Make forge API more fool-proof and automatically update container sizes to any depth.

4 files changed, 188 insertions, 152 deletions

diff --git a/lv2/lv2plug.in/ns/ext/atom/atom-test.c b/lv2/lv2plug.in/ns/ext/atom/atom-test.c
index 55d453c..2cc0da9 100644
--- a/lv2/lv2plug.in/ns/ext/atom/atom-test.c
+++ b/lv2/lv2plug.in/ns/ext/atom/atom-test.c
@@ -86,47 +86,48 @@ main()
 	uint8_t buf[BUF_SIZE];
 	lv2_atom_forge_set_buffer(&forge, buf, BUF_SIZE);
 
+	LV2_Atom_Forge_Frame obj_frame;
 	LV2_Atom* obj = (LV2_Atom*)lv2_atom_forge_resource(
-		&forge, NULL, 0, eg_Object);
+		&forge, &obj_frame, 0, eg_Object);
 
 	// eg_one = (Int32)1
-	lv2_atom_forge_property_head(&forge, obj, eg_one, 0);
-	LV2_Atom_Int32* one = lv2_atom_forge_int32(&forge, obj, 1);
+	lv2_atom_forge_property_head(&forge, eg_one, 0);
+	LV2_Atom_Int32* one = lv2_atom_forge_int32(&forge, 1);
 	if (one->value != 1) {
 		return test_fail("%d != 1\n", one->value);
 	}
 
 	// eg_two = (Int64)2
-	lv2_atom_forge_property_head(&forge, obj, eg_two, 0);
-	LV2_Atom_Int64* two = lv2_atom_forge_int64(&forge, obj, 2);
+	lv2_atom_forge_property_head(&forge, eg_two, 0);
+	LV2_Atom_Int64* two = lv2_atom_forge_int64(&forge, 2);
 	if (two->value != 2) {
 		return test_fail("%ld != 2\n", two->value);
 	}
 
 	// eg_three = (Float)3.0
-	lv2_atom_forge_property_head(&forge, obj, eg_three, 0);
-	LV2_Atom_Float* three = lv2_atom_forge_float(&forge, obj, 3.0f);
+	lv2_atom_forge_property_head(&forge, eg_three, 0);
+	LV2_Atom_Float* three = lv2_atom_forge_float(&forge, 3.0f);
 	if (three->value != 3) {
 		return test_fail("%f != 3\n", three->value);
 	}
 
 	// eg_four = (Double)4.0
-	lv2_atom_forge_property_head(&forge, obj, eg_four, 0);
-	LV2_Atom_Double* four = lv2_atom_forge_double(&forge, obj, 4.0);
+	lv2_atom_forge_property_head(&forge, eg_four, 0);
+	LV2_Atom_Double* four = lv2_atom_forge_double(&forge, 4.0);
 	if (four->value != 4) {
 		return test_fail("%ld != 4\n", four->value);
 	}
 
 	// eg_true = (Bool)1
-	lv2_atom_forge_property_head(&forge, obj, eg_true, 0);
-	LV2_Atom_Bool* t = lv2_atom_forge_bool(&forge, obj, true);
+	lv2_atom_forge_property_head(&forge, eg_true, 0);
+	LV2_Atom_Bool* t = lv2_atom_forge_bool(&forge, true);
 	if (t->value != 1) {
 		return test_fail("%ld != 1 (true)\n", t->value);
 	}
 
 	// eg_false = (Bool)0
-	lv2_atom_forge_property_head(&forge, obj, eg_false, 0);
-	LV2_Atom_Bool* f = lv2_atom_forge_bool(&forge, obj, false);
+	lv2_atom_forge_property_head(&forge, eg_false, 0);
+	LV2_Atom_Bool* f = lv2_atom_forge_bool(&forge, false);
 	if (f->value != 0) {
 		return test_fail("%ld != 0 (false)\n", f->value);
 	}
@@ -134,8 +135,8 @@ main()
 	// eg_uri = (URI)"http://example.org/value"
 	const uint8_t* ustr     = (const uint8_t*)"http://example.org/value";
 	const size_t   ustr_len = strlen((const char*)ustr);
-	lv2_atom_forge_property_head(&forge, obj, eg_uri, 0);
-	LV2_Atom_String* uri  = lv2_atom_forge_uri(&forge, obj, ustr, ustr_len);
+	lv2_atom_forge_property_head(&forge, eg_uri, 0);
+	LV2_Atom_String* uri  = lv2_atom_forge_uri(&forge, ustr, ustr_len);
 	uint8_t*         body = (uint8_t*)LV2_ATOM_BODY(uri);
 	if (strcmp((const char*)body, (const char*)ustr)) {
 		return test_fail("%s != \"%s\"\n",
@@ -144,25 +145,25 @@ main()
 
 	// eg_urid = (URID)"http://example.org/value"
 	LV2_URID eg_value = urid_map(NULL, "http://example.org/value");
-	lv2_atom_forge_property_head(&forge, obj, eg_urid, 0);
-	LV2_Atom_URID* urid = lv2_atom_forge_urid(&forge, obj, eg_value);
+	lv2_atom_forge_property_head(&forge, eg_urid, 0);
+	LV2_Atom_URID* urid = lv2_atom_forge_urid(&forge, eg_value);
 	if (urid->id != eg_value) {
 		return test_fail("%u != %u\n", urid->id, eg_value);
 	}
 
