From d7b017bcb84a76f0212ee6c8372818f34728091d Mon Sep 17 00:00:00 2001
From: Stefan Karpinski <stefan@karpinski.org>
Date: Fri, 31 Jan 2014 20:54:21 -0500
Subject: [PATCH] FloatRange: hook new type up to colon syntax [fixes #2333].

---
 base/range.jl  |  6 ++++++
 test/ranges.jl | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/base/range.jl b/base/range.jl
index 68132adca7d9fe..48d60ab52a7fb4 100644
--- a/base/range.jl
+++ b/base/range.jl
@@ -153,6 +153,12 @@ function frange{T<:FloatingPoint}(start::T, step::T, stop::T)
     start, step, one(step), floor(r)+1
 end
 
+colon{T<:FloatingPoint}(start::T, step::T, stop::T) =
+          step == 0              ? error("step cannot be zero in colon syntax") :
+         start == stop           ? FloatRange{T}(start,step,1,1) :
+    (0 < step) != (start < stop) ? FloatRange{T}(start,step,1,0) :
+                                   FloatRange{T}(frange(start,step,stop)...)
+
 similar(r::Ranges, T::Type, dims::Dims) = Array(T, dims)
 
 length(r::Ranges) = integer(r.len)
diff --git a/test/ranges.jl b/test/ranges.jl
index 07f94a25bcd432..8e46d5174594ca 100644
--- a/test/ranges.jl
+++ b/test/ranges.jl
@@ -159,3 +159,48 @@ else
     @test sum(int64(1:10^9)) == div(10^9 * (int64(10^9)+1), 2)
     @test sum(int64(1:10^9-1)) == div(10^9 * (int64(10^9)-1), 2)
 end
+
+# tricky floating-point ranges
+
+@test 0.1:0.1:0.3   == [1:3]./10
+@test 0.0:0.1:0.3   == [0:3]./10
+@test 0.3:-0.1:-0.1 == [3:-1:-1]./10
+@test 0.1:-0.1:-0.3 == [1:-1:-3]./10
+@test 0.0:0.1:1.0   == [0:10]./10
+@test 0.0:-0.1:1.0  == []
+@test 0.0:0.1:-1.0  == []
+@test 0.0:-0.1:-1.0 == [0:-1:-10]./10
+@test 1.0:1/49:27.0 == [49:1323]./49
+@test 0.0:0.7:2.1   == [0:7:21]./10
+@test 0.0:1.1:3.3   == [0:11:33]./10
+@test 0.1:1.1:3.4   == [1:11:34]./10
+@test 0.0:1.3:3.9   == [0:13:39]./10
+@test 0.1:1.3:4.0   == [1:13:40]./10
+@test 1.1:1.1:3.3   == [11:11:33]./10
+@test 0.3:0.1:1.1   == [3:1:11]./10
+
+@test 0.0:1.0:5.5   == [0:10:55]./10
+@test 0.0:-1.0:0.5  == []
+@test 0.0:1.0:0.5   == [0.0]
+
+@test prevfloat(0.1):0.1:0.3 == [prevfloat(0.1), 0.2, 0.3]
+@test nextfloat(0.1):0.1:0.3 == [nextfloat(0.1), 0.2]
+@test prevfloat(0.0):0.1:0.3 == [prevfloat(0.0), 0.1, 0.2]
+@test nextfloat(0.0):0.1:0.3 == [nextfloat(0.0), 0.1, 0.2]
+@test 0.1:0.1:prevfloat(0.3) == [0.1, 0.2]
+@test 0.1:0.1:nextfloat(0.3) == [0.1, 0.2, nextfloat(0.3)]
+@test 0.0:0.1:prevfloat(0.3) == [0.0, 0.1, 0.2]
+@test 0.0:0.1:nextfloat(0.3) == [0.0, 0.1, 0.2, nextfloat(0.3)]
+@test 0.1:prevfloat(0.1):0.3 == [0.1, 0.2, 0.3]
+@test 0.1:nextfloat(0.1):0.3 == [0.1, 0.2]
+@test 0.0:prevfloat(0.1):0.3 == [0.0, prevfloat(0.1), prevfloat(0.2), 0.3]
+@test 0.0:nextfloat(0.1):0.3 == [0.0, nextfloat(0.1), nextfloat(0.2)]
+
+for T = (Float32, Float64,),# BigFloat),
+    a = -5:25, s = [-5:-1;1:25], d = 1:25, n = -1:15
+    den   = convert(T,d)
+    start = convert(T,a)/den
+    step  = convert(T,s)/den
+    stop  = convert(T,(a+(n-1)*s))/den
+    @test [start:step:stop] == T[a:s:a+(n-1)*s]./den
+end