1
0
mirror of https://github.com/vlang/v.git synced 2023-08-10 21:13:21 +03:00
v/vlib/strings/builder.c.v

182 lines
4.7 KiB
V
Raw Normal View History

// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
2019-06-23 05:21:30 +03:00
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
2019-09-14 23:48:30 +03:00
module strings
2019-06-22 21:20:28 +03:00
// strings.Builder is used to efficiently append many strings to a large
2020-12-21 23:00:32 +03:00
// dynamically growing buffer, then use the resulting large string. Using
// a string builder is much better for performance/memory usage than doing
// constantly string concatenation.
2021-05-31 14:21:06 +03:00
pub type Builder = []byte
2019-06-22 21:20:28 +03:00
2020-12-21 23:00:32 +03:00
// new_builder returns a new string builder, with an initial capacity of `initial_size`
pub fn new_builder(initial_size int) Builder {
mut res := Builder([]byte{cap: initial_size})
unsafe { res.flags.set(.noslices) }
return res
}
// write_ptr writes `len` bytes provided byteptr to the accumulated buffer
[unsafe]
pub fn (mut b Builder) write_ptr(ptr &byte, len int) {
if len == 0 {
return
}
2021-05-31 14:21:06 +03:00
unsafe { b.push_many(ptr, len) }
2019-12-11 19:20:46 +03:00
}
// write_rune appends a single rune to the accumulated buffer
[manualfree]
pub fn (mut b Builder) write_rune(r rune) {
mut buffer := [5]byte{}
res := unsafe { utf32_to_str_no_malloc(u32(r), &buffer[0]) }
if res.len == 0 {
return
}
unsafe { b.push_many(res.str, res.len) }
}
// write_runes appends all the given runes to the accumulated buffer
pub fn (mut b Builder) write_runes(runes []rune) {
mut buffer := [5]byte{}
for r in runes {
res := unsafe { utf32_to_str_no_malloc(u32(r), &buffer[0]) }
if res.len == 0 {
continue
}
unsafe { b.push_many(res.str, res.len) }
}
}
2020-12-21 23:00:32 +03:00
// write_b appends a single `data` byte to the accumulated buffer
2020-05-17 14:51:18 +03:00
pub fn (mut b Builder) write_b(data byte) {
2021-05-31 14:21:06 +03:00
b << data
2019-12-06 23:02:09 +03:00
}
// write implements the Writer interface
pub fn (mut b Builder) write(data []byte) ?int {
if data.len == 0 {
return 0
}
2021-05-31 14:21:06 +03:00
b << data
return data.len
}
// drain_builder writes all of the `other` builder content, then re-initialises
// `other`, so that the `other` strings builder is ready to receive new content.
[manualfree]
pub fn (mut b Builder) drain_builder(mut other Builder, other_new_cap int) {
b.write(other) or { panic(err) }
unsafe { other.free() }
other = new_builder(other_new_cap)
}
// byte_at returns a byte, located at a given index `i`.
// NB: it can panic, if there are not enough bytes in the strings builder yet.
2021-05-31 14:21:06 +03:00
[inline]
pub fn (b &Builder) byte_at(n int) byte {
return unsafe { (&[]byte(b))[n] }
}
2020-12-21 23:00:32 +03:00
// write appends the string `s` to the buffer
[inline]
pub fn (mut b Builder) write_string(s string) {
if s.len == 0 {
2019-12-24 20:54:43 +03:00
return
}
2021-05-31 14:21:06 +03:00
unsafe { b.push_many(s.str, s.len) }
2019-12-20 00:29:37 +03:00
// for c in s {
// b.buf << c
// }
// b.buf << []byte(s) // TODO
2019-06-22 21:20:28 +03:00
}
2020-12-21 23:00:32 +03:00
// go_back discards the last `n` bytes from the buffer
2020-05-17 14:51:18 +03:00
pub fn (mut b Builder) go_back(n int) {
2021-05-31 14:21:06 +03:00
b.trim(b.len - n)
}
2020-03-11 01:21:26 +03:00
2020-12-21 23:00:32 +03:00
// cut_last cuts the last `n` bytes from the buffer and returns them
2020-06-17 01:59:33 +03:00
pub fn (mut b Builder) cut_last(n int) string {
2021-05-31 14:21:06 +03:00
cut_pos := b.len - n
x := unsafe { (&[]byte(b))[cut_pos..] }
res := x.bytestr()
b.trim(cut_pos)
return res
2020-06-17 01:59:33 +03:00
}
2021-05-07 19:41:27 +03:00
// cut_to cuts the string after `pos` and returns it.
