Implemented FormID counter.

espReader/Reader.c

@@ -44,6 +44,7 @@ void print_type4(Type4 val);
 Timestamp convert_ts(uint16_t ts);
 void print_callback(Node n, void *_);
 void dc_size_cb(Node n, void *dc_size_ptr);
+void formid_count_cb(Node n, void *count_ptr);
 
 //
 // === FUNCTIONS ===
@@ -95,6 +96,7 @@ size_t espr_decompressed_size(char *data, size_t size) {
 	return dc_size;
 }
 
+// Adds the size of every node up, reading decompressed size from compressed records.
 void dc_size_cb(Node n, void *dc_size_ptr) {
 	size_t *dcsp = dc_size_ptr;
 	switch (n.type) {
@@ -116,6 +118,23 @@ void dc_size_cb(Node n, void *dc_size_ptr) {
 	}
 }
 
+size_t espr_formid_count(char *data, size_t size) {
+	size_t count = 0;
+	espr_walk(data, size, formid_count_cb, &count);
+	return count;
+}
+
+/* FormID <-> Record relationship should be bijective. I do not believe
+ * groups have formids, and every record should have a unique formid,
+ * otherwise there would be clashes in the id space.
+ */
+void formid_count_cb(Node n, void *count_ptr) {
+	size_t *c = count_ptr;
+	if (n.type == NT_RECORD) {
+		(*c)++;
+	}
+}
+
 /* Unknown data will be some concatenation of groups and records.
  *
  * `walk_concat` will call the appropriate walking function