michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* bit vectors for sets of CSS properties */
michael@0: 
michael@0: #ifndef nsCSSPropertySet_h__
michael@0: #define nsCSSPropertySet_h__
michael@0: 
michael@0: #include "mozilla/ArrayUtils.h"
michael@0: 
michael@0: #include "nsCSSProperty.h"
michael@0: #include <limits.h> // for CHAR_BIT
michael@0: 
michael@0: /**
michael@0:  * nsCSSPropertySet maintains a set of non-shorthand CSS properties.  In
michael@0:  * other words, for each longhand CSS property we support, it has a bit
michael@0:  * for whether that property is in the set.
michael@0:  */
michael@0: class nsCSSPropertySet {
michael@0: public:
michael@0:     nsCSSPropertySet() { Empty(); }
michael@0:     // auto-generated copy-constructor OK
michael@0: 
michael@0:     void AssertInSetRange(nsCSSProperty aProperty) const {
michael@0:         NS_ASSERTION(0 <= aProperty &&
michael@0:                      aProperty < eCSSProperty_COUNT_no_shorthands,
michael@0:                      "out of bounds");
michael@0:     }
michael@0: 
michael@0:     // Conversion of aProperty to |size_t| after AssertInSetRange
michael@0:     // lets the compiler generate significantly tighter code.
michael@0: 
michael@0:     void AddProperty(nsCSSProperty aProperty) {
michael@0:         AssertInSetRange(aProperty);
michael@0:         size_t p = aProperty;
michael@0:         mProperties[p / kBitsInChunk] |=
michael@0:           property_set_type(1) << (p % kBitsInChunk);
michael@0:     }
michael@0: 
michael@0:     void RemoveProperty(nsCSSProperty aProperty) {
michael@0:         AssertInSetRange(aProperty);
michael@0:         size_t p = aProperty;
michael@0:         mProperties[p / kBitsInChunk] &=
michael@0:             ~(property_set_type(1) << (p % kBitsInChunk));
michael@0:     }
michael@0: 
michael@0:     bool HasProperty(nsCSSProperty aProperty) const {
michael@0:         AssertInSetRange(aProperty);
michael@0:         size_t p = aProperty;
michael@0:         return (mProperties[p / kBitsInChunk] &
michael@0:                 (property_set_type(1) << (p % kBitsInChunk))) != 0;
michael@0:     }
michael@0: 
michael@0:     void Empty() {
michael@0:         memset(mProperties, 0, sizeof(mProperties));
michael@0:     }
michael@0: 
michael@0:     void AssertIsEmpty(const char* aText) const {
michael@0:         for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
michael@0:             NS_ASSERTION(mProperties[i] == 0, aText);
michael@0:         }
michael@0:     }
michael@0: 
michael@0: private:
michael@0:     typedef unsigned long property_set_type;
michael@0: public:
michael@0:     // number of bits in |property_set_type|.
michael@0:     static const size_t kBitsInChunk = sizeof(property_set_type)*CHAR_BIT;
michael@0:     // number of |property_set_type|s in the set
michael@0:     static const size_t kChunkCount =
michael@0:         (eCSSProperty_COUNT_no_shorthands + kBitsInChunk - 1) / kBitsInChunk;
michael@0: 
michael@0:     /*
michael@0:      * For fast enumeration of all the bits that are set, callers can
michael@0:      * check each chunk against zero (since in normal cases few bits are
michael@0:      * likely to be set).
michael@0:      */
michael@0:     bool HasPropertyInChunk(size_t aChunk) const {
michael@0:         return mProperties[aChunk] != 0;
michael@0:     }
michael@0:     bool HasPropertyAt(size_t aChunk, size_t aBit) const {
michael@0:         return (mProperties[aChunk] & (property_set_type(1) << aBit)) != 0;
michael@0:     }
michael@0:     static nsCSSProperty CSSPropertyAt(size_t aChunk, size_t aBit) {
michael@0:         return nsCSSProperty(aChunk * kBitsInChunk + aBit);
michael@0:     }
michael@0: 
michael@0: private:
michael@0:     property_set_type mProperties[kChunkCount];
michael@0: };
michael@0: 
michael@0: #endif /* !defined(nsCSSPropertySet_h__) */