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)
+}

vlib/strings/builder_test.v

@@ -0,0 +1,15 @@
+import strings
+ 
+fn test_sb() {
+	mut sb := strings.Builder{}
+	sb.write('hi')
+	sb.write('!')
+	sb.write('hello')
+	assert sb.str() == 'hi!hello'
+	sb = strings.new_builder(10)
+	sb.write('a')
+	sb.write('b')
+	println(sb.str())
+	assert sb.str() == 'ab'
+}
+

vlib/strings/strings.v

@@ -0,0 +1,13 @@
+module strings 
+
+pub fn repeat(c byte, n int) string {
+	if n <= 0 {
+		return ''
+	}
+	mut arr := malloc(n + 1)
+	for i := 0; i < n; i++ {
+		arr[i] = c
+	}
+	arr[n] = `\0`
+	return tos(arr, n)
+}

vlib/strings/strings_test.v

@@ -0,0 +1,6 @@
+import strings
+
+fn test_repeat() {
+	assert strings.repeat(`x`, 10) == 'xxxxxxxxxx' 
+	assert strings.repeat(`a`, 1) == 'a' 
+}