v doc: implement color highlighting for the stdout format, enable it by default (#9312)

cmd/tools/vdoc/vdoc.v

@@ -11,6 +11,7 @@ import v.doc
 import v.pref
 import v.vmod
 import json
+import term
 
 const (
 	allowed_formats = ['md', 'markdown', 'json', 'text', 'stdout', 'html', 'htm']
@@ -44,6 +45,7 @@ struct Config {
 mut:
 	pub_only         bool = true
 	show_loc         bool // for plaintext
+	is_color         bool
 	is_multi         bool
 	is_vlib          bool
 	is_verbose       bool
@@ -86,7 +88,12 @@ fn (vd VDoc) gen_json(d doc.Doc) string {
 fn (vd VDoc) gen_plaintext(d doc.Doc) string {
 	cfg := vd.cfg
 	mut pw := strings.new_builder(200)
-	pw.writeln('$d.head.content\n')
+	if cfg.is_color {
+		content_arr := d.head.content.split(' ')
+		pw.writeln('${term.blue(content_arr[0])} ${term.green(content_arr[1])}\n')
+	} else {
+		pw.writeln('$d.head.content\n')
+	}
 	comments := if cfg.include_examples {
 		d.head.merge_comments()
 	} else {
@@ -103,7 +110,11 @@ fn (vd VDoc) write_plaintext_content(contents []doc.DocNode, mut pw strings.Buil
 	cfg := vd.cfg
 	for cn in contents {
 		if cn.content.len > 0 {
-			pw.writeln(cn.content)
+			if cfg.is_color {
+				pw.writeln(color_highlight(cn.content, vd.docs[0].table))
+			} else {
+				pw.writeln(cn.content)
+			}
 			if cn.comments.len > 0 && !cfg.pub_only {
 				comments := if cfg.include_examples {
 					cn.merge_comments()
@@ -369,6 +380,7 @@ fn (vd VDoc) vprintln(str string) {
 
 fn parse_arguments(args []string) Config {
 	mut cfg := Config{}
+	cfg.is_color = term.can_show_color_on_stdout()
 	for i := 0; i < args.len; i++ {
 		arg := args[i]
 		current_args := args[i..]
@@ -386,6 +398,12 @@ fn parse_arguments(args []string) Config {
 				cfg.output_type = set_output_type_from_str(format)
 				i++
 			}
+			'-color' {
+				cfg.is_color = true
+			}
+			'-no-color' {
+				cfg.is_color = false
+			}
 			'-inline-assets' {
 				cfg.inline_assets = true
 			}