1 /*
2  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #ifndef StringBuilder_h
27 #define StringBuilder_h
28 
29 #include <wtf/Vector.h>
30 #include <wtf/text/WTFString.h>
31 
32 namespace WTF {
33 
34 class StringBuilder {
35 public:
StringBuilder()36     StringBuilder()
37         : m_length(0)
38     {
39     }
40 
41     void append(const UChar*, unsigned);
42     void append(const char*, unsigned);
43 
append(const String & string)44     void append(const String& string)
45     {
46         // If we're appending to an empty string, and there is not buffer
47         // (in case reserveCapacity has been called) then just retain the
48         // string.
49         if (!m_length && !m_buffer) {
50             m_string = string;
51             m_length = string.length();
52             return;
53         }
54         append(string.characters(), string.length());
55     }
56 
append(const char * characters)57     void append(const char* characters)
58     {
59         if (characters)
60             append(characters, strlen(characters));
61     }
62 
append(UChar c)63     void append(UChar c)
64     {
65         if (m_buffer && m_length < m_buffer->length() && m_string.isNull())
66             m_bufferCharacters[m_length++] = c;
67         else
68             append(&c, 1);
69     }
70 
append(char c)71     void append(char c)
72     {
73         if (m_buffer && m_length < m_buffer->length() && m_string.isNull())
74             m_bufferCharacters[m_length++] = (unsigned char)c;
75         else
76             append(&c, 1);
77     }
78 
toString()79     String toString()
80     {
81         if (m_string.isNull()) {
82             shrinkToFit();
83             reifyString();
84         }
85         return m_string;
86     }
87 
toStringPreserveCapacity()88     String toStringPreserveCapacity()
89     {
90         if (m_string.isNull())
91             reifyString();
92         return m_string;
93     }
94 
length()95     unsigned length() const
96     {
97         return m_length;
98     }
99 
isEmpty()100     bool isEmpty() const { return !length(); }
101 
102     void reserveCapacity(unsigned newCapacity);
103 
104     void resize(unsigned newSize);
105 
106     void shrinkToFit();
107 
108     UChar operator[](unsigned i) const
109     {
110         ASSERT(i < m_length);
111         if (!m_string.isNull())
112             return m_string[i];
113         ASSERT(m_buffer);
114         return m_buffer->characters()[i];
115     }
116 
clear()117     void clear()
118     {
119         m_length = 0;
120         m_string = String();
121         m_buffer = 0;
122     }
123 
124 private:
125     void allocateBuffer(const UChar* currentCharacters, unsigned requiredLength);
126     UChar* appendUninitialized(unsigned length);
127     void reifyString();
128 
129     unsigned m_length;
130     String m_string;
131     RefPtr<StringImpl> m_buffer;
132     UChar* m_bufferCharacters;
133 };
134 
135 } // namespace WTF
136 
137 using WTF::StringBuilder;
138 
139 #endif // StringBuilder_h
140