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Add documentation and tests for operator 'as' #1080

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84f3ddb
Add 'as' (cast) operator to the documentation
mbrubeck Oct 27, 2011
a4da2ea
Add tests for the 'as' (cast) operator
mbrubeck Oct 27, 2011
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25 changes: 25 additions & 0 deletions doc/rust.texi
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Original file line number Diff line number Diff line change
Expand Up @@ -2930,6 +2930,7 @@ effects of the expression's evaluation.
* Ref.Expr.Ret:: Expression for stopping and producing a value.
@c * Ref.Expr.Be:: Expression for stopping and executing a tail call.
* Ref.Expr.Put:: Expression for pausing and producing a value.
* Ref.Expr.As:: Expression for casting a value to a different type.
* Ref.Expr.Fail:: Expression for causing task failure.
* Ref.Expr.Log:: Expression for logging values to diagnostic buffers.
* Ref.Expr.Note:: Expression for logging values during failure.
Expand Down Expand Up @@ -3116,6 +3117,30 @@ either continuing execution after the @code{put} expression, or terminating its
execution and destroying the iterator frame.


@node Ref.Expr.As
@subsection Ref.Expr.As
@c * Ref.Expr.As:: Expression for casting a value to a different type.
@cindex As expression
@cindex Cast
@cindex Typecast

Executing an @code{as} expression casts the value on the left-hand side to the
type on the right-hand side.

A numeric value can be cast to any numeric type. A native pointer value can
be cast to or from any integral type or native pointer type. Any other cast
is unsupported and will fail to compiler.

An example of an @code{as} expression:
@example
fn avg(v: [float]) -> float @{
let sum: float = sum(v);
let sz: float = std::vec::len(v) as float;
ret sum / sz;
@}
@end example


@node Ref.Expr.Fail
@subsection Ref.Expr.Fail
@c * Ref.Expr.Fail:: Expression for causing task failure.
Expand Down
8 changes: 8 additions & 0 deletions src/test/compile-fail/nonscalar-cast.rs
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@@ -0,0 +1,8 @@
// error-pattern:non-scalar cast

use std;
import std::os;

fn main() {
log { x: 1 } as int;
}
8 changes: 8 additions & 0 deletions src/test/compile-fail/unsupported-cast.rs
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@@ -0,0 +1,8 @@
// error-pattern:unsupported cast

use std;
import std::os;

fn main() {
log 1.0 as os::libc::FILE; // Can't cast float to native.
}
253 changes: 253 additions & 0 deletions src/test/run-pass/supported-cast.rs
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@@ -0,0 +1,253 @@
use std;
import std::os;

fn main() {
let f = 1 as os::libc::FILE;
log f as int;
log f as uint;
log f as i8;
log f as i16;
log f as i32;
log f as i64;
log f as u8;
log f as u16;
log f as u32;
log f as u64;

log 1 as int;
log 1 as uint;
log 1 as float;
log 1 as bool;
log 1 as os::libc::FILE;
log 1 as i8;
log 1 as i16;
log 1 as i32;
log 1 as i64;
log 1 as u8;
log 1 as u16;
log 1 as u32;
log 1 as u64;
log 1 as f32;
log 1 as f64;

log 1u as int;
log 1u as uint;
log 1u as float;
log 1u as bool;
log 1u as os::libc::FILE;
log 1u as i8;
log 1u as i16;
log 1u as i32;
log 1u as i64;
log 1u as u8;
log 1u as u16;
log 1u as u32;
log 1u as u64;
log 1u as f32;
log 1u as f64;

log 1i8 as int;
log 1i8 as uint;
log 1i8 as float;
log 1i8 as bool;
log 1i8 as os::libc::FILE;
log 1i8 as i8;
log 1i8 as i16;
log 1i8 as i32;
log 1i8 as i64;
log 1i8 as u8;
log 1i8 as u16;
log 1i8 as u32;
log 1i8 as u64;
log 1i8 as f32;
log 1i8 as f64;

log 1u8 as int;
log 1u8 as uint;
log 1u8 as float;
log 1u8 as bool;
log 1u8 as os::libc::FILE;
log 1u8 as i8;
log 1u8 as i16;
log 1u8 as i32;
log 1u8 as i64;
log 1u8 as u8;
log 1u8 as u16;
log 1u8 as u32;
log 1u8 as u64;
log 1u8 as f32;
log 1u8 as f64;

