Make nodes opaque

9 files changed, 318 insertions, 272 deletions

diff --git a/src/base64.h b/src/base64.h
index 8ff6acc4..6fbe6c5c 100644
--- a/src/base64.h
+++ b/src/base64.h
@@ -30,7 +30,8 @@
    @param wrap_lines Wrap lines at 76 characters to conform to RFC 2045.
    @return The length of the base64 encoding, excluding null terminator.
 */
-SERD_CONST_FUNC size_t
+SERD_CONST_FUNC
+size_t
 serd_base64_get_length(size_t size, bool wrap_lines);
 
 /**
diff --git a/src/env.c b/src/env.c
index 39da7a46..c4744885 100644
--- a/src/env.c
+++ b/src/env.c
@@ -14,6 +14,8 @@
   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
+#include "node.h"
+
 #include "serd/serd.h"
 
 #include <stdbool.h>
@@ -22,14 +24,14 @@
 #include <string.h>
 
 typedef struct {
-  SerdNode name;
-  SerdNode uri;
+  SerdNode* name;
+  SerdNode* uri;
 } SerdPrefix;
 
 struct SerdEnvImpl {
   SerdPrefix* prefixes;
   size_t      n_prefixes;
-  SerdNode    base_uri_node;
+  SerdNode*   base_uri_node;
   SerdURIView base_uri;
 };
 
@@ -52,12 +54,11 @@ serd_env_free(SerdEnv* env)
   }
 
   for (size_t i = 0; i < env->n_prefixes; ++i) {
-    serd_node_free(&env->prefixes[i].name);
-    serd_node_free(&env->prefixes[i].uri);
+    serd_node_free(env->prefixes[i].name);
+    serd_node_free(env->prefixes[i].uri);
   }
-
   free(env->prefixes);
-  serd_node_free(&env->base_uri_node);
+  serd_node_free(env->base_uri_node);
   free(env);
 }
 
@@ -67,8 +68,7 @@ serd_env_base_uri(const SerdEnv* env, SerdURIView* out)
   if (out) {
     *out = env->base_uri;
   }
-
-  return &env->base_uri_node;
+  return env->base_uri_node;
 }
 
 SerdStatus
@@ -78,50 +78,51 @@ serd_env_set_base_uri(SerdEnv* env, const SerdNode* uri)
     return SERD_ERR_BAD_ARG;
   }
 
-  if (!uri || !uri->buf) {
-    serd_node_free(&env->base_uri_node);
-    env->base_uri_node = SERD_NODE_NULL;
+  if (!uri) {
+    serd_node_free(env->base_uri_node);
+    env->base_uri_node = NULL;
     env->base_uri      = SERD_URI_NULL;
     return SERD_SUCCESS;
   }
 
   // Resolve base URI and create a new node and URI for it
   SerdURIView base_uri;
-  SerdNode    base_uri_node =
+  SerdNode*   base_uri_node =
     serd_new_uri_from_node(uri, &env->base_uri, &base_uri);
 
   // Replace the current base URI
-  serd_node_free(&env->base_uri_node);
+  serd_node_free(env->base_uri_node);
   env->base_uri_node = base_uri_node;
   env->base_uri      = base_uri;
 
   return SERD_SUCCESS;
 }
 
-static inline SERD_PURE_FUNC SerdPrefix*
+static inline SERD_PURE_FUNC
+SerdPrefix*
 serd_env_find(const SerdEnv* env, const char* name, size_t name_len)
 {
   for (size_t i = 0; i < env->n_prefixes; ++i) {
-    const SerdNode* const prefix_name = &env->prefixes[i].name;
+    const SerdNode* const prefix_name = env->prefixes[i].name;
     if (prefix_name->n_bytes == name_len) {
-      if (!memcmp(prefix_name->buf, name, name_len)) {
+      if (!memcmp(serd_node_string(prefix_name), name, name_len)) {
         return &env->prefixes[i];
       }
     }
   }
-
   return NULL;
 }
 
 static void
 serd_env_add(SerdEnv* env, const SerdNode* name, const SerdNode* uri)
 {
-  SerdPrefix* const prefix = serd_env_find(env, name->buf, name->n_bytes);
+  const char*       name_str = serd_node_string(name);
+  SerdPrefix* const prefix   = serd_env_find(env, name_str, name->n_bytes);
   if (prefix) {
-    if (!serd_node_equals(&prefix->uri, uri)) {
-      SerdNode old_prefix_uri = prefix->uri;
-      prefix->uri             = serd_node_copy(uri);
-      serd_node_free(&old_prefix_uri);
+    if (!serd_node_equals(prefix->uri, uri)) {
+      SerdNode* old_prefix_uri = prefix->uri;
+      prefix->uri              = serd_node_copy(uri);
+      serd_node_free(old_prefix_uri);
     }
   } else {
     env->prefixes = (SerdPrefix*)realloc(
@@ -134,22 +135,22 @@ serd_env_add(SerdEnv* env, const SerdNode* name, const SerdNode* uri)
 SerdStatus
 serd_env_set_prefix(SerdEnv* env, const SerdNode* name, const SerdNode* uri)
 {
-  if (!name->buf || uri->type != SERD_URI) {
+  if (!name || uri->type != SERD_URI) {
     return SERD_ERR_BAD_ARG;
   }
 
-  if (serd_uri_string_has_scheme(uri->buf)) {
+  if (serd_uri_string_has_scheme(serd_node_string(uri))) {
     // Set prefix to absolute URI
     serd_env_add(env, name, uri);
   } else {
     // Resolve relative URI and create a new node and URI for it
     SerdURIView abs_uri;
-    SerdNode    abs_uri_node =
+    SerdNode*   abs_uri_node =
       serd_new_uri_from_node(uri, &env->base_uri, &abs_uri);
 
     // Set prefix to resolved (absolute) URI
-    serd_env_add(env, name, &abs_uri_node);
-    serd_node_free(&abs_uri_node);
+    serd_env_add(env, name, abs_uri_node);
+    serd_node_free(abs_uri_node);
   }
 
   return SERD_SUCCESS;
@@ -160,24 +161,31 @@ serd_env_set_prefix_from_strings(SerdEnv*    env,
                                  const char* name,
                                  const char* uri)
 {
-  const SerdNode name_node = serd_node_from_string(SERD_LITERAL, name);
-  const SerdNode uri_node  = serd_node_from_string(SERD_URI, uri);
+  SerdNode* name_node = serd_new_string(SERD_LITERAL, name);
+  SerdNode* uri_node  = serd_new_string(SERD_URI, uri);
 
-  return serd_env_set_prefix(env, &name_node, &uri_node);
+  const SerdStatus st = serd_env_set_prefix(env, name_node, uri_node);
+
+  serd_node_free(name_node);
+  serd_node_free(uri_node);
+  return st;
 }
 
 bool
-serd_env_qualify(const SerdEnv*  env,
-                 const SerdNode* uri,
-                 SerdNode*       prefix,
-                 SerdStringView* suffix)
+serd_env_qualify(const SerdEnv*   env,
+                 const SerdNode*  uri,
+                 const SerdNode** prefix,
+                 SerdStringView*  suffix)
 {
   for (size_t i = 0; i < env->n_prefixes; ++i) {
-    const SerdNode* const prefix_uri = &env->prefixes[i].uri;
+    const SerdNode* const prefix_uri = env->prefixes[i].uri;
     if (uri->n_bytes >= prefix_uri->n_bytes) {
-      if (!strncmp(uri->buf, prefix_uri->buf, prefix_uri->n_bytes)) {
+      const char* prefix_str = serd_node_string(prefix_uri);
+      const char* uri_str    = serd_node_string(uri);
+
+      if (!strncmp(uri_str, prefix_str, prefix_uri->n_bytes)) {
         *prefix     = env->prefixes[i].name;
-        suffix->buf = uri->buf + prefix_uri->n_bytes;
+        suffix->buf = uri_str + prefix_uri->n_bytes;
         suffix->len = uri->n_bytes - prefix_uri->n_bytes;
         return true;
       }
@@ -192,17 +200,17 @@ serd_env_expand(const SerdEnv*  env,
                 SerdStringView* uri_prefix,
                 SerdStringView* uri_suffix)
 {
-  const char* const colon =
-    (const char*)memchr(curie->buf, ':', curie->n_bytes + 1);
+  const char* const str   = serd_node_string(curie);
+  const char* const colon = (const char*)memchr(str, ':', curie->n_bytes + 1);
   if (curie->type != SERD_CURIE || !colon) {
     return SERD_ERR_BAD_ARG;
   }
 
