[FileFormats] robust reading of dimensions in SDPA file (#1789)

Co-authored-by: odow <[email protected]>

Author: blegat

src/FileFormats/SDPA/SDPA.jl

@@ -235,6 +235,31 @@ function mat_to_vec_idx(i::Int, j::Int)
     end
 end
 
+function _dim_to_set(s::AbstractString)
+    block_dim = parse(Int, s)
+    if block_dim > 0
+        return MOI.PositiveSemidefiniteConeTriangle(block_dim)
+    else
+        return MOI.Nonnegatives(-block_dim)
+    end
+end
+function _parse_dimensions(dims)
+    isvalid(char) = isdigit(char) || char == '-'
+    start = findfirst(isvalid, dims)
+    stop = findlast(isvalid, dims)
+    if isnothing(start)
+        return Union{MOI.PositiveSemidefiniteConeTriangle,MOI.Nonnegatives}[]
+    end
+    function is_delimiter(char)
+        return isspace(char) || char == ','
+    end
+    s = split(dims[start:stop], is_delimiter)
+    s = filter(!isempty, s)
+    return Union{MOI.PositiveSemidefiniteConeTriangle,MOI.Nonnegatives}[
+        _dim_to_set(dim) for dim in s
+    ]
+end
+
 """
     Base.read!(io::IO, model::FileFormats.SDPA.Model)
 
@@ -247,14 +272,6 @@ function Base.read!(io::IO, model::Model{T}) where {T}
     num_variables_read = false
     num_blocks = nothing
     block_sets = nothing
-    function dim_to_set(s::AbstractString)
-        block_dim = parse(Int, s)
-        if block_dim > 0
-            return MOI.PositiveSemidefiniteConeTriangle(block_dim)
-        else
-            return MOI.Nonnegatives(-block_dim)
-        end
-    end
     objective_read = false
     integer_read = false
     scalar_vars = nothing
@@ -303,7 +320,7 @@ function Base.read!(io::IO, model::Model{T}) where {T}
             if isempty(line) && !iszero(num_blocks)
                 continue
             end
-            block_sets = dim_to_set.(split(line))
+            block_sets = _parse_dimensions(line)
             if length(block_sets) != num_blocks
                 error(
                     "The number of blocks ($num_blocks) does not match the length of the list of blocks dimensions ($(length(block_sets))).",

test/FileFormats/SDPA/SDPA.jl

@@ -283,6 +283,15 @@ const _EXAMPLE_MODELS = [
     x in Integer()
     y in Integer()
     z in Integer()
+""",
+    ),
+    (
+        "issue_1541.dat-s",
+        """
+    variables: x, y, z
+    minobjective: -1y + -2z
+    c1: [-1x + -1y + -1z + 1, 1x, 1y, 1z] in Nonnegatives(4)
+    c2: [1x + 3y, 4y + 2z, -1z] in PositiveSemidefiniteConeTriangle(2)
 """,
     ),
 ]
@@ -294,6 +303,28 @@ function test_examples()
     end
 end
 
+# See https://github.com/jump-dev/MathOptInterface.jl/issues/1541
+function _spacer(char)
+    return [" ", "$char", " $char", "$char ", " $char "]
+end
+function test_dim_reader()
+    for before in _spacer('{')
+        for sep in _spacer(',')
+            for after in _spacer('}')
+                line = string(before, "-4", sep, "2", after)
+                exp = [
+                    MOI.Nonnegatives(4),
+                    MOI.PositiveSemidefiniteConeTriangle(2),
+                ]
+                @test MOI.FileFormats.SDPA._parse_dimensions(line) == exp
+                line = string(before, "2", sep, "-4", after)
+                @test MOI.FileFormats.SDPA._parse_dimensions(line) ==
+                      exp[2:-1:1]
+            end
+        end
+    end
+end
+
 function runtests()
     for name in names(@__MODULE__, all = true)
         if startswith("$(name)", "test_")

test/FileFormats/SDPA/models/issue_1541.dat-s

@@ -0,0 +1,16 @@
+3 =mdim
+2 =nblocks
+{-4, 2}
+-0.0 -1 -2
+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 3.0
+2 2 1 2 4.0
+3 2 1 2 2.0
+3 2 2 2 -1.0