layout/style/CSSVariableDeclarations.h
author Cameron McCormack <cam@mcc.id.au>
Thu, 12 Dec 2013 13:09:40 +1100
changeset 160052 e6e4e9b6cf6a1a84b4c56882a10dffb908884150
child 160055 8eae39ddcb7734f710ff2252a213f4d0dbe482aa
permissions -rw-r--r--
Bug 773296 - Part 2: Parse CSS variable declarations and store them on Declaration objects. p=ebassi,heycam r=dbaron Patch co-authored by Emmanuele Bassi <ebassi@gmail.com> This defines a CSSVariableDeclarations class that holds a set of variable declarations. This is at the specified value stage, so values can either be 'initial', 'inherit' or a token stream (which is what you normally have). The variables are stored in a hash table. Although it's a bit of a hack, we store 'initial' and 'inherit' using special string values that can't be valid token streams (we use "!" and ";"). Declaration objects now can have two CSSVariableDeclarations objects on them, to store normal and !important variable declarations. So that we keep preserving the order of declarations on the object, we inflate mOrder to store uint32_ts, where values from eCSSProperty_COUNT onwards represent custom properties. mVariableOrder stores the names of the variables corresponding to those entries in mOrder. We also add a new nsCSSProperty value, eCSSPropertyExtra_variable, which is used to represent any custom property name. nsCSSProps::LookupProperty can return this value. The changes to nsCSSParser are straightforward. Custom properties are parsed and checked for syntactic validity (e.g. "var(a,)" being invalid) and stored on the Declaration. We use nsCSSScanner's recording ability to grab the unparsed CSS string corresponding to the variable's value.

/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* 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/. */

/* CSS Custom Property assignments for a Declaration at a given priority */

#ifndef mozilla_CSSVariableDeclarations_h
#define mozilla_CSSVariableDeclarations_h

#include "nsDataHashtable.h"

namespace mozilla {

class CSSVariableDeclarations
{
public:
  CSSVariableDeclarations();
  CSSVariableDeclarations(const CSSVariableDeclarations& aOther);
#ifdef DEBUG
  ~CSSVariableDeclarations();
#endif
  CSSVariableDeclarations& operator=(const CSSVariableDeclarations& aOther);

  /**
   * Returns whether this set of variable declarations includes a variable
   * with a given name.
   *
   * @param aName The variable name (not including any "var-" prefix that would
   *   be part of the custom property name).
   */
  bool Has(const nsAString& aName) const;

  /**
   * Represents the type of a variable value.
   */
  enum Type {
    eTokenStream,  // a stream of CSS tokens (the usual type for variables)
    eInitial,      // 'initial'
    eInherit       // 'inherit'
  };

  /**
   * Gets the value of a variable in this set of variable declarations.
   *
   * @param aName The variable name (not including any "var-" prefix that would
   *   be part of the custom property name).
   * @param aType Out parameter into which the type of the variable value will
   *   be stored.
   * @param aValue Out parameter into which the value of the variable will
   *   be stored.  If the variable is 'initial' or 'inherit', this will be
   *   the empty string.
   * @return Whether a variable with the given name was found.  When false
   *   is returned, aType and aValue will not be modified.
   */
  bool Get(const nsAString& aName, Type& aType, nsString& aValue) const;

  /**
   * Adds or modifies an existing entry in this set of variable declarations
   * to have the value 'initial'.
   *
   * @param aName The variable name (not including any "var-" prefix that would
   *   be part of the custom property name) whose value is to be set.
   */
  void PutInitial(const nsAString& aName);

  /**
   * Adds or modifies an existing entry in this set of variable declarations
   * to have the value 'inherit'.
   *
   * @param aName The variable name (not including any "var-" prefix that would
   *   be part of the custom property name) whose value is to be set.
   */
  void PutInherit(const nsAString& aName);

  /**
   * Adds or modifies an existing entry in this set of variable declarations
   * to have a token stream value.
   *
   * @param aName The variable name (not including any "var-" prefix that would
   *   be part of the custom property name) whose value is to be set.
   * @param aTokenStream The CSS token stream.
   */
  void PutTokenStream(const nsAString& aName, const nsString& aTokenStream);

  /**
   * Removes an entry in this set of variable declarations.
   *
   * @param aName The variable name (not including any "var-" prefix that would
   *   be part of the custom property name) whose entry is to be removed.
   */
  void Remove(const nsAString& aName);

  /**
   * Returns the number of entries in this set of variable declarations.
   */
  uint32_t Count() const { return mVariables.Count(); }

  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

private:
  /**
   * Adds all the variable declarations from aOther into this object.
   */
  void CopyVariablesFrom(const CSSVariableDeclarations& aOther);
  static PLDHashOperator EnumerateVariableForCopy(const nsAString& aName,
                                                  nsString aValue,
                                                  void* aData);

  nsDataHashtable<nsStringHashKey, nsString> mVariables;
};

} // namespace mozilla

#endif