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strings: add Builder.cut_to (#10042)

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Enzo 2021-05-07 18:41:27 +02:00 committed by GitHub
parent b34b56ee4e
commit 2d2b4f79cc
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3 changed files with 23 additions and 20 deletions

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@ -44,11 +44,6 @@ pub fn (b []byte) clone() []byte {
// TODO remove this once runes are implemented // TODO remove this once runes are implemented
pub fn (b []byte) bytestr() string { pub fn (b []byte) bytestr() string {
return bytes2string(b)
}
// TODO copy pasted from builder.v
fn bytes2string(b []byte) string {
unsafe { unsafe {
buf := malloc(b.len + 1) buf := malloc(b.len + 1)
C.memcpy(buf, b.data, b.len) C.memcpy(buf, b.data, b.len)

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@ -72,28 +72,24 @@ pub fn (mut b Builder) go_back(n int) {
b.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 // cut_last cuts the last `n` bytes from the buffer and returns them
pub fn (mut b Builder) cut_last(n int) string { pub fn (mut b Builder) cut_last(n int) string {
res := bytes2string(b.buf[b.len - n..]) res := b.buf[b.len - n..].bytestr()
b.buf.trim(b.buf.len - n) b.buf.trim(b.buf.len - n)
b.len -= n b.len -= n
return res return res
} }
/* // 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
pub fn (mut b Builder) cut_to(pos int) string { pub fn (mut b Builder) cut_to(pos int) string {
res := bytes2string( b.buf[pos..] ) if pos > b.len {
b.buf.trim(pos) return ''
b.len = pos }
return res return b.cut_last(b.buf.len - pos)
} }
*/
// go_back_to resets the buffer to the given position `pos` // go_back_to resets the buffer to the given position `pos`
// NB: pos should be < than the existing buffer length. // NB: pos should be < than the existing buffer length.
pub fn (mut b Builder) go_back_to(pos int) { pub fn (mut b Builder) go_back_to(pos int) {
@ -119,7 +115,7 @@ pub fn (b &Builder) last_n(n int) string {
if n > b.len { if n > b.len {
return '' return ''
} }
return bytes2string(b.buf[b.len - n..]) return b.buf[b.len - n..].bytestr()
} }
// buf == 'hello world' // buf == 'hello world'
@ -128,7 +124,7 @@ pub fn (b &Builder) after(n int) string {
if n >= b.len { if n >= b.len {
return '' return ''
} }
return bytes2string(b.buf[n..]) return b.buf[n..].bytestr()
} }
// str returns a copy of all of the accumulated buffer content. // str returns a copy of all of the accumulated buffer content.

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@ -82,3 +82,15 @@ fn test_strings_builder_reuse() {
sb.write_string('hello') sb.write_string('hello')
assert sb.str() == 'hello' assert sb.str() == 'hello'
} }
fn test_cut_to() {
mut sb := strings.new_builder(16)
sb.write_string('hello')
assert sb.cut_to(3) == 'lo'
assert sb.len == 3
assert sb.cut_to(3) == ''
assert sb.len == 3
assert sb.cut_to(0) == 'hel'
assert sb.cut_to(32) == ''
assert sb.len == 0
}