blocks: expose block iterator internals

so we don't need heap allocation. we will be calling this a lot in tight
render loops, we don't want to be allocating on each frame.

src/block.c

@@ -4,13 +4,6 @@
 #include "block.h"
 #include <stdlib.h>
 
-struct ndb_block_iterator {
-	const char *content;
-	struct ndb_blocks *blocks;
-	struct ndb_block block;
-	struct cursor cur;
-};
-
 int push_str_block(struct cursor *buf, const char *content, struct ndb_str_block *block) {
 	return cursor_push_varint(buf, block->str - content) &&
 	       cursor_push_varint(buf, block->len);
@@ -133,32 +126,25 @@ enum ndb_block_type ndb_get_block_type(struct ndb_block *block) {
 }
 
 // BLOCK ITERATORS
-struct ndb_block_iterator *ndb_blocks_iterate_start(const char *content, struct ndb_blocks *blocks) {
-	struct ndb_block_iterator *iter = malloc(sizeof(*iter));
-	if (!iter)
-		return NULL;
-
+void ndb_blocks_iterate_start(const char *content, struct ndb_blocks *blocks, struct ndb_block_iterator *iter) {
 	iter->blocks = blocks;
 	iter->content = content;
-
-	make_cursor((unsigned char *)blocks->blocks,
-		    blocks->blocks + blocks->blocks_size, &iter->cur);
-
-	return iter;
-}
-
-void ndb_blocks_iterate_free(struct ndb_block_iterator *iter)
-{
-	if (iter)
-		free(iter);
+	iter->p = blocks->blocks;
 }
 
 struct ndb_block *ndb_blocks_iterate_next(struct ndb_block_iterator *iter)
 {
-	while (iter->cur.p < iter->cur.end) {
-		if (!pull_block(iter->content, &iter->cur, &iter->block)) {
+	struct cursor cur;
+	cur.start = iter->blocks->blocks;
+	cur.p = iter->p;
+	cur.end = iter->blocks->blocks + iter->blocks->blocks_size;
+
+	while (cur.p < cur.end) {
+		if (!pull_block(iter->content, &cur, &iter->block)) {
+			iter->p = cur.p;
 			return NULL;
 		} else {
+			iter->p = cur.p;
 			return &iter->block;
 		}
 	}

src/block.h

@@ -29,26 +29,6 @@ struct ndb_blocks {
 
 #pragma pack(pop)
 
-struct ndb_mention_bech32_block {
-	struct ndb_str_block str;
-	struct nostr_bech32 bech32;
-};
-
-struct ndb_invoice_block {
-	struct ndb_str_block invstr;
-	struct ndb_invoice invoice;
-};
-
-struct ndb_block {
-	enum ndb_block_type type;
-	union {
-		struct ndb_str_block str;
-		struct ndb_invoice_block invoice;
-		struct ndb_mention_bech32_block mention_bech32;
-		uint32_t mention_index;
-	} block;
-};
-
 int push_str_block(struct cursor *buf, const char *content, struct ndb_str_block *block);
 int pull_str_block(struct cursor *buf, const char *content, struct ndb_str_block *block);
 

src/invoice.c

@@ -1,6 +1,7 @@
 
 #include "cursor.h"
 #include "invoice.h"
+#include "nostrdb.h"
 #include "bolt11/bolt11.h"
 #include "bolt11/amount.h"
 

src/invoice.h

@@ -4,18 +4,10 @@
 
 #include <inttypes.h>
 #include "cursor.h"
+#include "nostrdb.h"
 
 struct bolt11;
 
-struct ndb_invoice {
-	unsigned char version;
-	uint64_t amount;
-	uint64_t timestamp;
-	uint64_t expiry;
-	char *description;
-	unsigned char *description_hash;
-};
-
 // ENCODING
 int ndb_encode_invoice(struct cursor *cur, struct bolt11 *invoice);
 int ndb_decode_invoice(struct cursor *cur, struct ndb_invoice *invoice);

src/nostrdb.h

@@ -360,6 +360,42 @@ struct nostr_bech32 {
 };
 