-  const size_t            name_len = (size_t)(colon - curie->buf);
-  const SerdPrefix* const prefix   = serd_env_find(env, curie->buf, name_len);
+  const size_t            name_len = (size_t)(colon - str);
+  const SerdPrefix* const prefix   = serd_env_find(env, str, name_len);
   if (prefix) {
-    uri_prefix->buf = prefix->uri.buf;
-    uri_prefix->len = prefix->uri.n_bytes;
+    uri_prefix->buf = serd_node_string(prefix->uri);
+    uri_prefix->len = prefix->uri ? prefix->uri->n_bytes : 0;
     uri_suffix->buf = colon + 1;
     uri_suffix->len = curie->n_bytes - name_len - 1;
     return SERD_SUCCESS;
@@ -210,7 +218,7 @@ serd_env_expand(const SerdEnv*  env,
   return SERD_ERR_BAD_CURIE;
 }
 
-SerdNode
+SerdNode*
 serd_env_expand_node(const SerdEnv* env, const SerdNode* node)
 {
   switch (node->type) {
@@ -225,24 +233,25 @@ serd_env_expand_node(const SerdEnv* env, const SerdNode* node)
     SerdStringView prefix;
     SerdStringView suffix;
     if (serd_env_expand(env, node, &prefix, &suffix)) {
-      return SERD_NODE_NULL;
+      return NULL;
     }
     const size_t len = prefix.len + suffix.len;
-    char*        buf = (char*)malloc(len + 1);
-    SerdNode     ret = {buf, len, 0, SERD_URI};
-    snprintf(buf, ret.n_bytes + 1, "%s%s", prefix.buf, suffix.buf);
+    SerdNode*    ret = serd_node_malloc(len, 0, SERD_URI);
+    char*        buf = serd_node_buffer(ret);
+    snprintf(buf, len + 1, "%s%s", prefix.buf, suffix.buf);
+    ret->n_bytes = len;
     return ret;
   }
   case SERD_BLANK:
     break;
   }
-  return SERD_NODE_NULL;
+  return NULL;
 }
 
 void
 serd_env_foreach(const SerdEnv* env, SerdPrefixSink func, void* handle)
 {
   for (size_t i = 0; i < env->n_prefixes; ++i) {
-    func(handle, &env->prefixes[i].name, &env->prefixes[i].uri);
+    func(handle, env->prefixes[i].name, env->prefixes[i].uri);
   }
 }
diff --git a/src/n3.c b/src/n3.c
index e64cfc50..d5ee2832 100644
--- a/src/n3.c
+++ b/src/n3.c
@@ -15,6 +15,7 @@
 */
 
 #include "byte_source.h"
+#include "node.h"
 #include "reader.h"
 #include "serd_internal.h"
 #include "stack.h"
@@ -634,7 +635,8 @@ read_PN_PREFIX_tail(SerdReader* reader, Ref dest)
   }
 
   const SerdNode* const n = deref(reader, dest);
-  if (n->buf[n->n_bytes - 1] == '.' && read_PN_CHARS(reader, dest)) {
+  if (serd_node_string(n)[n->n_bytes - 1] == '.' &&
+      read_PN_CHARS(reader, dest)) {
     return r_err(reader, SERD_ERR_BAD_SYNTAX, "prefix ends with `.'\n");
   }
 
@@ -958,8 +960,8 @@ read_verb(SerdReader* reader, Ref* dest)
   bool       ate_dot = false;
   SerdNode*  node    = deref(reader, *dest);
   const int  next    = peek_byte(reader);
-  if (!st && node->n_bytes == 1 && node->buf[0] == 'a' && next != ':' &&
-      !is_PN_CHARS_BASE((uint32_t)next)) {
+  if (!st && node->n_bytes == 1 && serd_node_string(node)[0] == 'a' &&
+      next != ':' && !is_PN_CHARS_BASE((uint32_t)next)) {
     pop_node(reader, *dest);
     *dest = push_node(reader, SERD_URI, NS_RDF "type", 47);
     return SERD_SUCCESS;
@@ -1001,8 +1003,9 @@ read_BLANK_NODE_LABEL(SerdReader* reader, Ref* dest, bool* ate_dot)
     }
   }
 
-  SerdNode* n = deref(reader, ref);
-  if (n->buf[n->n_bytes - 1] == '.' && read_PN_CHARS(reader, ref)) {
+  SerdNode* n   = deref(reader, ref);
+  char*     buf = serd_node_buffer(n);
+  if (buf[n->n_bytes - 1] == '.' && read_PN_CHARS(reader, ref)) {
     // Ate trailing dot, pop it from stack/node and inform caller
     --n->n_bytes;
     serd_stack_pop(&reader->stack, 1);
@@ -1010,11 +1013,11 @@ read_BLANK_NODE_LABEL(SerdReader* reader, Ref* dest, bool* ate_dot)
   }
 
   if (fancy_syntax(reader)) {
-    if (is_digit(n->buf[reader->bprefix_len + 1])) {
-      if ((n->buf[reader->bprefix_len]) == 'b') {
-        ((char*)n->buf)[reader->bprefix_len] = 'B'; // Prevent clash
-        reader->seen_genid                   = true;
-      } else if (reader->seen_genid && n->buf[reader->bprefix_len] == 'B') {
+    if (is_digit(buf[reader->bprefix_len + 1])) {
+      if ((buf[reader->bprefix_len]) == 'b') {
+        buf[reader->bprefix_len] = 'B'; // Prevent clash
+        reader->seen_genid       = true;
+      } else if (reader->seen_genid && buf[reader->bprefix_len] == 'B') {
         *dest = pop_node(reader, *dest);
         return r_err(reader,
                      SERD_ERR_ID_CLASH,
@@ -1171,8 +1174,8 @@ read_object(SerdReader* reader, ReadContext* ctx, bool emit, bool* ate_dot)
     while (!read_PN_CHARS_BASE(reader, o)) {
     }
     node = deref(reader, o);
-    if ((node->n_bytes == 4 && !memcmp(node->buf, "true", 4)) ||
-        (node->n_bytes == 5 && !memcmp(node->buf, "false", 5))) {
+    if ((node->n_bytes == 4 && !memcmp(serd_node_string(node), "true", 4)) ||
+        (node->n_bytes == 5 && !memcmp(serd_node_string(node), "false", 5))) {
       node->type = SERD_LITERAL;
       datatype   = push_node(reader, SERD_URI, XSD_BOOLEAN, XSD_BOOLEAN_LEN);
       ret        = SERD_SUCCESS;
@@ -1554,7 +1557,7 @@ tokcmp(SerdReader* reader, Ref ref, const char* tok, size_t n)
     return -1;
   }
 
-  return serd_strncasecmp(node->buf, tok, n);
+  return serd_strncasecmp(serd_node_string(node), tok, n);
 }
 
