1 files changed, 85 insertions, 0 deletions
diff --git a/lib/rubygems/text.rb b/lib/rubygems/text.rb
new file mode 100644
index 0000000000..88d4ce59b4
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+++ b/lib/rubygems/text.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+##
+# A collection of text-wrangling methods
+
+module Gem::Text
+  ##
+  # Remove any non-printable characters and make the text suitable for
+  # printing.
+  def clean_text(text)
+    text.gsub(/[\000-\b\v-\f\016-\037\177]/, ".")
+  end
+
+  def truncate_text(text, description, max_length = 100_000)
+    raise ArgumentError, "max_length must be positive" unless max_length > 0
+    return text if text.size <= max_length
+    "Truncating #{description} to #{max_length.to_s.reverse.gsub(/...(?=.)/,'\&,').reverse} characters:\n" + text[0, max_length]
+  end
+
+  ##
+  # Wraps +text+ to +wrap+ characters and optionally indents by +indent+
+  # characters
+
+  def format_text(text, wrap, indent = 0)
+    result = []
+    work = clean_text(text)
+
+    while work.length > wrap do
+      if work =~ /^(.{0,#{wrap}})[ \n]/
+        result << $1.rstrip
+        work.slice!(0, $&.length)
+      else
+        result << work.slice!(0, wrap)
+      end
+    end
+
+    result << work if work.length.nonzero?
+    result.join("\n").gsub(/^/, " " * indent)
+  end
+
+  def min3(a, b, c) # :nodoc:
+    if a < b && a < c
+      a
+    elsif b < c
+      b
+    else
+      c
+    end
+  end
+
+  # Returns a value representing the "cost" of transforming str1 into str2
+  # Vendored version of DidYouMean::Levenshtein.distance from the ruby/did_you_mean gem @ 1.4.0
+  # https://github.com/ruby/did_you_mean/blob/2ddf39b874808685965dbc47d344cf6c7651807c/lib/did_you_mean/levenshtein.rb#L7-L37
+  def levenshtein_distance(str1, str2)
+    n = str1.length
+    m = str2.length
+    return m if n.zero?
+    return n if m.zero?
+
+    d = (0..m).to_a
+    x = nil
+
+    # to avoid duplicating an enumerable object, create it outside of the loop
+    str2_codepoints = str2.codepoints
+
+    str1.each_codepoint.with_index(1) do |char1, i|
+      j = 0
+      while j < m
+        cost = char1 == str2_codepoints[j] ? 0 : 1
+        x = min3(
+          d[j + 1] + 1, # insertion
+          i + 1,      # deletion
+          d[j] + cost # substitution
+        )
+        d[j] = i
+        i = x
+
+        j += 1
+      end
+      d[m] = x
+    end
+
+    x
+  end
+end