1 files changed, 158 insertions, 0 deletions
diff --git a/src/compare.c b/src/compare.c
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index 00000000..82ff998f
--- /dev/null
+++ b/src/compare.c
@@ -0,0 +1,158 @@
+/*
+  Copyright 2011-2021 David Robillard <d@drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "compare.h"
+
+#include "statement.h"
+
+#include "serd/serd.h"
+
+#include <assert.h>
+
+/// Compare a mandatory node with a node pattern
+static inline int
+serd_node_wildcard_compare(const SerdNode* SERD_NONNULL  a,
+                           const SerdNode* SERD_NULLABLE b)
+{
+  assert(a);
+  return b ? serd_node_compare(a, b) : 0;
+}
+
+/// Compare an optional graph node with a node pattern
+static inline int
+serd_node_graph_compare(const SerdNode* SERD_NULLABLE a,
+                        const SerdNode* SERD_NULLABLE b)
+{
+  if (a == b) {
+    return 0;
+  }
+
+  if (!a) {
+    return -1;
+  }
+
+  if (!b) {
+    return 1;
+  }
+
+  return serd_node_compare(a, b);
+}
+
+/// Compare statements lexicographically, ignoring graph
+int
+serd_triple_compare(const void* const x,
+                    const void* const y,
+                    const void* const user_data)
+{
+  const int* const           ordering = (const int*)user_data;
+  const SerdStatement* const s        = (const SerdStatement*)x;
+  const SerdStatement* const t        = (const SerdStatement*)y;
+
+  for (unsigned i = 0u; i < 3u; ++i) {
+    const int o = ordering[i];
+    assert(o < 3);
+
+    const int c = serd_node_compare(s->nodes[o], t->nodes[o]);
+    if (c) {
+      return c;
+    }
+  }
+
+  return 0;
+}
+
+/**
+   Compare statments with statement patterns lexicographically, ignoring graph.
+
+   Null nodes in the second argument are treated as wildcards, always less than
+   any node.
+*/
+int
+serd_triple_compare_pattern(const void* const x,
+                            const void* const y,
+                            const void* const user_data)
+{
+  const int* const           ordering = (const int*)user_data;
+  const SerdStatement* const s        = (const SerdStatement*)x;
+  const SerdStatement* const t        = (const SerdStatement*)y;
+
+  for (unsigned i = 0u; i < 3u; ++i) {
+    const int o = ordering[i];
+    assert(o < 3);
+
+    const int c = serd_node_wildcard_compare(s->nodes[o], t->nodes[o]);
+    if (c) {
+      return c;
+    }
+  }
+
+  return 0;
+}
+
+/// Compare statements lexicographically
+int
+serd_quad_compare(const void* const x,
+                  const void* const y,
+                  const void* const user_data)
+{
+  const int* const           ordering = (const int*)user_data;
+  const SerdStatement* const s        = (const SerdStatement*)x;
+  const SerdStatement* const t        = (const SerdStatement*)y;
+
+  for (unsigned i = 0u; i < 4u; ++i) {
+    const int o = ordering[i];
+    const int c =
+      (o == SERD_GRAPH)
+        ? serd_node_graph_compare(s->nodes[SERD_GRAPH], t->nodes[SERD_GRAPH])
+        : serd_node_compare(s->nodes[o], t->nodes[o]);
+
+    if (c) {
+      return c;
+    }
+  }
+
+  return 0;
+}
+
+/**
+   Compare statments with statement patterns lexicographically.
+
+   Null nodes in the second argument are treated as wildcards, always less than
+   any node.
+*/
+int
+serd_quad_compare_pattern(const void* const x,
+                          const void* const y,
+                          const void* const user_data)
+{
+  const int* const           ordering = (const int*)user_data;
+  const SerdStatement* const s        = (const SerdStatement*)x;
+  const SerdStatement* const t        = (const SerdStatement*)y;
+
+  for (unsigned i = 0u; i < 4u; ++i) {
+    const int o = ordering[i];
+    const int c =
+      (o == SERD_GRAPH)
+        ? serd_node_graph_compare(s->nodes[SERD_GRAPH], t->nodes[SERD_GRAPH])
+        : serd_node_wildcard_compare(s->nodes[o], t->nodes[o]);
+
+    if (c) {
+      return c;
+    }
+  }
+
+  return 0;
+}