auto merge of #7631 : MarkJr94/rust/ptr_arithmetic, r=thestinger
Added Add and Sub traits for pointer arithmetic. Any type that is a ```std::num::Int``` can be added to or subtracted from a pointer. Also my additions did not require any unsafe code, and the operators themselves are safe. Fixes #2122.
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commit
90db8628c5
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@ -15,6 +15,8 @@ use option::{Option, Some, None};
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use sys;
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use unstable::intrinsics;
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use util::swap;
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use ops::{Add,Sub};
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use num::Int;
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#[cfg(not(test))] use cmp::{Eq, Ord};
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use uint;
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@ -384,6 +386,46 @@ impl<T> Ord for *const T {
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}
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}
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#[cfg(not(test))]
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impl<T, I: Int> Add<I, *T> for *T {
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/// Add an integer value to a pointer to get an offset pointer.
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/// Is calculated according to the size of the type pointed to.
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#[inline]
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pub fn add(&self, rhs: &I) -> *T {
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self.offset(rhs.to_int() as uint)
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}
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}
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#[cfg(not(test))]
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impl<T, I: Int> Sub<I, *T> for *T {
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/// Subtract an integer value from a pointer to get an offset pointer.
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/// Is calculated according to the size of the type pointed to.
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#[inline]
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pub fn sub(&self, rhs: &I) -> *T {
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self.offset(-rhs.to_int() as uint)
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}
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}
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#[cfg(not(test))]
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impl<T, I: Int> Add<I, *mut T> for *mut T {
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/// Add an integer value to a pointer to get an offset pointer.
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/// Is calculated according to the size of the type pointed to.
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#[inline]
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pub fn add(&self, rhs: &I) -> *mut T {
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self.offset(rhs.to_int() as uint)
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}
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}
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#[cfg(not(test))]
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impl<T, I: Int> Sub<I, *mut T> for *mut T {
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/// Subtract an integer value from a pointer to get an offset pointer.
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/// Is calculated according to the size of the type pointed to.
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#[inline]
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pub fn sub(&self, rhs: &I) -> *mut T {
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self.offset(-rhs.to_int() as uint)
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}
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}
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#[cfg(test)]
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pub mod ptr_tests {
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use super::*;
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@ -501,6 +543,60 @@ pub mod ptr_tests {
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}
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}
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#[test]
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fn test_ptr_addition() {
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use vec::raw::*;
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unsafe {
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let xs = ~[5, ..16];
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let mut ptr = to_ptr(xs);
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let end = ptr + 16;
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while ptr < end {
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assert_eq!(*ptr, 5);
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ptr = ptr + 1u;
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}
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let mut xs_mut = xs.clone();
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let mut m_ptr = to_mut_ptr(xs_mut);
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let m_end = m_ptr + 16i16;
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while m_ptr < m_end {
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*m_ptr += 5;
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m_ptr = m_ptr + 1u8;
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}
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assert_eq!(xs_mut, ~[10, ..16]);
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}
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}
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#[test]
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fn test_ptr_subtraction() {
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use vec::raw::*;
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unsafe {
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let xs = ~[0,1,2,3,4,5,6,7,8,9];
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let mut idx = 9i8;
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let ptr = to_ptr(xs);
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while idx >= 0i8 {
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assert_eq!(*(ptr + idx), idx as int);
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idx = idx - 1i8;
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}
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let mut xs_mut = xs.clone();
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let mut m_start = to_mut_ptr(xs_mut);
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let mut m_ptr = m_start + 9u32;
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while m_ptr >= m_start {
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*m_ptr += *m_ptr;
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m_ptr = m_ptr - 1i8;
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}
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assert_eq!(xs_mut, ~[0,2,4,6,8,10,12,14,16,18]);
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}
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}
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#[test]
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fn test_ptr_array_each_with_len() {
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unsafe {
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