StringsBuilder => strings.Builder; strings.repeat()

vlib/strings/builder.v

@@ -0,0 +1,40 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module strings 
+
+struct Builder {
+mut: 
+	buf []byte
+	len int
+}
+
+pub fn new_builder(initial_size int) Builder {
+	return Builder {
+		buf: _make(0, initial_size, sizeof(byte))
+	}
+}
+
+pub fn (b mut Builder) write(s string) {
+	b.buf._push_many(s.str, s.len)
+	b.len += s.len
+}
+
+pub fn (b mut Builder) writeln(s string) {
+	b.buf._push_many(s.str, s.len)
+	b.buf << `\n`
+	b.len += s.len + 1
+}
+
+pub fn (b Builder) str() string {
+	return tos(b.buf.data, b.len)
+}
+
+pub fn (b Builder) cut(n int) {
+	b.len -= n
+}
+
+pub fn (b mut Builder) free() {
+	C.free(b.buf.data)
+}