[3.9] Backport GH-20370 and GH-20436: Soft keywords (GH-20458)

2 files changed, 35 insertions, 1 deletions

diff --git a/Parser/pegen/pegen.c b/Parser/pegen/pegen.c
index cd87a9f..b858b6b 100644
--- a/Parser/pegen/pegen.c
+++ b/Parser/pegen/pegen.c
@@ -708,7 +708,6 @@ _PyPegen_is_memoized(Parser *p, int type, void *pres)
     return 0;
 }
 
-
 int
 _PyPegen_lookahead_with_name(int positive, expr_ty (func)(Parser *), Parser *p)
 {
@@ -719,6 +718,15 @@ _PyPegen_lookahead_with_name(int positive, expr_ty (func)(Parser *), Parser *p)
 }
 
 int
+_PyPegen_lookahead_with_string(int positive, expr_ty (func)(Parser *, const char*), Parser *p, const char* arg)
+{
+    int mark = p->mark;
+    void *res = func(p, arg);
+    p->mark = mark;
+    return (res != NULL) == positive;
+}
+
+int
 _PyPegen_lookahead_with_int(int positive, Token *(func)(Parser *, int), Parser *p, int arg)
 {
     int mark = p->mark;
@@ -753,6 +761,30 @@ _PyPegen_expect_token(Parser *p, int type)
     return t;
 }
 
+expr_ty
+_PyPegen_expect_soft_keyword(Parser *p, const char *keyword)
+{
+    if (p->mark == p->fill) {
+        if (_PyPegen_fill_token(p) < 0) {
+            p->error_indicator = 1;
+            return NULL;
+        }
+    }
+    Token *t = p->tokens[p->mark];
+    if (t->type != NAME) {
+        return NULL;
+    }
+    char* s = PyBytes_AsString(t->bytes);
+    if (!s) {
+        p->error_indicator = 1;
+        return NULL;
+    }
+    if (strcmp(s, keyword) != 0) {
+        return NULL;
+    }
+    return _PyPegen_name_token(p);
+}
+
 Token *
 _PyPegen_get_last_nonnwhitespace_token(Parser *p)
 {
diff --git a/Parser/pegen/pegen.h b/Parser/pegen/pegen.h
index bd3056e..2585392 100644
--- a/Parser/pegen/pegen.h
+++ b/Parser/pegen/pegen.h
@@ -118,10 +118,12 @@ int _PyPegen_update_memo(Parser *p, int mark, int type, void *node);
 int _PyPegen_is_memoized(Parser *p, int type, void *pres);
 
 int _PyPegen_lookahead_with_name(int, expr_ty (func)(Parser *), Parser *);
+int _PyPegen_lookahead_with_string(int , expr_ty (func)(Parser *, const char*), Parser *, const char*);
 int _PyPegen_lookahead_with_int(int, Token *(func)(Parser *, int), Parser *, int);
 int _PyPegen_lookahead(int, void *(func)(Parser *), Parser *);
 
 Token *_PyPegen_expect_token(Parser *p, int type);
+expr_ty _PyPegen_expect_soft_keyword(Parser *p, const char *keyword);
 Token *_PyPegen_get_last_nonnwhitespace_token(Parser *);
 int _PyPegen_fill_token(Parser *p);
 expr_ty _PyPegen_name_token(Parser *p);