1 files changed, 247 insertions, 0 deletions
diff --git a/layout/style/nsCSSProps.h b/layout/style/nsCSSProps.h
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+++ b/layout/style/nsCSSProps.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * methods for dealing with CSS properties and tables of the keyword
+ * values they accept
+ */
+
+#ifndef nsCSSProps_h___
+#define nsCSSProps_h___
+
+#include <limits>
+#include <ostream>
+#include <type_traits>
+
+#include "nsString.h"
+#include "nsCSSPropertyID.h"
+#include "nsStyleStructFwd.h"
+#include "mozilla/UseCounter.h"
+#include "mozilla/CSSEnabledState.h"
+#include "mozilla/CSSPropFlags.h"
+#include "mozilla/EnumTypeTraits.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/gfx/gfxVarReceiver.h"
+#include "nsXULAppAPI.h"
+
+// Length of the "--" prefix on custom names (such as custom property names,
+// and, in the future, custom media query names).
+#define CSS_CUSTOM_NAME_PREFIX_LENGTH 2
+
+namespace mozilla {
+class ComputedStyle;
+}
+
+extern "C" {
+nsCSSPropertyID Servo_ResolveLogicalProperty(nsCSSPropertyID,
+                                             const mozilla::ComputedStyle*);
+nsCSSPropertyID Servo_Property_LookupEnabledForAllContent(const nsACString*);
+const uint8_t* Servo_Property_GetName(nsCSSPropertyID, uint32_t* aLength);
+}
+
+class nsCSSProps {
+ public:
+  typedef mozilla::CSSEnabledState EnabledState;
+  typedef mozilla::CSSPropFlags Flags;
+
+  static void AddRefTable(void);
+  static void ReleaseTable(void);
+
+  // Looks up the property with name aProperty and returns its corresponding
+  // nsCSSPropertyID value.  If aProperty is the name of a custom property,
+  // then eCSSPropertyExtra_variable will be returned.
+  //
+  // This only returns properties enabled for all content, and resolves aliases
+  // to return the aliased property.
+  static nsCSSPropertyID LookupProperty(const nsACString& aProperty) {
+    return Servo_Property_LookupEnabledForAllContent(&aProperty);
+  }
+
+  // As above, but looked up using a property's IDL name.
+  // eCSSPropertyExtra_variable won't be returned from this method.
+  static nsCSSPropertyID LookupPropertyByIDLName(
+      const nsACString& aPropertyIDLName, EnabledState aEnabled);
+
+  // Returns whether aProperty is a custom property name, i.e. begins with
+  // "--".  This assumes that the CSS Variables pref has been enabled.
+  static bool IsCustomPropertyName(const nsACString& aProperty);
+
+  static bool IsShorthand(nsCSSPropertyID aProperty) {
+    MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT,
+               "out of range");
+    return (aProperty >= eCSSProperty_COUNT_no_shorthands);
+  }
+
+  // Same but for @font-face descriptors
+  static nsCSSFontDesc LookupFontDesc(const nsACString& aProperty);
+
+  // The relevant invariants are asserted in Document.cpp
+  static mozilla::UseCounter UseCounterFor(nsCSSPropertyID aProperty) {
+    MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT_with_aliases,
+               "out of range");
+    return mozilla::UseCounter(size_t(mozilla::eUseCounter_FirstCSSProperty) +
+                               size_t(aProperty));
+  }
+
+  // Given a property enum, get the string value
+  //
+  // This string is static.
+  static const nsDependentCSubstring GetStringValue(nsCSSPropertyID aProperty) {
+    uint32_t len;
+    const uint8_t* chars = Servo_Property_GetName(aProperty, &len);
+    return nsDependentCSubstring(reinterpret_cast<const char*>(chars), len);
+  }
+
+  static const nsCString& GetStringValue(nsCSSFontDesc aFontDesc);
+  static const nsCString& GetStringValue(nsCSSCounterDesc aCounterDesc);
+
+ private:
+  static const Flags kFlagsTable[eCSSProperty_COUNT];
+
+ public:
+  static bool PropHasFlags(nsCSSPropertyID aProperty, Flags aFlags) {
+    MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT,
+               "out of range");
+    return (nsCSSProps::kFlagsTable[aProperty] & aFlags) == aFlags;
+  }
+
+  static nsCSSPropertyID Physicalize(nsCSSPropertyID aProperty,
+                                     const mozilla::ComputedStyle& aStyle) {
+    MOZ_ASSERT(!IsShorthand(aProperty));
+    if (PropHasFlags(aProperty, Flags::IsLogical)) {
+      return Servo_ResolveLogicalProperty(aProperty, &aStyle);
+    }
+    return aProperty;
+  }
+
+ private:
+  // A table for shorthand properties.  The appropriate index is the
+  // property ID minus eCSSProperty_COUNT_no_shorthands.
+  static const nsCSSPropertyID* const
+      kSubpropertyTable[eCSSProperty_COUNT - eCSSProperty_COUNT_no_shorthands];
+
+ public:
+  /**
+   * Returns true if the backdrop-filter pref and WebRender are enabled.