 
+struct ndb_mention_bech32_block {
+	struct ndb_str_block str;
+	struct nostr_bech32 bech32;
+};
+
+struct ndb_invoice {
+	unsigned char version;
+	uint64_t amount;
+	uint64_t timestamp;
+	uint64_t expiry;
+	char *description;
+	unsigned char *description_hash;
+};
+
+struct ndb_invoice_block {
+	struct ndb_str_block invstr;
+	struct ndb_invoice invoice;
+};
+
+struct ndb_block {
+	enum ndb_block_type type;
+	union {
+		struct ndb_str_block str;
+		struct ndb_invoice_block invoice;
+		struct ndb_mention_bech32_block mention_bech32;
+		uint32_t mention_index;
+	} block;
+};
+
+struct ndb_block_iterator {
+	const char *content;
+	struct ndb_blocks *blocks;
+	struct ndb_block block;
+	unsigned char *p;
+};
+
 // CONFIG
 void ndb_default_config(struct ndb_config *);
 void ndb_config_set_ingest_threads(struct ndb_config *config, int threads);
@@ -479,8 +515,7 @@ void ndb_blocks_free(struct ndb_blocks *blocks);
 struct ndb_blocks *ndb_get_blocks_by_key(struct ndb *ndb, struct ndb_txn *txn, uint64_t note_key);
 
 // BLOCK ITERATORS
-struct ndb_block_iterator *ndb_blocks_iterate_start(const char *, struct ndb_blocks *);
-void ndb_blocks_iterate_free(struct ndb_block_iterator *);
+void ndb_blocks_iterate_start(const char *, struct ndb_blocks *, struct ndb_block_iterator *);
 struct ndb_block *ndb_blocks_iterate_next(struct ndb_block_iterator *);
 
 // STR BLOCKS

test.c

@@ -782,14 +782,16 @@ static void test_parse_nevent() {
 	struct ndb_blocks *blocks;
 	struct ndb_block *block = NULL;
 	struct nostr_bech32 *bech32;
+	struct ndb_block_iterator iterator, *iter;
+	iter = &iterator;
 	int ok = 0;
 
 	static unsigned char event_id[] = { 0x50, 0x5f, 0x0f, 0x0c, 0x98, 0x1d, 0x4b, 0xea, 0x76, 0x82, 0x1b, 0x53,
   0x09, 0x59, 0xf2, 0xb8, 0x1d, 0x37, 0x31, 0x3c, 0x9c, 0x03, 0x12, 0x98,
   0x7c, 0x88, 0x9d, 0xd7, 0x91, 0x1e, 0x6a, 0x74 };
 
 	assert(ndb_parse_content(buf, sizeof(buf), content, strlen(content), &blocks));
-	struct ndb_block_iterator *iter = ndb_blocks_iterate_start(content, blocks);
+	ndb_blocks_iterate_start(content, blocks, iter);
 	assert(blocks->num_blocks == 3);
 	while ((block = ndb_blocks_iterate_next(iter))) {
 		switch (++ok) {
@@ -821,11 +823,13 @@ static void test_url_parsing() {
 	struct ndb_blocks *blocks;
 	struct ndb_block *block;
 	struct ndb_str_block *str;
+	struct ndb_block_iterator iterator, *iter;
+	iter = &iterator;
 
 	assert(ndb_parse_content(buf, sizeof(buf), content, strlen(content), &blocks));
 	assert(blocks->num_blocks == 5);
 
-	struct ndb_block_iterator *iter = ndb_blocks_iterate_start(content, blocks);
+	ndb_blocks_iterate_start(content, blocks, iter);
 	int i = 0;
 	while ((block = ndb_blocks_iterate_next(iter))) {
 		str = ndb_block_str(block);
@@ -839,8 +843,6 @@ static void test_url_parsing() {
 	}
 
 	assert(i == 5);
-	ndb_blocks_iterate_free(iter);
-
 }