111 lines
2.1 KiB
V
111 lines
2.1 KiB
V
// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module strings
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pub struct Builder {
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mut:
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buf []byte
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str_calls int
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pub mut:
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len int
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initial_size int = 1
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}
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pub fn new_builder(initial_size int) Builder {
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return Builder{
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//buf: make(0, initial_size)
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buf: []byte{cap: initial_size}
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initial_size: initial_size
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}
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}
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pub fn (b mut Builder) write_bytes(bytes byteptr, howmany int) {
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b.buf.push_many(bytes, howmany)
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b.len += howmany
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}
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pub fn (b mut Builder) write_b(data byte) {
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b.buf << data
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b.len++
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}
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pub fn (b mut Builder) write(s string) {
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if s == '' {
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return
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}
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b.buf.push_many(s.str, s.len)
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// for c in s {
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// b.buf << c
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// }
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// b.buf << []byte(s) // TODO
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b.len += s.len
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}
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pub fn (b mut Builder) go_back(n int) {
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b.buf.trim(b.buf.len-n)
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b.len -= n
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}
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pub fn (b mut Builder) go_back_to(pos int) {
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b.buf.trim(pos)
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b.len = pos
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}
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pub fn (b mut Builder) writeln(s string) {
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// for c in s {
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// b.buf << c
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// }
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b.buf.push_many(s.str, s.len)
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// b.buf << []byte(s) // TODO
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b.buf << `\n`
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b.len += s.len + 1
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}
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// buf == 'hello world'
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// last_n(5) returns 'world'
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pub fn (b &Builder) last_n(n int) string {
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if n > b.len {
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return ''
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}
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buf := b.buf[b.len-n..]
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return string(buf.clone())
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}
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// buf == 'hello world'
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// after(6) returns 'world'
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pub fn (b &Builder) after(n int) string {
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if n >= b.len {
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return ''
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}
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buf := b.buf[n..]
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mut copy := buf.clone()
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copy << `\0`
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return string(copy)
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}
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// NB: in order to avoid memleaks and additional memory copies, after a call to b.str(),
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// the builder b will be empty. The returned string *owns* the accumulated data so far.
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pub fn (b mut Builder) str() string {
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b.str_calls++
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if b.str_calls > 1 {
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panic('builder.str() should be called just once.\n' +
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'If you want to reuse a builder, call b.free() first.')
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}
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b.buf << `\0`
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s := string(b.buf,b.len)
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bis := b.initial_size
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b.buf = []byte{cap: bis}
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b.len = 0
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return s
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}
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pub fn (b mut Builder) free() {
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unsafe{
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free(b.buf.data)
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}
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//b.buf = []byte{cap: b.initial_size}
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b.len = 0
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b.str_calls = 0
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}
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