 SerdStatus
diff --git a/src/node.c b/src/node.c
index ee910725..b11625aa 100644
--- a/src/node.c
+++ b/src/node.c
@@ -38,43 +38,62 @@
 #  endif
 #endif
 
-SerdNode
-serd_node_from_string(SerdNodeType type, const char* str)
+SerdNode*
+serd_node_malloc(size_t n_bytes, SerdNodeFlags flags, SerdNodeType type)
 {
-  if (!str) {
-    return SERD_NODE_NULL;
-  }
-
-  SerdNodeFlags  flags   = 0;
-  const size_t   n_bytes = serd_strlen(str, &flags);
-  const SerdNode ret     = {str, n_bytes, flags, type};
-  return ret;
+  SerdNode* node = (SerdNode*)calloc(1, sizeof(SerdNode) + n_bytes + 1);
+  node->n_bytes  = 0;
+  node->flags    = flags;
+  node->type     = type;
+  return node;
 }
 
-SerdNode
-serd_node_from_substring(SerdNodeType type, const char* str, const size_t len)
+void
+serd_node_set(SerdNode** dst, const SerdNode* src)
 {
-  if (!str) {
-    return SERD_NODE_NULL;
+  if (src) {
+    if (!(*dst) || (*dst)->n_bytes < src->n_bytes) {
+      (*dst) = (SerdNode*)realloc(*dst, sizeof(SerdNode) + src->n_bytes + 1);
+    }
+
+    memcpy(*dst, src, sizeof(SerdNode) + src->n_bytes + 1);
+  } else if (*dst) {
+    memset(*dst, 0, sizeof(SerdNode));
   }
+}
+
+SerdNode*
+serd_new_string(SerdNodeType type, const char* str)
+{
+  SerdNodeFlags flags   = 0;
+  const size_t  n_bytes = serd_strlen(str, &flags);
+  SerdNode*     node    = serd_node_malloc(n_bytes, flags, type);
+  memcpy(serd_node_buffer(node), str, n_bytes);
+  node->n_bytes = n_bytes;
+  return node;
+}
 
-  SerdNodeFlags  flags   = 0;
-  const size_t   n_bytes = serd_substrlen(str, len, &flags);
-  const SerdNode ret     = {str, n_bytes, flags, type};
-  return ret;
+SerdNode*
+serd_new_substring(SerdNodeType type, const char* str, const size_t len)
+{
+  SerdNodeFlags flags   = 0;
+  const size_t  n_bytes = serd_substrlen(str, len, &flags);
+  SerdNode*     node    = serd_node_malloc(n_bytes, flags, type);
+  memcpy(serd_node_buffer(node), str, n_bytes);
+  node->n_bytes = n_bytes;
+  return node;
 }
 
-SerdNode
+SerdNode*
 serd_node_copy(const SerdNode* node)
 {
-  if (!node || !node->buf) {
-    return SERD_NODE_NULL;
+  if (!node) {
+    return NULL;
   }
 
-  SerdNode copy = *node;
-  char*    buf  = (char*)malloc(copy.n_bytes + 1);
-  memcpy(buf, node->buf, copy.n_bytes + 1);
-  copy.buf = buf;
+  const size_t size = sizeof(SerdNode) + node->n_bytes + 1;
+  SerdNode*    copy = (SerdNode*)malloc(size);
+  memcpy(copy, node, size);
   return copy;
 }
 
@@ -82,8 +101,8 @@ bool
 serd_node_equals(const SerdNode* a, const SerdNode* b)
 {
   return (a == b) ||
-         (a->type == b->type && a->n_bytes == b->n_bytes &&
-          ((a->buf == b->buf) || !memcmp(a->buf, b->buf, a->n_bytes + 1)));
+         (a && b && a->type == b->type && a->n_bytes == b->n_bytes &&
+          !memcmp(serd_node_string(a), serd_node_string(b), a->n_bytes));
 }
 
 static size_t
@@ -114,24 +133,25 @@ string_sink(const void* buf, size_t len, void* stream)
   return len;
 }
 
-SerdNode
+SerdNode*
 serd_new_uri_from_node(const SerdNode*    uri_node,
                        const SerdURIView* base,
                        SerdURIView*       out)
 {
-  return (uri_node->type == SERD_URI && uri_node->buf)
-           ? serd_new_uri_from_string(uri_node->buf, base, out)
-           : SERD_NODE_NULL;
+  const char* uri_str = serd_node_string(uri_node);
+  return (uri_node && uri_node->type == SERD_URI && uri_str)
+           ? serd_new_uri_from_string(uri_str, base, out)
+           : NULL;
 }
 
-SerdNode
+SerdNode*
 serd_new_uri_from_string(const char*        str,
                          const SerdURIView* base,
                          SerdURIView*       out)
 {
   if (!str || str[0] == '\0') {
     // Empty URI => Base URI, or nothing if no base is given
-    return base ? serd_new_uri(base, NULL, out) : SERD_NODE_NULL;
+    return base ? serd_new_uri(base, NULL, out) : NULL;
   }
 
   SerdURIView uri;
@@ -175,7 +195,7 @@ is_uri_path_char(const char c)
   }
 }
 
-SerdNode
+SerdNode*
 serd_new_file_uri(const char* path, const char* hostname, SerdURIView* out)
 {
   const size_t path_len     = strlen(path);
@@ -215,15 +235,17 @@ serd_new_file_uri(const char* path, const char* hostname, SerdURIView* out)
   }
   serd_buffer_sink_finish(&buffer);
 
+  SerdNode* node =
+    serd_new_substring(SERD_URI, (const char*)buffer.buf, buffer.len);
   if (out) {
-    serd_uri_parse((const char*)buffer.buf, out);
+    serd_uri_parse(serd_node_buffer(node), out);
   }
 
-  return serd_node_from_substring(
-    SERD_URI, (const char*)buffer.buf, buffer.len);
+  free(buffer.buf);
+  return node;
 }
 
-SerdNode
+SerdNode*
 serd_new_uri(const SerdURIView* uri, const SerdURIView* base, SerdURIView* out)
 {
   SerdURIView abs_uri = *uri;
@@ -232,22 +254,21 @@ serd_new_uri(const SerdURIView* uri, const SerdURIView* base, SerdURIView* out)
   }
 
   const size_t len        = serd_uri_string_length(&abs_uri);
-  char*        buf        = (char*)malloc(len + 1);
-  SerdNode     node       = {buf, len, 0, SERD_URI};
-  char*        ptr        = buf;
+  SerdNode*    node       = serd_node_malloc(len, 0, SERD_URI);
+  char*        ptr        = serd_node_buffer(node);
   const size_t actual_len = serd_uri_serialise(&abs_uri, string_sink, &ptr);
 
-  buf[actual_len] = '\0';
-  node.n_bytes    = actual_len;
+  serd_node_buffer(node)[actual_len] = '\0';
+  node->n_bytes                      = actual_len;
 
   if (out) {
-    serd_uri_parse(buf, out); // TODO: cleverly avoid double parse
+    serd_uri_parse(serd_node_buffer(node), out); // TODO: avoid double parse
   }
 
   return node;
 }
 
-SerdNode
+SerdNode*
 serd_new_relative_uri(const SerdURIView* uri,
                       const SerdURIView* base,
                       const SerdURIView* root,
@@ -255,17 +276,16 @@ serd_new_relative_uri(const SerdURIView* uri,
 {
   const size_t uri_len  = serd_uri_string_length(uri);
   const size_t base_len = serd_uri_string_length(base);
-  char*        buf      = (char*)malloc(uri_len + base_len + 1);
-  SerdNode     node     = {buf, 0, 0, SERD_URI};
-  char*        ptr      = buf;
+  SerdNode*    node     = serd_node_malloc(uri_len + base_len, 0, SERD_URI);
+  char*        ptr      = serd_node_buffer(node);
   const size_t actual_len =
     serd_uri_serialise_relative(uri, base, root, string_sink, &ptr);
 