 	// eg_string = (String)"hello"
-	lv2_atom_forge_property_head(&forge, obj, eg_string, 0);
+	lv2_atom_forge_property_head(&forge, eg_string, 0);
 	LV2_Atom_String* string = lv2_atom_forge_string(
-		&forge, obj, (const uint8_t*)"hello", strlen("hello"));
+		&forge, (const uint8_t*)"hello", strlen("hello"));
 	uint8_t* sbody = (uint8_t*)LV2_ATOM_BODY(string);
 	if (strcmp((const char*)sbody, "hello")) {
 		return test_fail("%s != \"hello\"\n", (const char*)body);
 	}
 
 	// eg_literal = (Literal)"hello"@fr
-	lv2_atom_forge_property_head(&forge, obj, eg_literal, 0);
+	lv2_atom_forge_property_head(&forge, eg_literal, 0);
 	LV2_Atom_Literal* literal = lv2_atom_forge_literal(
-		&forge, obj, (const uint8_t*)"bonjour", strlen("bonjour"),
+		&forge, (const uint8_t*)"bonjour", strlen("bonjour"),
 		0, urid_map(NULL, "http://lexvo.org/id/term/fr"));
 	body = (uint8_t*)LV2_ATOM_CONTENTS(LV2_Atom_Literal, literal);
 	if (strcmp((const char*)body, "bonjour")) {
@@ -170,12 +171,14 @@ main()
 	}
 
 	// eg_tuple = "foo",true
-	lv2_atom_forge_property_head(&forge, obj, eg_tuple, 0);
-	LV2_Atom_Tuple*  tuple = lv2_atom_forge_tuple(&forge, obj);
-	LV2_Atom_String* tup0  = lv2_atom_forge_string(
-		&forge, (LV2_Atom*)tuple, (const uint8_t*)"foo", strlen("foo"));
-	LV2_Atom_Bool* tup1 = lv2_atom_forge_bool(&forge, (LV2_Atom*)tuple, true);
-	obj->size += ((LV2_Atom*)tuple)->size;
+	lv2_atom_forge_property_head(&forge, eg_tuple, 0);
+	LV2_Atom_Forge_Frame tuple_frame;
+	LV2_Atom_Tuple*      tuple = (LV2_Atom_Tuple*)lv2_atom_forge_tuple(
+		&forge, &tuple_frame);
+	LV2_Atom_String* tup0 = lv2_atom_forge_string(
+		&forge, (const uint8_t*)"foo", strlen("foo"));
+	LV2_Atom_Bool* tup1 = lv2_atom_forge_bool(&forge, true);
+	lv2_atom_forge_pop(&forge, &tuple_frame);
 	LV2_Atom_Tuple_Iter i = lv2_tuple_begin(tuple);
 	if (lv2_tuple_is_end(tuple, i)) {
 		return test_fail("Tuple iterator is empty\n");
@@ -198,23 +201,26 @@ main()
 	}
 
 	// eg_vector = (Vector<Int32>)1,2,3,4
-	lv2_atom_forge_property_head(&forge, obj, eg_vector, 0);
+	lv2_atom_forge_property_head(&forge, eg_vector, 0);
 	int32_t elems[] = { 1, 2, 3, 4 };
 	LV2_Atom_Vector* vector = lv2_atom_forge_vector(
-		&forge, obj, 4, forge.Int32, sizeof(int32_t), elems);
+		&forge, 4, forge.Int32, sizeof(int32_t), elems);
 	void* vec_body = LV2_ATOM_CONTENTS(LV2_Atom_Vector, vector);
 	if (memcmp(elems, vec_body, sizeof(elems))) {
 		return test_fail("Corrupt vector\n");
 	}
 
 	// eg_seq = (Sequence)1, 2
-	lv2_atom_forge_property_head(&forge, obj, eg_seq, 0);
-	LV2_Atom_Sequence* seq = lv2_atom_forge_sequence_head(&forge, obj, 0, 0);
-	lv2_atom_forge_audio_time(&forge, (LV2_Atom*)seq, 0, 0);
-	lv2_atom_forge_int32(&forge, (LV2_Atom*)seq, 1);
-	lv2_atom_forge_audio_time(&forge, (LV2_Atom*)seq, 1, 0);
-	lv2_atom_forge_int32(&forge, (LV2_Atom*)seq, 2);
-	obj->size += seq->atom.size - sizeof(LV2_Atom);
+	lv2_atom_forge_property_head(&forge, eg_seq, 0);
+	LV2_Atom_Forge_Frame seq_frame;
+	LV2_Atom_Sequence* seq = (LV2_Atom_Sequence*)lv2_atom_forge_sequence_head(&forge, &seq_frame, 0);
+	lv2_atom_forge_audio_time(&forge, 0, 0);
+	lv2_atom_forge_int32(&forge, 1);
+	lv2_atom_forge_audio_time(&forge, 1, 0);
+	lv2_atom_forge_int32(&forge, 2);
+	lv2_atom_forge_pop(&forge, &seq_frame);
+
+	lv2_atom_forge_pop(&forge, &obj_frame);
 
