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author | Kaz Kylheku <kaz@kylheku.com> | 2014-07-19 19:19:21 -0700 |
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committer | Kaz Kylheku <kaz@kylheku.com> | 2014-07-19 19:19:21 -0700 |
commit | 8fe8e46c6dce8292f2c12660d0c383e521f9233a (patch) | |
tree | 347e192c467d2140b61ecc77356e18b544535fef | |
parent | 5f9d1d22af102a8e9d2a769ea02243fb5763fe74 (diff) | |
download | txr-8fe8e46c6dce8292f2c12660d0c383e521f9233a.tar.gz txr-8fe8e46c6dce8292f2c12660d0c383e521f9233a.tar.bz2 txr-8fe8e46c6dce8292f2c12660d0c383e521f9233a.zip |
* lib.c (search_str): Support negative starting index.
Hoist uselessly repeated c_str operation out of loop.
* txr.1: Document negative starting index for search-str.
-rw-r--r-- | ChangeLog | 7 | ||||
-rw-r--r-- | lib.c | 18 | ||||
-rw-r--r-- | txr.1 | 8 |
3 files changed, 27 insertions, 6 deletions
@@ -1,5 +1,12 @@ 2014-07-19 Kaz Kylheku <kaz@kylheku.com> + * lib.c (search_str): Support negative starting index. + Hoist uselessly repeated c_str operation out of loop. + + * txr.1: Document negative starting index for search-str. + +2014-07-19 Kaz Kylheku <kaz@kylheku.com> + * hash.c (hash_construct): Nullify the pairs argument so that it works correctly with an empty vector. @@ -2145,11 +2145,14 @@ val search_str(val haystack, val needle, val start_num, val from_end) const wchar_t *n = c_str(needle), *h; if (!h_is_lazy) { - do { - const wchar_t *f; - h = c_str(haystack); + h = c_str(haystack); + + if (start < 0) + start += wcslen(h); - f = wcsstr(h + start, n); + nonlazy: + do { + const wchar_t *f = wcsstr(h + start, n); if (f) pos = f - h; @@ -2159,6 +2162,13 @@ val search_str(val haystack, val needle, val start_num, val from_end) } else { size_t ln = c_num(length_str(needle)); + if (start < 0) { + lazy_str_force(haystack); + h = c_str(haystack->ls.prefix); + start += wcslen(h); + goto nonlazy; + } + do { lazy_str_force_upto(haystack, plus(num(start + 1), length_str(needle))); h = c_str(haystack->ls.prefix); @@ -9337,8 +9337,12 @@ The search-str function finds an occurrence of the string <needle> inside the <haystack> string and returns its position. If no such occurrence exists, it returns nil. -If a <start> argument is specified, it gives the starting index for the -search. If the <from-end> argument is specified and is not nil, it means +If a <start> argument is not specified, it defaults to zero. If it is +a non-negative integer, it specifies the starting character position for +the search. Negative values of <start> indicate positions from the end of the +string, such that -1 is the last character of the string. + +If the <from-end> argument is specified and is not nil, it means that the search is conducted right-to-left. If multiple matches are possible, it will find the rightmost one rather than the leftmost one. |