Merge pull request #29 from JuliaGeometry/sjk/getindex

Improve codegen for getindex(::Array, ::Face)

src/GeometryTypes.jl

@@ -42,6 +42,7 @@ include("display.jl")
 include("slice.jl")
 include("decompose.jl")
 include("deprecated.jl")
+include("checkbounds.jl")
 
 export AABB,
        AbsoluteRectangle,

src/checkbounds.jl

@@ -0,0 +1,19 @@
+"""
+Check the `Face` indices to ensure they are in the bounds of the vertex
+array of the `AbstractMesh`.
+"""
+function Base.checkbounds{VT,FT,FD,FO}(m::AbstractMesh{VT,Face{FD,FT,FO}})
+    isempty(faces(m)) && return true # nothing to worry about I guess
+
+    # index max and min
+    const i = one(FO) + FO # normalize face offset
+    s = length(vertices(m)) + FO
+
+    for face in faces(m)
+        # I hope this is unrolled
+        for elt in face
+            i <= elt && elt <= s || return false
+        end
+    end
+    return true
+end

src/faces.jl

@@ -1,6 +1,21 @@
-function getindex{T,N,FD,FT,Offset}(a::Array{T,N}, i::Face{FD, FT, Offset})
-    a[[(map(Int,i)-Offset)...]]
+"""
+Given an Array, `a`, and a face, `f`, return a tuple of numbers
+interpreting the values and offset of the face as indices into `A`.
+
+Note: This is not bounds checked. It is recommended that you use
+`checkbounds` to confirm the indices are safe for loops.
+Also be aware when writing generic code that faces may be of more than
+3 vertices.
+"""
+@generated function Base.getindex{T,N,FD,FT,Offset}(a::Array{T,N},
+                                               f::Face{FD, FT, Offset})
+    v = Expr(:tuple)
+    for i = 1:FD
+        push!(v.args, Expr(:call, Base.unsafe_getindex, :a, :(f[$i]-Offset)))
+    end
+    Expr(:(::), v, :(NTuple{FD,T}))
 end
+
 function setindex!{T,N,FD,FT,Offset}(a::Array{T,N}, b::Array{T,N}, i::Face{FD, FT, Offset})
     a[[(map(Int,i)-Offset)...]] = b
 end

test/faces.jl

@@ -0,0 +1,6 @@
+context("faces") do
+    a = [1,2,3,4]
+    @fact a[Face{3,Int,0}(1,2,3)] --> (1,2,3)
+    @fact a[Face{3,Int,-1}(0,1,2)] --> (1,2,3)
+    @fact a[Face{3,Int,1}(2,3,4)] --> (1,2,3)
+end

test/meshtypes.jl

@@ -85,4 +85,23 @@ context("Slice") do
     @fact length(s2) --> length(exp2)
 end
 
+context("checkbounds") do
+    m1 = HomogenousMesh([Point{3,Float64}(0.0,0.0,10.0),
+                         Point{3,Float64}(0.0,10.0,10.0),
+                         Point{3,Float64}(0.0,0.0,0.0)],
+                        [Face{3,Int,0}(1,2,3)])
+    @fact checkbounds(m1) --> true
+    m2 = HomogenousMesh([Point{3,Float64}(0.0,0.0,10.0),
+                         Point{3,Float64}(0.0,10.0,10.0),
+                         Point{3,Float64}(0.0,0.0,0.0)],
+                        [Face{3,Int,-1}(1,2,3)])
+    @fact checkbounds(m2) --> false
+    # empty case
+    m3 = HomogenousMesh([Point{3,Float64}(0.0,0.0,10.0),
+                         Point{3,Float64}(0.0,10.0,10.0),
+                         Point{3,Float64}(0.0,0.0,0.0)],
+                        Face{3,Int,-1}[])
+    @fact checkbounds(m3) --> true
+end
+
 end

test/runtests.jl

@@ -5,6 +5,7 @@ typealias Vec3f0 Vec{3, Float32}
 
 facts("GeometryTypes") do
     include("hyperrectangles.jl")
+    include("faces.jl")
     include("meshtypes.jl")
     include("distancefields.jl")
     include("primitives.jl")