 	// Test equality
 	LV2_Atom_Int32 itwo = { { forge.Int32, sizeof(int32_t) }, 2 };
@@ -279,6 +285,7 @@ main()
 		{ eg_four,    &matches.four },
 		{ eg_true,    &matches.affirmative },
 		{ eg_false,   &matches.negative },
+		{ eg_uri,     &matches.uri },
 		{ eg_urid,    &matches.urid },
 		{ eg_string,  &matches.string },
 		{ eg_literal, &matches.literal },
diff --git a/lv2/lv2plug.in/ns/ext/atom/forge.h b/lv2/lv2plug.in/ns/ext/atom/forge.h
index 9735302..0f32db3 100644
--- a/lv2/lv2plug.in/ns/ext/atom/forge.h
+++ b/lv2/lv2plug.in/ns/ext/atom/forge.h
@@ -19,8 +19,7 @@
 
    This file provides a simple API which can be used to create complex nested
    atoms by calling the provided functions to append atoms (or atom headers) in
-   the correct order.  The size of the parent atom is automatically updated,
-   but the caller must handle this situation if atoms are more deeply nested.
+   the correct order.
 
    All output is written to a user-provided buffer.  This entire API is
    realtime safe and suitable for writing to output port buffers in the run
@@ -53,9 +52,13 @@ typedef uint32_t (*LV2_Atom_Forge_Sink)(LV2_Atom_Forge_Sink_Handle handle,
                                         const void*                buf,
                                         uint32_t                   size);
 
-/**
-   A "forge" for creating atoms by appending to a buffer.
-*/
+/** A stack frame used for keeping track of nested Atom containers. */
+typedef struct _LV2_Atom_Forge_Frame {
+	struct _LV2_Atom_Forge_Frame* parent;
+	LV2_Atom*                     atom;
+} LV2_Atom_Forge_Frame;
+
+/** A "forge" for creating atoms by appending to a buffer. */
 typedef struct {
 	uint8_t* buf;
 	uint32_t offset;
@@ -64,6 +67,8 @@ typedef struct {
 	LV2_Atom_Forge_Sink        sink;
 	LV2_Atom_Forge_Sink_Handle handle;
 
+	LV2_Atom_Forge_Frame* stack;
+
 	LV2_URID Blank;
 	LV2_URID Bool;
 	LV2_URID Double;
@@ -81,7 +86,25 @@ typedef struct {
 	LV2_URID Vector;
 } LV2_Atom_Forge;
 
-/** Set the output buffer where @c forge will write atoms. */
+static inline LV2_Atom*
+lv2_atom_forge_push(LV2_Atom_Forge*       forge,
+                    LV2_Atom_Forge_Frame* frame,
+                    LV2_Atom*             atom)
+{
+	frame->parent = forge->stack;
+	frame->atom   = atom;
+	forge->stack  = frame;
+	return atom;
+}
+
+static inline void
+lv2_atom_forge_pop(LV2_Atom_Forge* forge, LV2_Atom_Forge_Frame* frame)
+{
+	assert(frame == forge->stack);
+	forge->stack = frame->parent;
+}
+
+/** Set the output buffer where @p forge will write atoms. */
 static inline void
 lv2_atom_forge_set_buffer(LV2_Atom_Forge* forge, uint8_t* buf, size_t size)
 {
@@ -90,6 +113,7 @@ lv2_atom_forge_set_buffer(LV2_Atom_Forge* forge, uint8_t* buf, size_t size)
 	forge->offset = 0;
 }
 
+/** Set the sink function where @p forge will write output. */
 static inline void
 lv2_atom_forge_set_sink(LV2_Atom_Forge*            forge,
                         LV2_Atom_Forge_Sink        sink,
@@ -102,15 +126,16 @@ lv2_atom_forge_set_sink(LV2_Atom_Forge*            forge,
 }
 
 /**
-   Initialise @c forge.
+   Initialise @p forge.
 
-   URIs will be mapped using @c map and stored, a reference to @c map itself is
+   URIs will be mapped using @p map and stored, a reference to @p map itself is
    not held.
 */
 static inline void
 lv2_atom_forge_init(LV2_Atom_Forge* forge, LV2_URID_Map* map)
 {
 	lv2_atom_forge_set_buffer(forge, NULL, 0);
+	forge->stack    = NULL;
 	forge->Blank    = map->map(map->handle, LV2_ATOM_URI "#Blank");
 	forge->Bool     = map->map(map->handle, LV2_ATOM_URI "#Bool");
 	forge->Double   = map->map(map->handle, LV2_ATOM_URI "#Double");
@@ -130,7 +155,6 @@ lv2_atom_forge_init(LV2_Atom_Forge* forge, LV2_URID_Map* map)
 