// if `pos` is superior to builder length, returns an empty string
// and cancel further operations
2020-06-17 01:59:33 +03:00
pub fn (mut b Builder) cut_to(pos int) string {
2021-05-07 19:41:27 +03:00
if pos > b.len {
return ''
}
2021-05-31 14:21:06 +03:00
return b.cut_last(b.len - pos)
2020-06-17 01:59:33 +03:00
}
2021-05-07 19:41:27 +03:00
2020-12-21 23:00:32 +03:00
// go_back_to resets the buffer to the given position `pos`
// NB: pos should be < than the existing buffer length.
2020-05-17 14:51:18 +03:00
pub fn (mut b Builder) go_back_to(pos int) {
2021-05-31 14:21:06 +03:00
b.trim(pos)
2020-04-28 14:15:37 +03:00
}
2020-12-21 23:00:32 +03:00
// writeln appends the string `s`, and then a newline character.
[inline]
2020-05-17 14:51:18 +03:00
pub fn (mut b Builder) writeln(s string) {
2019-12-20 00:29:37 +03:00
// for c in s {
// b.buf << c
// }
if s.len > 0 {
unsafe { b.push_many(s.str, s.len) }
}
2019-12-20 00:29:37 +03:00
// b.buf << []byte(s) // TODO
2021-05-31 14:21:06 +03:00
b << byte(`\n`)
2019-06-22 21:20:28 +03:00
}
2020-03-21 09:01:06 +03:00
// last_n(5) returns 'world'
// buf == 'hello world'
2020-03-21 09:04:53 +03:00
pub fn (b &Builder) last_n(n int) string {
2020-03-21 09:01:06 +03:00
if n > b.len {
return ''
}
2021-05-31 14:21:06 +03:00
x := unsafe { (&[]byte(b))[b.len - n..] }
return x.bytestr()
2020-03-21 09:01:06 +03:00
}
// after(6) returns 'world'
// buf == 'hello world'
2020-03-21 09:04:53 +03:00
pub fn (b &Builder) after(n int) string {
2020-03-21 09:01:06 +03:00
if n >= b.len {
return ''
}
2021-05-31 14:21:06 +03:00
x := unsafe { (&[]byte(b))[n..] }
return x.bytestr()
2020-03-21 09:01:06 +03:00
}
// str returns a copy of all of the accumulated buffer content.
// NB: after a call to b.str(), the builder b should not be
// used again, you need to call b.free() first, or just leave
// it to be freed by -autofree when it goes out of scope.
// The returned string *owns* its own separate copy of the
// accumulated data that was in the string builder, before the
// .str() call.
2020-05-17 14:51:18 +03:00
pub fn (mut b Builder) str() string {
2021-05-31 14:21:06 +03:00
b << byte(0)
bcopy := unsafe { &byte(memdup_noscan(b.data, b.len)) }
2021-05-31 14:21:06 +03:00
s := unsafe { bcopy.vstring_with_len(b.len - 1) }
b.trim(0)
return s
2019-06-22 21:20:28 +03:00
}
// free is for manually freeing the contents of the buffer
[unsafe]
2020-05-17 14:51:18 +03:00
pub fn (mut b Builder) free() {
if b.data != 0 {
unsafe { free(b.data) }
unsafe {
b.data = voidptr(0)
}
}
2019-06-24 23:34:21 +03:00
}