diff options
Diffstat (limited to 'libguile/strings.c')
-rw-r--r-- | libguile/strings.c | 37 |
1 files changed, 28 insertions, 9 deletions
diff --git a/libguile/strings.c b/libguile/strings.c index 7399d8831..ffc1eb312 100644 --- a/libguile/strings.c +++ b/libguile/strings.c @@ -218,6 +218,12 @@ get_str_buf_start (SCM *str, SCM *buf, size_t *start) } SCM +scm_i_make_read_only_string (SCM str) +{ + return scm_i_substring_read_only (str, 0, STRING_LENGTH (str)); +} + +SCM scm_i_substring (SCM str, size_t start, size_t end) { SCM buf; @@ -234,15 +240,28 @@ scm_i_substring (SCM str, size_t start, size_t end) SCM scm_i_substring_read_only (SCM str, size_t start, size_t end) { - SCM buf; - size_t str_start; - get_str_buf_start (&str, &buf, &str_start); - scm_i_pthread_mutex_lock (&stringbuf_write_mutex); - SET_STRINGBUF_SHARED (buf); - scm_i_pthread_mutex_unlock (&stringbuf_write_mutex); - return scm_double_cell (RO_STRING_TAG, SCM_UNPACK(buf), - (scm_t_bits)str_start + start, - (scm_t_bits) end - start); + SCM result; + + if (SCM_UNLIKELY (STRING_LENGTH (str) == 0)) + /* We want the empty string to be `eq?' with the read-only empty + string. */ + result = str; + else + { + SCM buf; + size_t str_start; + + get_str_buf_start (&str, &buf, &str_start); + scm_i_pthread_mutex_lock (&stringbuf_write_mutex); + SET_STRINGBUF_SHARED (buf); + scm_i_pthread_mutex_unlock (&stringbuf_write_mutex); + + result = scm_double_cell (RO_STRING_TAG, SCM_UNPACK (buf), + (scm_t_bits) str_start + start, + (scm_t_bits) end - start); + } + + return result; } SCM |