author Sylvestre Ledru <>
Fri, 24 Feb 2017 17:04:50 +0100
changeset 489671 05d9746016f47666c00390aacc9f9d62c8ffffb4
parent 489668 cbb8fdf1daf98a15f7d57f6b08d273bdf96aa1a0
permissions -rw-r--r--
Move to 99 chars instead of 80 MozReview-Commit-ID: 6NxbMuFVI7e

/* -*- 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 */

 * A struct that represents the value (type and actual data) of an
 * attribute.

#ifndef nsAttrValue_h___
#define nsAttrValue_h___

#include <type_traits>

#include "nscore.h"
#include "nsStringGlue.h"
#include "nsStringBuffer.h"
#include "nsColor.h"
#include "nsCaseTreatment.h"
#include "nsMargin.h"
#include "nsCOMPtr.h"
#include "SVGAttrValueWrapper.h"
#include "nsTArrayForwardDeclare.h"
#include "nsIAtom.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/EnumTypeTraits.h"

// Undefine LoadImage to prevent naming conflict with Windows.
#undef LoadImage

class nsAString;
class nsIDocument;
class nsStyledElement;
struct MiscContainer;

namespace mozilla {
class DeclarationBlock;
namespace css {
struct URLValue;
struct ImageValue;
} // namespace css
} // namespace mozilla


#define NS_ATTRVALUE_BASETYPE_MASK (uintptr_t(3))


#define NS_ATTRVALUE_ENUMTABLEINDEX_MASK                                                          \
  (uintptr_t((((1 << NS_ATTRVALUE_ENUMTABLEINDEX_BITS) - 1) &                                     \

 * A class used to construct a nsString from a nsStringBuffer (we might
 * want to move this to nsString at some point).
 * WARNING: Note that nsCheapString doesn't take an explicit length -- it
 * assumes the string is maximally large, given the nsStringBuffer's storage
 * size.  This means the given string buffer *must* be sized exactly correctly
 * for the string it contains (including one byte for a null terminator).  If
 * it has any unused storage space, then that will result in bogus characters
 * at the end of our nsCheapString.
class nsCheapString : public nsString
  explicit nsCheapString(nsStringBuffer* aBuf)
    if (aBuf)
      aBuf->ToString(aBuf->StorageSize() / sizeof(char16_t) - 1, *this);

class nsAttrValue
  friend struct MiscContainer;

  typedef nsTArray<nsCOMPtr<nsIAtom>> AtomArray;

  // This has to be the same as in ValueBaseType
  enum ValueType
    eString = 0x00,  //   00
                     //   01  this value indicates a 'misc' struct
    eAtom = 0x02,    //   10
    eInteger = 0x03, // 0011
    eColor = 0x07,   // 0111
    eEnum = 0x0B,    // 1011  This should eventually die
    ePercent = 0x0F, // 1111
    // Values below here won't matter, they'll be always stored in the 'misc'
    // struct.
    eCSSDeclaration = 0x10,
    eSVGTypesBegin = eSVGAngle,
    eSVGTypesEnd = eSVGViewBox,

  nsAttrValue(const nsAttrValue& aOther);
  explicit nsAttrValue(const nsAString& aValue);
  explicit nsAttrValue(nsIAtom* aValue);
  nsAttrValue(already_AddRefed<mozilla::DeclarationBlock> aValue, const nsAString* aSerialized);
  explicit nsAttrValue(const nsIntMargin& aValue);

  inline const nsAttrValue& operator=(const nsAttrValue& aOther);

  static nsresult Init();
  static void Shutdown();

  ValueType Type() const;
  // Returns true when this value is self-contained and does not depend on
  // the state of its associated element.
  // Returns false when this value depends on the state of its associated
  // element and may be invalid if that state has been changed by changes to
  // that element state outside of attribute setting.
  inline bool StoresOwnData() const;

  void Reset();

