3 files changed, 75 insertions, 0 deletions

diff --git a/include/serd/serd.h b/include/serd/serd.h
index 4f713a2f..09017175 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -985,6 +985,16 @@ SERD_API
 SerdEnv* SERD_ALLOCATED
 serd_env_new(SerdStringView base_uri);
 
+/// Copy an environment
+SERD_API
+SerdEnv* SERD_ALLOCATED
+serd_env_copy(const SerdEnv* SERD_NULLABLE env);
+
+/// Return true iff `a` is equal to `b`
+SERD_PURE_API
+bool
+serd_env_equals(const SerdEnv* SERD_NULLABLE a, const SerdEnv* SERD_NULLABLE b);
+
 /// Free `env`
 SERD_API
 void
diff --git a/src/env.c b/src/env.c
index 6ff8e3f5..29df5286 100644
--- a/src/env.c
+++ b/src/env.c
@@ -48,6 +48,26 @@ serd_env_new(const SerdStringView base_uri)
   return env;
 }
 
+SerdEnv*
+serd_env_copy(const SerdEnv* env)
+{
+  if (!env) {
+    return NULL;
+  }
+
+  SerdEnv* copy = (SerdEnv*)calloc(1, sizeof(struct SerdEnvImpl));
+
+  copy->n_prefixes = env->n_prefixes;
+  copy->prefixes   = (SerdPrefix*)malloc(copy->n_prefixes * sizeof(SerdPrefix));
+  for (size_t i = 0; i < copy->n_prefixes; ++i) {
+    copy->prefixes[i].name = serd_node_copy(env->prefixes[i].name);
+    copy->prefixes[i].uri  = serd_node_copy(env->prefixes[i].uri);
+  }
+
+  serd_env_set_base_uri(copy, serd_node_string_view(serd_env_base_uri(env)));
+  return copy;
+}
+
 void
 serd_env_free(SerdEnv* env)
 {
@@ -64,6 +84,28 @@ serd_env_free(SerdEnv* env)
   free(env);
 }
 
+bool
+serd_env_equals(const SerdEnv* a, const SerdEnv* b)
+{
+  if (!a || !b) {
+    return !a == !b;
+  }
+
+  if (a->n_prefixes != b->n_prefixes ||
+      !serd_node_equals(a->base_uri_node, b->base_uri_node)) {
+    return false;
+  }
+
+  for (size_t i = 0; i < a->n_prefixes; ++i) {
+    if (!serd_node_equals(a->prefixes[i].name, b->prefixes[i].name) ||
+        !serd_node_equals(a->prefixes[i].uri, b->prefixes[i].uri)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 SerdURIView
 serd_env_base_uri_view(const SerdEnv* env)
 {
diff --git a/test/test_env.c b/test/test_env.c
index da53df45..c00ae37b 100644
--- a/test/test_env.c
+++ b/test/test_env.c
@@ -93,11 +93,34 @@ test_env(void)
   SerdNode* qualified = serd_env_qualify(env, foo_u);
   assert(serd_node_equals(qualified, foo_c));
 
+  SerdEnv* env_copy = serd_env_copy(env);
+  assert(serd_env_equals(env, env_copy));
+  assert(!serd_env_equals(env, NULL));
+  assert(!serd_env_equals(NULL, env));
+  assert(serd_env_equals(NULL, NULL));
+
+  SerdNode* qualified2 = serd_env_expand(env_copy, foo_u);
+  assert(serd_node_equals(qualified, foo_c));
+  serd_node_free(qualified2);
+
+  serd_env_set_prefix(env_copy,
+                      SERD_STATIC_STRING("test"),
+                      SERD_STATIC_STRING("http://example.org/test"));
+
+  assert(!serd_env_equals(env, env_copy));
+
+  serd_env_set_prefix(env,
+                      SERD_STATIC_STRING("test2"),
+                      SERD_STATIC_STRING("http://example.org/test"));
+
+  assert(!serd_env_equals(env, env_copy));
+
   serd_node_free(qualified);
   serd_sink_free(count_prefixes_sink);
   serd_node_free(foo_c);
   serd_node_free(foo_u);
   serd_node_free(b);
+  serd_env_free(env_copy);
 
   serd_env_free(env);
 }