auto merge of #9291 : jzelinskie/rust/remove-cond, r=alexcrichton

This is my first contribution, so please point out anything that I may have missed.

I consulted IRC and settled on `match () { ... }` for most of the replacements.

Author: bors

src/libextra/num/bigint.rs

@@ -115,8 +115,8 @@ impl TotalOrd for BigUint {
         if s_len > o_len { return Greater;  }
 
         for (&self_i, &other_i) in self.data.rev_iter().zip(other.data.rev_iter()) {
-            cond!((self_i < other_i) { return Less; }
-                  (self_i > other_i) { return Greater; })
+            if self_i < other_i { return Less; }
+            if self_i > other_i { return Greater; }
         }
         return Equal;
     }

src/libstd/char.rs

@@ -281,11 +281,11 @@ pub fn escape_unicode(c: char, f: &fn(char)) {
     // avoid calling str::to_str_radix because we don't really need to allocate
     // here.
     f('\\');
-    let pad = cond!(
-        (c <= '\xff')   { f('x'); 2 }
-        (c <= '\uffff') { f('u'); 4 }
-        _               { f('U'); 8 }
-    );
+    let pad = match () {
+        _ if c <= '\xff'    => { f('x'); 2 }
+        _ if c <= '\uffff'  => { f('u'); 4 }
+        _                   => { f('U'); 8 }
+    };
     for offset in range_step::<i32>(4 * (pad - 1), -1, -4) {
         unsafe {
             match ((c as i32) >> offset) & 0xf {
@@ -329,13 +329,13 @@ pub fn len_utf8_bytes(c: char) -> uint {
     static MAX_FOUR_B:  uint = 2097152u;
 
     let code = c as uint;
-    cond!(
-        (code < MAX_ONE_B)   { 1u }
-        (code < MAX_TWO_B)   { 2u }
-        (code < MAX_THREE_B) { 3u }
-        (code < MAX_FOUR_B)  { 4u }
-        _ { fail!("invalid character!") }
-    )
+    match () {
+        _ if code < MAX_ONE_B   => 1u,
+        _ if code < MAX_TWO_B   => 2u,
+        _ if code < MAX_THREE_B => 3u,
+        _ if code < MAX_FOUR_B  => 4u,
+        _                       => fail!("invalid character!"),
+    }
 }
 
 impl ToStr for char {

src/libstd/num/f32.rs

@@ -206,35 +206,35 @@ impl Orderable for f32 {
     /// Returns `NaN` if either of the numbers are `NaN`.
     #[inline]
     fn min(&self, other: &f32) -> f32 {
-        cond!(
-            (self.is_NaN())  { *self  }
-            (other.is_NaN()) { *other }
-            (*self < *other) { *self  }
-            _                { *other }
-        )
+        match () {
+            _ if self.is_NaN()  => *self,
+            _ if other.is_NaN() => *other,
+            _ if *self < *other => *self,
+            _                   => *other,
+        }
     }
 
     /// Returns `NaN` if either of the numbers are `NaN`.
     #[inline]
     fn max(&self, other: &f32) -> f32 {
-        cond!(
-            (self.is_NaN())  { *self  }
-            (other.is_NaN()) { *other }
-            (*self > *other) { *self  }
-            _                { *other }
-        )
+        match () {
+            _ if self.is_NaN()  => *self,
+            _ if other.is_NaN() => *other,
+            _ if *self > *other => *self,
+            _                   => *other,
+        }
     }
 
     /// Returns the number constrained within the range `mn <= self <= mx`.
     /// If any of the numbers are `NaN` then `NaN` is returned.
     #[inline]
     fn clamp(&self, mn: &f32, mx: &f32) -> f32 {
-        cond!(
-            (self.is_NaN())   { *self }
-            (!(*self <= *mx)) { *mx   }
-            (!(*self >= *mn)) { *mn   }
-            _                 { *self }
-        )
+        match () {
+            _ if self.is_NaN()   => *self,
+            _ if !(*self <= *mx) => *mx,
+            _ if !(*self >= *mn) => *mn,
+            _                    => *self,
+        }
     }
 }
 

src/libstd/num/f64.rs

@@ -229,35 +229,35 @@ impl Orderable for f64 {
     /// Returns `NaN` if either of the numbers are `NaN`.
     #[inline]
     fn min(&self, other: &f64) -> f64 {
-        cond!(
-            (self.is_NaN())  { *self  }
-            (other.is_NaN()) { *other }
-            (*self < *other) { *self  }
-            _                { *other }
-        )
+        match () {
+            _ if self.is_NaN()  => *self,
+            _ if other.is_NaN() => *other,
+            _ if *self < *other => *self,
+            _                   => *other,
+        }
     }
 
     /// Returns `NaN` if either of the numbers are `NaN`.
     #[inline]
     fn max(&self, other: &f64) -> f64 {
-        cond!(
-            (self.is_NaN())  { *self  }
-            (other.is_NaN()) { *other }
-            (*self > *other) { *self  }
-            _                { *other }
-        )
+        match () {
+            _ if self.is_NaN()  => *self,
+            _ if other.is_NaN() => *other,
+            _ if *self > *other => *self,
+            _                   => *other,
+        }
     }
 
     /// Returns the number constrained within the range `mn <= self <= mx`.
     /// If any of the numbers are `NaN` then `NaN` is returned.
     #[inline]
     fn clamp(&self, mn: &f64, mx: &f64) -> f64 {
-        cond!(
-            (self.is_NaN())   { *self }
-            (!(*self <= *mx)) { *mx   }
-            (!(*self >= *mn)) { *mn   }
-            _                 { *self }
-        )
+        match () {
+            _ if self.is_NaN()   => *self,
+            _ if !(*self <= *mx) => *mx,
+            _ if !(*self >= *mn) => *mn,
+            _                    => *self,
+        }
     }
 }
 

src/libstd/num/uint_macros.rs

@@ -70,11 +70,11 @@ impl Orderable for $T {
     /// Returns the number constrained within the range `mn <= self <= mx`.
     #[inline]
     fn clamp(&self, mn: &$T, mx: &$T) -> $T {
-        cond!(
-            (*self > *mx) { *mx   }
-            (*self < *mn) { *mn   }
-            _             { *self }
-        )
+        match () {
+            _ if (*self > *mx) => *mx,
+            _ if (*self < *mn) => *mn,
+            _                  => *self,
+        }
     }
 }
 

src/libsyntax/ext/expand.rs

@@ -894,42 +894,6 @@ pub fn std_macros() -> @str {
         }
     )
 
-    //
-    // A scheme-style conditional that helps to improve code clarity in some instances when
-    // the `if`, `else if`, and `else` keywords obscure predicates undesirably.
-    //
-    // # Example
-    //
-    // ~~~
-    // let clamped =
-    //     if x > mx { mx }
-    //     else if x < mn { mn }
-    //     else { x };
-    // ~~~
-    //
-    // Using `cond!`, the above could be written as:
-    //
-    // ~~~
-    // let clamped = cond!(
-    //     (x > mx) { mx }
-    //     (x < mn) { mn }
-    //     _        { x  }
-    // );
-    // ~~~
-    //
-    // The optional default case is denoted by `_`.
-    //
-    macro_rules! cond (
-        ( $(($pred:expr) $body:block)+ _ $default:block ) => (
-            $(if $pred $body else)+
-            $default
-        );
-        // for if the default case was ommitted
-        ( $(($pred:expr) $body:block)+ ) => (
-            $(if $pred $body)else+
-        );
-    )
-
     // NOTE(acrichto): start removing this after the next snapshot
     macro_rules! printf (
         ($arg:expr) => (