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