trac #18346: Turn the backends into cdef classes

src/sage/graphs/base/c_graph.pxd

@@ -6,6 +6,7 @@
 #**************************************************************************
 
 from sage.data_structures.bitset cimport bitset_t
+from graph_backends cimport GenericGraphBackend
 
 cdef class CGraph:
     cdef int num_verts
@@ -39,9 +40,18 @@ cdef class CGraph:
     cpdef realloc(self, int)
     cdef int add_vertex_unsafe(self, int) except -1
 
-cdef int get_vertex(object u, dict vertex_ints, dict vertex_labels, CGraph G) except ? -2
-cdef object vertex_label(int u_int, dict vertex_ints, dict vertex_labels, CGraph G)
-cdef int check_vertex(object u, dict vertex_ints, dict vertex_labels, CGraph G, CGraph G_revx, bint reverse) except ? -1
+cdef class CGraphBackend(GenericGraphBackend):
+    cdef int get_vertex(self, object u) except ? -2
+    cdef object vertex_label(self, int u_int)
+    cdef int check_labelled_vertex(self, object u, bint reverse) except ? -1
+    cdef CGraph _cg
+    cdef CGraph _cg_rev
+    cdef bint _directed
+    cdef dict vertex_labels
+    cdef dict vertex_ints
+    cdef dict edge_labels
+    cdef bint _loops
+    cdef bint _multiple_edges
 # TODO: edge functions!
 
 

src/sage/graphs/base/c_graph.pyx

@@ -39,7 +39,6 @@ method :meth:`realloc <sage.graphs.base.c_graph.CGraph.realloc>`.
 
 include "sage/data_structures/bitset.pxi"
 
-from graph_backends import GenericGraphBackend
 from sage.rings.integer cimport Integer
 
 cdef class CGraph:
@@ -1115,7 +1114,7 @@ cdef class CGraph:
         """
         return self.num_arcs
 
-class CGraphBackend(GenericGraphBackend):
+cdef class CGraphBackend(GenericGraphBackend):
     """
     Base class for sparse and dense graph backends.
 
@@ -1136,7 +1135,7 @@ class CGraphBackend(GenericGraphBackend):
         sage: CGB.degree(0, True)
         Traceback (most recent call last):
         ...
-        AttributeError: 'CGraphBackend' object has no attribute 'vertex_ints'
+        TypeError: 'NoneType' object is not iterable
 
     The appropriate way to use these backends is via Sage graphs::
 
@@ -1154,10 +1153,6 @@ class CGraphBackend(GenericGraphBackend):
           -- backend for dense graphs.
     """
 
-    _cg = None
-    _cg_rev = None
-    _directed = None
-
     cdef int get_vertex(self, object u) except ? -2:
         """
         Returns an int representing the arbitrary hashable vertex u (whether or not
@@ -1941,23 +1936,23 @@ class CGraphBackend(GenericGraphBackend):
             2
             sage: from sage.graphs.base.sparse_graph import SparseGraphBackend
             sage: S = SparseGraphBackend(7)
-            sage: S.num_edges(directed=False)
+            sage: S.num_edges(False)
             0
             sage: S.loops(True)
             sage: S.add_edge(1, 1, None, directed=False)
-            sage: S.num_edges(directed=False)
+            sage: S.num_edges(False)
             1
             sage: S.multiple_edges(True)
             sage: S.add_edge(1, 1, None, directed=False)
-            sage: S.num_edges(directed=False)
+            sage: S.num_edges(False)
             2
             sage: from sage.graphs.base.dense_graph import DenseGraphBackend
             sage: D = DenseGraphBackend(7)
-            sage: D.num_edges(directed=False)
+            sage: D.num_edges(False)
             0
             sage: D.loops(True)
             sage: D.add_edge(1, 1, None, directed=False)
-            sage: D.num_edges(directed=False)
+            sage: D.num_edges(False)
             1
         """
         if directed:
@@ -2974,7 +2969,7 @@ cdef class Search_iterator:
         self.graph = graph
         self.direction = direction
 
-        bitset_init(self.seen, (<CGraph>self.graph._cg).active_vertices.size)
+        bitset_init(self.seen, self.graph._cg.active_vertices.size)
         bitset_set_first_n(self.seen, 0)
 
         cdef int v_id = self.graph.get_vertex(v)

src/sage/graphs/base/dense_graph.pyx

@@ -234,13 +234,14 @@ cdef class DenseGraph(CGraph):
         """
         from sage.graphs.all import DiGraph
         D = DiGraph(implementation='c_graph', sparse=False)
-        D._backend._cg = self
+        cdef CGraphBackend cgb = <CGraphBackend> D._backend
+        cgb._cg = self
         cdef int i
-        D._backend.vertex_labels = {}
+        cgb.vertex_labels = {}
         for i from 0 <= i < self.active_vertices.size:
             if bitset_in(self.active_vertices, i):
-                D._backend.vertex_labels[i] = i
-        D._backend.vertex_ints = D._backend.vertex_labels
+                cgb.vertex_labels[i] = i
+        cgb.vertex_ints = cgb.vertex_labels
         return (DenseGraph, (0, self.active_vertices.size, self.verts(), D.edges(labels=False)))
 
     cpdef realloc(self, int total_verts):
@@ -694,7 +695,7 @@ def _test_adjacency_sequence_out():
 
 from c_graph cimport CGraphBackend
 
-class DenseGraphBackend(CGraphBackend):
+cdef class DenseGraphBackend(CGraphBackend):
     """
     Backend for Sage graphs using DenseGraphs.
 

