Bug 1385478 - Part 2: Change Required/IsRequired() to look at NS_EVENT_STATE_REQUIRED instead. r=bz

In order to speed up Required/IsRequired(), instead of querying for the
@required attribute, we're now using the NS_EVENT_STATE_REQUIRED flag to know
whether an element's value is required.

For this to work correctly, we need to set NS_EVENT_STATE_REQUIRED earlier,
that is, in AfterSetAttr(), before any consumer of IsRequired(). We also need
to update or clear our required states when input type changes, since we may
have changed from a required input type to a non-required input type or
vice versa.

Note that NS_EVENT_STATE_REQUIRED/OPTIONAL is now part of the
EXTERNALLY_MANAGED_STATES.

MozReview-Commit-ID: Bjiby9GqJSB

dom/events/EventStates.h

@@ -330,6 +330,8 @@ private:
 
 #define DISABLED_STATES (NS_EVENT_STATE_DISABLED | NS_EVENT_STATE_ENABLED)
 
+#define REQUIRED_STATES (NS_EVENT_STATE_REQUIRED | NS_EVENT_STATE_OPTIONAL)
+
 // Event states that can be added and removed through
 // Element::{Add,Remove}ManuallyManagedStates.
 //
@@ -350,6 +352,7 @@ private:
   MANUALLY_MANAGED_STATES |                   \
   DIR_ATTR_STATES |                           \
   DISABLED_STATES |                           \
+  REQUIRED_STATES |                           \
   NS_EVENT_STATE_ACTIVE |                     \
   NS_EVENT_STATE_DRAGOVER |                   \
   NS_EVENT_STATE_FOCUS |                      \

dom/html/HTMLInputElement.cpp

@@ -1453,6 +1453,13 @@ HTMLInputElement::AfterSetAttr(int32_t aNameSpaceID, nsIAtom* aName,
         UpdateDisabledState(aNotify);
       }
 
+      if (aName == nsGkAtoms::required && DoesRequiredApply()) {
+        // This *has* to be called *before* UpdateValueMissingValidityState
+        // because UpdateValueMissingValidityState depends on our required
+        // state.
+        UpdateRequiredState(!!aValue, aNotify);
+      }
+
       UpdateValueMissingValidityState();
 
       // This *has* to be called *after* validity has changed.
@@ -5005,6 +5012,17 @@ HTMLInputElement::HandleTypeChange(uint8_t aNewType, bool aNotify)
     mFocusedValue.Truncate();
   }
 
+  // Update or clear our required states since we may have changed from a
+  // required input type to a non-required input type or viceversa.
+  if (DoesRequiredApply()) {
+    bool isRequired = HasAttr(kNameSpaceID_None, nsGkAtoms::required);
+    UpdateRequiredState(isRequired, aNotify);
+  } else if (aNotify) {
+    RemoveStates(REQUIRED_STATES);
+  } else {
+    RemoveStatesSilently(REQUIRED_STATES);
+  }
+
   UpdateHasRange();
 
   // Do not notify, it will be done after if needed.
@@ -6554,12 +6572,6 @@ HTMLInputElement::IntrinsicState() const
     state |= nsImageLoadingContent::ImageState();
   }
 
-  if (DoesRequiredApply() && IsRequired()) {
-    state |= NS_EVENT_STATE_REQUIRED;
-  } else {
-    state |= NS_EVENT_STATE_OPTIONAL;
-  }
-
   if (IsCandidateForConstraintValidation()) {
     if (IsValid()) {
       state |= NS_EVENT_STATE_VALID;

dom/html/HTMLInputElement.h

@@ -942,11 +942,19 @@ public:
   static void Shutdown();
 
   /**
-   * Returns the current required state of the element.
+   * Returns if the required attribute applies for the current type.
+   */
+  bool DoesRequiredApply() const;
+
+  /**
+   * Returns the current required state of the element. This function differs
+   * from Required() in that this function only returns true for input types
+   * that @required attribute applies and the attribute is set; in contrast,
+   * Required() returns true whenever @required attribute is set.
    */
   bool IsRequired() const
   {
-    return HasAttr(kNameSpaceID_None, nsGkAtoms::required);
+    return State().HasState(NS_EVENT_STATE_REQUIRED);
   }
 
 protected:
@@ -1145,11 +1153,6 @@ protected:
    */
   bool DoesReadOnlyApply() const;
 
-  /**
-   * Returns if the required attribute applies for the current type.
-   */
-  bool DoesRequiredApply() const;
-
   /**
    * Returns if the min and max attributes apply for the current type.
    */

dom/html/HTMLSelectElement.cpp

@@ -1333,6 +1333,11 @@ HTMLSelectElement::AfterSetAttr(int32_t aNameSpaceID, nsIAtom* aName,
       UpdateValueMissingValidityState();
       UpdateBarredFromConstraintValidation();
     } else if (aName == nsGkAtoms::required) {
+      // This *has* to be called *before* UpdateValueMissingValidityState
+      // because UpdateValueMissingValidityState depends on our required
+      // state.
+      UpdateRequiredState(!!aValue, aNotify);
+
       UpdateValueMissingValidityState();
     } else if (aName == nsGkAtoms::autocomplete) {
       // Clear the cached @autocomplete attribute and autocompleteInfo state.
@@ -1530,12 +1535,6 @@ HTMLSelectElement::IntrinsicState() const
     }
   }
 
