From 55c99dfaec6fac007cff00c75fa9bd2cc5664934 Mon Sep 17 00:00:00 2001
From: Demian Ferreiro <epidemian@gmail.com>
Date: Fri, 1 Mar 2013 22:42:26 -0300
Subject: [PATCH] Show colorized error messages

---
 lib/coffee-script/command.js |  4 ++--
 lib/coffee-script/error.js   | 15 +++++++++++----
 src/command.coffee           |  3 ++-
 src/error.coffee             | 11 ++++++++---
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/lib/coffee-script/command.js b/lib/coffee-script/command.js
index dc8954f1..3dd12d03 100644
--- a/lib/coffee-script/command.js
+++ b/lib/coffee-script/command.js
@@ -161,7 +161,7 @@
   };
 
   compileScript = function(file, input, base) {
-    var message, o, options, t, task;
+    var message, o, options, t, task, useColors;
     o = opts;
     options = compileOptions(file);
     try {
@@ -196,7 +196,7 @@
       if (CoffeeScript.listeners('failure').length) {
         return;
       }
-      message = err instanceof CompilerError ? err.prettyMessage(file || '[stdin]', input) : err.stack || ("ERROR: " + err);
+      message = err instanceof CompilerError ? (useColors = process.stdout.isTTY && !process.env.NODE_DISABLE_COLORS, err.prettyMessage(file || '[stdin]', input, useColors)) : err.stack || ("ERROR: " + err);
       if (o.watch) {
         if (o.watch) {
           return printLine(message + '\x07');
diff --git a/lib/coffee-script/error.js b/lib/coffee-script/error.js
index 67100f9b..98f1a472 100644
--- a/lib/coffee-script/error.js
+++ b/lib/coffee-script/error.js
@@ -29,12 +29,19 @@
       return new CompilerError(message, first_line, first_column, last_line, last_column);
     };
 
-    CompilerError.prototype.prettyMessage = function(fileName, code) {
-      var end, errorLine, marker, message, start;
+    CompilerError.prototype.prettyMessage = function(fileName, code, useColors) {
+      var colorize, end, errorLine, marker, message, start;
       errorLine = code.split('\n')[this.startLine];
       start = this.startColumn;
-      end = this.startLine === this.endLine ? this.endColumn : errorLine.length - 1;
-      marker = repeat(' ', start) + repeat('^', end - start + 1);
+      end = this.startLine === this.endLine ? this.endColumn + 1 : errorLine.length;
+      marker = repeat(' ', start) + repeat('^', end - start);
+      if (useColors) {
+        colorize = function(str) {
+          return "\x1B[1;31m" + str + "\x1B[0m";
+        };
+        errorLine = errorLine.slice(0, start) + colorize(errorLine.slice(start, end)) + errorLine.slice(end);
+        marker = colorize(marker);
+      }
       message = "" + fileName + ":" + (this.startLine + 1) + ":" + (this.startColumn + 1) + ": error: " + this.message + "\n" + errorLine + "\n" + marker;
       return message;
     };
diff --git a/src/command.coffee b/src/command.coffee
index 1ca16b1f..f542b0d2 100644
--- a/src/command.coffee
+++ b/src/command.coffee
@@ -141,7 +141,8 @@ compileScript = (file, input, base) ->
     return if CoffeeScript.listeners('failure').length
 
     message = if err instanceof CompilerError
-      err.prettyMessage file or '[stdin]', input
+      useColors = process.stdout.isTTY and not process.env.NODE_DISABLE_COLORS
+      err.prettyMessage file or '[stdin]', input, useColors
     else
       err.stack or "ERROR: #{err}"
 
diff --git a/src/error.coffee b/src/error.coffee
index 8076c214..e0e07402 100644
--- a/src/error.coffee
+++ b/src/error.coffee
@@ -17,12 +17,17 @@ exports.CompilerError = class CompilerError extends Error
   # Creates a nice error message like, following the "standard" format
   # <filename>:<line>:<col>: <message> plus the line with the error and a marker
   # showing where the error is.
-  prettyMessage: (fileName, code) ->
+  prettyMessage: (fileName, code, useColors) ->
     errorLine = code.split('\n')[@startLine]
     start     = @startColumn
     # Show only the first line on multi-line errors.
-    end       = if @startLine is @endLine then @endColumn else errorLine.length - 1
-    marker    = repeat(' ', start) + repeat('^', end - start + 1)
+    end       = if @startLine is @endLine then @endColumn + 1 else errorLine.length
+    marker    = repeat(' ', start) + repeat('^', end - start)
+
+    if useColors
+      colorize  = (str) -> "\x1B[1;31m#{str}\x1B[0m"
+      errorLine = errorLine[...start] + colorize(errorLine[start...end]) + errorLine[end..]
+      marker    = colorize marker
 
     message = """
       #{fileName}:#{@startLine + 1}:#{@startColumn + 1}: error: #{@message}