-  buf[actual_len] = '\0';
-  node.n_bytes    = actual_len;
+  serd_node_buffer(node)[actual_len] = '\0';
+  node->n_bytes                      = actual_len;
 
   if (out) {
-    serd_uri_parse(buf, out); // TODO: cleverly avoid double parse
+    serd_uri_parse(serd_node_buffer(node), out); // TODO: avoid double parse
   }
 
   return node;
@@ -278,18 +298,19 @@ serd_digits(double abs)
   return lg < 1.0 ? 1U : (unsigned)lg;
 }
 
-SerdNode
+SerdNode*
 serd_new_decimal(double d, unsigned frac_digits)
 {
   if (isnan(d) || isinf(d)) {
-    return SERD_NODE_NULL;
+    return NULL;
   }
 
-  const double   abs_d      = fabs(d);
-  const unsigned int_digits = serd_digits(abs_d);
-  char*          buf        = (char*)calloc(int_digits + frac_digits + 3, 1);
-  SerdNode       node       = {buf, 0, 0, SERD_LITERAL};
-  const double   int_part   = floor(abs_d);
+  const double    abs_d      = fabs(d);
+  const unsigned  int_digits = serd_digits(abs_d);
+  const size_t    len        = int_digits + frac_digits + 3;
+  SerdNode* const node       = serd_node_malloc(len, 0, SERD_LITERAL);
+  char* const     buf        = serd_node_buffer(node);
+  const double    int_part   = floor(abs_d);
 
   // Point s to decimal point location
   char* s = buf + int_digits;
@@ -310,8 +331,8 @@ serd_new_decimal(double d, unsigned frac_digits)
   // Write fractional part (right to left)
   double frac_part = fabs(d - int_part);
   if (frac_part < DBL_EPSILON) {
-    *s++         = '0';
-    node.n_bytes = (size_t)(s - buf);
+    *s++          = '0';
+    node->n_bytes = (size_t)(s - buf);
   } else {
     uint64_t frac = (uint64_t)llround(frac_part * pow(10.0, (int)frac_digits));
     s += frac_digits - 1;
@@ -321,7 +342,7 @@ serd_new_decimal(double d, unsigned frac_digits)
     for (; i < frac_digits - 1 && !(frac % 10); ++i, --s, frac /= 10) {
     }
 
-    node.n_bytes = (size_t)(s - buf) + 1u;
+    node->n_bytes = (size_t)(s - buf) + 1u;
 
     // Write digits from last trailing zero to decimal point
     for (; i < frac_digits; ++i) {
@@ -333,13 +354,13 @@ serd_new_decimal(double d, unsigned frac_digits)
   return node;
 }
 
-SerdNode
+SerdNode*
 serd_new_integer(int64_t i)
 {
   uint64_t       abs_i  = (i < 0) ? -i : i;
   const unsigned digits = serd_digits((double)abs_i);
-  char*          buf    = (char*)calloc(digits + 2, 1);
-  SerdNode       node   = {(const char*)buf, 0, 0, SERD_LITERAL};
+  SerdNode*      node   = serd_node_malloc(digits + 2, 0, SERD_LITERAL);
+  char*          buf    = serd_node_buffer(node);
 
   // Point s to the end
   char* s = buf + digits - 1;
@@ -348,7 +369,7 @@ serd_new_integer(int64_t i)
     ++s;
   }
 
-  node.n_bytes = (size_t)(s - buf) + 1u;
+  node->n_bytes = (size_t)(s - buf) + 1u;
 
   // Write integer part (right to left)
   do {
@@ -358,16 +379,22 @@ serd_new_integer(int64_t i)
   return node;
 }
 
-SerdNode
+SerdNode*
 serd_new_blob(const void* buf, size_t size, bool wrap_lines)
 {
+  if (!buf || !size) {
+    return NULL;
+  }
+
   const size_t len  = serd_base64_get_length(size, wrap_lines);
-  uint8_t*     str  = (uint8_t*)calloc(len + 2, 1);
-  SerdNode     node = {(const char*)str, len, 0, SERD_LITERAL};
+  SerdNode*    node = serd_node_malloc(len + 1, 0, SERD_LITERAL);
+  uint8_t*     str  = (uint8_t*)serd_node_buffer(node);
 
   if (serd_base64_encode(str, buf, size, wrap_lines)) {
-    node.flags |= SERD_HAS_NEWLINE;
+    node->flags |= SERD_HAS_NEWLINE;
   }
+
+  node->n_bytes = len;
   return node;
 }
 
@@ -380,7 +407,7 @@ serd_node_type(const SerdNode* node)
 const char*
 serd_node_string(const SerdNode* node)
 {
-  return node->buf;
+  return (const char*)(node + 1);
 }
 
 size_t
@@ -398,8 +425,5 @@ serd_node_flags(const SerdNode* node)
 void
 serd_node_free(SerdNode* node)
 {
-  if (node && node->buf) {
-    free((char*)node->buf);
-    node->buf = NULL;
-  }
+  free(node);
 }
diff --git a/src/reader.c b/src/reader.c
index 9b4fe189..97d5dcfd 100644
--- a/src/reader.c
+++ b/src/reader.c
@@ -44,9 +44,11 @@ void
 set_blank_id(SerdReader* reader, Ref ref, size_t buf_size)
 {
   SerdNode*   node   = deref(reader, ref);
+  char*       buf    = (char*)(node + 1);
   const char* prefix = reader->bprefix ? (const char*)reader->bprefix : "";
-  node->n_bytes      = (size_t)snprintf(
-    (char*)node->buf, buf_size, "%sb%u", prefix, reader->next_id++);
+
+  node->n_bytes =
+    (size_t)snprintf(buf, buf_size, "%sb%u", prefix, reader->next_id++);
 }
 
 size_t
@@ -93,7 +95,6 @@ push_node_padded(SerdReader*  reader,
   node->n_bytes        = n_bytes;
   node->flags          = 0;
   node->type           = type;
-  node->buf            = NULL;
 
   char* buf = (char*)(node + 1);
   memcpy(buf, str, n_bytes + 1);
@@ -118,12 +119,7 @@ push_node(SerdReader*  reader,
 SerdNode*
 deref(SerdReader* reader, const Ref ref)
 {
-  if (ref) {
-    SerdNode* node = (SerdNode*)(reader->stack.buf + ref);
-    node->buf      = (char*)node + sizeof(SerdNode);
-    return node;
-  }
-  return NULL;
+  return ref ? (SerdNode*)(reader->stack.buf + ref) : NULL;
 }
 
 Ref
@@ -146,8 +142,8 @@ SerdStatus
 emit_statement(SerdReader* reader, ReadContext ctx, Ref o, Ref d, Ref l)
 {
   SerdNode* graph = deref(reader, ctx.graph);
-  if (!graph && reader->default_graph.buf) {
-    graph = &reader->default_graph;
+  if (!graph && reader->default_graph) {
+    graph = reader->default_graph;
   }
 
   const SerdStatus st = !reader->statement_sink
@@ -194,7 +190,7 @@ serd_reader_new(SerdSyntax syntax,
   me->prefix_sink    = prefix_sink;
   me->statement_sink = statement_sink;
   me->end_sink       = end_sink;
-  me->default_graph  = SERD_NODE_NULL;
+  me->default_graph  = NULL;
   me->stack          = serd_stack_new(SERD_PAGE_SIZE);
   me->syntax         = syntax;
   me->next_id        = 1;
@@ -232,7 +228,7 @@ serd_reader_free(SerdReader* reader)
   pop_node(reader, reader->rdf_nil);
   pop_node(reader, reader->rdf_rest);
   pop_node(reader, reader->rdf_first);
-  serd_node_free(&reader->default_graph);
+  serd_node_free(reader->default_graph);
 
