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1 # |
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2 # Chunker! |
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3 # |
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4 # Mahlon E. Smith <mahlon@martini.nu> |
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5 # |
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6 |
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7 |
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8 ### Namespace for the datablock parser. |
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9 ### |
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10 module Chunker |
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11 |
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12 require 'strscan' |
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13 require 'stringio' |
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14 |
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15 # SVN Revision |
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16 # |
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17 SVNRev = %q$Rev$ |
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18 |
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19 # SVN Id |
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20 # |
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21 SVNId = %q$Id$ |
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22 |
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23 # Package version |
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24 # |
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25 VERSION = '0.1' |
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26 |
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27 |
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28 ### Parser class for __END__ data blocks. |
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29 ### Find each __MARKER__ within the __END__, and put each into a |
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30 ### DATA_MARKER constant within the namespace that included us. |
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31 ### |
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32 class DataParser |
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33 |
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34 # The mark for a DATA block. |
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35 # |
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36 END_MARKER = /^__END__\r?\n/ |
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37 |
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38 # The mark for a 'sub' block. |
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39 # |
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40 CHUNK_MARKER = /^__([A-Z\_0-9]+)__\r?\n/ |
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41 |
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42 |
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43 ### Constructor: Given a +klass+ and an +io+ to the class file, |
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44 ### extract the data blocks and install constants. |
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45 ### |
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46 def initialize( klass, io ) |
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47 io.open if io.closed? |
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48 end_string = io.read.split( END_MARKER, 2 ).last |
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49 |
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50 @klass = klass |
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51 @scanner = StringScanner.new( end_string ) |
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52 io.close |
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53 |
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54 if @scanner.check_until( CHUNK_MARKER ) |
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55 # put each chunk into its own constant |
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56 self.extract_blocks |
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57 else |
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58 # no sub blocks, put the whole mess into DATA_END |
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59 @klass.const_set( :DATA_END, StringIO.new( end_string ) ) |
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60 end |
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61 end |
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62 |
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63 |
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64 ######### |
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65 protected |
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66 ######### |
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67 |
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68 ### Parse the current +io+ for data blocks, set contents to |
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69 ### IO constants in the including class. |
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70 ### |
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71 def extract_blocks |
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72 label = nil |
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73 |
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74 while @scanner.scan_until( CHUNK_MARKER ) and ! @scanner.eos? |
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75 data = '' |
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76 |
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77 # First pass, __END__ contents (until next marker, instead |
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78 # of entire data block.) |
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79 # |
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80 if label.nil? |
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81 label = 'END' |
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82 data = @scanner.pre_match |
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83 |
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84 @scanner.pos = self.next_position |
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85 else |
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86 label = @scanner[1] |
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87 |
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88 if data = @scanner.scan_until( CHUNK_MARKER ) |
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89 # Pull the next marker text out of the data, set up the next pass |
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90 # |
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91 data = data[ 0, data.length - @scanner[0].length ] |
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92 @scanner.pos = self.next_position |
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93 else |
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94 # No additional blocks |
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95 # |
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96 data = @scanner.rest |
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97 end |
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98 end |
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99 |
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100 # Add the IO constant to the class that included me. |
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101 # |
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102 @klass.const_set( "DATA_#{label}".to_sym, StringIO.new( data ) ) |
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103 end |
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104 end |
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105 |
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106 |
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107 ### Return the next scanner position for searching. |
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108 ### |
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109 def next_position |
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110 return @scanner.pos - @scanner[0].length |
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111 end |
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112 end |
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113 |
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114 |
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115 ### Included hook: Find the file path for how we arrived here, and open |
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116 ### it as an IO object. __FILE__ won't work, so we find it via caller(). |
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117 ### Start parsing this file for data blocks. |
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118 ### |
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119 def self.included( klass ) |
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120 # klass.instance_eval{ __FILE__ } awww, nope. |
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121 io = File.open( caller(1).last.sub(/:.*?$/, ''), 'r' ) |
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122 DataParser.new( klass, io ) |
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123 end |
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124 end |
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125 |