frog: life is better with colors :)

frog/source.dart

Index: frog/source.dart
diff --git a/frog/source.dart b/frog/source.dart
index ab62a2fe3a43592c14adba3e54dc23484e70d16c..c73fa118133171c07d6a71d8c6176ec82a5cb147 100644
--- a/frog/source.dart
+++ b/frog/source.dart
@@ -72,12 +72,12 @@ class SourceFile implements Comparable {
    * Create a pretty string representation from a character position
    * in the file.
    */
-  String getLocationMessage(String message, int start, [int end, bool includeText=false]) {
+  String getLocationMessage(String message, int start,
+      [int end, bool includeText=false]) {
     var line = getLine(start);
     var column = getColumn(line, start);
 
-    var buf = new StringBuffer(
-        '${filename}:${line + 1}:${column + 1}: $message');
+    var buf = new StringBuffer('${filename}:${line + 1}:${column + 1}: $message');

[Jennifer Messerly, 2011/12/06 22:50:03]

long line

[Siggi Cherem (dart-lang), 2011/12/06 23:37:38]

Done.

     if (includeText) {
       buf.add('\n');
       var textLine;
@@ -87,16 +87,24 @@ class SourceFile implements Comparable {
       } else {
         textLine = text.substring(_lineStarts[line]) + '\n';
       }
-      buf.add(textLine);
-      int i = 0;
-      for (; i < column; i++) {
-        buf.add(' ');
-      }
 
       int toColumn = Math.min(column + (end-start), textLine.length);
-
-      for (; i < toColumn; i++) {
-        buf.add('^');
+      if (options.useColors) {
+        buf.add(textLine.substring(0, column));
+        buf.add(_RED_COLOR);
+        buf.add(textLine.substring(column, toColumn));
+        buf.add(_NO_COLOR);
+        buf.add(textLine.substring(toColumn));
+      } else {
+        buf.add(textLine);
+        int i = 0;
+        for (; i < column; i++) {
+          buf.add(' ');
+        }
+
+        for (; i < toColumn; i++) {

[Jennifer Messerly, 2011/12/06 22:50:03]

Would it be nice to display the arrows even in color mode? I'm thinking if I get
a log file some day from a dumb terminal or something. But I'm not sure.

[Bob Nystrom, 2011/12/06 23:12:46]

+1 for always showing ^^^^

[Siggi Cherem (dart-lang), 2011/12/06 23:37:38]

I added them back, but with colors too. 

I was not convinced of this, because in these cases we shouldn't use colors at
all (use the --no_colors option). Otherwise, the color-escape chars are visible
on plain text. For instance,

code code\033[31merror error\033[0m...
         ^^^^^^^

I made the ^^ colored, so that it aligns well with the error:
code code\033[31merror error\033[0m...
         \033[31m^^^^^^^^^^^\033[0m

+          buf.add('^');
+        }
       }
     }
 
@@ -138,7 +146,7 @@ class SourceSpan implements Comparable {
   }
 
   toMessageString(String message) {
-    return file.getLocationMessage(message, start, end, true);
+    return file.getLocationMessage(message, start, end: end, includeText: true);
   }
 
   String get locationText() {