 #ifdef SERD_STACK_CHECK
   free(reader->allocs);
@@ -269,7 +265,7 @@ serd_reader_add_blank_prefix(SerdReader* reader, const char* prefix)
 void
 serd_reader_set_default_graph(SerdReader* reader, const SerdNode* graph)
 {
-  serd_node_free(&reader->default_graph);
+  serd_node_free(reader->default_graph);
   reader->default_graph = serd_node_copy(graph);
 }
 
diff --git a/src/reader.h b/src/reader.h
index f12fbf56..b86a7596 100644
--- a/src/reader.h
+++ b/src/reader.h
@@ -18,6 +18,7 @@
 #define SERD_READER_H
 
 #include "byte_source.h"
+#include "node.h"
 #include "stack.h"
 
 #include "serd/serd.h"
@@ -67,7 +68,7 @@ struct SerdReaderImpl {
   Ref               rdf_first;
   Ref               rdf_rest;
   Ref               rdf_nil;
-  SerdNode          default_graph;
+  SerdNode*         default_graph;
   SerdByteSource    source;
   SerdStack         stack;
   SerdSyntax        syntax;
@@ -100,7 +101,8 @@ push_node(SerdReader*  reader,
           const char*  str,
           size_t       n_bytes);
 
-SERD_PURE_FUNC size_t
+SERD_PURE_FUNC
+size_t
 genid_size(SerdReader* reader);
 
 Ref
diff --git a/src/serdi.c b/src/serdi.c
index f075ce13..3d3b414c 100644
--- a/src/serdi.c
+++ b/src/serdi.c
@@ -67,7 +67,8 @@ get_syntax(const char* name)
   return (SerdSyntax)0;
 }
 
-static SERD_PURE_FUNC SerdSyntax
+static SERD_PURE_FUNC
+SerdSyntax
 guess_syntax(const char* filename)
 {
   const char* ext = strrchr(filename, '.');
@@ -309,7 +310,7 @@ main(int argc, char** argv)
     choose_style(input_syntax, output_syntax, ascii, bulk_write, full_uris);
 
   SerdURIView base_uri = SERD_URI_NULL;
-  SerdNode    base     = SERD_NODE_NULL;
+  SerdNode*   base     = NULL;
   if (a < argc) { // Base URI given on command line
     base = serd_new_uri_from_string((const char*)argv[a], NULL, &base_uri);
   } else if (from_file && in_fd != stdin) { // Use input file URI
@@ -317,7 +318,7 @@ main(int argc, char** argv)
   }
 
   FILE* const    out_fd = stdout;
-  SerdEnv* const env    = serd_env_new(&base);
+  SerdEnv* const env    = serd_env_new(base);
 
   SerdWriter* const writer = serd_writer_new(
     output_syntax, writer_flags, env, &base_uri, serd_file_sink, out_fd);
@@ -337,10 +338,11 @@ main(int argc, char** argv)
     serd_writer_set_error_sink(writer, quiet_error_sink, NULL);
   }
 
-  SerdNode root = serd_node_from_string(SERD_URI, root_uri);
-  serd_writer_set_root_uri(writer, &root);
+  SerdNode* root = root_uri ? serd_new_string(SERD_URI, root_uri) : NULL;
+  serd_writer_set_root_uri(writer, root);
   serd_writer_chop_blank_prefix(writer, chop_prefix);
   serd_reader_add_blank_prefix(reader, add_prefix);
+  serd_node_free(root);
 
   SerdStatus st = SERD_SUCCESS;
   if (!from_file) {
@@ -359,7 +361,7 @@ main(int argc, char** argv)
   serd_writer_finish(writer);
   serd_writer_free(writer);
   serd_env_free(env);
-  serd_node_free(&base);
+  serd_node_free(base);
   free(input_path);
 
   if (from_file) {
diff --git a/src/uri_utils.h b/src/uri_utils.h
index 03d397d2..6b07ec48 100644
--- a/src/uri_utils.h
+++ b/src/uri_utils.h
@@ -50,7 +50,8 @@ uri_path_at(const SerdURIView* uri, size_t i)
    Return the index of the first differing character after the last root slash,
    or zero if `uri` is not under `root`.
 */
-static inline SERD_PURE_FUNC size_t
+static inline SERD_PURE_FUNC
+size_t
 uri_rooted_index(const SerdURIView* uri, const SerdURIView* root)
 {
   if (!root || !root->scheme.len ||
@@ -80,14 +81,16 @@ uri_rooted_index(const SerdURIView* uri, const SerdURIView* root)
 }
 
 /** Return true iff `uri` shares path components with `root` */
-static inline SERD_PURE_FUNC bool
+static inline SERD_PURE_FUNC
+bool
 uri_is_related(const SerdURIView* uri, const SerdURIView* root)
 {
   return uri_rooted_index(uri, root) > 0;
 }
 
 /** Return true iff `uri` is within the base of `root` */
-static inline SERD_PURE_FUNC bool
+static inline SERD_PURE_FUNC
+bool
 uri_is_under(const SerdURIView* uri, const SerdURIView* root)
 {
   const size_t index = uri_rooted_index(uri, root);
diff --git a/src/writer.c b/src/writer.c
index 89600e9c..dd16e732 100644
--- a/src/writer.c
+++ b/src/writer.c
@@ -15,6 +15,7 @@
 */
 
 #include "byte_sink.h"
+#include "node.h"
 #include "serd_internal.h"
 #include "stack.h"
 #include "string_utils.h"
@@ -39,14 +40,12 @@ typedef enum {
 } Field;
 
 typedef struct {
-  SerdNode graph;
-  SerdNode subject;
-  SerdNode predicate;
+  SerdNode* graph;
+  SerdNode* subject;
+  SerdNode* predicate;
 } WriteContext;
 
-static const WriteContext WRITE_CONTEXT_NULL = {{0, 0, 0, SERD_NOTHING},
-                                                {0, 0, 0, SERD_NOTHING},
-                                                {0, 0, 0, SERD_NOTHING}};
+static const WriteContext WRITE_CONTEXT_NULL = {NULL, NULL, NULL};
 
 typedef enum {
   SEP_NONE,
@@ -95,7 +94,7 @@ struct SerdWriterImpl {
   SerdSyntax      syntax;
   SerdWriterFlags flags;
   SerdEnv*        env;
-  SerdNode        root_node;
+  SerdNode*       root_node;
   SerdURIView     root_uri;
   SerdURIView     base_uri;
   SerdStack       anon_stack;
@@ -103,7 +102,7 @@ struct SerdWriterImpl {
   SerdErrorSink   error_sink;
   void*           error_handle;
   WriteContext    context;
-  SerdNode        list_subj;
+  SerdNode*       list_subj;
   unsigned        list_depth;
   unsigned        indent;
   char*           bprefix;
@@ -150,26 +149,28 @@ w_err(SerdWriter* writer, SerdStatus st, const char* fmt, ...)
   va_end(args);
 }
 
-static inline SERD_PURE_FUNC WriteContext*
-                             anon_stack_top(SerdWriter* writer)
+static inline SERD_PURE_FUNC
+WriteContext*
+anon_stack_top(SerdWriter* writer)
 {
   assert(!serd_stack_is_empty(&writer->anon_stack));
   return (WriteContext*)(writer->anon_stack.buf + writer->anon_stack.size -
                          sizeof(WriteContext));
 }
 
