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in guides generator, broken link warning now suggests the existing an…

…chor with min Levenshtein distance
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1 parent 3b89aa6 commit 732d97a1b1d5d0e88476e2f13cd19bfd9e3aecae @fxn fxn committed Mar 15, 2009
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1 railties/guides/rails_guides.rb
@@ -22,6 +22,7 @@ module RailsGuides
autoload :Indexer, "rails_guides/indexer"
autoload :Helpers, "rails_guides/helpers"
autoload :TextileExtensions, "rails_guides/textile_extensions"
+ autoload :Levenshtein, "rails_guides/levenshtein"
end
RedCloth.send(:include, RailsGuides::TextileExtensions)
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5 railties/guides/rails_guides/generator.rb
@@ -146,7 +146,10 @@ def warn_about_broken_links(html)
html.scan(/<a\s+href="#([^"]+)/).flatten.each do |fragment_identifier|
next if fragment_identifier == 'mainCol' # in layout, jumps to some DIV
unless anchors.member?(fragment_identifier)
- puts "BROKEN LINK: ##{fragment_identifier}"
+ guess = anchors.min { |a, b|
+ Levenshtein.distance(fragment_identifier, a) <=> Levenshtein.distance(fragment_identifier, b)
+ }
+ puts "*** BROKEN LINK: ##{fragment_identifier}, perhaps you meant ##{guess}."
end
end
end
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112 railties/guides/rails_guides/levenshtein.rb
@@ -0,0 +1,112 @@
+#
+# Levenshtein distance algorithm implementation for Ruby, with UTF-8 support
+#
+# Author:: Paul BATTLEY (pbattley @ gmail.com)
+# Version:: 1.3
+# Date:: 2005-04-19
+#
+# == About
+#
+# The Levenshtein distance is a measure of how similar two strings s and t are,
+# calculated as the number of deletions/insertions/substitutions needed to
+# transform s into t. The greater the distance, the more the strings differ.
+#
+# The Levenshtein distance is also sometimes referred to as the
+# easier-to-pronounce-and-spell 'edit distance'.
+#
+# == Revision history
+#
+# * 2005-05-19 1.3 Repairing an oversight, distance can now be called via
+# Levenshtein.distance(s, t)
+# * 2005-05-04 1.2 Now uses just one 1-dimensional array. I think this is as
+# far as optimisation can go.
+# * 2005-05-04 1.1 Now storing only the current and previous rows of the matrix
+# instead of the whole lot.
+#
+# == Licence
+#
+# Copyright (c) 2005 Paul Battley
+#
+# Usage of the works is permitted provided that this instrument is retained
+# with the works, so that any entity that uses the works is notified of this
+# instrument.
+#
+# DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.
+#
+
+module Levenshtein
+
+ #
+ # Calculate the Levenshtein distance between two strings +str1+ and +str2+.
+ # +str1+ and +str2+ should be ASCII or UTF-8.
+ #
+ def distance(str1, str2)
+ s = str1.unpack('U*')
+ t = str2.unpack('U*')
+ n = s.length
+ m = t.length
+ return m if (0 == n)
+ return n if (0 == m)
+
+ d = (0..m).to_a
+ x = nil
+
+ (0...n).each do |i|
+ e = i+1
+ (0...m).each do |j|
+ cost = (s[i] == t[j]) ? 0 : 1
+ x = [
+ d[j+1] + 1, # insertion
+ e + 1, # deletion
+ d[j] + cost # substitution
+ ].min
+ d[j] = e
+ e = x
+ end
+ d[m] = x
+ end
+
+ return x
+ end
+
+ extend self
+end
+
+if (__FILE__ == $0)
+ require 'test/unit'
+
+ class LevenshteinTest < Test::Unit::TestCase
+ include Levenshtein
+
+ EXPECTED = [
+ # Easy ones
+ ['test', 'test', 0],
+ ['test', 'tent', 1],
+ ['gumbo', 'gambol', 2],
+ ['kitten', 'sitting', 3],
+ # Empty strings
+ ['foo', '', 3],
+ ['', '', 0],
+ ['a', '', 1],
+ # UTF-8
+ ["f\303\266o", 'foo', 1],
+ ["fran\303\247ais", 'francais', 1],
+ ["fran\303\247ais", "fran\303\246ais", 1],
+ ["\347\247\201\343\201\256\345\220\215\345\211\215\343\201\257"<<
+ "\343\203\235\343\203\274\343\203\253\343\201\247\343\201\231",
+ "\343\201\274\343\201\217\343\201\256\345\220\215\345\211\215\343\201"<<
+ "\257\343\203\235\343\203\274\343\203\253\343\201\247\343\201\231",
+ 2], # Japanese
+ # Edge cases
+ ['a', 'a', 0],
+ ['0123456789', 'abcdefghijklmnopqrstuvwxyz', 26]
+ ]
+
+ def test_known_distances
+ EXPECTED.each do |a,b,x|
+ assert_equal(x, distance(a, b))
+ assert_equal(x, distance(b, a))
+ end
+ end
+ end
+end

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