 static inline void*
 lv2_atom_forge_write_nopad(LV2_Atom_Forge* forge,
-                           LV2_Atom*       parent,
                            const void*     data,
                            uint32_t        size)
 {
@@ -138,97 +162,94 @@ lv2_atom_forge_write_nopad(LV2_Atom_Forge* forge,
 	if (forge->offset + size > forge->size) {
 		return NULL;
 	}
-	if (parent) {
-		parent->size += size;
-	}
 	forge->offset += size;
 	memcpy(out, data, size);
+	for (LV2_Atom_Forge_Frame* f = forge->stack; f; f = f->parent) {
+		f->atom->size += size;
+	}
 	return out;
 }
 
 static inline void
 lv2_atom_forge_pad(LV2_Atom_Forge* forge,
-                   LV2_Atom*       parent,
                    uint32_t        written)
 {
 	const uint64_t pad      = 0;
 	const uint32_t pad_size = lv2_atom_pad_size(written) - written;
-	lv2_atom_forge_write_nopad(forge, parent, &pad, pad_size);
+	lv2_atom_forge_write_nopad(forge, &pad, pad_size);
 }
 
 static inline void*
 lv2_atom_forge_write(LV2_Atom_Forge* forge,
-                     LV2_Atom*       parent,
                      const void*     data,
                      uint32_t        size)
 {
-	void* out = lv2_atom_forge_write_nopad(forge, parent, data, size);
+	void* out = lv2_atom_forge_write_nopad(forge, data, size);
 	if (out) {
-		lv2_atom_forge_pad(forge, parent, size);
+		lv2_atom_forge_pad(forge, size);
 	}
 	return out;
 }
 
 /** Write an atom:Int32. */
 static inline LV2_Atom_Int32*
-lv2_atom_forge_int32(LV2_Atom_Forge* forge, LV2_Atom* parent, int32_t val)
+lv2_atom_forge_int32(LV2_Atom_Forge* forge, int32_t val)
 {
 	const LV2_Atom_Int32 a = { { forge->Int32, sizeof(val) }, val };
-	return (LV2_Atom_Int32*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	return (LV2_Atom_Int32*)lv2_atom_forge_write(forge, &a, sizeof(a));
 }
 
 /** Write an atom:Int64. */
 static inline LV2_Atom_Int64*
-lv2_atom_forge_int64(LV2_Atom_Forge* forge, LV2_Atom* parent, int64_t val)
+lv2_atom_forge_int64(LV2_Atom_Forge* forge, int64_t val)
 {
 	const LV2_Atom_Int64 a = { { forge->Int64, sizeof(val) }, val };
-	return (LV2_Atom_Int64*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	return (LV2_Atom_Int64*)lv2_atom_forge_write(forge, &a, sizeof(a));
 }
 
 /** Write an atom:Float. */
 static inline LV2_Atom_Float*
-lv2_atom_forge_float(LV2_Atom_Forge* forge, LV2_Atom* parent, float val)
+lv2_atom_forge_float(LV2_Atom_Forge* forge, float val)
 {
 	const LV2_Atom_Float a = { { forge->Float, sizeof(val) }, val };
-	return (LV2_Atom_Float*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	return (LV2_Atom_Float*)lv2_atom_forge_write(forge, &a, sizeof(a));
 }
 
 /** Write an atom:Double. */
 static inline LV2_Atom_Double*
-lv2_atom_forge_double(LV2_Atom_Forge* forge, LV2_Atom* parent, double val)
+lv2_atom_forge_double(LV2_Atom_Forge* forge, double val)
 {
 	const LV2_Atom_Double a = { { forge->Double, sizeof(val) }, val };
 	return (LV2_Atom_Double*)lv2_atom_forge_write(
-		forge, parent, &a, sizeof(a));
+		forge, &a, sizeof(a));
 }
 
 /** Write an atom:Bool. */
 static inline LV2_Atom_Bool*
-lv2_atom_forge_bool(LV2_Atom_Forge* forge, LV2_Atom* parent, bool val)
+lv2_atom_forge_bool(LV2_Atom_Forge* forge, bool val)
 {
 	const LV2_Atom_Bool a = { { forge->Bool, sizeof(val) }, val };
-	return (LV2_Atom_Bool*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	return (LV2_Atom_Bool*)lv2_atom_forge_write(forge, &a, sizeof(a));
 }
 
 /** Write an atom:URID. */
 static inline LV2_Atom_URID*
-lv2_atom_forge_urid(LV2_Atom_Forge* forge, LV2_Atom* parent, LV2_URID id)
+lv2_atom_forge_urid(LV2_Atom_Forge* forge, LV2_URID id)
 {
 	const LV2_Atom_URID a = { { forge->Int32, sizeof(id) }, id };
-	return (LV2_Atom_URID*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	return (LV2_Atom_URID*)lv2_atom_forge_write(forge, &a, sizeof(a));
 }
 
