wingo pushed a commit to branch wip-whippet
in repository guile.
commit c370d12d03f8e454888174462710655a3ed643fa
Author: Andy Wingo <wi...@pobox.com>
AuthorDate: Mon Jun 23 09:15:19 2025 +0200
Better type-safety for snarfed immutable strings
* libguile/strings.h: Add struct types for stringbufs and strings.
(SCM_IMMUTABLE_STRINGBUF, SCM_IMMUTABLE_STRING): Use the new data types.
---
libguile/strings.h | 60 +++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 44 insertions(+), 16 deletions(-)
diff --git a/libguile/strings.h b/libguile/strings.h
index e7e0099d3..66399e191 100644
--- a/libguile/strings.h
+++ b/libguile/strings.h
@@ -175,29 +175,57 @@ SCM_API SCM scm_makfromstrs (int argc, char **argv);
/* Snarfing support. See snarf.h. */
+struct scm_stringbuf
+{
+ scm_t_bits tag_and_flags;
+ size_t length;
+};
+
+struct scm_narrow_stringbuf
+{
+ struct scm_stringbuf header;
+ char contents[];
+};
+
+struct scm_wide_stringbuf
+{
+ struct scm_stringbuf header;
+ scm_t_wchar contents[];
+};
+
+struct scm_string
+{
+ scm_t_bits tag_and_flags;
+ union
+ {
+ /* Usually a string is just a slice of a stringbuf. */
+ struct scm_stringbuf *stringbuf;
+ /* Sometimes though it aliases another string. */
+ struct scm_string *string;
+ };
+ size_t start;
+ size_t length;
+};
+
#define SCM_IMMUTABLE_STRINGBUF(c_name, contents) \
- static SCM_UNUSED SCM_ALIGNED(8) const \
- struct \
- { \
- scm_t_bits word_0; \
- scm_t_bits word_1; \
- const char buffer[sizeof (contents)]; \
- } \
- c_name = \
+ static SCM_ALIGNED(8) const struct scm_narrow_stringbuf c_name = \
{ \
- scm_tc7_stringbuf, \
- sizeof (contents) - 1, \
+ { scm_tc7_stringbuf, sizeof (contents) - 1 }, \
contents \
}
#define SCM_IMMUTABLE_STRING(c_name, contents) \
SCM_IMMUTABLE_STRINGBUF (scm_i_paste (c_name, _stringbuf), contents);
\
- SCM_IMMUTABLE_DOUBLE_CELL (c_name, \
- scm_tc7_ro_string, \
- (scm_t_bits) &scm_i_paste (c_name, \
- _stringbuf), \
- (scm_t_bits) 0, \
- (scm_t_bits) (sizeof (contents) - 1))
+ static SCM_ALIGNED(8) const struct scm_string scm_i_paste (c_name, _raw) = \
+ { \
+ scm_tc7_ro_string, \
+ /* Discard "const" attr. */ \
+ { (struct scm_stringbuf *) &scm_i_paste (c_name, _stringbuf).header }, \
+ 0, \
+ (sizeof (contents) - 1) \
+ }; \
+ static const SCM c_name = SCM_PACK (&scm_i_paste (c_name, _raw))
+
