Add SerdStatement

1 files changed, 89 insertions, 6 deletions

diff --git a/include/serd/serd.h b/include/serd/serd.h
index 611b0176..49cfcee4 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -893,6 +893,9 @@ serd_caret_column(const SerdCaret* SERD_NONNULL caret);
    @{
 */
 
+/// A subject, predicate, and object, with optional graph context
+typedef struct SerdStatementImpl SerdStatement;
+
 /// Index of a node in a statement
 typedef enum {
   SERD_SUBJECT   = 0, ///< Subject
@@ -902,6 +905,81 @@ typedef enum {
 } SerdField;
 
 /**
+   Create a new statement.
+
+   Note that, to minimise model overhead, statements do not own their nodes, so
+   they must have a longer lifetime than the statement for it to be valid.  For
+   statements in models, this is the lifetime of the model.  For user-created
+   statements, the simplest way to handle this is to use `SerdNodes`.
+
+   @param s The subject
+   @param p The predicate ("key")
+   @param o The object ("value")
+   @param g The graph ("context")
+   @param caret Optional caret at the origin of this statement
+   @return A new statement that must be freed with serd_statement_free()
+*/
+SERD_API
+SerdStatement* SERD_ALLOCATED
+serd_statement_new(const SerdNode* SERD_NONNULL   s,
+                   const SerdNode* SERD_NONNULL   p,
+                   const SerdNode* SERD_NONNULL   o,
+                   const SerdNode* SERD_NULLABLE  g,
+                   const SerdCaret* SERD_NULLABLE caret);
+
+/// Return a copy of `statement`
+SERD_API
+SerdStatement* SERD_ALLOCATED
+serd_statement_copy(const SerdStatement* SERD_NULLABLE statement);
+
+/// Free `statement`
+SERD_API
+void
+serd_statement_free(SerdStatement* SERD_NULLABLE statement);
+
+/// Return the given node of the statement
+SERD_PURE_API
+const SerdNode* SERD_NULLABLE
+serd_statement_node(const SerdStatement* SERD_NONNULL statement,
+                    SerdField                         field);
+
+/// Return the subject of the statement
+SERD_PURE_API
+const SerdNode* SERD_NONNULL
+serd_statement_subject(const SerdStatement* SERD_NONNULL statement);
+
+/// Return the predicate of the statement
+SERD_PURE_API
+const SerdNode* SERD_NONNULL
+serd_statement_predicate(const SerdStatement* SERD_NONNULL statement);
+
+/// Return the object of the statement
+SERD_PURE_API
+const SerdNode* SERD_NONNULL
+serd_statement_object(const SerdStatement* SERD_NONNULL statement);
+
+/// Return the graph of the statement
+SERD_PURE_API
+const SerdNode* SERD_NULLABLE
+serd_statement_graph(const SerdStatement* SERD_NONNULL statement);
+
+/// Return the source location where the statement originated, or NULL
+SERD_PURE_API
+const SerdCaret* SERD_NULLABLE
+serd_statement_caret(const SerdStatement* SERD_NONNULL statement);
+
+/**
+   Return true iff `a` is equal to `b`, ignoring statement caret metadata.
+
+   Only returns true if nodes are equivalent, does not perform wildcard
+   matching.
+*/
+SERD_PURE_API
+bool
+serd_statement_equals(const SerdStatement* SERD_NULLABLE a,
+                      const SerdStatement* SERD_NULLABLE b);
+
+/**
    @}
    @defgroup serd_world World
    @{
@@ -1007,12 +1085,10 @@ typedef SerdStatus (*SerdPrefixFunc)(void* SERD_NULLABLE          handle,
 
    Called for every RDF statement in the serialisation.
 */
-typedef SerdStatus (*SerdStatementFunc)(void* SERD_NULLABLE           handle,
-                                        SerdStatementFlags            flags,
-                                        const SerdNode* SERD_NULLABLE graph,
-                                        const SerdNode* SERD_NONNULL  subject,
-                                        const SerdNode* SERD_NONNULL  predicate,
-                                        const SerdNode* SERD_NONNULL  object);
+typedef SerdStatus (*SerdStatementFunc)(void* SERD_NULLABLE handle,
+                                        SerdStatementFlags  flags,
+                                        const SerdStatement* SERD_NONNULL
+                                          statement);
 
 /**
    Sink function for anonymous node end markers.
@@ -1092,6 +1168,13 @@ serd_sink_write_prefix(const SerdSink* SERD_NONNULL sink,
                        const SerdNode* SERD_NONNULL name,
                        const SerdNode* SERD_NONNULL uri);
 
+/// Write a statement
+SERD_API
+SerdStatus
+serd_sink_write_statement(const SerdSink* SERD_NONNULL      sink,
+                          SerdStatementFlags                flags,
+                          const SerdStatement* SERD_NONNULL statement);
+
 /// Write a statement from individual nodes
 SERD_API
 SerdStatus