rust/src/libcore/ptr.rs
2012-10-01 14:36:55 -07:00

321 lines
9.1 KiB
Rust

//! Unsafe pointer utility functions
use cmp::{Eq, Ord};
use libc::{c_void, size_t};
#[nolink]
#[abi = "cdecl"]
extern mod libc_ {
#[rust_stack]
fn memcpy(dest: *mut c_void, src: *const c_void,
n: libc::size_t) -> *c_void;
#[rust_stack]
fn memmove(dest: *mut c_void, src: *const c_void,
n: libc::size_t) -> *c_void;
#[rust_stack]
fn memset(dest: *mut c_void, c: libc::c_int,
len: libc::size_t) -> *c_void;
}
#[abi = "rust-intrinsic"]
extern mod rusti {
fn addr_of<T>(val: T) -> *T;
}
/*
Remove this after snapshot; make p2::addr_of addr_of
*/
/// Get an unsafe pointer to a value
#[inline(always)]
pub pure fn addr_of<T>(val: T) -> *T { unsafe { rusti::addr_of(val) } }
pub mod p2 {
/// Get an unsafe pointer to a value
#[inline(always)]
pub pure fn addr_of<T>(val: &T) -> *T { unsafe { rusti::addr_of(*val) } }
}
/// Get an unsafe mut pointer to a value
#[inline(always)]
pub pure fn mut_addr_of<T>(val: &T) -> *mut T {
unsafe {
cast::reinterpret_cast(&rusti::addr_of(*val))
}
}
/// Calculate the offset from a pointer
#[inline(always)]
pub pure fn offset<T>(ptr: *T, count: uint) -> *T {
unsafe {
(ptr as uint + count * sys::size_of::<T>()) as *T
}
}
/// Calculate the offset from a const pointer
#[inline(always)]
pub pure fn const_offset<T>(ptr: *const T, count: uint) -> *const T {
unsafe {
(ptr as uint + count * sys::size_of::<T>()) as *T
}
}
/// Calculate the offset from a mut pointer
#[inline(always)]
pub pure fn mut_offset<T>(ptr: *mut T, count: uint) -> *mut T {
(ptr as uint + count * sys::size_of::<T>()) as *mut T
}
/// Return the offset of the first null pointer in `buf`.
#[inline(always)]
pub unsafe fn buf_len<T>(buf: **T) -> uint {
position(buf, |i| *i == null())
}
/// Return the first offset `i` such that `f(buf[i]) == true`.
#[inline(always)]
pub unsafe fn position<T>(buf: *T, f: fn(&T) -> bool) -> uint {
let mut i = 0;
loop {
if f(&(*offset(buf, i))) { return i; }
else { i += 1; }
}
}
/// Create an unsafe null pointer
#[inline(always)]
pub pure fn null<T>() -> *T { unsafe { cast::reinterpret_cast(&0u) } }
/// Create an unsafe mutable null pointer
#[inline(always)]
pub pure fn mut_null<T>() -> *mut T { unsafe { cast::reinterpret_cast(&0u) } }
/// Returns true if the pointer is equal to the null pointer.
pub pure fn is_null<T>(ptr: *const T) -> bool { ptr == null() }
/// Returns true if the pointer is not equal to the null pointer.
pub pure fn is_not_null<T>(ptr: *const T) -> bool { !is_null(ptr) }
/**
* Copies data from one location to another
*
* Copies `count` elements (not bytes) from `src` to `dst`. The source
* and destination may not overlap.
*/
#[inline(always)]
pub unsafe fn memcpy<T>(dst: *mut T, src: *const T, count: uint) {
let n = count * sys::size_of::<T>();
libc_::memcpy(dst as *mut c_void, src as *c_void, n as size_t);
}
/**
* Copies data from one location to another
*
* Copies `count` elements (not bytes) from `src` to `dst`. The source
* and destination may overlap.
*/
#[inline(always)]
pub unsafe fn memmove<T>(dst: *mut T, src: *const T, count: uint) {
let n = count * sys::size_of::<T>();
libc_::memmove(dst as *mut c_void, src as *c_void, n as size_t);
}
#[inline(always)]
pub unsafe fn memset<T>(dst: *mut T, c: int, count: uint) {
let n = count * sys::size_of::<T>();
libc_::memset(dst as *mut c_void, c as libc::c_int, n as size_t);
}
/**
Transform a region pointer - &T - to an unsafe pointer - *T.
This is safe, but is implemented with an unsafe block due to
reinterpret_cast.
*/
#[inline(always)]
pub pure fn to_unsafe_ptr<T>(thing: &T) -> *T {
unsafe { cast::reinterpret_cast(&thing) }
}
/**
Transform a const region pointer - &const T - to a const unsafe pointer -
*const T. This is safe, but is implemented with an unsafe block due to
reinterpret_cast.
*/
#[inline(always)]
pub pure fn to_const_unsafe_ptr<T>(thing: &const T) -> *const T {
unsafe { cast::reinterpret_cast(&thing) }
}
/**
Transform a mutable region pointer - &mut T - to a mutable unsafe pointer -
*mut T. This is safe, but is implemented with an unsafe block due to
reinterpret_cast.
*/
#[inline(always)]
pub pure fn to_mut_unsafe_ptr<T>(thing: &mut T) -> *mut T {
unsafe { cast::reinterpret_cast(&thing) }
}
/**
Cast a region pointer - &T - to a uint.
