From 819235bac3990795f25e292910a3d76c0cda4e00 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Tue, 12 Sep 2017 12:00:00 -0700
Subject: [PATCH] Limit the number of stack nodes that are included in a
 summary

---
 src/runtime/parser.c |  5 +++--
 src/runtime/stack.c  | 35 +++++++++++++++++++----------------
 src/runtime/stack.h  |  2 +-
 3 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/src/runtime/parser.c b/src/runtime/parser.c
index 60aa7da4..548becc3 100644
--- a/src/runtime/parser.c
+++ b/src/runtime/parser.c
@@ -34,7 +34,8 @@
 
 #define SYM_NAME(symbol) ts_language_symbol_name(self->language, symbol)
 
-static const uint32_t MAX_VERSION_COUNT = 10;
+static const unsigned MAX_VERSION_COUNT = 10;
+static const unsigned MAX_SUMMARY_DEPTH = 16;
 
 static void parser__log(Parser *self) {
   if (self->lexer.logger.log) {
@@ -797,7 +798,7 @@ static void parser__handle_error(Parser *self, StackVersion version, TSSymbol lo
     ts_stack_force_merge(self->stack, version, previous_version_count);
   }
 
-  ts_stack_record_summary(self->stack, version);
+  ts_stack_record_summary(self->stack, version, MAX_SUMMARY_DEPTH);
   LOG_STACK();
 }
 
diff --git a/src/runtime/stack.c b/src/runtime/stack.c
index f3907ffd..b4d3feb6 100644
--- a/src/runtime/stack.c
+++ b/src/runtime/stack.c
@@ -477,24 +477,33 @@ StackPopResult ts_stack_pop_all(Stack *self, StackVersion version) {
   return stack__iter(self, version, pop_all_callback, NULL, true);
 }
 
+typedef struct {
+  StackSummary *summary;
+  unsigned max_depth;
+} SummarizeStackSession;
+
 inline StackIterateAction summarize_stack_callback(void *payload, const Iterator *iterator) {
-  StackSummary *summary = payload;
+  SummarizeStackSession *session = payload;
   TSStateId state = iterator->node->state;
   unsigned depth = iterator->tree_count;
-  for (unsigned i = summary->size - 1; i + 1 > 0; i--) {
-    StackSummaryEntry entry = summary->contents[i];
+  if (depth > session->max_depth) return StackIterateStop;
+  for (unsigned i = session->summary->size - 1; i + 1 > 0; i--) {
+    StackSummaryEntry entry = session->summary->contents[i];
     if (entry.depth < depth) break;
     if (entry.depth == depth && entry.state == state) return StackIterateNone;
   }
-  array_push(summary, ((StackSummaryEntry){.depth = depth, .state = state}));
+  array_push(session->summary, ((StackSummaryEntry){.depth = depth, .state = state}));
   return StackIterateNone;
 }
 
-void ts_stack_record_summary(Stack *self, StackVersion version) {
-  StackSummary *result = ts_malloc(sizeof(StackSummary));
-  array_init(result);
-  stack__iter(self, version, summarize_stack_callback, result, false);
-  self->heads.contents[version].summary = result;
+void ts_stack_record_summary(Stack *self, StackVersion version, unsigned max_depth) {
+  SummarizeStackSession session = {
+    .summary = ts_malloc(sizeof(StackSummary)),
+    .max_depth = max_depth
+  };
+  array_init(session.summary);
+  stack__iter(self, version, summarize_stack_callback, &session, false);
+  self->heads.contents[version].summary = session.summary;
 }
 
 StackSummary *ts_stack_get_summary(Stack *self, StackVersion version) {
@@ -502,13 +511,7 @@ StackSummary *ts_stack_get_summary(Stack *self, StackVersion version) {
 }
 
 unsigned ts_stack_depth_since_error(Stack *self, StackVersion version) {
-  unsigned result = 0;
-  StackNode *node = array_get(&self->heads, version)->node;
-  while (node->state == 0) {
-    result++;
-    node = node->links[0].node;
-  }
-  return result - 1;
+  return array_get(&self->heads, version)->node->depth;
 }
 
 void ts_stack_remove_version(Stack *self, StackVersion version) {
diff --git a/src/runtime/stack.h b/src/runtime/stack.h
index 36e41c50..ce0a30ed 100644
--- a/src/runtime/stack.h
+++ b/src/runtime/stack.h
@@ -103,7 +103,7 @@ StackPopResult ts_stack_pop_all(Stack *, StackVersion);
 
 unsigned ts_stack_depth_since_error(Stack *, StackVersion);
 
-void ts_stack_record_summary(Stack *, StackVersion);
+void ts_stack_record_summary(Stack *, StackVersion, unsigned max_depth);
 
 StackSummary *ts_stack_get_summary(Stack *, StackVersion);