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Rewrite str::push_char in rust.

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Avoid crossing to C to reallocate underlying array when possible,
if we must we now only cross once per char (not once per byte.)
This commit is contained in:
Grahame Bowland 2012-03-29 01:27:37 +08:00 committed by Brian Anderson
parent b7b66b6cb3
commit 7a87258155
1 changed files with 66 additions and 27 deletions
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93
src/libcore/str.rs
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@ -13,7 +13,6 @@ export
from_byte,
from_char,
from_chars,
push_char,
concat,
connect,
@ -102,6 +101,8 @@ export
native mod rustrt {
fn rust_str_push(&s: str, ch: u8);
fn str_reserve_shared(&ss: str, nn: libc::size_t);
#[rust_stack]
fn upcall_vec_grow(&s: str, new_sz: libc::size_t);
}
/*
@ -138,34 +139,72 @@ fn from_byte(b: u8) -> str unsafe {
#[doc = "Appends a character at the end of a string"]
fn push_char(&s: str, ch: char) unsafe {
let code = ch as uint;
if code < max_one_b {
rustrt::rust_str_push(s, code as u8);
} else if code < max_two_b {
rustrt::rust_str_push(s, (code >> 6u & 31u | tag_two_b) as u8);
rustrt::rust_str_push(s, (code & 63u | tag_cont) as u8);
} else if code < max_three_b {
rustrt::rust_str_push(s, (code >> 12u & 15u | tag_three_b) as u8);
rustrt::rust_str_push(s, (code >> 6u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code & 63u | tag_cont) as u8);
} else if code < max_four_b {
rustrt::rust_str_push(s, (code >> 18u & 7u | tag_four_b) as u8);
rustrt::rust_str_push(s, (code >> 12u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code >> 6u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code & 63u | tag_cont) as u8);
} else if code < max_five_b {
rustrt::rust_str_push(s, (code >> 24u & 3u | tag_five_b) as u8);
rustrt::rust_str_push(s, (code >> 18u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code >> 12u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code >> 6u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code & 63u | tag_cont) as u8);
let nb = if code < max_one_b { 1u }
else if code < max_two_b { 2u }
else if code < max_three_b { 3u }
else if code < max_four_b { 4u }
else if code < max_five_b { 5u }
else { 6u };
let mut repr: *vec::unsafe::vec_repr = ::unsafe::reinterpret_cast(s);
let fill = (*repr).fill;
if fill + nb <= (*repr).alloc {
(*repr).fill = fill + nb;
} else {
rustrt::rust_str_push(s, (code >> 30u & 1u | tag_six_b) as u8);
rustrt::rust_str_push(s, (code >> 24u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code >> 18u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code >> 12u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code >> 6u & 63u | tag_cont) as u8);
rustrt::rust_str_push(s, (code & 63u | tag_cont) as u8);
rustrt::upcall_vec_grow(s, fill + nb);
// possibly realloc'd
repr = ::unsafe::reinterpret_cast(s);
}
let off = fill - 1u;
if nb == 1u {
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off) =
code as u8;
} else if nb == 2u {
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off) =
(code >> 6u & 31u | tag_two_b) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 1u) =
(code & 63u | tag_cont) as u8;
} else if nb == 3u {
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off) =
(code >> 12u & 15u | tag_three_b) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 1u) =
(code >> 6u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 2u) =
(code & 63u | tag_cont) as u8;
} else if nb == 4u {
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off) =
(code >> 18u & 7u | tag_four_b) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 1u) =
(code >> 12u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 2u) =
(code >> 6u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 3u) =
(code & 63u | tag_cont) as u8;
} else if nb == 5u {
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off) =
(code >> 24u & 3u | tag_five_b) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 1u) =
(code >> 18u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 2u) =
(code >> 12u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 3u) =
(code >> 6u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 4u) =
(code & 63u | tag_cont) as u8;
} else if nb == 6u {
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off) =
(code >> 30u & 1u | tag_six_b) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 1u) =
(code >> 24u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 2u) =
(code >> 18u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 3u) =
(code >> 12u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 4u) =
(code >> 6u & 63u | tag_cont) as u8;
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + 5u) =
(code & 63u | tag_cont) as u8;
}
*ptr::mut_offset(ptr::mut_addr_of((*repr).data), off + nb) = 0u8;
}
#[doc = "Convert a char to a string"]