-static void
-copy_node(SerdNode* dst, const SerdNode* src)
+static inline SerdNode*
+ctx(SerdWriter* writer, const Field field)
 {
-  if (src) {
-    dst->buf     = (char*)realloc((char*)dst->buf, src->n_bytes + 1);
-    dst->n_bytes = src->n_bytes;
-    dst->flags   = src->flags;
-    dst->type    = src->type;
-    memcpy((char*)dst->buf, src->buf, src->n_bytes + 1);
-  } else {
-    dst->type = SERD_NOTHING;
+  SerdNode* node = NULL;
+  if (field == FIELD_SUBJECT) {
+    node = writer->context.subject;
+  } else if (field == FIELD_PREDICATE) {
+    node = writer->context.predicate;
+  } else if (field == FIELD_GRAPH) {
+    node = writer->context.graph;
   }
+
+  return node && node->type ? node : NULL;
 }
 
 static inline size_t
@@ -261,6 +262,12 @@ write_uri(SerdWriter* writer, const char* utf8, size_t n_bytes)
   return len;
 }
 
+static size_t
+write_uri_from_node(SerdWriter* writer, const SerdNode* node)
+{
+  return write_uri(writer, serd_node_string(node), node->n_bytes);
+}
+
 static bool
 lname_must_escape(const char c)
 {
@@ -469,23 +476,26 @@ write_sep(SerdWriter* writer, const Sep sep)
 static SerdStatus
 reset_context(SerdWriter* writer, bool graph)
 {
-  if (graph) {
-    writer->context.graph.type = SERD_NOTHING;
+  if (graph && writer->context.graph) {
+    memset(writer->context.graph, 0, sizeof(SerdNode));
   }
-
-  writer->context.subject.type   = SERD_NOTHING;
-  writer->context.predicate.type = SERD_NOTHING;
-  writer->empty                  = false;
+  if (writer->context.subject) {
+    memset(writer->context.subject, 0, sizeof(SerdNode));
+  }
+  if (writer->context.predicate) {
+    memset(writer->context.predicate, 0, sizeof(SerdNode));
+  }
+  writer->empty = false;
   return SERD_SUCCESS;
 }
 
 static SerdStatus
 free_context(SerdWriter* writer)
 {
-  serd_node_free(&writer->context.graph);
-  serd_node_free(&writer->context.subject);
-  serd_node_free(&writer->context.predicate);
-  return reset_context(writer, true);
+  serd_node_free(writer->context.graph);
+  serd_node_free(writer->context.subject);
+  serd_node_free(writer->context.predicate);
+  return SERD_SUCCESS;
 }
 
 static bool
@@ -503,23 +513,24 @@ write_literal(SerdWriter*        writer,
               const SerdNode*    lang,
               SerdStatementFlags flags)
 {
-  if (supports_abbrev(writer) && datatype && datatype->buf) {
-    const char* type_uri = datatype->buf;
+  const char* node_str = serd_node_string(node);
+  const char* type_uri = datatype ? serd_node_string(datatype) : NULL;
+  if (supports_abbrev(writer) && type_uri) {
     if (!strncmp(type_uri, NS_XSD, sizeof(NS_XSD) - 1) &&
         (!strcmp(type_uri + sizeof(NS_XSD) - 1, "boolean") ||
          !strcmp(type_uri + sizeof(NS_XSD) - 1, "integer"))) {
-      sink(node->buf, node->n_bytes, writer);
+      sink(node_str, node->n_bytes, writer);
       return true;
     }
 
     if (!strncmp(type_uri, NS_XSD, sizeof(NS_XSD) - 1) &&
         !strcmp(type_uri + sizeof(NS_XSD) - 1, "decimal") &&
-        strchr(node->buf, '.') && node->buf[node->n_bytes - 1] != '.') {
+        strchr(node_str, '.') && node_str[node->n_bytes - 1] != '.') {
       /* xsd:decimal literals without trailing digits, e.g. "5.", can
          not be written bare in Turtle.  We could add a 0 which is
          prettier, but changes the text and breaks round tripping.
       */
-      sink(node->buf, node->n_bytes, writer);
+      sink(node_str, node->n_bytes, writer);
       return true;
     }
   }
@@ -527,17 +538,17 @@ write_literal(SerdWriter*        writer,
   if (supports_abbrev(writer) &&
       (node->flags & (SERD_HAS_NEWLINE | SERD_HAS_QUOTE))) {
     sink("\"\"\"", 3, writer);
-    write_text(writer, WRITE_LONG_STRING, node->buf, node->n_bytes);
+    write_text(writer, WRITE_LONG_STRING, node_str, node->n_bytes);
     sink("\"\"\"", 3, writer);
   } else {
     sink("\"", 1, writer);
-    write_text(writer, WRITE_STRING, node->buf, node->n_bytes);
+    write_text(writer, WRITE_STRING, node_str, node->n_bytes);
     sink("\"", 1, writer);
   }
-  if (lang && lang->buf) {
+  if (lang && serd_node_string(lang)) {
     sink("@", 1, writer);
-    sink(lang->buf, lang->n_bytes, writer);
-  } else if (datatype && datatype->buf) {
+    sink(serd_node_string(lang), lang->n_bytes, writer);
+  } else if (type_uri) {
     sink("^^", 2, writer);
     return write_node(writer, datatype, NULL, NULL, FIELD_NONE, flags);
   }
@@ -564,8 +575,8 @@ write_uri_node(SerdWriter* const        writer,
                const Field              field,
                const SerdStatementFlags flags)
 {
-  SerdNode       prefix;
-  SerdStringView suffix;
+  const SerdNode* prefix = NULL;
+  SerdStringView  suffix = {NULL, 0};
 
   if (is_inline_start(writer, field, flags)) {
     ++writer->indent;
@@ -573,20 +584,21 @@ write_uri_node(SerdWriter* const        writer,
     sink("== ", 3, writer);
   }
 
-  const bool has_scheme = serd_uri_string_has_scheme(node->buf);
+  const char* node_str   = serd_node_string(node);
+  const bool  has_scheme = serd_uri_string_has_scheme(node_str);
   if (supports_abbrev(writer)) {
-    if (field == FIELD_PREDICATE && !strcmp(node->buf, NS_RDF "type")) {
+    if (field == FIELD_PREDICATE && !strcmp(node_str, NS_RDF "type")) {
       return sink("a", 1, writer) == 1;
     }
 
-    if (!strcmp(node->buf, NS_RDF "nil")) {
+    if (!strcmp(node_str, NS_RDF "nil")) {
       return sink("()", 2, writer) == 2;
     }
 
     if (has_scheme && (writer->flags & SERD_WRITE_CURIED) &&
         serd_env_qualify(writer->env, node, &prefix, &suffix) &&
         is_name(suffix.buf, suffix.len)) {
-      write_uri(writer, prefix.buf, prefix.n_bytes);
+      write_uri_from_node(writer, prefix);
       sink(":", 1, writer);
       write_uri(writer, suffix.buf, suffix.len);
       return true;
@@ -594,11 +606,11 @@ write_uri_node(SerdWriter* const        writer,
   }
 
   if (!has_scheme && !supports_uriref(writer) &&
-      !serd_env_base_uri(writer->env, NULL)->buf) {
+      !serd_env_base_uri(writer->env, NULL)) {
     w_err(writer,
           SERD_ERR_BAD_ARG,
           "syntax does not support URI reference <%s>\n",
-          node->buf);
+          node_str);
     return false;
   }
 