-  if (Required()) {
-    state |= NS_EVENT_STATE_REQUIRED;
-  } else {
-    state |= NS_EVENT_STATE_OPTIONAL;
-  }
-
   return state;
 }
 

dom/html/HTMLSelectElement.h

@@ -211,7 +211,7 @@ public:
   }
   bool Required() const
   {
-    return GetBoolAttr(nsGkAtoms::required);
+    return State().HasState(NS_EVENT_STATE_REQUIRED);
   }
   void SetRequired(bool aVal, ErrorResult& aRv)
   {

dom/html/HTMLTextAreaElement.cpp

@@ -958,12 +958,6 @@ HTMLTextAreaElement::IntrinsicState() const
 {
   EventStates state = nsGenericHTMLFormElementWithState::IntrinsicState();
 
-  if (Required()) {
-    state |= NS_EVENT_STATE_REQUIRED;
-  } else {
-    state |= NS_EVENT_STATE_OPTIONAL;
-  }
-
   if (IsCandidateForConstraintValidation()) {
     if (IsValid()) {
       state |= NS_EVENT_STATE_VALID;
@@ -1114,6 +1108,13 @@ HTMLTextAreaElement::AfterSetAttr(int32_t aNameSpaceID, nsIAtom* aName,
         UpdateDisabledState(aNotify);
       }
 
+      if (aName == nsGkAtoms::required) {
+        // This *has* to be called *before* UpdateValueMissingValidityState
+        // because UpdateValueMissingValidityState depends on our required
+        // state.
+        UpdateRequiredState(!!aValue, aNotify);
+      }
+
       UpdateValueMissingValidityState();
 
       // This *has* to be called *after* validity has changed.

dom/html/HTMLTextAreaElement.h

@@ -254,7 +254,7 @@ public:
   }
   bool Required() const
   {
-    return GetBoolAttr(nsGkAtoms::required);
+    return State().HasState(NS_EVENT_STATE_REQUIRED);
   }
 
   void SetRangeText(const nsAString& aReplacement, ErrorResult& aRv);
@@ -410,6 +410,7 @@ protected:
   void GetSelectionRange(uint32_t* aSelectionStart,
                          uint32_t* aSelectionEnd,
                          ErrorResult& aRv);
+
 private:
   static void MapAttributesIntoRule(const nsMappedAttributes* aAttributes,
                                     GenericSpecifiedValues* aGenericData);

dom/html/nsGenericHTMLElement.cpp

@@ -109,6 +109,7 @@
 #include "mozilla/StyleSetHandleInlines.h"
 #include "ReferrerPolicy.h"
 #include "mozilla/dom/HTMLLabelElement.h"
+#include "mozilla/dom/HTMLInputElement.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -2425,6 +2426,40 @@ void nsGenericHTMLFormElement::UpdateDisabledState(bool aNotify)
   }
 }
 
+void
+nsGenericHTMLFormElement::UpdateRequiredState(bool aIsRequired, bool aNotify)
+{
+#ifdef DEBUG
+  int32_t type = ControlType();
+#endif
+  MOZ_ASSERT((type & NS_FORM_INPUT_ELEMENT) ||
+              type == NS_FORM_SELECT ||
+              type == NS_FORM_TEXTAREA,
+             "This should be called only on types that @required applies");
+
+#ifdef DEBUG
+  HTMLInputElement* input = HTMLInputElement::FromContent(this);
+  if (input) {
+    MOZ_ASSERT(input->DoesRequiredApply(),
+               "This should be called only on input types that @required applies");
+  }
+#endif
+
+  EventStates requiredStates;
+  if (aIsRequired) {
+    requiredStates |= NS_EVENT_STATE_REQUIRED;
+  } else {
+    requiredStates |= NS_EVENT_STATE_OPTIONAL;
+  }
+
+  EventStates oldRequiredStates = State() & REQUIRED_STATES;
+  EventStates changedStates = requiredStates ^ oldRequiredStates;
+
+  if (!changedStates.IsEmpty()) {
+    ToggleStates(changedStates, aNotify);
+  }
+}
+
 void
 nsGenericHTMLFormElement::FieldSetDisabledChanged(bool aNotify)
 {

dom/html/nsGenericHTMLElement.h

@@ -1101,6 +1101,11 @@ public:
    */
   void UpdateDisabledState(bool aNotify);
 
+  /**
+   * Update our required/optional flags to match the given aIsRequired boolean.
+   */
+  void UpdateRequiredState(bool aIsRequired, bool aNotify);
+
   void FieldSetFirstLegendChanged(bool aNotify) {
     UpdateFieldSet(aNotify);
   }