Add Document parse_count() method, for tracking if trees are still valid

include/tree_sitter/runtime.h

@@ -74,6 +74,7 @@ void ts_document_edit(TSDocument *, TSInputEdit);
 TSDebugger ts_document_debugger(const TSDocument *);
 void ts_document_set_debugger(TSDocument *, TSDebugger);
 TSNode ts_document_root_node(const TSDocument *);
+size_t ts_document_parse_count(const TSDocument *);
 
 #define ts_builtin_sym_error 0
 #define ts_builtin_sym_end 1

spec/runtime/parser_spec.cc

@@ -394,6 +394,16 @@ describe("Parser", [&]() {
             "(identifier) (member_access (identifier) (identifier))))))"));
       });
     });
+
+    it("updates the document's parse-count", [&]() {
+      AssertThat(ts_document_parse_count(doc), Equals<size_t>(0));
+
+      set_text("{ x: (b.c) };");
+      AssertThat(ts_document_parse_count(doc), Equals<size_t>(1));
+
+      insert_text(strlen("{ x"), "yz");
+      AssertThat(ts_document_parse_count(doc), Equals<size_t>(2));
+    });
   });
 
   describe("lexing", [&]() {

src/runtime/document.c

@@ -26,6 +26,7 @@ static void ts_document__reparse(TSDocument *document, TSInputEdit *edit) {
       ts_tree_release(document->tree);
     document->tree = tree;
     ts_tree_retain(tree);
+    document->parse_count++;
   }
 }
 
@@ -74,3 +75,7 @@ TSNode ts_document_root_node(const TSDocument *document) {
     result = ts_node_named_child(result, 0);
   return result;
 }
+
+size_t ts_document_parse_count(const TSDocument *document) {
+  return document->parse_count;
+}

src/runtime/document.h

@@ -9,6 +9,7 @@ struct TSDocument {
   TSParser parser;
   TSInput input;
   TSTree *tree;
+  size_t parse_count;
 };
 
 #endif