Enable color customization of `util.inspect`

This is rewrite of #3701 and #3603 before.

This patch introduce `util.inspect.styles`
and `util.inspect.colors` objects, which enables customization
of color sequences.

doc/api/util.markdown

@@ -81,6 +81,7 @@ in `null` for `depth`.
 
 If `colors` is `true`, the output will be styled with ANSI color codes.
 Defaults to `false`.
+Colors are customizable, see below.
 
 Example of inspecting all properties of the `util` object:
 
@@ -88,6 +89,28 @@ Example of inspecting all properties of the `util` object:
 
     console.log(util.inspect(util, true, null));
 
+### Customizing `util.inspect` colors
+
+Color output (if enabled) of `util.inspect` is customizable globally
+via `util.inspect.styles` and `util.inspect.colors` objects.
+
+`util.inspect.styles` is a map assigning each style a color
+from `util.inspect.colors`.
+Highlighted styles and their default values are:
+ * `number` (yellow)
+ * `boolean` (yellow)
+ * `string` (green)
+ * `date` (magenta)
+ * `regexp` (red)
+ * `null` (bold)
+ * `undefined` (grey)
+ * `special` - only function at this time (cyan)
+ * `name` (intentionally no styling)
+
+Predefined color codes are: `white`, `grey`, `black`, `blue`, `cyan`, 
+`green`, `magenta`, `red` and `yellow`.
+There are also `bold`, `italic`, `underline` and `inverse` codes.
+
 
 ## util.isArray(object)
 

lib/util.js

@@ -128,7 +128,7 @@ exports.inspect = inspect;
 
 
 // http://en.wikipedia.org/wiki/ANSI_escape_code#graphics
-var colors = {
+inspect.colors = {
   'bold' : [1, 22],
   'italic' : [3, 23],
   'underline' : [4, 24],
@@ -145,7 +145,7 @@ var colors = {
 };
 
 // Don't use 'blue' not visible on cmd.exe
-var styles = {
+inspect.styles = {
   'special': 'cyan',
   'number': 'yellow',
   'boolean': 'yellow',
@@ -159,11 +159,11 @@ var styles = {
 
 
 function stylizeWithColor(str, styleType) {
-  var style = styles[styleType];
+  var style = inspect.styles[styleType];
 
   if (style) {
-    return '\u001b[' + colors[style][0] + 'm' + str +
-           '\u001b[' + colors[style][1] + 'm';
+    return '\u001b[' + inspect.colors[style][0] + 'm' + str +
+           '\u001b[' + inspect.colors[style][1] + 'm';
   } else {
     return str;
   }

test/simple/test-util-inspect.js

@@ -107,3 +107,26 @@ assert.doesNotThrow(function() {
 // GH-2225
 var x = { inspect: util.inspect };
 assert.ok(util.inspect(x).indexOf('inspect') != -1);
+
+// util.inspect.styles and util.inspect.colors
+function test_color_style(style, input, implicit) {
+  var color_name = util.inspect.styles[style];
+  var color = ['', ''];
+  if(util.inspect.colors[color_name])
+    color = util.inspect.colors[color_name];
+
+  var without_color = util.inspect(input, false, 0, false);
+  var with_color = util.inspect(input, false, 0, true);
+  var expect = '\u001b[' + color[0] + 'm' + without_color +
+               '\u001b[' + color[1] + 'm';
+  assert.equal(with_color, expect, 'util.inspect color for style '+style);
+}
+
+test_color_style('special', function(){});
+test_color_style('number', 123.456);
+test_color_style('boolean', true);
+test_color_style('undefined', undefined);
+test_color_style('null', null);
+test_color_style('string', 'test string');
+test_color_style('date', new Date);
+test_color_style('regexp', /regexp/);