@@ -608,7 +620,7 @@ write_uri_node(SerdWriter* const        writer,
     SerdURIView uri;
     SerdURIView abs_uri;
     serd_env_base_uri(writer->env, &in_base_uri);
-    serd_uri_parse(node->buf, &uri);
+    serd_uri_parse(node_str, &uri);
     serd_uri_resolve(&uri, &in_base_uri, &abs_uri);
     bool         rooted = uri_is_under(&writer->base_uri, &writer->root_uri);
     SerdURIView* root   = rooted ? &writer->root_uri : &writer->base_uri;
@@ -620,7 +632,7 @@ write_uri_node(SerdWriter* const        writer,
         &uri, &writer->base_uri, root, uri_sink, writer);
     }
   } else {
-    write_uri(writer, node->buf, node->n_bytes);
+    write_uri_from_node(writer, node);
   }
   write_sep(writer, SEP_URI_END);
   if (is_inline_start(writer, field, flags)) {
@@ -636,6 +648,8 @@ write_curie(SerdWriter* const        writer,
             const Field              field,
             const SerdStatementFlags flags)
 {
+  const char* node_str = serd_node_string(node);
+
   SerdStringView prefix = {NULL, 0};
   SerdStringView suffix = {NULL, 0};
   SerdStatus     st     = SERD_SUCCESS;
@@ -643,7 +657,7 @@ write_curie(SerdWriter* const        writer,
   case SERD_NTRIPLES:
   case SERD_NQUADS:
     if ((st = serd_env_expand(writer->env, node, &prefix, &suffix))) {
-      w_err(writer, st, "undefined namespace prefix `%s'\n", node->buf);
+      w_err(writer, st, "undefined namespace prefix `%s'\n", node_str);
       return false;
     }
     write_sep(writer, SEP_URI_BEGIN);
@@ -658,7 +672,7 @@ write_curie(SerdWriter* const        writer,
       write_sep(writer, SEP_ANON_BEGIN);
       sink("== ", 3, writer);
     }
-    write_lname(writer, node->buf, node->n_bytes);
+    write_lname(writer, node_str, node->n_bytes);
     if (is_inline_start(writer, field, flags)) {
       sink(" ;", 2, writer);
       write_newline(writer);
@@ -673,6 +687,7 @@ write_blank(SerdWriter* const        writer,
             const Field              field,
             const SerdStatementFlags flags)
 {
+  const char* node_str = serd_node_string(node);
   if (supports_abbrev(writer)) {
     if (is_inline_start(writer, field, flags)) {
       ++writer->indent;
@@ -681,7 +696,7 @@ write_blank(SerdWriter* const        writer,
 
     if (field == FIELD_SUBJECT && (flags & SERD_LIST_S_BEGIN)) {
       assert(writer->list_depth == 0);
-      copy_node(&writer->list_subj, node);
+      serd_node_set(&writer->list_subj, node);
       ++writer->list_depth;
       ++writer->indent;
       return write_sep(writer, SEP_LIST_BEGIN);
@@ -701,12 +716,12 @@ write_blank(SerdWriter* const        writer,
 
   sink("_:", 2, writer);
   if (writer->bprefix &&
-      !strncmp(node->buf, writer->bprefix, writer->bprefix_len)) {
-    sink(node->buf + writer->bprefix_len,
+      !strncmp(node_str, writer->bprefix, writer->bprefix_len)) {
+    sink(node_str + writer->bprefix_len,
          node->n_bytes - writer->bprefix_len,
          writer);
   } else {
-    sink(node->buf, node->n_bytes, writer);
+    sink(node_str, node->n_bytes, writer);
   }
 
   return true;
@@ -745,7 +760,7 @@ write_node(SerdWriter*        writer,
 static inline bool
 is_resource(const SerdNode* node)
 {
-  return node && node->buf && node->type > SERD_LITERAL;
+  return node && node->type > SERD_LITERAL;
 }
 
 static void
@@ -753,7 +768,7 @@ write_pred(SerdWriter* writer, SerdStatementFlags flags, const SerdNode* pred)
 {
   write_node(writer, pred, NULL, NULL, FIELD_PREDICATE, flags);
   write_sep(writer, SEP_P_O);
-  copy_node(&writer->context.predicate, pred);
+  serd_node_set(&writer->context.predicate, pred);
 }
 
 static bool
@@ -764,13 +779,13 @@ write_list_obj(SerdWriter*        writer,
                const SerdNode*    datatype,
                const SerdNode*    lang)
 {
-  if (!strcmp(object->buf, NS_RDF "nil")) {
+  if (!strcmp(serd_node_string(object), NS_RDF "nil")) {
     --writer->indent;
     write_sep(writer, SEP_LIST_END);
     return true;
   }
 
-  if (!strcmp(predicate->buf, NS_RDF "first")) {
+  if (!strcmp(serd_node_string(predicate), NS_RDF "first")) {
     write_sep(writer, SEP_LIST_SEP);
     write_node(writer, object, datatype, lang, FIELD_OBJECT, flags);
   }
@@ -788,8 +803,7 @@ serd_writer_write_statement(SerdWriter*        writer,
                             const SerdNode*    datatype,
                             const SerdNode*    lang)
 {
-  if (!is_resource(subject) || !is_resource(predicate) || !object ||
-      !object->buf) {
+  if (!is_resource(subject) || !is_resource(predicate) || !object) {
     return SERD_ERR_BAD_ARG;
   }
 
@@ -814,15 +828,13 @@ serd_writer_write_statement(SerdWriter*        writer,
     return SERD_SUCCESS;
   }
 
-  if ((graph && !serd_node_equals(graph, &writer->context.graph)) ||
-      (!graph && writer->context.graph.type)) {
+  if ((graph && !serd_node_equals(graph, writer->context.graph)) ||
+      (!graph && ctx(writer, FIELD_GRAPH))) {
     writer->indent = 0;
-
-    if (writer->context.subject.type) {
+    if (ctx(writer, FIELD_SUBJECT)) {
       write_sep(writer, SEP_END_S);
     }
-
-    if (writer->context.graph.type) {
+    if (ctx(writer, FIELD_GRAPH)) {
       write_sep(writer, SEP_GRAPH_END);
     }
 
@@ -831,23 +843,23 @@ serd_writer_write_statement(SerdWriter*        writer,
       TRY(write_node(writer, graph, datatype, lang, FIELD_GRAPH, flags));
       ++writer->indent;
       write_sep(writer, SEP_GRAPH_BEGIN);
-      copy_node(&writer->context.graph, graph);
+      serd_node_set(&writer->context.graph, graph);
     }
   }
 
   if ((flags & SERD_LIST_CONT)) {
     if (write_list_obj(writer, flags, predicate, object, datatype, lang)) {
       // Reached end of list
-      if (--writer->list_depth == 0 && writer->list_subj.type) {
+      if (--writer->list_depth == 0 && writer->list_subj) {
         reset_context(writer, false);
-        serd_node_free(&writer->context.subject);
+        serd_node_free(writer->context.subject);
         writer->context.subject = writer->list_subj;
-        writer->list_subj       = SERD_NODE_NULL;
+        writer->list_subj       = NULL;
       }
       return SERD_SUCCESS;
     }
-  } else if (serd_node_equals(subject, &writer->context.subject)) {
-    if (serd_node_equals(predicate, &writer->context.predicate)) {
+  } else if (serd_node_equals(subject, writer->context.subject)) {
+    if (serd_node_equals(predicate, writer->context.predicate)) {
       // Abbreviate S P
       if (!(flags & SERD_ANON_O_BEGIN)) {
         ++writer->indent;
@@ -859,14 +871,14 @@ serd_writer_write_statement(SerdWriter*        writer,
       }
     } else {
       // Abbreviate S
-      Sep sep = writer->context.predicate.type ? SEP_END_P : SEP_S_P;
+      Sep sep = ctx(writer, FIELD_PREDICATE) ? SEP_END_P : SEP_S_P;
       write_sep(writer, sep);
       write_pred(writer, flags, predicate);
       write_node(writer, object, datatype, lang, FIELD_OBJECT, flags);
     }
   } else {
     // No abbreviation
-    if (writer->context.subject.type) {
+    if (ctx(writer, FIELD_SUBJECT)) {
       assert(writer->indent > 0);
       --writer->indent;
       if (serd_stack_is_empty(&writer->anon_stack)) {
@@ -885,7 +897,7 @@ serd_writer_write_statement(SerdWriter*        writer,
     }
 
