1 # vim: set nosta noet ts=4 sw=4: |
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2 |
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3 require 'strscan' |
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4 require 'stringio' |
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5 |
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6 # |
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7 # Chunker: A convenience library for parsing __END__ tokens consistently. |
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8 # |
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9 # == Version |
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10 # |
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11 # $Id$ |
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12 # |
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13 # == Author |
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14 # |
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15 # * Mahlon E. Smith <mahlon@martini.nu> |
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16 # |
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17 # :include: LICENSE |
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18 # |
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19 |
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20 ### Namespace for the datablock parser. |
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21 ### |
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22 module Chunker |
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23 |
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24 # VCS Revision |
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25 VCSRev = %q$Rev$ |
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26 |
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27 # VCS Id |
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28 VCSId = %q$Id$ |
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29 |
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30 # Package version |
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31 VERSION = '1.0.0' |
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32 |
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33 |
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34 ### Parser class for __END__ data blocks. |
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35 ### Find each __TOKEN__ within the __END__, and put each into a |
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36 ### DATA_TOKEN constant within the namespace that included us. |
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37 ### |
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38 class DataParser |
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39 |
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40 # The mark for a DATA block. |
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41 END_TOKEN = /^__END__\r?\n/ |
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42 |
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43 # The mark for a 'sub' block. |
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44 CHUNK_TOKEN = /^__([A-Z\_0-9]+)__\r?\n/ |
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45 |
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46 |
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47 ### Constructor: Given a +klass+ and an +io+ to the class file, |
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48 ### extract the data blocks and install constants. |
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49 ### |
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50 def initialize( klass, io ) |
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51 io.open if io.closed? |
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52 end_string = io.read.split( END_TOKEN, 2 ).last |
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53 |
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54 @klass = klass |
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55 @scanner = StringScanner.new( end_string ) |
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56 io.close |
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57 |
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58 # put each chunk into its own constant |
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59 # |
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60 if @scanner.check_until( CHUNK_TOKEN ) |
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61 self.extract_blocks |
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62 |
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63 # no sub blocks, put the whole mess into DATA_END |
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64 # |
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65 else |
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66 @klass.const_set( :DATA_END, StringIO.new( end_string ) ) |
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67 end |
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68 end |
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69 |
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70 |
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71 ######### |
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72 protected |
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73 ######### |
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74 |
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75 ### Parse the current +io+ for data blocks, set contents to |
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76 ### IO constants in the including class. |
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77 ### |
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78 def extract_blocks |
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79 label = nil |
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80 |
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81 while @scanner.scan_until( CHUNK_TOKEN ) and ! @scanner.eos? |
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82 data = '' |
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83 |
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84 # First pass, __END__ contents (until next token, instead |
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85 # of entire data block.) |
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86 # |
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87 if label.nil? |
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88 label = 'END' |
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89 data = @scanner.pre_match |
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90 |
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91 @scanner.pos = self.next_position |
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92 else |
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93 label = @scanner[1] |
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94 |
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95 # Pull the next token text out of the data, set up the next pass |
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96 # |
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97 if data = @scanner.scan_until( CHUNK_TOKEN ) |
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98 data = data[ 0, data.length - @scanner[0].length ] |
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99 @scanner.pos = self.next_position |
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100 |
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101 # No additional blocks |
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102 # |
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103 else |
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104 data = @scanner.rest |
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105 end |
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106 end |
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107 |
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108 # Add the IO constant to the class that included me. |
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109 @klass.const_set( "DATA_#{label}".to_sym, StringIO.new( data ) ) |
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110 end |
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111 end |
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112 |
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113 |
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114 ### Return the next scanner position for searching. |
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115 ### |
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116 def next_position |
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117 return @scanner.pos - @scanner[0].length |
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118 end |
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119 end |
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120 |
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121 |
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122 ### Hook included: Find the file path for how we arrived here, and open |
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123 ### it as an IO object. Parse the IO for data block tokens. |
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124 ### |
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125 def self.included( klass ) |
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126 # klass.instance_eval{ __FILE__ } awww, nope. |
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127 # __FILE__ won't work here, so we find the filename via caller(). |
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128 io = File.open( caller(1).last.sub(/:.*?$/, ''), 'r' ) |
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129 |
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130 DataParser.new( klass, io ) |
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131 end |
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132 end |
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133 |
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