The Tor Browser: layout/style/nsCSSPropertySet.h@141e0f1194b1

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 /* bit vectors for sets of CSS properties */

     7 #ifndef nsCSSPropertySet_h__

     8 #define nsCSSPropertySet_h__

    10 #include "mozilla/ArrayUtils.h"

    12 #include "nsCSSProperty.h"

    13 #include <limits.h> // for CHAR_BIT

    15 /**

    16  * nsCSSPropertySet maintains a set of non-shorthand CSS properties.  In

    17  * other words, for each longhand CSS property we support, it has a bit

    18  * for whether that property is in the set.

    19  */

    20 class nsCSSPropertySet {

    21 public:

    22     nsCSSPropertySet() { Empty(); }

    23     // auto-generated copy-constructor OK

    25     void AssertInSetRange(nsCSSProperty aProperty) const {

    26         NS_ASSERTION(0 <= aProperty &&

    27                      aProperty < eCSSProperty_COUNT_no_shorthands,

    28                      "out of bounds");

    29     }

    31     // Conversion of aProperty to |size_t| after AssertInSetRange

    32     // lets the compiler generate significantly tighter code.

    34     void AddProperty(nsCSSProperty aProperty) {

    35         AssertInSetRange(aProperty);

    36         size_t p = aProperty;

    37         mProperties[p / kBitsInChunk] |=

    38           property_set_type(1) << (p % kBitsInChunk);

    39     }

    41     void RemoveProperty(nsCSSProperty aProperty) {

    42         AssertInSetRange(aProperty);

    43         size_t p = aProperty;

    44         mProperties[p / kBitsInChunk] &=

    45             ~(property_set_type(1) << (p % kBitsInChunk));

    46     }

    48     bool HasProperty(nsCSSProperty aProperty) const {

    49         AssertInSetRange(aProperty);

    50         size_t p = aProperty;

    51         return (mProperties[p / kBitsInChunk] &

    52                 (property_set_type(1) << (p % kBitsInChunk))) != 0;

    53     }

    55     void Empty() {

    56         memset(mProperties, 0, sizeof(mProperties));

    57     }

    59     void AssertIsEmpty(const char* aText) const {

    60         for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {

    61             NS_ASSERTION(mProperties[i] == 0, aText);

    62         }

    63     }

    65 private:

    66     typedef unsigned long property_set_type;

    67 public:

    68     // number of bits in |property_set_type|.

    69     static const size_t kBitsInChunk = sizeof(property_set_type)*CHAR_BIT;

    70     // number of |property_set_type|s in the set

    71     static const size_t kChunkCount =

    72         (eCSSProperty_COUNT_no_shorthands + kBitsInChunk - 1) / kBitsInChunk;

    74     /*

    75      * For fast enumeration of all the bits that are set, callers can

    76      * check each chunk against zero (since in normal cases few bits are

    77      * likely to be set).

    78      */

    79     bool HasPropertyInChunk(size_t aChunk) const {

    80         return mProperties[aChunk] != 0;

    81     }

    82     bool HasPropertyAt(size_t aChunk, size_t aBit) const {

    83         return (mProperties[aChunk] & (property_set_type(1) << aBit)) != 0;

    84     }

    85     static nsCSSProperty CSSPropertyAt(size_t aChunk, size_t aBit) {

    86         return nsCSSProperty(aChunk * kBitsInChunk + aBit);

    87     }

    89 private:

    90     property_set_type mProperties[kChunkCount];

    91 };

    93 #endif /* !defined(nsCSSPropertySet_h__) */

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