aa wrapper and KLU migration to PNM for PFs

Project.toml

@@ -15,15 +15,12 @@ SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 SuiteSparse_jll = "bea87d4a-7f5b-5778-9afe-8cc45184846c"
 
 [weakdeps]
-AppleAccelerate = "13e28ba4-7ad8-5781-acae-3021b1ed3924"
 Pardiso = "46dd5b70-b6fb-5a00-ae2d-e8fea33afaf2"
 
 [extensions]
-AppleAccelerateExt = "AppleAccelerate"
 MKLPardisoExt = "Pardiso"
 
 [compat]
-AppleAccelerate = "^0.4"
 DataStructures = "^0.19"
 DocStringExtensions = "~0.8, ~0.9"
 HDF5 = "0.17"

src/AccelerateWrapper/AccelerateWrapper.jl

@@ -0,0 +1,72 @@
+"""
+    AccelerateWrapper
+
+A small, allocation-aware wrapper over Apple's `libSparse.dylib`
+(`/System/Library/Frameworks/Accelerate.framework/.../libSparse.dylib`)
+designed for the access patterns of `PowerNetworkMatrices`:
+
+- Cache the symbolic and numeric factorizations of a symmetric sparse matrix
+  (LDLT by default) and reuse them across many solves.
+- Refresh the numeric factor (`numeric_refactor!`) while keeping the symbolic
+  analysis, without re-allocating the structural arrays.
+- Solve dense and **sparse** right-hand sides in place, with the sparse path
+  packing only non-empty RHS columns into a bounded scratch block.
+- Compute `A·X` and `A·x` directly via libSparse's `SparseMultiply`.
+
+This module is intentionally lighter than the upstream `AppleAccelerate.jl`
+package: it owns no high-level Julia wrappers over libSparse, exposes the
+symbolic/numeric split directly, binds only the entry points used by PNM,
+and is compile-gated to macOS so non-Apple builds never codegen the
+`@ccall` sites.
+"""
+module AccelerateWrapper
+
+import SparseArrays
+import SparseArrays: SparseMatrixCSC, getcolptr, rowvals, nonzeros, nzrange
+import LinearAlgebra
+
+export AAFactorCache,
+    aa_factorize,
+    symbolic_factor!,
+    numeric_refactor!,
+    full_factor!,
+    full_refactor!,
+    solve!,
+    solve_sparse!,
+    solve_sparse,
+    is_factored,
+    aa_spmm!,
+    aa_spmv!
+
+@static if Sys.isapple()
+    include("libsparse_bindings.jl")
+    include("aa_cache.jl")
+    include("solve_dense.jl")
+    include("solve_sparse_rhs.jl")
+    include("spmm.jl")
+else
+    # Stub layer. Non-Apple builds never bind libSparse symbols, never codegen
+    # the `@ccall` sites, and never instantiate `SparseOpaqueFactorization`.
+    # The whole submodule reduces to these short bodies on Linux/Windows.
+    struct AAFactorCache end
+
+    _unavailable() = error(
+        "AccelerateWrapper is macOS-only (Sys.isapple() returned false). " *
+        "Use the KLU backend on non-Apple platforms.",
+    )
+
+    AAFactorCache(args...; kwargs...) = _unavailable()
+    aa_factorize(args...; kwargs...) = _unavailable()
+    symbolic_factor!(args...) = _unavailable()
+    numeric_refactor!(args...) = _unavailable()
+    full_factor!(args...) = _unavailable()
+    full_refactor!(args...) = _unavailable()
+    solve!(args...) = _unavailable()
+    solve_sparse!(args...; kwargs...) = _unavailable()
+    solve_sparse(args...; kwargs...) = _unavailable()
+    is_factored(::AAFactorCache) = false
+    aa_spmm!(args...) = _unavailable()
+    aa_spmv!(args...) = _unavailable()
+end
+
+end # module