Fix quadratic behavior in yaml_parser_fetch_more_tokens

Author: dtolnay

src/scanner.rs

@@ -186,7 +186,10 @@ pub(crate) unsafe fn yaml_parser_fetch_more_tokens(parser: *mut yaml_parser_t) -
             if yaml_parser_stale_simple_keys(parser).fail {
                 return FAIL;
             }
-            simple_key = (*parser).simple_keys.start;
+            simple_key = (*parser)
+                .simple_keys
+                .start
+                .add((*parser).not_simple_keys as usize);
             while simple_key != (*parser).simple_keys.top {
                 if (*simple_key).possible && (*simple_key).token_number == (*parser).tokens_parsed {
                     need_more_tokens = true;
@@ -334,7 +337,10 @@ unsafe fn yaml_parser_fetch_next_token(parser: *mut yaml_parser_t) -> Success {
 
 unsafe fn yaml_parser_stale_simple_keys(parser: *mut yaml_parser_t) -> Success {
     let mut simple_key: *mut yaml_simple_key_t;
-    simple_key = (*parser).simple_keys.start;
+    simple_key = (*parser)
+        .simple_keys
+        .start
+        .add((*parser).not_simple_keys as usize);
     while simple_key != (*parser).simple_keys.top {
         if (*simple_key).possible
             && ((*simple_key).mark.line < (*parser).mark.line
@@ -350,6 +356,14 @@ unsafe fn yaml_parser_stale_simple_keys(parser: *mut yaml_parser_t) -> Success {
                 return FAIL;
             }
             (*simple_key).possible = false;
+            if (*parser)
+                .simple_keys
+                .start
+                .add((*parser).not_simple_keys as usize)
+                == simple_key
+            {
+                (*parser).not_simple_keys += 1;
+            }
         }
         simple_key = simple_key.wrapping_offset(1);
     }
@@ -372,6 +386,14 @@ unsafe fn yaml_parser_save_simple_key(parser: *mut yaml_parser_t) -> Success {
             return FAIL;
         }
         *(*parser).simple_keys.top.wrapping_offset(-1_isize) = simple_key;
+        if (*parser)
+            .simple_keys
+            .start
+            .add((*parser).not_simple_keys as usize)
+            == (*parser).simple_keys.top
+        {
+            (*parser).not_simple_keys -= 1;
+        }
     }
     OK
 }
@@ -418,6 +440,14 @@ unsafe fn yaml_parser_decrease_flow_level(parser: *mut yaml_parser_t) {
     if (*parser).flow_level != 0 {
         let fresh8 = addr_of_mut!((*parser).flow_level);
         *fresh8 -= 1;
+        if (*parser)
+            .simple_keys
+            .start
+            .add((*parser).not_simple_keys as usize)
+            == (*parser).simple_keys.top
+        {
+            (*parser).not_simple_keys -= 1;
+        }
         let _ = POP!((*parser).simple_keys);
     }
 }
@@ -497,6 +527,7 @@ unsafe fn yaml_parser_fetch_stream_start(parser: *mut yaml_parser_t) {
     let token = token.as_mut_ptr();
     (*parser).indent = -1;
     PUSH!((*parser).simple_keys, simple_key);
+    (*parser).not_simple_keys = 1;
     (*parser).simple_key_allowed = true;
     (*parser).stream_start_produced = true;
     memset(

src/yaml.rs

@@ -916,6 +916,8 @@ pub struct yaml_parser_t {
     pub(crate) simple_key_allowed: bool,
     /// The stack of simple keys.
     pub(crate) simple_keys: yaml_stack_t<yaml_simple_key_t>,
+    /// At least this many leading elements of simple_keys have possible=0.
+    pub(crate) not_simple_keys: libc::c_int,
     /// The parser states stack.
     pub(crate) states: yaml_stack_t<yaml_parser_state_t>,
     /// The current parser state.