  void SetTo(const nsAttrValue& aOther);
  void SetTo(const nsAString& aValue);
  void SetTo(nsIAtom* aValue);
  void SetTo(int16_t aInt);
  void SetTo(int32_t aInt, const nsAString* aSerialized);
  void SetTo(double aValue, const nsAString* aSerialized);
  void SetTo(already_AddRefed<mozilla::DeclarationBlock> aValue, const nsAString* aSerialized);
  void SetTo(mozilla::css::URLValue* aValue, const nsAString* aSerialized);
  void SetTo(const nsIntMargin& aValue);
  void SetTo(const nsSVGAngle& aValue, const nsAString* aSerialized);
  void SetTo(const nsSVGIntegerPair& aValue, const nsAString* aSerialized);
  void SetTo(const nsSVGLength2& aValue, const nsAString* aSerialized);
  void SetTo(const mozilla::SVGLengthList& aValue, const nsAString* aSerialized);
  void SetTo(const mozilla::SVGNumberList& aValue, const nsAString* aSerialized);
  void SetTo(const nsSVGNumberPair& aValue, const nsAString* aSerialized);
  void SetTo(const mozilla::SVGPathData& aValue, const nsAString* aSerialized);
  void SetTo(const mozilla::SVGPointList& aValue, const nsAString* aSerialized);
  void SetTo(const mozilla::SVGAnimatedPreserveAspectRatio& aValue, const nsAString* aSerialized);
  void SetTo(const mozilla::SVGStringList& aValue, const nsAString* aSerialized);
  void SetTo(const mozilla::SVGTransformList& aValue, const nsAString* aSerialized);
  void SetTo(const nsSVGViewBox& aValue, const nsAString* aSerialized);

   * Sets this object with the string or atom representation of aValue.
   * After calling this method, this object will have type eString unless the
   * type of aValue is eAtom, in which case this object will also have type
   * eAtom.
  void SetToSerialized(const nsAttrValue& aValue);

  void SwapValueWith(nsAttrValue& aOther);

  void ToString(nsAString& aResult) const;
  inline void ToString(mozilla::dom::DOMString& aResult) const;

   * Returns the value of this object as an atom. If necessary, the value will
   * first be serialised using ToString before converting to an atom.
  already_AddRefed<nsIAtom> GetAsAtom() const;

  // Methods to get value. These methods do not convert so only use them
  // to retrieve the datatype that this nsAttrValue has.
  inline bool IsEmptyString() const;
  const nsCheapString GetStringValue() const;
  inline nsIAtom* GetAtomValue() const;
  inline int32_t GetIntegerValue() const;
  bool GetColorValue(nscolor& aColor) const;
  inline int16_t GetEnumValue() const;
  inline float GetPercentValue() const;
  inline AtomArray* GetAtomArrayValue() const;
  inline mozilla::DeclarationBlock* GetCSSDeclarationValue() const;
  inline mozilla::css::URLValue* GetURLValue() const;
  inline mozilla::css::ImageValue* GetImageValue() const;
  inline double GetDoubleValue() const;
  bool GetIntMarginValue(nsIntMargin& aMargin) const;

   * Returns the string corresponding to the stored enum value.
   * @param aResult   the string representing the enum tag
   * @param aRealTag  wheter we want to have the real tag or the saved one
  void GetEnumString(nsAString& aResult, bool aRealTag) const;

  // Methods to get access to atoms we may have
  // Returns the number of atoms we have; 0 if we have none.  It's OK
  // to call this without checking the type first; it handles that.
  uint32_t GetAtomCount() const;
  // Returns the atom at aIndex (0-based).  Do not call this with
  // aIndex >= GetAtomCount().
  nsIAtom* AtomAt(int32_t aIndex) const;

  uint32_t HashValue() const;
  bool Equals(const nsAttrValue& aOther) const;
  // aCaseSensitive == eIgnoreCase means ASCII case-insenstive matching
  bool Equals(const nsAString& aValue, nsCaseTreatment aCaseSensitive) const;
  bool Equals(nsIAtom* aValue, nsCaseTreatment aCaseSensitive) const;

   * Compares this object with aOther according to their string representation.
   * For example, when called on an object with type eInteger and value 4, and
   * given aOther of type eString and value "4", EqualsAsStrings will return
   * true (while Equals will return false).
  bool EqualsAsStrings(const nsAttrValue& aOther) const;

