffset = UINT32_MAX;
+        mString->Truncate();
+        mReversed = false;
+        // Let's keep the writing mode for avoiding temporarily changing the
+        // writing mode at no selection range.
+      }
+      AssignReason(aOther.mCausedByComposition, aOther.mCausedBySelectionEvent,
+                   aOther.mOccurredDuringComposition);
+    }
+    void Assign(const WidgetQueryContentEvent& aQuerySelectedTextEvent);
+    void AssignReason(bool aCausedByComposition, bool aCausedBySelectionEvent,
+                      bool aOccurredDuringComposition) {
+      mCausedByComposition = aCausedByComposition;
+      mCausedBySelectionEvent = aCausedBySelectionEvent;
+      mOccurredDuringComposition = aOccurredDuringComposition;
+    }
+
+    bool EqualsRange(const SelectionChangeDataBase& aOther) const {
+      if (HasRange() != aOther.HasRange()) {
+        return false;
+      }
+      if (!HasRange()) {
+        return true;
+      }
+      return mOffset == aOther.mOffset && mString->Equals(*aOther.mString);
+    }
+    bool EqualsRangeAndDirection(const SelectionChangeDataBase& aOther) const {
+      return EqualsRange(aOther) &&
+             (!HasRange() || mReversed == aOther.mReversed);
+    }
+    bool EqualsRangeAndDirectionAndWritingMode(
+        const SelectionChangeDataBase& aOther) const {
+      return EqualsRangeAndDirection(aOther) &&
+             mWritingModeBits == aOther.mWritingModeBits;
+    }
+
+    bool EqualsRange(const ContentSelection& aContentSelection) const;
+    bool EqualsRangeAndWritingMode(
+        const ContentSelection& aContentSelection) const;
+
+    OffsetAndData<uint32_t> ToUint32OffsetAndData() const {
+      return OffsetAndData<uint32_t>(mOffset, *mString,
+                                     OffsetAndDataFor::SelectedString);
+    }
+  };
+
+  // SelectionChangeDataBase cannot have constructors because it's used in
+  // the union.  Therefore, SelectionChangeData should only implement
+  // constructors.  In other words, add other members to
+  // SelectionChangeDataBase.
+  struct SelectionChangeData final : public SelectionChangeDataBase {
+    SelectionChangeData() {
+      mString = &mStringInstance;
+      Clear();
+    }
+    explicit SelectionChangeData(const SelectionChangeDataBase& aOther) {
+      mString = &mStringInstance;
+      Assign(aOther);
+    }
+    SelectionChangeData(const SelectionChangeData& aOther) {
+      mString = &mStringInstance;
+      Assign(aOther);
+    }
+    SelectionChangeData& operator=(const SelectionChangeDataBase& aOther) {
+      mString = &mStringInstance;
+      Assign(aOther);
+      return *this;
+    }
+    SelectionChangeData& operator=(const SelectionChangeData& aOther) {
+      mString = &mStringInstance;
+      Assign(aOther);
+      return *this;
+    }
+
+   private:
+    // When SelectionChangeData is used outside of union, it shouldn't create
+    // nsString instance in the heap as far as possible.
+    nsString mStringInstance;
+  };
+
+  struct TextChangeDataBase {
+    // mStartOffset is the start offset of modified or removed text in
+    // original content and inserted text in new content.
+    uint32_t mStartOffset;
+    // mRemovalEndOffset is the end offset of modified or removed text in
+    // original content.  If the value is same as mStartOffset, no text hasn't
+    // been removed yet.
+    uint32_t mRemovedEndOffset;
+    // mAddedEndOffset is the end offset of inserted text or same as
+    // mStartOffset if just removed.  The vlaue is offset in the new content.
+    uint32_t mAddedEndOffset;
+
+    // Note that TextChangeDataBase may be the result of merging two or more
+    // changes especially in e10s mode.
+
+    // mCausedOnlyByComposition is true only when *all* merged changes are
+    // caused by composition.
+    bool mCausedOnlyByComposition;
+    // mIncludingChangesDuringComposition is true if at least one change which
+    // is not caused by composition occurred during the last composition.
+    // Note that if after the last composition is finished and there are some
+    // changes not caused by composition, this is set to false.
+    bool mIncludingChangesDuringComposition;
+    // mIncludingChangesWithoutComposition is true if there is at least one
+    // change which did occur when there wasn't a composition ongoing.
+    bool mIncludingChangesWithoutComposition;
+
+    uint32_t OldLength() const {
+      MOZ_ASSERT(IsValid());
+      return mRemovedEndOffset - mStartOffset;
+    }
+    uint32_t NewLength() const {
+      MOZ_ASSERT(IsValid());
+      return mAddedEndOffset - mStartOffset;
+    }
+
+    // Positive if text is added. Negative if text is removed.
