From bcd9e4a9754b226715cd1acf79d42f8af58ad0fc Mon Sep 17 00:00:00 2001
From: Jeff Fessler <fessler@umich.edu>
Date: Sat, 11 May 2024 10:12:33 -0400
Subject: [PATCH] Support Char ranges

---
 src/ndgrid-avect.jl  |  2 +-
 src/ndgrid-range.jl  | 13 +++++++------
 test/ndgrid-avect.jl |  2 +-
 test/ndgrid-range.jl | 15 +++++++++++++++
 4 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/src/ndgrid-avect.jl b/src/ndgrid-avect.jl
index 53ae286..104cc2b 100644
--- a/src/ndgrid-avect.jl
+++ b/src/ndgrid-avect.jl
@@ -42,7 +42,7 @@ _grid(d::Int, dims::Dims, v::AbstractVector) = GridAV(dims, v, d)
 _grid_type(d::Int, D::Int, ::Base.OneTo{T})     where T = GridOT{T, d, D}
 _grid_type(d::Int, D::Int, ::UnitRange{T})      where T = GridUR{T, d, D}
 _grid_type(d::Int, D::Int, ::StepRangeLen{T,R,S}) where {T,R,S} = GridSL{T, d, D, R, S}
-_grid_type(d::Int, D::Int, ::AbstractRange{T})  where T = GridAR{T, d, D}
+_grid_type(d::Int, D::Int, v::AbstractRange{T})  where T = GridAR{T, d, D, typeof(step(v))}
 _grid_type(d::Int, D::Int, ::AbstractVector{T}) where T = GridAV{T, d, D}
 
 
diff --git a/src/ndgrid-range.jl b/src/ndgrid-range.jl
index a9f89f5..22d20aa 100644
--- a/src/ndgrid-range.jl
+++ b/src/ndgrid-range.jl
@@ -5,26 +5,27 @@ ndgrid type for an AbstractRange input.
 
 
 """
-    GridAR{T,d,D} <: AbstractGrid{T,d,D}
+    GridAR{T,d,D,S} <: AbstractGrid{T,d,D}
 The `d`th component of `D`-dimensional `ndgrid(v₁, v₂, ...)`
 where `1 ≤ d ≤ D` and `v_d` is an `AbstractRange`.
 """
-struct GridAR{T,d,D} <: AbstractGrid{T,d,D}
+struct GridAR{T,d,D,S} <: AbstractGrid{T,d,D}
     dims::Dims{D}
     first0::T # first - step
-    step::T
+    step::S
 
     function GridAR(dims::Dims{D}, v::AbstractRange{T}, d::Int) where {D, T}
         1 ≤ d ≤ D || throw(ArgumentError("$d for $dims"))
-        new{T,d,D}(dims, first(v) - step(v), step(v))
+        S = typeof(step(v))
+        new{T,d,D,S}(dims, first(v) - step(v), step(v))
     end
 end
 
 
 @inline Base.@propagate_inbounds function Base.getindex(
-    a::GridAR{T,d,D},
+    a::GridAR{T,d,D,S},
     i::Vararg{Int,D},
-) where {T,d,D}
+) where {T,d,D,S}
      @boundscheck checkbounds(a, i...)
      return a.first0 + (@inbounds i[d]) * a.step
 end
diff --git a/test/ndgrid-avect.jl b/test/ndgrid-avect.jl
index 4112196..1d5807b 100644
--- a/test/ndgrid-avect.jl
+++ b/test/ndgrid-avect.jl
@@ -1,4 +1,4 @@
-# ndgrid-avect.jl
+# ndgrid-avect.jl test AbstractVector types
 
 using LazyGrids: ndgrid, ndgrid_array, GridAV, GridUR
 using Test: @test, @testset, @test_throws, @inferred
diff --git a/test/ndgrid-range.jl b/test/ndgrid-range.jl
index 3ce821b..94c7e71 100644
--- a/test/ndgrid-range.jl
+++ b/test/ndgrid-range.jl
@@ -4,6 +4,21 @@ using LazyGrids: ndgrid, ndgrid_array, GridAR, GridSL, GridUR
 using Test: @test, @testset, @test_throws, @inferred
 
 
+@testset "cvect" begin
+    x = 'a':9:'z' # character range
+    y = 1:2
+    xx, yy = @inferred ndgrid(x, y)
+    @test eltype(xx) === eltype(x)
+    @test eltype(yy) === eltype(y)
+    @test size(xx) === (length(x), length(y))
+    @test size(yy) === (length(x), length(y))
+    @test xx isa GridAR
+    @test yy isa GridUR
+    @test xx[:,1] == x
+    @test yy[1,:] == y
+end
+
+
 @testset "StepRangeLen" begin
     (x, y) = (1:3, (-3:4)/11)
     (xa, ya) = @inferred ndgrid_array(x, y)