   * Returns true if this AttrValue is equal to the given atom, or is an
   * array which contains the given atom.
  bool Contains(nsIAtom* aValue, nsCaseTreatment aCaseSensitive) const;
   * Returns true if this AttrValue is an atom equal to the given
   * string, or is an array of atoms which contains the given string.
   * This always does a case-sensitive comparison.
  bool Contains(const nsAString& aValue) const;

  void ParseAtom(const nsAString& aValue);
  void ParseAtomArray(const nsAString& aValue);
  void ParseStringOrAtom(const nsAString& aValue);

   * Structure for a mapping from int (enum) values to strings.  When you use
   * it you generally create an array of them.
   * Instantiate like this:
   * EnumTable myTable[] = {
   *   { "string1", 1 },
   *   { "string2", 2 },
   *   { nullptr, 0 }
   * }
  struct EnumTable
    // EnumTable can be initialized either with an int16_t value
    // or a value of an enumeration type that can fit within an int16_t.

    constexpr EnumTable(const char* aTag, int16_t aValue)
      : tag(aTag)
      , value(aValue)

    template<typename T, typename = typename std::enable_if<std::is_enum<T>::value>::type>
    constexpr EnumTable(const char* aTag, T aValue)
      : tag(aTag)
      , value(static_cast<int16_t>(aValue))
      static_assert(mozilla::EnumTypeFitsWithin<T, int16_t>::value,
                    "aValue must be an enum that fits within int16_t");

    /** The string the value maps to */
    const char* tag;
    /** The enum value that maps to this string */
    int16_t value;

   * Parse into an enum value.
   * @param aValue the string to find the value for
   * @param aTable the enumeration to map with
   * @param aCaseSensitive specify if the parsing has to be case sensitive
   * @param aDefaultValue if non-null, this function will always return true.
   *        Failure to parse aValue as one of the values in aTable will just
   *        cause aDefaultValue->value to be stored as the enumeration value.
   * @return whether the enum value was found or not
  bool ParseEnumValue(const nsAString& aValue,
                      const EnumTable* aTable,
                      bool aCaseSensitive,
                      const EnumTable* aDefaultValue = nullptr);

   * Parse a string into an integer. Can optionally parse percent (n%).
   * This method explicitly sets a lower bound of zero on the element,
   * whether it be percent or raw integer.
   * @param aString the string to parse
   * @return whether the value could be parsed
   * @see
  bool ParseSpecialIntValue(const nsAString& aString);

   * Parse a string value into an integer.
   * @param aString the string to parse
   * @return whether the value could be parsed
  bool ParseIntValue(const nsAString& aString)
    return ParseIntWithBounds(aString, INT32_MIN, INT32_MAX);

   * Parse a string value into an integer with minimum value and maximum value.
   * @param aString the string to parse
   * @param aMin the minimum value (if value is less it will be bumped up)
   * @param aMax the maximum value (if value is greater it will be chopped down)
   * @return whether the value could be parsed
  bool ParseIntWithBounds(const nsAString& aString, int32_t aMin, int32_t aMax = INT32_MAX);

   * Parse a string value into an integer with a fallback for invalid values.
   * Also allows clamping to a maximum value to support col/colgroup.span (this
   * is not per spec right now).
   * @param aString the string to parse
   * @param aDefault the default value
   * @param aMax the maximum value (if value is greater it will be clamped)
  void ParseIntWithFallback(const nsAString& aString, int32_t aDefault, int32_t aMax = INT32_MAX);

   * Parse a string value into a non-negative integer.
   * This method follows the rules for parsing non-negative integer from:
   * @param  aString the string to parse
   * @return whether the value is valid
  bool ParseNonNegativeIntValue(const nsAString& aString);

   * Parse a string value into a positive integer.
   * This method follows the rules for parsing non-negative integer from:
   * In addition of these rules, the value has to be greater than zero.
   * This is generally used for parsing content attributes which reflecting IDL
   * attributes are limited to only non-negative numbers greater than zero, see:
   * @param aString       the string to parse
   * @return              whether the value was valid
  bool ParsePositiveIntValue(const nsAString& aString);

   * Parse a string into a color.  This implements what HTML5 calls the
   * "rules for parsing a legacy color value".
   * @param aString the string to parse
   * @return whether the value could be parsed
  bool ParseColor(const nsAString& aString);

   * Parse a string value into a double-precision floating point value.
   * @param aString the string to parse
   * @return whether the value could be parsed
  bool ParseDoubleValue(const nsAString& aString);