+    int64_t Difference() const { return mAddedEndOffset - mRemovedEndOffset; }
+
+    bool IsInInt32Range() const {
+      MOZ_ASSERT(IsValid());
+      return mStartOffset <= INT32_MAX && mRemovedEndOffset <= INT32_MAX &&
+             mAddedEndOffset <= INT32_MAX;
+    }
+
+    bool IsValid() const {
+      return !(mStartOffset == UINT32_MAX && !mRemovedEndOffset &&
+               !mAddedEndOffset);
+    }
+
+    void Clear() {
+      mStartOffset = UINT32_MAX;
+      mRemovedEndOffset = mAddedEndOffset = 0;
+    }
+
+    void MergeWith(const TextChangeDataBase& aOther);
+    TextChangeDataBase& operator+=(const TextChangeDataBase& aOther) {
+      MergeWith(aOther);
+      return *this;
+    }
+
+#ifdef DEBUG
+    void Test();
+#endif  // #ifdef DEBUG
+  };
+
+  // TextChangeDataBase cannot have constructors because they are used in union.
+  // Therefore, TextChangeData should only implement constructor.  In other
+  // words, add other members to TextChangeDataBase.
+  struct TextChangeData : public TextChangeDataBase {
+    TextChangeData() { Clear(); }
+
+    TextChangeData(uint32_t aStartOffset, uint32_t aRemovedEndOffset,
+                   uint32_t aAddedEndOffset, bool aCausedByComposition,
+                   bool aOccurredDuringComposition) {
+      MOZ_ASSERT(aRemovedEndOffset >= aStartOffset,
+                 "removed end offset must not be smaller than start offset");
+      MOZ_ASSERT(aAddedEndOffset >= aStartOffset,
+                 "added end offset must not be smaller than start offset");
+      mStartOffset = aStartOffset;
+      mRemovedEndOffset = aRemovedEndOffset;
+      mAddedEndOffset = aAddedEndOffset;
+      mCausedOnlyByComposition = aCausedByComposition;
+      mIncludingChangesDuringComposition =
+          !aCausedByComposition && aOccurredDuringComposition;
+      mIncludingChangesWithoutComposition =
+          !aCausedByComposition && !aOccurredDuringComposition;
+    }
+  };
+
+  struct MouseButtonEventData {
+    // The value of WidgetEvent::mMessage
+    EventMessage mEventMessage;
+    // Character offset from the start of the focused editor under the cursor
+    uint32_t mOffset;
+    // Cursor position in pixels relative to the widget
+    LayoutDeviceIntPoint mCursorPos;
+    // Character rect in pixels under the cursor relative to the widget
+    LayoutDeviceIntRect mCharRect;
+    // The value of WidgetMouseEventBase::button and buttons
+    int16_t mButton;
+    int16_t mButtons;
+    // The value of WidgetInputEvent::modifiers
+    Modifiers mModifiers;
+  };
+
+  union {
+    // NOTIFY_IME_OF_SELECTION_CHANGE specific data
+    SelectionChangeDataBase mSelectionChangeData;
+
+    // NOTIFY_IME_OF_TEXT_CHANGE specific data
+    TextChangeDataBase mTextChangeData;
+
+    // NOTIFY_IME_OF_MOUSE_BUTTON_EVENT specific data
+    MouseButtonEventData mMouseButtonEventData;
+  };
+
+  void SetData(const SelectionChangeDataBase& aSelectionChangeData) {
+    MOZ_RELEASE_ASSERT(mMessage == NOTIFY_IME_OF_SELECTION_CHANGE);
+    mSelectionChangeData.Assign(aSelectionChangeData);
+  }
+
+  void SetData(const TextChangeDataBase& aTextChangeData) {
+    MOZ_RELEASE_ASSERT(mMessage == NOTIFY_IME_OF_TEXT_CHANGE);
+    mTextChangeData = aTextChangeData;
+  }
+};
+
+struct CandidateWindowPosition {
+  // Upper left corner of the candidate window if mExcludeRect is false.
+  // Otherwise, the position currently interested.  E.g., caret position.
+  LayoutDeviceIntPoint mPoint;
+  // Rect which shouldn't be overlapped with the candidate window.
+  // This is valid only when mExcludeRect is true.
+  LayoutDeviceIntRect mRect;
+  // See explanation of mPoint and mRect.
+  bool mExcludeRect;
+};
+
+std::ostream& operator<<(std::ostream& aStream, const IMEEnabled& aEnabled);
+std::ostream& operator<<(std::ostream& aStream, const IMEState::Open& aOpen);
+std::ostream& operator<<(std::ostream& aStream, const IMEState& aState);
+std::ostream& operator<<(std::ostream& aStream,
+                         const InputContext::Origin& aOrigin);
+std::ostream& operator<<(std::ostream& aStream, const InputContext& aContext);
+std::ostream& operator<<(std::ostream& aStream,
+                         const InputContextAction::Cause& aCause);
+std::ostream& operator<<(std::ostream& aStream,
+                         const InputContextAction::FocusChange& aFocusChange);
+std::ostream& operator<<(std::ostream& aStream,
+                         const IMENotification::SelectionChangeDataBase& aData);
+std::ostream& operator<<(std::ostream& aStream,
+                         const IMENotification::TextChangeDataBase& aData);
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // #ifndef mozilla_widget_IMEData_h_