SDPA reader errors on valid file

[matbesancon]

I am handling a bunch of SDPA files with which the CSDP native reader seems happy:

3 =mdim
2 =nblocks
{-4, 2}
-0.0 -0.3333333333333333 -0.6666666666666666
0 1 1 1 -1
1 1 1 1 -1
1 1 2 2 1
2 1 1 1 -1
2 1 3 3 1
3 1 1 1 -1
3 1 4 4 1
1 2 1 1 1.0
2 2 1 1 0.3333333333333333
2 2 1 2 0.3333333333333333
3 2 1 2 0.3333333333333333
3 2 2 2 0.3333333333333333

But MOF errors:

ERROR: ArgumentError: invalid base 10 digit '{' in "{-4,"
Stacktrace:
  [1] tryparse_internal(#unused#::Type{Int64}, s::SubString{String}, startpos::Int64, endpos::Int64, base_::Int64, raise::Bool)
    @ Base ./parse.jl:137
  [2] parse(::Type{Int64}, s::SubString{String}; base::Nothing)
    @ Base ./parse.jl:241
  [3] parse
    @ ./parse.jl:241 [inlined]
  [4] dim_to_set
    @ ~/.julia/packages/MathOptInterface/YDdD3/src/FileFormats/SDPA/SDPA.jl:253 [inlined]
  [5] _broadcast_getindex_evalf
    @ ./broadcast.jl:648 [inlined]
  [6] _broadcast_getindex
    @ ./broadcast.jl:621 [inlined]
  [7] getindex
    @ ./broadcast.jl:575 [inlined]
  [8] copy
    @ ./broadcast.jl:922 [inlined]
  [9] materialize
    @ ./broadcast.jl:883 [inlined]
 [10] read!(io::IOStream, model::MathOptInterface.Utilities.GenericModel{Float64, MathOptInterface.FileFormats.SDPA.ModelVectorConstraints{Float64, MathOptInterface.Utilities.VectorOfConstraints{MathOptInterface.VectorAffineFunction{Float64}, MathOptInterface.Nonnegatives}, MathOptInterface.Utilities.VectorOfConstraints{MathOptInterface.VectorAffineFunction{Float64}, MathOptInterface.PositiveSemidefiniteConeTriangle}}})
    @ MathOptInterface.FileFormats.SDPA ~/.julia/packages/MathOptInterface/YDdD3/src/FileFormats/SDPA/SDPA.jl:308
 [11] #7
    @ ~/.julia/packages/MathOptInterface/YDdD3/src/FileFormats/FileFormats.jl:101 [inlined]
 [12] open(::MathOptInterface.FileFormats.var"#7#8"{MathOptInterface.Utilities.GenericModel{Float64, MathOptInterface.FileFormats.SDPA.ModelVectorConstraints{Float64, MathOptInterface.Utilities.VectorOfConstraints{MathOptInterface.VectorAffineFunction{Float64}, MathOptInterface.Nonnegatives}, MathOptInterface.Utilities.VectorOfConstraints{MathOptInterface.VectorAffineFunction{Float64}, MathOptInterface.PositiveSemidefiniteConeTriangle}}}}, ::String, ::Vararg{String, N} where N; kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ Base ./io.jl:330
 [13] open(::Function, ::String, ::String)
    @ Base ./io.jl:328
 [14] compressed_open(f::Function, filename::String, mode::String, #unused#::MathOptInterface.FileFormats.NoCompression)
    @ MathOptInterface.FileFormats ~/.julia/packages/MathOptInterface/YDdD3/src/FileFormats/utils.jl:178
 [15] compressed_open(f::Function, filename::String, mode::String, #unused#::MathOptInterface.FileFormats.AutomaticCompression)
    @ MathOptInterface.FileFormats ~/.julia/packages/MathOptInterface/YDdD3/src/FileFormats/utils.jl:216
 [16] read_from_file
    @ ~/.julia/packages/MathOptInterface/YDdD3/src/FileFormats/FileFormats.jl:100 [inlined]

[matbesancon]

The issue is on line 3, the reader works with -4 2 instead. The parser should accept both options

[matbesancon]

This line here: https://github.com/jump-dev/MathOptInterface.jl/blob/master/src/FileFormats/SDPA/SDPA.jl#L306
should have a wrapper to detect whether the format is a list with curly bracket or just space-separated

[blegat]

Indeed, I followed http://plato.asu.edu/ftp/sdpa_format.txt which does not mention the possibility of {. We would add support for it if it's part of an extension.

[matbesancon]

OK, the curly braces appeared here:
https://github.com/vsdp/SDPLIB

[matbesancon]

If not part of the specification we could just avoid bothering with it altogether, happy to close this

[odow]

If CSDP is happy, we should fix this reader.

[blegat]

Yes, if it's in SDPLIB, let's support it, we can add in the docstring why the reader supports it by mentioning it.
@brianborchers would you have some context on this syntax so that we accurately document its support?

[matbesancon]

OK so this line seems very robust to changes:

{-4,2
-4,2
-4 2
-4 2}
{-4 2}
 {-4 2} (space before)
 {-4, 2}
-4,2 3 (one space one comma)

All of these are valid options for CSDP