Enhancement - caseless find

- Added support for a starting offset.

src/tests/text.t.cpp

@@ -34,7 +34,7 @@ Context context;
 ////////////////////////////////////////////////////////////////////////////////
 int main (int argc, char** argv)
 {
-  UnitTest t (176);
+  UnitTest t (178);
 
   // void wrapText (std::vector <std::string>& lines, const std::string& text, const int width)
   std::string text = "This is a test of the line wrapping code.";
@@ -356,6 +356,9 @@ int main (int argc, char** argv)
   t.is ((int) find ("FOO", "fo", false),  0, "FOO contains fo (caseless)");
   t.is ((int) find ("FOO", "FO", false),  0, "FOO contains FO (caseless)");
 
+  // Test start offset.
+  t.is ((int) find ("one two three", "e",  3, true), (int) 11, "offset obeyed");
+  t.is ((int) find ("one two three", "e", 11, true), (int) 11, "offset obeyed");
   return 0;
 }
 

src/text.cpp

@@ -519,3 +519,50 @@ std::string::size_type find (
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+std::string::size_type find (
+  const std::string& text,
+  const std::string& pattern,
+  std::string::size_type begin,
+  bool sensitive /*= true*/)
+{
+  // Implement a sensitive find, which is really just a loop withing a loop,
+  // comparing lower-case versions of each character in turn.
+  if (!sensitive)
+  {
+    // Handle empty pattern.
+    const char* p = pattern.c_str ();
+    size_t len = pattern.length ();
+    if (len == 0)
+      return 0;
+
+    // Handle bad begin.
+    if (begin >= len)
+      return std::string::npos;
+
+    // Evaluate these once, for performance reasons.
+    const char* t = text.c_str ();
+    const char* start = t + begin;
+    const char* end = start + text.size ();
+
+    for (; t < end - len; ++t)
+    {
+      int diff;
+      for (size_t i = 0; i < len; ++i)
+        if ((diff = tolower (t[i]) - tolower (p[i])))
+          break;
+
+      // diff == 0 means there was no break from the loop, which only occurs
+      // when a difference is detected.  Therefore, the loop terminated, and
+      // diff is zero.
+      if (diff == 0)
+        return t - start;
+    }
+
+    return std::string::npos;
+  }
+
+  // Otherwise, just use std::string::find.
+  return text.find (pattern, begin);
+}
+
+////////////////////////////////////////////////////////////////////////////////

src/text.h

@@ -56,6 +56,7 @@ bool isWordStart (const std::string&, std::string::size_type);
 bool isWordEnd (const std::string&, std::string::size_type);
 bool compare (const std::string&, const std::string&, bool sensitive = true);
 std::string::size_type find (const std::string&, const std::string&, bool sensitive = true);
+std::string::size_type find (const std::string&, const std::string&, std::string::size_type, bool sensitive = true);
 
 #endif
 ////////////////////////////////////////////////////////////////////////////////