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1 /*******************************************************************************
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2
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3 copyright: Copyright (c) 2004 Kris Bell. All rights reserved
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4
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5 license: BSD style: $(LICENSE)
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6
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7 version: Initial release: March 2004
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8
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9 author: Kris
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10
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11 *******************************************************************************/
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12
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13 module tango.io.GrowBuffer;
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14
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15 private import tango.io.Buffer;
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16
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17 public import tango.io.model.IBuffer;
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18
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19 /*******************************************************************************
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20
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21 Subclass to provide support for content growth. This is handy when
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22 you want to keep a buffer around as a scratchpad.
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23
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24 *******************************************************************************/
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25
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26 class GrowBuffer : Buffer
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27 {
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28 private uint increment;
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29
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30 alias Buffer.slice slice;
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31 alias Buffer.append append;
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32
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33 /***********************************************************************
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34
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35 Create a GrowBuffer with the specified initial size.
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36
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37 ***********************************************************************/
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38
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39 this (uint size = 1024, uint increment = 1024)
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40 {
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41 super (size);
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42
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43 assert (increment >= 32);
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44 this.increment = increment;
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45 }
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46
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47 /***********************************************************************
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48
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49 Create a GrowBuffer with the specified initial size.
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50
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51 ***********************************************************************/
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52
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53 this (IConduit conduit, uint size = 1024)
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54 {
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55 this (size, size);
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56 setConduit (conduit);
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57 }
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58
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59 /***********************************************************************
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60
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61 Read a chunk of data from the buffer, loading from the
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62 conduit as necessary. The specified number of bytes is
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63 loaded into the buffer, and marked as having been read
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64 when the 'eat' parameter is set true. When 'eat' is set
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65 false, the read position is not adjusted.
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66
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67 Returns the corresponding buffer slice when successful.
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68
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69 ***********************************************************************/
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70
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71 override void[] slice (uint size, bool eat = true)
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72 {
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73 if (size > readable)
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74 {
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75 if (source is null)
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76 error (underflow);
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77
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78 if (size + index > dimension)
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79 makeRoom (size);
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80
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81 // populate tail of buffer with new content
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82 do {
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83 if (fill(source) is IConduit.Eof)
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84 error (eofRead);
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85 } while (size > readable);
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86 }
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87
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88 uint i = index;
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89 if (eat)
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90 index += size;
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91 return data [i .. i + size];
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92 }
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93
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94 /***********************************************************************
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95
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96 Append an array of data to this buffer. This is often used
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97 in lieu of a Writer.
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98
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99 ***********************************************************************/
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100
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101 override IBuffer append (void *src, uint length)
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102 {
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103 if (length > writable)
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104 makeRoom (length);
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105
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106 copy (src, length);
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107 return this;
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108 }
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109
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110 /***********************************************************************
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111
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112 Try to fill the available buffer with content from the
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113 specified conduit.
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114
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115 Returns the number of bytes read, or IConduit.Eof
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116
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117 ***********************************************************************/
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118
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119 override uint fill (InputStream src)
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120 {
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121 if (writable <= increment/8)
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122 makeRoom (increment);
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123
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124 return write (&src.read);
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125 }
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126
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127 /***********************************************************************
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128
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129 Expand and consume the conduit content, up to the maximum
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130 size indicated by the argument or until conduit.Eof
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131
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132 Returns the number of bytes in the buffer
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133
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134 ***********************************************************************/
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135
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136 uint fill (uint size = uint.max)
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137 {
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138 while (readable < size)
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139 if (fill(source) is IConduit.Eof)
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140 break;
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141 return readable;
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142 }
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143
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144 /***********************************************************************
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145
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146 make some room in the buffer
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147
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148 ***********************************************************************/
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149
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150 private uint makeRoom (uint size)
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151 {
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152 if (size < increment)
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153 size = increment;
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154
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155 dimension += size;
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156 data.length = dimension;
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157 return writable();
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158 }
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159 }
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