 /** Write a string body.  Used internally. */
 static inline uint8_t*
 lv2_atom_forge_string_body(LV2_Atom_Forge* forge,
-                           LV2_Atom*       parent,
                            const uint8_t*  str,
                            size_t          len)
 {
 	uint8_t* out = NULL;
-	if ((out = lv2_atom_forge_write_nopad(forge, parent, str, len))
-	    && (out = lv2_atom_forge_write_nopad(forge, parent, "", 1))) {
-		lv2_atom_forge_pad(forge, parent, len + 1);
+	if ((out = lv2_atom_forge_write_nopad(forge, str, len))
+	    && (out = lv2_atom_forge_write_nopad(forge, "", 1))) {
+		lv2_atom_forge_pad(forge, len + 1);
 	}
 	return out;
 }
@@ -236,15 +257,14 @@ lv2_atom_forge_string_body(LV2_Atom_Forge* forge,
 /** Write an atom:String.  Note that @p str need not be NULL terminated. */
 static inline LV2_Atom_String*
 lv2_atom_forge_string(LV2_Atom_Forge* forge,
-                      LV2_Atom*       parent,
                       const uint8_t*  str,
                       size_t          len)
 {
 	const LV2_Atom_String a = { { forge->String, len + 1 } };
 	LV2_Atom_String* out = (LV2_Atom_String*)
-		lv2_atom_forge_write_nopad(forge, parent, &a, sizeof(a));
+		lv2_atom_forge_write_nopad(forge, &a, sizeof(a));
 	if (out) {
-		if (!lv2_atom_forge_string_body(forge, parent, str, len)) {
+		if (!lv2_atom_forge_string_body(forge, str, len)) {
 			out->atom.type = 0;
 			out->atom.size = 0;
 			out = NULL;
@@ -260,17 +280,16 @@ lv2_atom_forge_string(LV2_Atom_Forge* forge,
 */
 static inline LV2_Atom_String*
 lv2_atom_forge_uri(LV2_Atom_Forge* forge,
-                   LV2_Atom*       parent,
                    const uint8_t*  uri,
                    size_t          len)
 {
 	const LV2_Atom_String a = { { forge->URI, len + 1 } };
 	LV2_Atom_String* out = (LV2_Atom_String*)
-		lv2_atom_forge_write_nopad(forge, parent, &a, sizeof(a));
+		lv2_atom_forge_write_nopad(forge, &a, sizeof(a));
 	if (!out) {
 		return NULL;
 	}
-	if (!lv2_atom_forge_string_body(forge, parent, uri, len)) {
+	if (!lv2_atom_forge_string_body(forge, uri, len)) {
 		out->atom.type = 0;
 		out->atom.size = 0;
 		return NULL;
@@ -281,7 +300,6 @@ lv2_atom_forge_uri(LV2_Atom_Forge* forge,
 /** Write an atom:Literal. */
 static inline LV2_Atom_Literal*
 lv2_atom_forge_literal(LV2_Atom_Forge* forge,
-                       LV2_Atom*       parent,
                        const uint8_t*  str,
                        size_t          len,
                        uint32_t        datatype,
@@ -294,9 +312,9 @@ lv2_atom_forge_literal(LV2_Atom_Forge* forge,
 		lang
 	};
 	LV2_Atom_Literal* out = (LV2_Atom_Literal*)
-		lv2_atom_forge_write_nopad(forge, parent, &a, sizeof(a));
+		lv2_atom_forge_write_nopad(forge, &a, sizeof(a));
 	if (out) {
-		if (!lv2_atom_forge_string_body(forge, parent, str, len)) {
+		if (!lv2_atom_forge_string_body(forge, str, len)) {
 			out->atom.type = 0;
 			out->atom.size = 0;
 			out = NULL;
@@ -308,7 +326,6 @@ lv2_atom_forge_literal(LV2_Atom_Forge* forge,
 /** Write an atom:Vector header, but not the vector body. */
 static inline LV2_Atom_Vector*
 lv2_atom_forge_vector_head(LV2_Atom_Forge* forge,
-                           LV2_Atom*       parent,
                            uint32_t        elem_count,
                            uint32_t        elem_type,
                            uint32_t        elem_size)
@@ -320,22 +337,21 @@ lv2_atom_forge_vector_head(LV2_Atom_Forge* forge,
 		elem_type
 	};
 	return (LV2_Atom_Vector*)lv2_atom_forge_write(
-		forge, parent, &a, sizeof(a));
+		forge, &a, sizeof(a));
 }
 
 /** Write a complete atom:Vector. */
 static inline LV2_Atom_Vector*
 lv2_atom_forge_vector(LV2_Atom_Forge* forge,
-                      LV2_Atom*       parent,
                       uint32_t        elem_count,
                       uint32_t        elem_type,
                       uint32_t        elem_size,
                       void*           elems)
 {
 	LV2_Atom_Vector* out = lv2_atom_forge_vector_head(
-		forge, parent, elem_count, elem_type, elem_size);
+		forge, elem_count, elem_type, elem_size);
 	if (out) {
-		lv2_atom_forge_write(forge, parent, elems, elem_size * elem_count);
+		lv2_atom_forge_write(forge, elems, elem_size * elem_count);
 	}
 	return out;
 }
@@ -343,32 +359,34 @@ lv2_atom_forge_vector(LV2_Atom_Forge* forge,
 /**
    Write the header of an atom:Tuple.
 
-   To complete the tuple, write a sequence of atoms, always passing the
-   returned tuple as the @c parent parameter (or otherwise ensuring the size is
-   updated correctly).
+   The passed frame will be initialised to represent this tuple.  To complete
+   the tuple, write a sequence of atoms, then pop the frame with
+   lv2_atom_forge_pop().
 