log 1i16 as int;
log 1i16 as uint;
log 1i16 as float;
log 1i16 as bool;
log 1i16 as os::libc::FILE;
log 1i16 as i8;
log 1i16 as i16;
log 1i16 as i32;
log 1i16 as i64;
log 1i16 as u8;
log 1i16 as u16;
log 1i16 as u32;
log 1i16 as u64;
log 1i16 as f32;
log 1i16 as f64;

log 1u16 as int;
log 1u16 as uint;
log 1u16 as float;
log 1u16 as bool;
log 1u16 as os::libc::FILE;
log 1u16 as i8;
log 1u16 as i16;
log 1u16 as i32;
log 1u16 as i64;
log 1u16 as u8;
log 1u16 as u16;
log 1u16 as u32;
log 1u16 as u64;
log 1u16 as f32;
log 1u16 as f64;

log 1i32 as int;
log 1i32 as uint;
log 1i32 as float;
log 1i32 as bool;
log 1i32 as os::libc::FILE;
log 1i32 as i8;
log 1i32 as i16;
log 1i32 as i32;
log 1i32 as i64;
log 1i32 as u8;
log 1i32 as u16;
log 1i32 as u32;
log 1i32 as u64;
log 1i32 as f32;
log 1i32 as f64;

log 1u32 as int;
log 1u32 as uint;
log 1u32 as float;
log 1u32 as bool;
log 1u32 as os::libc::FILE;
log 1u32 as i8;
log 1u32 as i16;
log 1u32 as i32;
log 1u32 as i64;
log 1u32 as u8;
log 1u32 as u16;
log 1u32 as u32;
log 1u32 as u64;
log 1u32 as f32;
log 1u32 as f64;

log 1i64 as int;
log 1i64 as uint;
log 1i64 as float;
log 1i64 as bool;
log 1i64 as os::libc::FILE;
log 1i64 as i8;
log 1i64 as i16;
log 1i64 as i32;
log 1i64 as i64;
log 1i64 as u8;
log 1i64 as u16;
log 1i64 as u32;
log 1i64 as u64;
log 1i64 as f32;
log 1i64 as f64;

log 1u64 as int;
log 1u64 as uint;
log 1u64 as float;
log 1u64 as bool;
log 1u64 as os::libc::FILE;
log 1u64 as i8;
log 1u64 as i16;
log 1u64 as i32;
log 1u64 as i64;
log 1u64 as u8;
log 1u64 as u16;
log 1u64 as u32;
log 1u64 as u64;
log 1u64 as f32;
log 1u64 as f64;

log 1u64 as int;
log 1u64 as uint;
log 1u64 as float;
log 1u64 as bool;
log 1u64 as os::libc::FILE;
log 1u64 as i8;
log 1u64 as i16;
log 1u64 as i32;
log 1u64 as i64;
log 1u64 as u8;
log 1u64 as u16;
log 1u64 as u32;
log 1u64 as u64;
log 1u64 as f32;
log 1u64 as f64;

log true as int;
log true as uint;
log true as float;
log true as bool;
log true as os::libc::FILE;
log true as i8;
log true as i16;
log true as i32;
log true as i64;
log true as u8;
log true as u16;
log true as u32;
log true as u64;
log true as f32;
log true as f64;

log 1. as int;
log 1. as uint;
log 1. as float;
log 1. as bool;
log 1. as i8;
log 1. as i16;
log 1. as i32;
log 1. as i64;
log 1. as u8;
log 1. as u16;
log 1. as u32;
log 1. as u64;
log 1. as f32;
log 1. as f64;

log 1f32 as int;
log 1f32 as uint;
log 1f32 as float;
log 1f32 as bool;
log 1f32 as i8;
log 1f32 as i16;
log 1f32 as i32;
log 1f32 as i64;
log 1f32 as u8;
log 1f32 as u16;
log 1f32 as u32;
log 1f32 as u64;
log 1f32 as f32;
log 1f32 as f64;

log 1f64 as int;
log 1f64 as uint;
log 1f64 as float;
log 1f64 as bool;
log 1f64 as i8;
log 1f64 as i16;
log 1f64 as i32;
log 1f64 as i64;
log 1f64 as u8;
log 1f64 as u16;
log 1f64 as u32;
log 1f64 as u64;
log 1f64 as f32;
log 1f64 as f64;
}