src/sage/graphs/base/sparse_graph.pxd

@@ -39,4 +39,7 @@ cdef class SparseGraph(CGraph):
     cdef int out_neighbors_BTNode_unsafe(self, int u, SparseGraphBTNode *** p_pointers)
     cdef list out_arcs_unsafe(self, int u, bint labels)
 
+cdef class SparseGraphBackend(CGraphBackend):
+    pass
+
 cdef int new_edge_label(object l, dict edge_labels)

src/sage/graphs/base/sparse_graph.pyx

@@ -415,14 +415,15 @@ cdef class SparseGraph(CGraph):
         """
         from sage.graphs.all import DiGraph
         D = DiGraph(implementation='c_graph', sparse=True, multiedges=True, loops=True)
-        D._backend._cg = self
+        cdef CGraphBackend cgb = <CGraphBackend?> D._backend
+        cgb._cg = self
         cdef int i
-        D._backend.vertex_labels = {}
+        cgb.vertex_labels = {}
         for i from 0 <= i < self.active_vertices.size:
             if bitset_in(self.active_vertices, i):
-                D._backend.vertex_labels[i] = i
-        D._backend.vertex_ints = D._backend.vertex_labels
-        D._backend.edge_labels = id_dict()
+                cgb.vertex_labels[i] = i
+        cgb.vertex_ints = cgb.vertex_labels
+        cgb.edge_labels = id_dict()
         arcs = [(u,v,l) if l is not None else (u,v,0) for u,v,l in D.edges(labels=True)]
         return (SparseGraph, (0, self.hash_length, self.active_vertices.size, self.verts(), arcs))
 
@@ -1605,7 +1606,7 @@ cdef int new_edge_label(object l, dict edge_labels):
     edge_labels[max+1] = l
     return max+1
 
-class SparseGraphBackend(CGraphBackend):
+cdef class SparseGraphBackend(CGraphBackend):
     """
     Backend for Sage graphs using SparseGraphs.
 

src/sage/graphs/base/static_sparse_backend.pxd

@@ -10,3 +10,9 @@ cdef class StaticSparseCGraph(CGraph):
 
     cpdef int out_degree(self, int u) except -1
     cpdef int in_degree(self, int u) except -1
+
+cdef class StaticSparseBackend(CGraphBackend):
+    cdef int _order
+    cdef bint _multiedges
+    cdef list _vertex_to_labels
+    cdef dict _vertex_to_int

src/sage/graphs/base/static_sparse_backend.pyx

@@ -323,7 +323,7 @@ cdef class StaticSparseCGraph(CGraph):
         else:
             return self.g_rev.neighbors[u+1] - self.g_rev.neighbors[u]
 
-class StaticSparseBackend(CGraphBackend):
+cdef class StaticSparseBackend(CGraphBackend):
 
     def __init__(self, G, loops = False, multiedges=False):
         """
@@ -1136,9 +1136,9 @@ def _run_it_on_static_instead(f):
         sage: Graph.new_graph_method = new_graph_method
         sage: g = Graph(5)
         sage: print "My backend is of type", g._backend
-        My backend is of type <class 'sage.graphs.base.sparse_graph.SparseGraphBackend'>
+        My backend is of type <type 'sage.graphs.base.sparse_graph.SparseGraphBackend'>
         sage: g.new_graph_method()
-        My backend is of type <class 'sage.graphs.base.static_sparse_backend.StaticSparseBackend'>
+        My backend is of type <type 'sage.graphs.base.static_sparse_backend.StaticSparseBackend'>
     """
     def same_function_on_static_version(*kwd,**kwds):
         if not isinstance(kwd[0]._backend,StaticSparseBackend):

src/sage/graphs/base/static_sparse_graph.pyx

@@ -517,7 +517,7 @@ def triangles_count(G):
     # g is a copy of G. If G is internally a static sparse graph, we use it.
     cdef short_digraph g
     G = G.copy(immutable=True)
-    g[0] = (<StaticSparseCGraph?> (G._backend._cg)).g[0]
+    g[0] = (<StaticSparseCGraph> (<StaticSparseBackend> G._backend)._cg).g[0]
 
     cdef uint64_t count = 0
     cdef uint32_t u,v,i