    For example:
    @code
    // Write tuple (1, 2.0)
-   LV2_Atom* tup = (LV2_Atom*)lv2_atom_forge_tuple(forge, NULL);
-   lv2_atom_forge_int32(forge, tup, 1);
-   lv2_atom_forge_float(forge, tup, 2.0);
+   LV2_Atom_Forge_Frame frame;
+   LV2_Atom* tup = (LV2_Atom*)lv2_atom_forge_tuple(forge, &frame);
+   lv2_atom_forge_int32(forge, 1);
+   lv2_atom_forge_float(forge, 2.0);
+   lv2_atom_forge_pop(forge, &frame);
    @endcode
 */
-static inline LV2_Atom_Tuple*
-lv2_atom_forge_tuple(LV2_Atom_Forge* forge,
-                     LV2_Atom*       parent)
+static inline LV2_Atom*
+lv2_atom_forge_tuple(LV2_Atom_Forge* forge, LV2_Atom_Forge_Frame* frame)
 {
-	const LV2_Atom_Tuple a = { { forge->Tuple, 0 } };
-	return (LV2_Atom_Tuple*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	const LV2_Atom_Tuple a    = { { forge->Tuple, 0 } };
+	LV2_Atom*            atom = lv2_atom_forge_write(forge, &a, sizeof(a));
+	return lv2_atom_forge_push(forge, frame, atom);
 }
 
 /**
    Write the header of an atom:Resource.
 
-   To complete the object, write a sequence of properties, always passing the
-   object as the @c parent parameter (or otherwise ensuring the size is updated
-   correctly).
+   The passed frame will be initialised to represent this object.  To complete
+   the object, write a sequence of properties, then pop the frame with
+   lv2_atom_forge_pop().
 
    For example:
    @code
@@ -376,42 +394,48 @@ lv2_atom_forge_tuple(LV2_Atom_Forge* forge,
    LV2_URID eg_name = map("http://example.org/name");
 
    // Write object header
-   LV2_Atom* obj = (LV2_Atom*)lv2_atom_forge_resource(forge, NULL, 0, eg_Cat);
+   LV2_Atom_Forge_Frame frame;
+   LV2_Atom* obj = (LV2_Atom*)lv2_atom_forge_resource(forge, &frame, 1, eg_Cat);
 
    // Write property: eg:name = "Hobbes"
-   lv2_atom_forge_property_head(forge, obj, eg_name, 0);
-   lv2_atom_forge_string(forge, obj, "Hobbes", strlen("Hobbes"));
+   lv2_atom_forge_property_head(forge, eg_name, 0);
+   lv2_atom_forge_string(forge, "Hobbes", strlen("Hobbes"));
+
+   // Finish object
+   lv2_atom_forge_pop(forge, &frame);
    @endcode
 */
-static inline LV2_Atom_Object*
-lv2_atom_forge_resource(LV2_Atom_Forge* forge,
-                        LV2_Atom*       parent,
-                        LV2_URID        id,
-                        LV2_URID        otype)
+static inline LV2_Atom*
+lv2_atom_forge_resource(LV2_Atom_Forge*       forge,
+                        LV2_Atom_Forge_Frame* frame,
+                        LV2_URID              id,
+                        LV2_URID              otype)
 {
 	const LV2_Atom_Object a = {
 		{ forge->Resource, sizeof(LV2_Atom_Object) - sizeof(LV2_Atom) },
 		id,
 		otype
 	};
-	return (LV2_Atom_Object*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	LV2_Atom* atom = (LV2_Atom*)lv2_atom_forge_write(forge, &a, sizeof(a));
+	return lv2_atom_forge_push(forge, frame, atom);
 }
 
 /**
    The same as lv2_atom_forge_resource(), but for object:Blank.
 */
-static inline LV2_Atom_Object*
-lv2_atom_forge_blank(LV2_Atom_Forge* forge,
-                     LV2_Atom*       parent,
-                     uint32_t        id,
-                     LV2_URID        otype)
+static inline LV2_Atom*
+lv2_atom_forge_blank(LV2_Atom_Forge*       forge,
+                     LV2_Atom_Forge_Frame* frame,
+                     uint32_t              id,
+                     LV2_URID              otype)
 {
 	const LV2_Atom_Object a = {
 		{ forge->Blank, sizeof(LV2_Atom_Object) - sizeof(LV2_Atom) },
 		id,
 		otype
 	};
-	return (LV2_Atom_Object*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	LV2_Atom* atom = (LV2_Atom*)lv2_atom_forge_write(forge, &a, sizeof(a));
+	return lv2_atom_forge_push(forge, frame, atom);
 }
 
 /**
@@ -420,13 +444,12 @@ lv2_atom_forge_blank(LV2_Atom_Forge* forge,
 */
 static inline LV2_Atom_Property_Body*
 lv2_atom_forge_property_head(LV2_Atom_Forge* forge,
-                             LV2_Atom*       parent,
                              LV2_URID        key,
                              LV2_URID        context)
 {
 	const LV2_Atom_Property_Body a = { key, context, { 0, 0 } };
 	return (LV2_Atom_Property_Body*)lv2_atom_forge_write(
-		forge, parent, &a, 2 * sizeof(uint32_t));
+		forge, &a, 2 * sizeof(uint32_t));
 }
 
