gh-102856: Python tokenizer implementation for PEP 701 (#104323)

This commit replaces the Python implementation of the tokenize module with an implementation
that reuses the real C tokenizer via a private extension module. The tokenize module now implements
a compatibility layer that transforms tokens from the C tokenizer into Python tokenize tokens for backward
compatibility.

As the C tokenizer does not emit some tokens that the Python tokenizer provides (such as comments and non-semantic newlines), a new special mode has been added to the C tokenizer mode that currently is only used via
the extension module that exposes it to the Python layer. This new mode forces the C tokenizer to emit these new extra tokens and add the appropriate metadata that is needed to match the old Python implementation.

Co-authored-by: Pablo Galindo <pablogsal@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/Parser/pegen_errors.c b/Parser/pegen_errors.c
index 1f227da..af52905 100644
--- a/Parser/pegen_errors.c
+++ b/Parser/pegen_errors.c
@@ -165,7 +165,7 @@ _PyPegen_tokenize_full_source_to_check_for_errors(Parser *p) {
 
     int ret = 0;
     struct token new_token;
-    new_token.metadata = NULL;
+    _PyToken_Init(&new_token);
 
     for (;;) {
         switch (_PyTokenizer_Get(p->tok, &new_token)) {
@@ -193,7 +193,7 @@ _PyPegen_tokenize_full_source_to_check_for_errors(Parser *p) {
 
 
 exit:
-    Py_XDECREF(new_token.metadata);
+    _PyToken_Free(&new_token);
     // If we're in an f-string, we want the syntax error in the expression part
     // to propagate, so that tokenizer errors (like expecting '}') that happen afterwards
     // do not swallow it.