145 lines
3.5 KiB
V
145 lines
3.5 KiB
V
// Copyright (c) 2019-2021 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
|
|
|
|
// strings.Builder is used to efficiently append many strings to a large
|
|
// 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.
|
|
pub struct Builder {
|
|
pub mut:
|
|
buf []byte
|
|
len int
|
|
initial_size int = 1
|
|
}
|
|
|
|
// new_builder returns a new string builder, with an initial capacity of `initial_size`
|
|
pub fn new_builder(initial_size int) Builder {
|
|
return Builder{
|
|
// buf: make(0, initial_size)
|
|
buf: []byte{cap: initial_size}
|
|
len: 0
|
|
initial_size: initial_size
|
|
}
|
|
}
|
|
|
|
// write_bytes appends `bytes` to the accumulated buffer
|
|
[unsafe]
|
|
pub fn (mut b Builder) write_bytes(bytes byteptr, howmany int) {
|
|
b.buf.push_many(bytes, howmany)
|
|
b.len += howmany
|
|
}
|
|
|
|
// write_b appends a single `data` byte to the accumulated buffer
|
|
pub fn (mut b Builder) write_b(data byte) {
|
|
b.buf << data
|
|
b.len++
|
|
}
|
|
|
|
[deprecated: 'write(string) will be changed to write([]byte)']
|
|
pub fn (mut b Builder) write(s string) {
|
|
b.write_string(s)
|
|
}
|
|
|
|
// write appends the string `s` to the buffer
|
|
[inline]
|
|
pub fn (mut b Builder) write_string(s string) {
|
|
if s == '' {
|
|
return
|
|
}
|
|
b.buf.push_many(s.str, s.len)
|
|
// for c in s {
|
|
// b.buf << c
|
|
// }
|
|
// b.buf << []byte(s) // TODO
|
|
b.len += s.len
|
|
}
|
|
|
|
// go_back discards the last `n` bytes from the buffer
|
|
pub fn (mut b Builder) go_back(n int) {
|
|
b.buf.trim(b.buf.len - n)
|
|
b.len -= n
|
|
}
|
|
|
|
fn bytes2string(b []byte) string {
|
|
mut copy := b.clone()
|
|
copy << byte(`\0`)
|
|
return unsafe { tos(copy.data, copy.len - 1) }
|
|
}
|
|
|
|
// cut_last cuts the last `n` bytes from the buffer and returns them
|
|
pub fn (mut b Builder) cut_last(n int) string {
|
|
res := bytes2string(b.buf[b.len - n..])
|
|
b.buf.trim(b.buf.len - n)
|
|
b.len -= n
|
|
return res
|
|
}
|
|
|
|
/*
|
|
pub fn (mut b Builder) cut_to(pos int) string {
|
|
res := bytes2string( b.buf[pos..] )
|
|
b.buf.trim(pos)
|
|
b.len = pos
|
|
return res
|
|
}
|
|
*/
|
|
// go_back_to resets the buffer to the given position `pos`
|
|
// NB: pos should be < than the existing buffer length.
|
|
pub fn (mut b Builder) go_back_to(pos int) {
|
|
b.buf.trim(pos)
|
|
b.len = pos
|
|
}
|
|
|
|
// writeln appends the string `s`, and then a newline character.
|
|
[inline]
|
|
pub fn (mut b Builder) writeln(s string) {
|
|
// for c in s {
|
|
// b.buf << c
|
|
// }
|
|
b.buf.push_many(s.str, s.len)
|
|
// b.buf << []byte(s) // TODO
|
|
b.buf << `\n`
|
|
b.len += s.len + 1
|
|
}
|
|
|
|
// buf == 'hello world'
|
|
// last_n(5) returns 'world'
|
|
pub fn (b &Builder) last_n(n int) string {
|
|
if n > b.len {
|
|
return ''
|
|
}
|
|
return bytes2string(b.buf[b.len - n..])
|
|
}
|
|
|
|
// buf == 'hello world'
|
|
// after(6) returns 'world'
|
|
pub fn (b &Builder) after(n int) string {
|
|
if n >= b.len {
|
|
return ''
|
|
}
|
|
return bytes2string(b.buf[n..])
|
|
}
|
|
|
|
// 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.
|
|
pub fn (mut b Builder) str() string {
|
|
b.buf << `\0`
|
|
s := unsafe { byteptr(memdup(b.buf.data, b.len)).vstring_with_len(b.len) }
|
|
b.len = 0
|
|
b.buf.trim(0)
|
|
return s
|
|
}
|
|
|
|
// free - manually free the contents of the buffer
|
|
[unsafe]
|
|
pub fn (mut b Builder) free() {
|
|
unsafe { free(b.buf.data) }
|
|
b.len = 0
|
|
}
|