 /**
@@ -434,48 +457,45 @@ lv2_atom_forge_property_head(LV2_Atom_Forge* forge,
    The size of the returned sequence will be 0, so passing it as the parent
    parameter to other forge methods will do the right thing.
 */
-static inline LV2_Atom_Sequence*
-lv2_atom_forge_sequence_head(LV2_Atom_Forge* forge,
-                             LV2_Atom*       parent,
-                             uint32_t        capacity,
-                             uint32_t        unit)
+static inline LV2_Atom*
+lv2_atom_forge_sequence_head(LV2_Atom_Forge*       forge,
+                             LV2_Atom_Forge_Frame* frame,
+                             uint32_t              unit)
 {
 	const LV2_Atom_Sequence a = {
 		{ forge->Sequence, sizeof(LV2_Atom_Sequence) - sizeof(LV2_Atom) },
 		unit,
 		0
 	};
-	return (LV2_Atom_Sequence*)lv2_atom_forge_write(
-		forge, parent, &a, sizeof(a));
+	LV2_Atom* atom = (LV2_Atom*)lv2_atom_forge_write(forge, &a, sizeof(a));
+	return lv2_atom_forge_push(forge, frame, atom);
 }
 
 /**
    Write the time stamp header of an Event (in a Sequence) in audio frames.
    After this, call the appropriate forge method(s) to write the body, passing
-   the same @c parent parameter.  Note the returned LV2_Event is NOT an Atom.
+   the same @p parent parameter.  Note the returned LV2_Event is NOT an Atom.
 */
 static inline LV2_Atom_Event*
 lv2_atom_forge_audio_time(LV2_Atom_Forge* forge,
-                          LV2_Atom*       parent,
                           uint32_t        frames,
                           uint32_t        subframes)
 {
 	const LV2_Atom_Audio_Time a = { frames, subframes };
-	return (LV2_Atom_Event*)lv2_atom_forge_write(forge, parent, &a, sizeof(a));
+	return (LV2_Atom_Event*)lv2_atom_forge_write(forge, &a, sizeof(a));
 }
 
 /**
    Write the time stamp header of an Event (in a Sequence) in beats.
    After this, call the appropriate forge method(s) to write the body, passing
-   the same @c parent parameter.  Note the returned LV2_Event is NOT an Atom.
+   the same @p parent parameter.  Note the returned LV2_Event is NOT an Atom.
 */
 static inline LV2_Atom_Event*
 lv2_atom_forge_beat_time(LV2_Atom_Forge* forge,
-                         LV2_Atom*       parent,
                          double          beats)
 {
 	return (LV2_Atom_Event*)lv2_atom_forge_write(
-		forge, parent, &beats, sizeof(beats));
+		forge, &beats, sizeof(beats));
 }
 
 #ifdef __cplusplus
diff --git a/plugins/eg-sampler.lv2/sampler.c b/plugins/eg-sampler.lv2/sampler.c
index 8ef7bf9..904f026 100644
--- a/plugins/eg-sampler.lv2/sampler.c
+++ b/plugins/eg-sampler.lv2/sampler.c
@@ -354,24 +354,25 @@ static void
 run(LV2_Handle instance,
     uint32_t   sample_count)
 {
-	Sampler*   plugin      = (Sampler*)instance;
-	sf_count_t start_frame = 0;
-	sf_count_t pos         = 0;
-	float*     output      = plugin->output_port;
+	Sampler*     plugin      = (Sampler*)instance;
+	SamplerURIs* uris        = &plugin->uris;
+	sf_count_t   start_frame = 0;
+	sf_count_t   pos         = 0;
+	float*       output      = plugin->output_port;
 
 	/* Read incoming events */
 	LV2_SEQUENCE_FOREACH((LV2_Atom_Sequence*)plugin->control_port->data, i) {
 		LV2_Atom_Event* const ev = lv2_sequence_iter_get(i);
-		if (ev->body.type == plugin->uris.midi_Event) {
+		if (ev->body.type == uris->midi_Event) {
 			uint8_t* const data = (uint8_t* const)(ev + 1);
 			if ((data[0] & 0xF0) == 0x90) {
 				start_frame   = ev->time.audio.frames;
 				plugin->frame = 0;
 				plugin->play  = true;
 			}
-		} else if (is_object_type(&plugin->uris, ev->body.type)) {
+		} else if (is_object_type(uris, ev->body.type)) {
 			const LV2_Atom_Object* obj = (LV2_Atom_Object*)&ev->body;
-			if (obj->type == plugin->uris.msg_Set) {
+			if (obj->type == uris->msg_Set) {
 				/* Received a set message, send it to the worker thread. */
 				fprintf(stderr, "Queueing set message\n");
 				zix_ring_write(plugin->to_worker,
@@ -414,6 +415,8 @@ run(LV2_Handle instance,
 
