From 229443778ffc6b26a13322983b81f4f1912427af Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Thu, 20 Dec 2018 13:02:24 -0500
Subject: Add serd_node_compare()

---
 include/serd/serd.h | 12 ++++++++++++
 src/node.c          | 25 +++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/include/serd/serd.h b/include/serd/serd.h
index 6aeb9138..4cf00f02 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -1032,6 +1032,18 @@ bool
 serd_node_equals(const SerdNode* SERD_NULLABLE a,
                  const SerdNode* SERD_NULLABLE b);
 
+/**
+   Compare two nodes.
+
+   Returns less than, equal to, or greater than zero if `a` is less than, equal
+   to, or greater than `b`, respectively.  NULL is treated as less than any
+   other node.
+*/
+SERD_PURE_API
+int
+serd_node_compare(const SerdNode* SERD_NULLABLE a,
+                  const SerdNode* SERD_NULLABLE b);
+
 /**
    @}
    @defgroup serd_event Event Handlers
diff --git a/src/node.c b/src/node.c
index 4c76ed9b..268b53af 100644
--- a/src/node.c
+++ b/src/node.c
@@ -436,6 +436,31 @@ serd_node_equals(const SerdNode* a, const SerdNode* b)
   return serd_node_total_size(b) == a_size && !memcmp(a, b, a_size);
 }
 
+int
+serd_node_compare(const SerdNode* a, const SerdNode* b)
+{
+  if (a == b) {
+    return 0;
+  }
+
+  if (!a) {
+    return -1;
+  }
+
+  if (!b) {
+    return 1;
+  }
+
+  if (a->type != b->type) {
+    return (a->type < b->type) ? -1 : 1;
+  }
+
+  const int cmp = strcmp(serd_node_string(a), serd_node_string(b));
+  return cmp ? cmp
+             : serd_node_compare(serd_node_maybe_get_meta_c(a),
+                                 serd_node_maybe_get_meta_c(b));
+}
+
 SerdNode*
 serd_new_uri(const SerdStringView str)
 {
-- 
cgit v1.2.1