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1 /*******************************************************************************
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2
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3 copyright: Copyright (c) 2007 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: Oct 2007: Initial version
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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.vfs.LinkedFolder;
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14
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15 private import tango.io.vfs.model.Vfs;
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16
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17 private import tango.core.Exception;
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18
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19 private import tango.io.vfs.VirtualFolder;
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20
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21 /*******************************************************************************
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22
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23 LinkedFolder is derived from VirtualFolder, and behaves exactly the
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24 same in all but one aspect: it treats mounted folders as an ordered
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25 list of alternatives to look for a file. This supports the notion of
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26 file 'overrides', whereby "customized" files can be inserted into a
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27 chain of alternatives.
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28
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29 (overridden folders are not currently supported)
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30
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31 *******************************************************************************/
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32
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33
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34 class LinkedFolder : VirtualFolder
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35 {
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36 private Link* head;
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37
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38 /***********************************************************************
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39
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40 Linked-list of folders
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41
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42 ***********************************************************************/
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43
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44 private struct Link
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45 {
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46 Link* next;
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47 VfsFolder folder;
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48
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49 static Link* opCall(VfsFolder folder)
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50 {
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51 auto p = new Link;
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52 p.folder = folder;
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53 return p;
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54 }
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55 }
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56
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57 /***********************************************************************
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58
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59 All folder must have a name. No '.' or '/' chars are
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60 permitted
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61
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62 ***********************************************************************/
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63
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64 this (char[] name)
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65 {
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66 super (name);
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67 }
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68
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69 /***********************************************************************
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70
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71 Add a child folder. The child cannot 'overlap' with others
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72 in the tree of the same type. Circular references across a
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73 tree of virtual folders are detected and trapped.
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74
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75 We add the new child at the end of an ordered list, which
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76 we subsequently traverse when looking up a file
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77
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78 The second argument represents an optional name that the
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79 mount should be known as, instead of the name exposed by
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80 the provided folder (it is not an alias).
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81
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82 ***********************************************************************/
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83
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84 final VfsHost mount (VfsFolder folder, char[] name=null)
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85 {
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86 // traverse to the end of the list
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87 auto link = &head;
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88 while (*link)
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89 link = &(*link).next;
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90
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91 // hook up the new folder
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92 *link = Link (folder);
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93
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94 // and let superclass deal with it
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95 return super.mount (folder, name);
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96 }
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97
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98 /***********************************************************************
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99
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100 TODO: unhook a child folder.
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101
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102 ***********************************************************************/
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103
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104 final VfsHost dismount (VfsFolder folder)
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105 {
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106 assert (0, "LinkedFolder.dismount not implemented");
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107 }
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108
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109 /***********************************************************************
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110
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111 Return a file representation of the given path. If the
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112 path-head does not refer to an immediate child folder,
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113 and does not match a symbolic link, it is considered to
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114 be unknown.
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115
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116 We scan the set of mounted folders, in the order mounted,
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117 looking for a match. Where one is found, we test to see
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118 that it really exists before returning the reference
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119
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120 ***********************************************************************/
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121
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122 final override VfsFile file (char[] path)
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123 {
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124 auto link = head;
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125 while (link)
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126 {
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127 //Stdout.formatln ("looking in {}", link.folder.toString);
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128 try {
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129 auto file = link.folder.file (path);
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130 if (file.exists)
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131 return file;
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132 } catch (VfsException x) {}
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133 link = link.next;
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134 }
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135 super.error ("file '"~path~"' not found");
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136 return null;
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137 }
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138 }
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139
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140
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141 debug (LinkedFolder)
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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
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147 import tango.io.Stdout;
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148 import tango.io.Buffer;
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149 import tango.io.vfs.FileFolder;
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150
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151 void main()
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152 {
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153 auto root = new LinkedFolder ("root");
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154 auto sub = new VirtualFolder ("sub");
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155 sub.mount (new FileFolder (r"d:/d/import/temp"));
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156 sub.map (sub.file(r"temp/subtree/test.txt"), "wumpus");
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157
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158 root.mount (new FileFolder (r"d:/d/import/tango"))
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159 .mount (new FileFolder (r"c:/"), "windows");
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160 root.mount (sub);
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161
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162 auto file = root.file (r"wumpus");
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163 Stdout.formatln ("file = {}", file);
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164 }
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165 }
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