From 31be8b79dfff87df97ae0f17c72035a1eb0002fa Mon Sep 17 00:00:00 2001
From: Brendan Zabarauskas <bjzaba@yahoo.com.au>
Date: Sun, 21 Jul 2013 13:20:28 +1000
Subject: [PATCH] Add map_as_vec{2,3,4} methods and document AsVec method impls

These are useful for when for reusing methods available on the Vec{2,3,4} types.
---
 src/math/macros.rs | 18 ++++++++++++++----
 src/math/vec.rs    |  3 +++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/math/macros.rs b/src/math/macros.rs
index 76dfe33..94b06ad 100644
--- a/src/math/macros.rs
+++ b/src/math/macros.rs
@@ -61,25 +61,35 @@ macro_rules! impl_to_vec_helper(
 )
 
 macro_rules! impl_as_vec(
-    ($Self:ident, 2) => (impl_as_vec_helper!(AsVec2, $Self, Vec2, as_vec2, as_mut_vec2));
-    ($Self:ident, 3) => (impl_as_vec_helper!(AsVec3, $Self, Vec3, as_vec3, as_mut_vec3));
-    ($Self:ident, 4) => (impl_as_vec_helper!(AsVec4, $Self, Vec4, as_vec4, as_mut_vec4));
+    ($Self:ident, 2) => (impl_as_vec_helper!(AsVec2, $Self, Vec2, as_vec2, as_mut_vec2, map_as_vec2));
+    ($Self:ident, 3) => (impl_as_vec_helper!(AsVec3, $Self, Vec3, as_vec3, as_mut_vec3, map_as_vec3));
+    ($Self:ident, 4) => (impl_as_vec_helper!(AsVec4, $Self, Vec4, as_vec4, as_mut_vec4, map_as_vec4));
 )
 
 macro_rules! impl_as_vec_helper(
-    ($AsVec:ident, $Self:ident, $Vec:ident, $as_vec:ident, $as_mut_vec:ident) => (
+    ($AsVec:ident, $Self:ident, $Vec:ident, $as_vec:ident, $as_mut_vec:ident, $map_as_vec:ident) => (
         impl<T> $AsVec<T> for $Self<T> {
+            /// Safely transmute to a vec.
             #[inline]
             pub fn $as_vec<'a>(&'a self) -> &'a $Vec<T> {
                 use std::cast::transmute;
                 unsafe { transmute(self) }
             }
 
+            /// Safely transmute to a mutable vec.
             #[inline]
             pub fn $as_mut_vec<'a>(&'a mut self) -> &'a mut $Vec<T> {
                 use std::cast::transmute;
                 unsafe { transmute(self) }
             }
+
+            /// Operate on `self` transmuted to a vec, then return the result as
+            /// transmuted back to the `Self` type.
+            #[inline]
+            pub fn $map_as_vec<'a>(&'a self, f: &fn(&'a $Vec<T>) -> $Vec<T>) -> $Self<T> {
+                use std::cast::transmute;
+                unsafe { transmute(f(self.$as_vec())) }
+            }
         }
     )
 )
diff --git a/src/math/vec.rs b/src/math/vec.rs
index 3371e83..f3a104c 100644
--- a/src/math/vec.rs
+++ b/src/math/vec.rs
@@ -136,6 +136,7 @@ pub trait ToVec2<T> {
 pub trait AsVec2<T> {
     pub fn as_vec2<'a>(&'a self) -> &'a Vec2<T>;
     pub fn as_mut_vec2<'a>(&'a mut self) -> &'a mut Vec2<T>;
+    pub fn map_as_vec2<'a>(&'a self, f: &fn(&'a Vec2<T>) -> Vec2<T>) -> Self;
 }
 
 impl_dimensioned!(Vec2, T, 2)
@@ -755,6 +756,7 @@ pub trait ToVec3<T> {
 pub trait AsVec3<T> {
     pub fn as_vec3<'a>(&'a self) -> &'a Vec3<T>;
     pub fn as_mut_vec3<'a>(&'a mut self) -> &'a mut Vec3<T>;
+    pub fn map_as_vec3<'a>(&'a self, f: &fn(&'a Vec3<T>) -> Vec3<T>) -> Self;
 }
 
 impl_dimensioned!(Vec3, T, 3)
@@ -1446,6 +1448,7 @@ pub trait ToVec4<T> {
 pub trait AsVec4<T> {
     pub fn as_vec4<'a>(&'a self) -> &'a Vec4<T>;
     pub fn as_mut_vec4<'a>(&'a mut self) -> &'a mut Vec4<T>;
+    pub fn map_as_vec4<'a>(&'a self, f: &fn(&'a Vec4<T>) -> Vec4<T>) -> Self;
 }
 
 impl_dimensioned!(Vec4, T, 4)