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core: add str::as_bytes function

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This pattern is used in a couple places, so it'd be nice
to abstract it away.
This commit is contained in:
Erick Tryzelaar 2012-02-08 10:18:29 -08:00
parent 526e73d7f8
commit 3a413aabd4
1 changed files with 31 additions and 20 deletions
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51
src/libcore/str.rs
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@ -95,6 +95,7 @@ export
char_at,
substr_all,
escape_char,
as_bytes,
as_buf,
//buf,
sbuf,
@ -390,10 +391,7 @@ Converts a string to a vector of bytes. The result vector is not
null-terminated.
*/
fn bytes(s: str) -> [u8] unsafe {
let v = ::unsafe::reinterpret_cast(s);
let vcopy = vec::slice(v, 0u, vec::len(v) - 1u);
::unsafe::leak(v);
ret vcopy;
as_bytes(s) { |v| vec::slice(v, 0u, vec::len(v) - 1u) }
}
/*
@ -1026,12 +1024,12 @@ Returns the length in bytes of a string
FIXME: rename to 'len_bytes'
*/
pure fn byte_len(s: str) -> uint unsafe {
let v: [u8] = ::unsafe::reinterpret_cast(s);
let vlen = vec::len(v);
::unsafe::leak(v);
// There should always be a null terminator
assert (vlen > 0u);
ret vlen - 1u;
as_bytes(s) { |v|
let vlen = vec::len(v);
// There should always be a null terminator
assert (vlen > 0u);
vlen - 1u
}
}
/*
@ -1298,6 +1296,24 @@ const tag_five_b: uint = 248u;
const max_five_b: uint = 67108864u;
const tag_six_b: uint = 252u;
/*
Function: as_bytes
Work with the byte buffer of a string. Allows for unsafe manipulation
of strings, which is useful for native interop.
Example:
> let i = str::as_bytes("Hello World") { |bytes| vec::len(bytes) };
*/
fn as_bytes<T>(s: str, f: fn([u8]) -> T) -> T unsafe {
let v: [u8] = ::unsafe::reinterpret_cast(s);
let r = f(v);
::unsafe::leak(v);
r
}
/*
Function: as_buf
@ -1310,10 +1326,7 @@ Example:
*/
fn as_buf<T>(s: str, f: fn(sbuf) -> T) -> T unsafe {
let v: [u8] = ::unsafe::reinterpret_cast(s);
let r = vec::as_buf(v, f);
::unsafe::leak(v);
r
as_bytes(s) { |v| vec::as_buf(v, f) }
}
/*
@ -1373,13 +1386,11 @@ mod unsafe {
assert (begin <= end);
assert (end <= byte_len(s));
let v: [u8] = ::unsafe::reinterpret_cast(s);
let v2 = vec::slice(v, begin, end);
let v = as_bytes(s) { |v| vec::slice(v, begin, end) };
v += [0u8];
let s: str = ::unsafe::reinterpret_cast(v);
::unsafe::leak(v);
v2 += [0u8];
let s2: str = ::unsafe::reinterpret_cast(v2);
::unsafe::leak(v2);
ret s2;
ret s;
}
/*