Improve showing unstored values

Project.toml

@@ -1,14 +1,15 @@
 name = "BlockSparseArrays"
 uuid = "2c9a651f-6452-4ace-a6ac-809f4280fbb4"
 authors = ["ITensor developers <[email protected]> and contributors"]
-version = "0.2.3"
+version = "0.2.4"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
 BlockArrays = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
 DerivableInterfaces = "6c5e35bf-e59e-4898-b73c-732dcc4ba65f"
 Dictionaries = "85a47980-9c8c-11e8-2b9f-f7ca1fa99fb4"
+FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"
 GradedUnitRanges = "e2de450a-8a67-46c7-b59c-01d5a3d041c5"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
@@ -32,6 +33,7 @@ ArrayLayouts = "1.10.4"
 BlockArrays = "1.2.0"
 DerivableInterfaces = "0.3.7"
 Dictionaries = "0.4.3"
+FillArrays = "1.13.0"
 GPUArraysCore = "0.1.0, 0.2"
 GradedUnitRanges = "0.1.0"
 LabelledNumbers = "0.1.0"

src/abstractblocksparsearray/wrappedabstractblocksparsearray.jl

@@ -335,3 +335,61 @@
 function Base.Array(a::AnyAbstractBlockSparseArray)
   return Array{eltype(a)}(a)
 end
+
+using SparseArraysBase: ReplacedUnstoredSparseArray
+
+# Wraps a block sparse array but replaces the unstored values.
+# This is used in printing in order to customize printing
+# of zero/unstored values.
+struct ReplacedUnstoredBlockSparseArray{T,N,F,Parent<:AbstractArray{T,N}} <:
+       AbstractBlockSparseArray{T,N}
+  parent::Parent
+  getunstoredblock::F
+end
+Base.parent(a::ReplacedUnstoredBlockSparseArray) = a.parent
+Base.axes(a::ReplacedUnstoredBlockSparseArray) = axes(parent(a))
+function BlockArrays.blocks(a::ReplacedUnstoredBlockSparseArray)
+  return ReplacedUnstoredSparseArray(blocks(parent(a)), a.getunstoredblock)
+end
+
+# This is copied from `SparseArraysBase.jl` since it is not part
+# of the public interface.
+# Like `Char` but prints without quotes.
+struct UnquotedChar <: AbstractChar
+  char::Char
+end
+Base.show(io::IO, c::UnquotedChar) = print(io, c.char)
+Base.show(io::IO, ::MIME"text/plain", c::UnquotedChar) = show(io, c)
+
+using FillArrays: Fill
+struct GetUnstoredBlockShow{Axes}
+  axes::Axes
+end
+@inline function (f::GetUnstoredBlockShow)(
+  a::AbstractArray{<:Any,N}, I::Vararg{Int,N}
+) where {N}
+  # TODO: Make sure this works for sparse or block sparse blocks, immutable
+  # blocks, diagonal blocks, etc.!
+  b_size = ntuple(ndims(a)) do d
+    return length(f.axes[d][Block(I[d])])
+  end
+  return Fill(UnquotedChar('.'), b_size)
+end
+# TODO: Use `Base.to_indices`.
+@inline function (f::GetUnstoredBlockShow)(
+  a::AbstractArray{<:Any,N}, I::CartesianIndex{N}
+) where {N}
+  return f(a, Tuple(I)...)
+end
+
+# TODO: Make this an `@interface ::AbstractBlockSparseArrayInterface` function
+# once we delete the hacky `Base.show` definitions in `BlockSparseArraysTensorAlgebraExt`.
+function Base.show(io::IO, mime::MIME"text/plain", a::AnyAbstractBlockSparseArray)
+  summary(io, a)
+  isempty(a) && return nothing
+  print(io, ":")
+  println(io)
+  a′ = ReplacedUnstoredBlockSparseArray(a, GetUnstoredBlockShow(axes(a)))
+  Base.print_array(io, a′)
+  return nothing
+end

test/basics/test_basics.jl

@@ -1045,4 +1045,16 @@ arrayts = (Array, JLArray)
     @test blockstoredlength(b) == 2
     @test storedlength(b) == 17
   end
+  @testset "show" begin
+    if elt === Float64
+      # Not testing other element types since they change the
+      # spacing so it isn't easy to make the test general.
+      a = BlockSparseArray{elt}([2, 2], [2, 2])
+      a[1, 2] = 12
+      # TODO: Reenable this once we delete the hacky `Base.show` definitions
+      # in `BlockSparseArraysTensorAlgebraExt`.
+      @test_broken sprint(show, "text/plain", a) ==
+        "$(summary(a)):$(zero(eltype(a)))  $(eltype(a)(12))  │  ⋅  ⋅\n $(zero(eltype(a)))   $(zero(eltype(a)))  │  ⋅  ⋅\n ───────────┼──────\n  ⋅     ⋅   │  ⋅  ⋅\n  ⋅     ⋅   │  ⋅  ⋅"
+    end
+  end
 end