     reset_context(writer, false);
-    copy_node(&writer->context.subject, subject);
+    serd_node_set(&writer->context.subject, subject);
 
     if (!(flags & SERD_LIST_S_BEGIN)) {
       write_pred(writer, flags, predicate);
@@ -899,15 +911,15 @@ serd_writer_write_statement(SerdWriter*        writer,
       (WriteContext*)serd_stack_push(&writer->anon_stack, sizeof(WriteContext));
     *ctx                     = writer->context;
     WriteContext new_context = {
-      serd_node_copy(graph), serd_node_copy(subject), SERD_NODE_NULL};
+      serd_node_copy(graph), serd_node_copy(subject), NULL};
     if ((flags & SERD_ANON_S_BEGIN)) {
       new_context.predicate = serd_node_copy(predicate);
     }
     writer->context = new_context;
   } else {
-    copy_node(&writer->context.graph, graph);
-    copy_node(&writer->context.subject, subject);
-    copy_node(&writer->context.predicate, predicate);
+    serd_node_set(&writer->context.graph, graph);
+    serd_node_set(&writer->context.subject, subject);
+    serd_node_set(&writer->context.predicate, predicate);
   }
 
   return SERD_SUCCESS;
@@ -919,40 +931,37 @@ serd_writer_end_anon(SerdWriter* writer, const SerdNode* node)
   if (writer->syntax == SERD_NTRIPLES || writer->syntax == SERD_NQUADS) {
     return SERD_SUCCESS;
   }
-
   if (serd_stack_is_empty(&writer->anon_stack) || writer->indent == 0) {
     w_err(writer, SERD_ERR_UNKNOWN, "unexpected end of anonymous node\n");
     return SERD_ERR_UNKNOWN;
   }
-
   --writer->indent;
   write_sep(writer, SEP_ANON_END);
   free_context(writer);
   writer->context = *anon_stack_top(writer);
   serd_stack_pop(&writer->anon_stack, sizeof(WriteContext));
-  const bool is_subject = serd_node_equals(node, &writer->context.subject);
+  const bool is_subject = serd_node_equals(node, writer->context.subject);
   if (is_subject) {
-    copy_node(&writer->context.subject, node);
-    writer->context.predicate.type = SERD_NOTHING;
+    serd_node_set(&writer->context.subject, node);
+    memset(writer->context.predicate, 0, sizeof(SerdNode));
   }
-
   return SERD_SUCCESS;
 }
 
 SerdStatus
 serd_writer_finish(SerdWriter* writer)
 {
-  if (writer->context.subject.type) {
+  if (ctx(writer, FIELD_SUBJECT)) {
     write_sep(writer, SEP_END_S);
   }
-
-  if (writer->context.graph.type) {
+  if (ctx(writer, FIELD_GRAPH)) {
     write_sep(writer, SEP_GRAPH_END);
   }
-
   serd_byte_sink_flush(&writer->byte_sink);
-  writer->indent = 0;
-  return free_context(writer);
+  free_context(writer);
+  writer->indent  = 0;
+  writer->context = WRITE_CONTEXT_NULL;
+  return SERD_SUCCESS;
 }
 
 SerdWriter*
@@ -969,12 +978,12 @@ serd_writer_new(SerdSyntax         syntax,
   writer->syntax     = syntax;
   writer->flags      = flags;
   writer->env        = env;
-  writer->root_node  = SERD_NODE_NULL;
+  writer->root_node  = NULL;
   writer->root_uri   = SERD_URI_NULL;
   writer->base_uri   = base_uri ? *base_uri : SERD_URI_NULL;
   writer->anon_stack = serd_stack_new(4 * sizeof(WriteContext));
   writer->context    = context;
-  writer->list_subj  = SERD_NODE_NULL;
+  writer->list_subj  = NULL;
   writer->empty      = true;
   writer->byte_sink  = serd_byte_sink_new(
     ssink, stream, (flags & SERD_WRITE_BULK) ? SERD_PAGE_SIZE : 1);
@@ -1013,12 +1022,12 @@ serd_writer_set_base_uri(SerdWriter* writer, const SerdNode* uri)
     serd_env_base_uri(writer->env, &writer->base_uri);
 
     if (writer->syntax == SERD_TURTLE || writer->syntax == SERD_TRIG) {
-      if (writer->context.graph.type || writer->context.subject.type) {
+      if (ctx(writer, FIELD_GRAPH) || ctx(writer, FIELD_SUBJECT)) {
         sink(" .\n\n", 4, writer);
         reset_context(writer, true);
       }
       sink("@base <", 7, writer);
-      sink(uri->buf, uri->n_bytes, writer);
+      sink(serd_node_string(uri), uri->n_bytes, writer);
       sink("> .\n", 4, writer);
     }
     writer->indent = 0;
@@ -1030,16 +1039,14 @@ serd_writer_set_base_uri(SerdWriter* writer, const SerdNode* uri)
 SerdStatus
 serd_writer_set_root_uri(SerdWriter* writer, const SerdNode* uri)
 {
-  serd_node_free(&writer->root_node);
-
-  if (uri && uri->buf) {
+  serd_node_free(writer->root_node);
+  if (uri) {
     writer->root_node = serd_node_copy(uri);
-    serd_uri_parse(uri->buf, &writer->root_uri);
+    serd_uri_parse(serd_node_string(writer->root_node), &writer->root_uri);
   } else {
-    writer->root_node = SERD_NODE_NULL;
+    writer->root_node = NULL;
     writer->root_uri  = SERD_URI_NULL;
   }
-
   return SERD_SUCCESS;
 }
 
@@ -1050,20 +1057,19 @@ serd_writer_set_prefix(SerdWriter*     writer,
 {
   if (!serd_env_set_prefix(writer->env, name, uri)) {
     if (writer->syntax == SERD_TURTLE || writer->syntax == SERD_TRIG) {
-      if (writer->context.graph.type || writer->context.subject.type) {
+      if (ctx(writer, FIELD_GRAPH) || ctx(writer, FIELD_SUBJECT)) {
         sink(" .\n\n", 4, writer);
         reset_context(writer, true);
       }
       sink("@prefix ", 8, writer);
-      sink(name->buf, name->n_bytes, writer);
+      sink(serd_node_string(name), name->n_bytes, writer);
       sink(": <", 3, writer);
-      write_uri(writer, uri->buf, uri->n_bytes);
+      write_uri_from_node(writer, uri);
       sink("> .\n", 4, writer);
     }
     writer->indent = 0;
     return reset_context(writer, true);
   }
-
   return SERD_ERR_UNKNOWN;
 }
 
@@ -1078,7 +1084,7 @@ serd_writer_free(SerdWriter* writer)
   serd_stack_free(&writer->anon_stack);
   free(writer->bprefix);
   serd_byte_sink_free(&writer->byte_sink);
-  serd_node_free(&writer->root_node);
+  serd_node_free(writer->root_node);
   free(writer);
 }