+   */
+  static bool IsBackdropFilterAvailable(JSContext*, JSObject*) {
+    return IsEnabled(eCSSProperty_backdrop_filter);
+  }
+
+  /**
+   * Recoumputes the enabled state of a pref. If aPrefName is nullptr,
+   * recomputes the state of all prefs in gPropertyEnabled.
+   * aClosure is the pref callback closure data, which is not used.
+   */
+  static void RecomputeEnabledState(const char* aPrefName,
+                                    void* aClosure = nullptr);
+
+  /**
+   * Retrieve a singleton receiver to register with gfxVars
+   */
+  static mozilla::gfx::gfxVarReceiver& GfxVarReceiver();
+
+  static const nsCSSPropertyID* SubpropertyEntryFor(nsCSSPropertyID aProperty) {
+    MOZ_ASSERT(eCSSProperty_COUNT_no_shorthands <= aProperty &&
+                   aProperty < eCSSProperty_COUNT,
+               "out of range");
+    return nsCSSProps::kSubpropertyTable[aProperty -
+                                         eCSSProperty_COUNT_no_shorthands];
+  }
+
+ private:
+  static bool gPropertyEnabled[eCSSProperty_COUNT_with_aliases];
+
+ private:
+  // Defined in the generated nsCSSPropsGenerated.inc.
+  static const char* const kIDLNameTable[eCSSProperty_COUNT];
+
+ public:
+  /**
+   * Returns the IDL name of the specified property, which must be a
+   * longhand, logical or shorthand property.  The IDL name is the property
+   * name with any hyphen-lowercase character pairs replaced by an
+   * uppercase character:
+   * https://drafts.csswg.org/cssom/#css-property-to-idl-attribute
+   *
+   * As a special case, the string "cssFloat" is returned for the float
+   * property.  nullptr is returned for internal properties.
+   */
+  static const char* PropertyIDLName(nsCSSPropertyID aProperty) {
+    MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT,
+               "out of range");
+    return kIDLNameTable[aProperty];
+  }
+
+ private:
+  static const int32_t kIDLNameSortPositionTable[eCSSProperty_COUNT];
+
+ public:
+  /**
+   * Returns the position of the specified property in a list of all
+   * properties sorted by their IDL name.
+   */
+  static int32_t PropertyIDLNameSortPosition(nsCSSPropertyID aProperty) {
+    MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT,
+               "out of range");
+    return kIDLNameSortPositionTable[aProperty];
+  }
+
+  static bool IsEnabled(nsCSSPropertyID aProperty) {
+    MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT_with_aliases,
+               "out of range");
+    // In the child process, assert that we're not trying to parse stylesheets
+    // before we've gotten all our prefs.
+    MOZ_ASSERT_IF(!XRE_IsParentProcess(),
+                  mozilla::Preferences::ArePrefsInitedInContentProcess());
+    return gPropertyEnabled[aProperty];
+  }
+
+ public:
+  static bool IsEnabled(nsCSSPropertyID aProperty, EnabledState aEnabled) {
+    if (IsEnabled(aProperty)) {
+      return true;
+    }
+    if (aEnabled == EnabledState::IgnoreEnabledState) {
+      return true;
+    }
+    if ((aEnabled & EnabledState::InUASheets) &&
+        PropHasFlags(aProperty, Flags::EnabledInUASheets)) {
+      return true;
+    }
+    if ((aEnabled & EnabledState::InChrome) &&
+        PropHasFlags(aProperty, Flags::EnabledInChrome)) {
+      return true;
+    }
+    return false;
+  }
+
+ public:
+  struct PropertyPref {
+    nsCSSPropertyID mPropID;
+    const char* mPref;
+  };
+  static const PropertyPref kPropertyPrefTable[];
+
+// Storing the enabledstate_ value in an nsCSSPropertyID variable is a small
+// hack to avoid needing a separate variable declaration for its real type
+// (CSSEnabledState), which would then require using a block and
+// therefore a pair of macros by consumers for the start and end of the loop.
+#define CSSPROPS_FOR_SHORTHAND_SUBPROPERTIES(it_, prop_, enabledstate_)  \
+  for (const nsCSSPropertyID *                                           \
+           it_ = nsCSSProps::SubpropertyEntryFor(prop_),                 \
+          es_ = (nsCSSPropertyID)((enabledstate_) | CSSEnabledState(0)); \
+       *it_ != eCSSProperty_UNKNOWN; ++it_)                              \
+    if (nsCSSProps::IsEnabled(*it_, (mozilla::CSSEnabledState)es_))
+};
+
+// MOZ_DBG support for nsCSSPropertyID
+
+inline std::ostream& operator<<(std::ostream& aOut, nsCSSPropertyID aProperty) {
+  return aOut << nsCSSProps::GetStringValue(aProperty);
+}
+
+#endif /* nsCSSProps_h___ */