   * Parse a lazy URI.  This just sets up the storage for the URI; it
   * doesn't actually allocate it.
  bool ParseLazyURIValue(const nsAString& aString);

   * Parse a margin string of format 'top, right, bottom, left' into
   * an nsIntMargin.
   * @param aString the string to parse
   * @return whether the value could be parsed
  bool ParseIntMarginValue(const nsAString& aString);

   * Convert a URL nsAttrValue to an Image nsAttrValue.
   * @param aDocument the document this nsAttrValue belongs to.
  void LoadImage(nsIDocument* aDocument);

   * Parse a string into a CSS style rule.
   * @param aString the style attribute value to be parsed.
   * @param aElement the element the attribute is set on.
  bool ParseStyleAttribute(const nsAString& aString, nsStyledElement* aElement);

  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

  // These have to be the same as in ValueType
  enum ValueBaseType
    eStringBase = eString, // 00
    eOtherBase = 0x01,     // 01
    eAtomBase = eAtom,     // 10
    eIntegerBase = 0x03    // 11

  inline ValueBaseType BaseType() const;
  inline bool IsSVGType(ValueType aType) const;

   * Get the index of an EnumTable in the sEnumTableArray.
   * If the EnumTable is not in the sEnumTableArray, it is added.
   * @param aTable   the EnumTable to get the index of.
   * @return         the index of the EnumTable.
  int16_t GetEnumTableIndex(const EnumTable* aTable);

  inline void SetPtrValueAndType(void* aValue, ValueBaseType aType);
  void SetIntValueAndType(int32_t aValue, ValueType aType, const nsAString* aStringValue);
  void SetColorValue(nscolor aColor, const nsAString& aString);
  void SetMiscAtomOrString(const nsAString* aValue);
  void ResetMiscAtomOrString();
  void SetSVGType(ValueType aType, const void* aValue, const nsAString* aSerialized);
  inline void ResetIfSet();

  inline void* GetPtr() const;
  inline MiscContainer* GetMiscContainer() const;
  inline int32_t GetIntInternal() const;

  // Clears the current MiscContainer.  This will return null if there is no
  // existing container.
  MiscContainer* ClearMiscContainer();
  // Like ClearMiscContainer, except allocates a new container if one does not
  // exist already.
  MiscContainer* EnsureEmptyMiscContainer();
  bool EnsureEmptyAtomArray();
  already_AddRefed<nsStringBuffer> GetStringBuffer(const nsAString& aValue) const;
  // Given an enum table and a particular entry in that table, return
  // the actual integer value we should store.
  int32_t EnumTableEntryToValue(const EnumTable* aEnumTable, const EnumTable* aTableEntry);

  static nsTArray<const EnumTable*>* sEnumTableArray;

  uintptr_t mBits;

inline const nsAttrValue&
nsAttrValue::operator=(const nsAttrValue& aOther)
  return *this;

inline nsIAtom*
nsAttrValue::GetAtomValue() const
  NS_PRECONDITION(Type() == eAtom, "wrong type");
  return reinterpret_cast<nsIAtom*>(GetPtr());

inline nsAttrValue::ValueBaseType
nsAttrValue::BaseType() const
  return static_cast<ValueBaseType>(mBits & NS_ATTRVALUE_BASETYPE_MASK);

inline void*
nsAttrValue::GetPtr() const
  NS_ASSERTION(BaseType() != eIntegerBase, "getting pointer from non-pointer");
  return reinterpret_cast<void*>(mBits & NS_ATTRVALUE_POINTERVALUE_MASK);

inline bool
nsAttrValue::IsEmptyString() const
  return !mBits;

inline void
nsAttrValue::ToString(mozilla::dom::DOMString& aResult) const
  switch (Type()) {
    case eString: {
      nsStringBuffer* str = static_cast<nsStringBuffer*>(GetPtr());
      if (str) {
        aResult.SetStringBuffer(str, str->StorageSize() / sizeof(char16_t) - 1);
      // else aResult is already empty
    case eAtom: {
      nsIAtom* atom = static_cast<nsIAtom*>(GetPtr());
      aResult.SetStringBuffer(atom->GetStringBuffer(), atom->GetLength());
    default: {