This is safe, but is implemented with an unsafe block due to
reinterpret_cast.
(I couldn't think of a cutesy name for this one.)
*/
#[inline(always)]
pub fn to_uint<T>(thing: &T) -> uint unsafe {
cast::reinterpret_cast(&thing)
}
/// Determine if two borrowed pointers point to the same thing.
#[inline(always)]
pub fn ref_eq<T>(thing: &a/T, other: &b/T) -> bool {
to_uint(thing) == to_uint(other)
}
pub trait Ptr<T> {
pure fn is_null() -> bool;
pure fn is_not_null() -> bool;
pure fn offset(count: uint) -> self;
}
/// Extension methods for pointers
impl<T> *T: Ptr<T> {
/// Returns true if the pointer is equal to the null pointer.
#[inline(always)]
pure fn is_null() -> bool { is_null(self) }
/// Returns true if the pointer is not equal to the null pointer.
#[inline(always)]
pure fn is_not_null() -> bool { is_not_null(self) }
/// Calculates the offset from a pointer.
#[inline(always)]
pure fn offset(count: uint) -> *T { offset(self, count) }
}
// Equality for pointers
impl<T> *const T : Eq {
pure fn eq(other: &*const T) -> bool unsafe {
let a: uint = cast::reinterpret_cast(&self);
let b: uint = cast::reinterpret_cast(&(*other));
return a == b;
}
pure fn ne(other: &*const T) -> bool { !self.eq(other) }
}
// Comparison for pointers
impl<T> *const T : Ord {
pure fn lt(other: &*const T) -> bool unsafe {
let a: uint = cast::reinterpret_cast(&self);
let b: uint = cast::reinterpret_cast(&(*other));
return a < b;
}
pure fn le(other: &*const T) -> bool unsafe {
let a: uint = cast::reinterpret_cast(&self);
let b: uint = cast::reinterpret_cast(&(*other));
return a <= b;
}
pure fn ge(other: &*const T) -> bool unsafe {
let a: uint = cast::reinterpret_cast(&self);
let b: uint = cast::reinterpret_cast(&(*other));
return a >= b;
}
pure fn gt(other: &*const T) -> bool unsafe {
let a: uint = cast::reinterpret_cast(&self);
let b: uint = cast::reinterpret_cast(&(*other));
return a > b;
}
}
// Equality for region pointers
impl<T:Eq> &const T : Eq {
pure fn eq(other: & &const T) -> bool { return *self == *(*other); }
pure fn ne(other: & &const T) -> bool { return *self != *(*other); }
}
// Comparison for region pointers
impl<T:Ord> &const T : Ord {
pure fn lt(other: & &const T) -> bool { *self < *(*other) }
pure fn le(other: & &const T) -> bool { *self <= *(*other) }
pure fn ge(other: & &const T) -> bool { *self >= *(*other) }
pure fn gt(other: & &const T) -> bool { *self > *(*other) }
}
#[test]
pub fn test() {
unsafe {
type Pair = {mut fst: int, mut snd: int};
let p = {mut fst: 10, mut snd: 20};
let pptr: *mut Pair = mut_addr_of(&p);
let iptr: *mut int = cast::reinterpret_cast(&pptr);
assert (*iptr == 10);;
*iptr = 30;
assert (*iptr == 30);
assert (p.fst == 30);;
*pptr = {mut fst: 50, mut snd: 60};
assert (*iptr == 50);
assert (p.fst == 50);
assert (p.snd == 60);
let mut v0 = ~[32000u16, 32001u16, 32002u16];
let mut v1 = ~[0u16, 0u16, 0u16];
ptr::memcpy(ptr::mut_offset(vec::raw::to_mut_ptr(v1), 1u),
ptr::offset(vec::raw::to_ptr(v0), 1u), 1u);
assert (v1[0] == 0u16 && v1[1] == 32001u16 && v1[2] == 0u16);
ptr::memcpy(vec::raw::to_mut_ptr(v1),
ptr::offset(vec::raw::to_ptr(v0), 2u), 1u);
assert (v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 0u16);
ptr::memcpy(ptr::mut_offset(vec::raw::to_mut_ptr(v1), 2u),
vec::raw::to_ptr(v0), 1u);
assert (v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 32000u16);
}
}
#[test]
pub fn test_position() {
use str::as_c_str;
use libc::c_char;
let s = ~"hello";
unsafe {
assert 2u == as_c_str(s, |p| position(p, |c| *c == 'l' as c_char));
assert 4u == as_c_str(s, |p| position(p, |c| *c == 'o' as c_char));
assert 5u == as_c_str(s, |p| position(p, |c| *c == 0 as c_char));
}
}
#[test]
pub fn test_buf_len() {
let s0 = ~"hello";
let s1 = ~"there";
let s2 = ~"thing";
do str::as_c_str(s0) |p0| {
do str::as_c_str(s1) |p1| {
do str::as_c_str(s2) |p2| {
let v = ~[p0, p1, p2, null()];
do vec::as_imm_buf(v) |vp, len| {
assert unsafe { buf_len(vp) } == 3u;
assert len == 4u;
}
}
}
}
}
#[test]
pub fn test_is_null() {
let p: *int = ptr::null();
assert p.is_null();
assert !p.is_not_null();
let q = ptr::offset(p, 1u);
assert !q.is_null();
assert q.is_not_null();
}