term: add writeln_color() (#24463)

vlib/term/colors.v

@@ -3,6 +3,8 @@
 // that can be found in the LICENSE file.
 module term
 
+import strings
+
 // format_esc produces an ANSI escape code, for selecting the graphics rendition of the following
 // text. Each of the attributes that can be passed in `code`, separated by `;`, will be in effect,
 // until the terminal encounters another SGR ANSI escape code. For more details about the different
@@ -275,3 +277,77 @@ pub fn bright_bg_white(msg string) string {
 pub fn highlight_command(command string) string {
 	return bright_white(bg_cyan(' ${command} '))
 }
+
+pub enum TextStyle {
+	bold      = 1
+	dim       = 2
+	italic    = 3
+	underline = 4
+	blink     = 5
+	reverse   = 7
+}
+
+pub enum FgColor {
+	black   = 30
+	red     = 31
+	green   = 32
+	yellow  = 33
+	blue    = 34
+	magenta = 35
+	cyan    = 36
+	white   = 37
+}
+
+pub enum BgColor {
+	black   = 40
+	red     = 41
+	green   = 42
+	yellow  = 43
+	blue    = 44
+	magenta = 45
+	cyan    = 46
+	white   = 47
+}
+
+@[params]
+pub struct ColorConfig {
+pub mut:
+	styles []TextStyle
+	fg     ?FgColor
+	bg     ?BgColor
+	custom string
+}
+
+// write_color appends the ANSI colorful string `s` to the buffer.
+pub fn write_color(mut b strings.Builder, s string, config ColorConfig) {
+	mut codes := []string{cap: 3}
+
+	for style in config.styles {
+		codes << int(style).str()
+	}
+
+	if fg := config.fg {
+		codes << int(fg).str()
+	}
+
+	if bg := config.bg {
+		codes << int(bg).str()
+	}
+
+	if config.custom != '' {
+		codes << config.custom
+	}
+
+	if codes.len > 0 {
+		code_str := codes.join(';')
+		b.write_string('\x1b[${code_str}m${s}\x1b[0m')
+	} else {
+		b.write_string(s)
+	}
+}
+
+// writeln_color appends the ANSI colorful string `s`, and then a newline character.
+pub fn writeln_color(mut b strings.Builder, s string, color ColorConfig) {
+	write_color(mut b, s, color)
+	b.writeln('')
+}

vlib/term/term_test.v

@@ -1,5 +1,6 @@
 import os
 import term
+import strings
 
 fn test_get_terminal_size() {
 	cols, _ := term.get_terminal_size()
@@ -113,14 +114,32 @@ fn test_set_tab_title() {
 }
 
 fn test_strip_ansi() {
-	strings := [
+	string_list := [
 		'abc',
 		term.bold('abc'),
 		term.yellow('abc'),
 		term.bold(term.red('abc')),
 		term.strikethrough(term.inverse(term.dim(term.bold(term.bright_bg_blue('abc'))))),
 	]
-	for s in strings {
+	for s in string_list {
 		assert term.strip_ansi(s) == 'abc'
 	}
 }
+
+fn test_write_color() {
+	mut sb := strings.new_builder(100)
+	term.writeln_color(mut sb, 'hello')
+	term.writeln_color(mut sb, 'hello', fg: .red)
+	term.writeln_color(mut sb, 'hello', bg: .cyan)
+	term.writeln_color(mut sb, 'hello', styles: [.bold, .italic, .underline], fg: .red, bg: .cyan)
+	term.writeln_color(mut sb, 'hello', custom: '38;5;214')
+
+	output := sb.str()
+	println(output)
+
+	assert output.contains('\x1b[0m')
+	assert output.contains('\x1b[31m')
+	assert output.contains('\x1b[46m')
+	assert output.contains('\x1b[1;3;4;31;46m')
+	assert output.contains('\x1b[38;5;214m')
+}