From 291818c33da9cda1ca22c663bae834607c212734 Mon Sep 17 00:00:00 2001
From: Paul Beckingham <paul@beckingham.net>
Date: Fri, 13 May 2011 18:01:02 -0400
Subject: [PATCH] i18n

- Added function utf8_text_length which calculates the length of
  text in characters, not bytes, and excludes color control codes.
---
 src/text.cpp |  6 +++---
 src/utf8.cpp | 38 ++++++++++++++++++++++++++++++++++++++
 src/utf8.h   |  1 +
 3 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/src/text.cpp b/src/text.cpp
index 8a26426c2..3e4eb1dcc 100644
--- a/src/text.cpp
+++ b/src/text.cpp
@@ -254,7 +254,7 @@ void extractLine (std::string& text, std::string& line, int length)
 
   // Special case: no \n, and less than length characters total.
   // special case: text.find ("\n") == std::string::npos && text.length () < length
-  if (eol == std::string::npos && utf8_length (text) <= length)
+  if (eol == std::string::npos && utf8_text_length (text) <= length)
   {
     line = text;
     text = "";
@@ -730,7 +730,7 @@ std::string leftJustify (const int input, const int width)
 ////////////////////////////////////////////////////////////////////////////////
 std::string leftJustify (const std::string& input, const int width)
 {
-  return input + std::string (width - utf8_length (input), ' ');
+  return input + std::string (width - utf8_text_length (input), ' ');
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -744,7 +744,7 @@ std::string rightJustify (const int input, const int width)
 ////////////////////////////////////////////////////////////////////////////////
 std::string rightJustify (const std::string& input, const int width)
 {
-  return std::string (width - utf8_length (input), ' ') + input;
+  return std::string (width - utf8_text_length (input), ' ') + input;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/utf8.cpp b/src/utf8.cpp
index ae81c8207..2cd81d60a 100644
--- a/src/utf8.cpp
+++ b/src/utf8.cpp
@@ -185,3 +185,41 @@ int utf8_length (const std::string& str)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+int utf8_text_length (const std::string& str)
+{
+  int byteLength = str.length ();
+  int charLength = byteLength;
+  const char* data = str.data ();
+  bool in_color = false;
+
+  // Decrement the number of bytes for each byte that matches 0b10??????
+  // this way only the first byte of any utf8 sequence is counted.
+  for (int i = 0; i < byteLength; i++)
+  {
+    if (in_color)
+    {
+      if (data[i] == 'm')
+        in_color = false;
+
+      --charLength;
+    }
+    else
+    {
+      if (data[i] == 033)
+      {
+        in_color = true;
+        --charLength;
+      }
+      else
+      {
+        // Extract the first two bits and check whether they are 10
+        if ((data[i] & 0xC0) == 0x80)
+          --charLength;
+      }
+    }
+  }
+
+  return charLength;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/src/utf8.h b/src/utf8.h
index 7f5ac618b..c76b08210 100644
--- a/src/utf8.h
+++ b/src/utf8.h
@@ -34,6 +34,7 @@ unsigned int utf8_next_char (const std::string&, std::string::size_type&);
 std::string utf8_character (unsigned int);
 int utf8_sequence (unsigned int);
 int utf8_length (const std::string&);
+int utf8_text_length (const std::string&);
 
 
 #endif