builtin.string: new fn (s string) is_ascii() bool (#14418)

vlib/builtin/string.v

@@ -2002,3 +2002,8 @@ pub fn (name string) match_glob(pattern string) bool {
 	// Matched all of `pattern` to all of `name`
 	return true
 }
+
+// is_ascii returns true  if all characters belong to the US-ASCII set ([` `..`~`])
+pub fn (s string) is_ascii() bool {
+	return !s.bytes().any(it < u8(` `) || it > u8(`~`))
+}

vlib/builtin/string_test.v

@@ -989,6 +989,16 @@ fn test_string_f32() {
 	assert '-123.456'.f32() - (-123.456) <= f32_epsilon
 }
 
+fn test_string_is_ascii() {
+	assert ''.is_ascii() == true
+	assert ' '.is_ascii() == true
+	assert '~~'.is_ascii() == true
+	assert ' Az~'.is_ascii() == true
+	assert ' Aö~'.is_ascii() == false
+	assert '👋'.is_ascii() == false
+	assert 'a👋bc'.is_ascii() == false
+}
+
 fn test_string_with_zero_byte_escape() {
 	assert '\x00'.bytes() == [u8(0)]
 }