 	/* Set up forge to write directly to notify output port buffer */
 	LV2_Atom* seq = plugin->notify_port->data;
+	LV2_Atom_Forge_Frame seq_frame;
+	lv2_atom_forge_push(&plugin->forge, &seq_frame, seq);
 	lv2_atom_forge_set_buffer(
 		&plugin->forge,
 		LV2_ATOM_CONTENTS(LV2_Atom_Sequence, seq),
@@ -423,10 +426,10 @@ run(LV2_Handle instance,
 	SampleMessage  m;
 	const uint32_t msize = lv2_atom_pad_size(sizeof(m));
 	while (zix_ring_read(plugin->from_worker, &m, msize) == msize) {
-		if (m.atom.type == plugin->uris.eg_applySample) {
+		if (m.atom.type == uris->eg_applySample) {
 			/* Send a message to the worker to free the current sample */
 			SampleMessage free_msg = {
-				{ plugin->uris.eg_freeSample, sizeof(plugin->sample) },
+				{ uris->eg_freeSample, sizeof(plugin->sample) },
 				plugin->sample
 			};
 			zix_ring_write(plugin->to_worker,
@@ -439,26 +442,29 @@ run(LV2_Handle instance,
 
 			/* Send a notification that we're using a new sample. */
 
-			lv2_atom_forge_audio_time(&plugin->forge, seq, 0, 0);
+			lv2_atom_forge_audio_time(&plugin->forge, 0, 0);
 
-			LV2_Atom* set = (LV2_Atom*)lv2_atom_forge_blank(
-				&plugin->forge, NULL, 1, plugin->uris.msg_Set);
+			LV2_Atom_Forge_Frame set_frame;
+			lv2_atom_forge_blank(&plugin->forge, &set_frame, 1, uris->msg_Set);
 
-			lv2_atom_forge_property_head(&plugin->forge, set, plugin->uris.msg_body, 0);
-			LV2_Atom* body = (LV2_Atom*)lv2_atom_forge_blank(&plugin->forge, NULL, 2, 0);
+			lv2_atom_forge_property_head(&plugin->forge, uris->msg_body, 0);
+			LV2_Atom_Forge_Frame body_frame;
+			lv2_atom_forge_blank(&plugin->forge, &body_frame, 2, 0);
 
-			lv2_atom_forge_property_head(&plugin->forge, body, plugin->uris.eg_file, 0);
-			lv2_atom_forge_uri(&plugin->forge, body,
+			lv2_atom_forge_property_head(&plugin->forge, uris->eg_file, 0);
+			lv2_atom_forge_uri(&plugin->forge,
 			                   (const uint8_t*)plugin->sample->uri,
 			                   plugin->sample->uri_len);
 
+			lv2_atom_forge_pop(&plugin->forge, &body_frame);
+			lv2_atom_forge_pop(&plugin->forge, &set_frame);
 
-			set->size += lv2_atom_total_size(body);
-			seq->size += lv2_atom_total_size(set);
 		} else {
 			fprintf(stderr, "Unknown message from worker\n");
 		}
 	}
+
+	lv2_atom_forge_pop(&plugin->forge, &seq_frame);
 }
 
 static void
diff --git a/plugins/eg-sampler.lv2/sampler_ui.c b/plugins/eg-sampler.lv2/sampler_ui.c
index e21a8a9..056f0bb 100644
--- a/plugins/eg-sampler.lv2/sampler_ui.c
+++ b/plugins/eg-sampler.lv2/sampler_ui.c
@@ -95,21 +95,24 @@ on_load_clicked(GtkWidget* widget,
 	 *     ] ;
 	 * ]
 	 */
+	LV2_Atom_Forge_Frame set_frame;
 	LV2_Atom* set = (LV2_Atom*)lv2_atom_forge_blank(
-		&ui->forge, NULL, 1, ui->uris.msg_Set);
+		&ui->forge, &set_frame, 1, ui->uris.msg_Set);
 
-	lv2_atom_forge_property_head(&ui->forge, set, ui->uris.msg_body, 0);
-	LV2_Atom* body = (LV2_Atom*)lv2_atom_forge_blank(&ui->forge, NULL, 2, 0);
+	lv2_atom_forge_property_head(&ui->forge, ui->uris.msg_body, 0);
+	LV2_Atom_Forge_Frame body_frame;
+	lv2_atom_forge_blank(&ui->forge, &body_frame, 2, 0);
 
-	lv2_atom_forge_property_head(&ui->forge, body, ui->uris.eg_file, 0);
-	lv2_atom_forge_uri(&ui->forge, body, (const uint8_t*)file_uri, file_uri_len);
-
-	set->size += lv2_atom_total_size(body);
+	lv2_atom_forge_property_head(&ui->forge, ui->uris.eg_file, 0);
+	lv2_atom_forge_uri(&ui->forge, (const uint8_t*)file_uri, file_uri_len);
 
 	ui->write(ui->controller, 0, lv2_atom_total_size(set),
 	          ui->uris.atom_eventTransfer,
 	          set);
 
+	lv2_atom_forge_pop(&ui->forge, &body_frame);
+	lv2_atom_forge_pop(&ui->forge, &set_frame);
+
 	g_free(filename);
 	g_free(file_uri);
 }