[njs] Improved njs_lexer_rollback().

[Dmitry Volyntsev]

details:   https://hg.nginx.org/njs/rev/2f1f71863953
branches:  
changeset: 936:2f1f71863953
user:      hongzhidao <hongzhidao at gmail.com>
date:      Sat Apr 27 09:04:24 2019 +0800
description:
Improved njs_lexer_rollback().

diffstat:

 njs/njs_lexer.c          |  14 ++++++++------
 njs/njs_lexer.h          |   1 -
 njs/test/njs_unit_test.c |   6 ++++++
 3 files changed, 14 insertions(+), 7 deletions(-)

diffs (58 lines):

diff -r 277845bea37a -r 2f1f71863953 njs/njs_lexer.c
--- a/njs/njs_lexer.c	Sat Apr 27 20:28:37 2019 +0300
+++ b/njs/njs_lexer.c	Sat Apr 27 09:04:24 2019 +0800
@@ -307,11 +307,6 @@ njs_lexer_token(njs_vm_t *vm, njs_lexer_
 
     lexer->prev_start = lexer->start;
 
-    if (lexer->lexer_token != NULL) {
-        lexer->prev_token = lexer->lexer_token->token;
-        nxt_mp_free(vm->mem_pool, lexer->lexer_token);
-    }
-
     if (nxt_queue_is_empty(&lexer->preread)) {
         lt = njs_lexer_token_push(vm, lexer);
         if (nxt_slow_path(lt == NULL)) {
@@ -319,7 +314,14 @@ njs_lexer_token(njs_vm_t *vm, njs_lexer_
         }
     }
 
-    lexer->lexer_token = njs_lexer_token_pop(lexer);
+    lt = njs_lexer_token_pop(lexer);
+
+    if (lexer->lexer_token != NULL && lexer->lexer_token != lt) {
+        lexer->prev_token = lexer->lexer_token->token;
+        nxt_mp_free(vm->mem_pool, lexer->lexer_token);
+    }
+
+    lexer->lexer_token = lt;
 
     return njs_lexer_token_name_resolve(lexer, lexer->lexer_token);
 }
diff -r 277845bea37a -r 2f1f71863953 njs/njs_lexer.h
--- a/njs/njs_lexer.h	Sat Apr 27 20:28:37 2019 +0300
+++ b/njs/njs_lexer.h	Sat Apr 27 09:04:24 2019 +0800
@@ -264,7 +264,6 @@ void njs_lexer_keyword(njs_lexer_t *lexe
 #define njs_lexer_rollback(lexer)                                              \
     do {                                                                       \
         nxt_queue_insert_head(&(lexer)->preread, &(lexer)->lexer_token->link); \
-        (lexer)->lexer_token = NULL;                                           \
     } while (0)
 
 
diff -r 277845bea37a -r 2f1f71863953 njs/test/njs_unit_test.c
--- a/njs/test/njs_unit_test.c	Sat Apr 27 20:28:37 2019 +0300
+++ b/njs/test/njs_unit_test.c	Sat Apr 27 09:04:24 2019 +0800
@@ -2157,6 +2157,12 @@ static njs_unit_test_t  njs_test[] =
 
     /* automatic semicolon insertion. */
 
+    { nxt_string("(a\n--"),
+      nxt_string("SyntaxError: Unexpected token \"--\" in 2") },
+
+    { nxt_string("(a\n++"),
+      nxt_string("SyntaxError: Unexpected token \"++\" in 2") },
+
     { nxt_string("var x = 0, y = 2; x\n--\ny; [x,y]"),
       nxt_string("0,1") },