Enhancement - caseless find

- Added support for a starting offset.

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);
+}
+
+////////////////////////////////////////////////////////////////////////////////