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Fix search/replace for the replacement not to change search results

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Fix the search & replace algorithm to make sure a replacement won't
possibly affect the next one (e.g. in case of lookahead and lookbehind
regular expressions).

To do so, first find all occurrences and only then perform replacements,
instead of doing both together.

This fixes searching/replacing of any pattern that may be affected by
its replacement (e.g. patterns that look for something not a character
in the match range), including:

 * Start/end of line:
   Before this change, searching with regular expression "^A" and
   replacing with an empty string on the input "AA" would have resulted
   in an empty output ("^A" matching again after removing the first
   one).  Now it properly only removes the leading "A".
 * Lookahead/lookbehind:
   Pattern "(?<=a)b" with empty replacement and input "abb" would have
   resulted in the output "a" instead of "ab".
 * And more generally, many patterns matching non-characters like
   positions or out-of-match characters.
This commit is contained in:
Colomban Wendling 2012-12-24 03:20:17 +01:00
parent 0191659663
commit c83a93eb65
1 changed files with 36 additions and 42 deletions
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78
src/search.c
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@ -2115,62 +2115,56 @@ void search_find_usage(const gchar *search_text, const gchar *original_search_te
/* ttf is updated to include the last match position (ttf->chrg.cpMin) and
* the new search range end (ttf->chrg.cpMax).
* Note: Normally you would call sci_start/end_undo_action() around this call. */
/* Warning: Scintilla recommends caching replacements to do all at once to avoid
* performance issues with SCI_GETCHARACTERPOINTER. */
guint search_replace_range(ScintillaObject *sci, struct Sci_TextToFind *ttf,
gint flags, const gchar *replace_text)
{
gint count = 0;
const gchar *find_text = ttf->lpstrText;
gint start = ttf->chrg.cpMin;
gint end = ttf->chrg.cpMax;
gint offset = 0; /* difference between sear pos and replace pos */
GList *match, *matches = NULL;
g_return_val_if_fail(sci != NULL && find_text != NULL && replace_text != NULL, 0);
if (! *find_text)
g_return_val_if_fail(sci != NULL && ttf->lpstrText != NULL && replace_text != NULL, 0);
if (! *ttf->lpstrText)
return 0;
while (TRUE)
/* first, search for all matches */
while (search_find_text(sci, flags, ttf) != -1)
{
gint search_pos;
gint find_len = 0, replace_len = 0;
if (ttf->chrgText.cpMax > ttf->chrg.cpMax)
break; /* found text is partially out of range */
search_pos = search_find_text(sci, flags, ttf);
find_len = ttf->chrgText.cpMax - ttf->chrgText.cpMin;
if (search_pos == -1)
break; /* no more matches */
matches = g_list_prepend(matches, g_memdup(ttf, sizeof *ttf));
ttf->chrg.cpMin = ttf->chrgText.cpMax;
if (search_pos + find_len > end)
break; /* found text is partly out of range */
else
/* forward after empty matches, see find_document_usage() */
if (ttf->chrgText.cpMax == ttf->chrgText.cpMin)
ttf->chrg.cpMin ++;
}
matches = g_list_reverse(matches);
/* then replace them all */
foreach_list (match, matches)
{
struct Sci_TextToFind *m = match->data;
gint replace_len;
sci_set_target_start(sci, offset + m->chrgText.cpMin);
sci_set_target_end(sci, offset + m->chrgText.cpMax);
replace_len = search_replace_target(sci, replace_text, flags & SCFIND_REGEXP);
offset += replace_len - (m->chrgText.cpMax - m->chrgText.cpMin);
count ++;
/* on last match, update the last match/new range end */
if (! match->next)
{
gint movepastEOL = 0;
sci_set_target_start(sci, search_pos);
sci_set_target_end(sci, search_pos + find_len);
if (find_len <= 0)
{
gchar chNext = sci_get_char_at(sci, sci_get_target_end(sci));
if (chNext == '\r' || chNext == '\n')
movepastEOL = 1;
}
replace_len = search_replace_target(sci, replace_text,
flags & SCFIND_REGEXP);
count++;
if (search_pos == end)
break; /* Prevent hang when replacing regex $ */
/* make the next search start after the replaced text */
start = search_pos + replace_len + movepastEOL;
if (find_len == 0)
start = sci_get_position_after(sci, start); /* prevent '[ ]*' regex rematching part of replaced text */
ttf->chrg.cpMin = start;
end += replace_len - find_len; /* update end of range now text has changed */
ttf->chrg.cpMax = end;
ttf->chrg.cpMin = m->chrgText.cpMin;
ttf->chrg.cpMax += offset;
}
g_free(m);
}
g_list_free(matches);
return count;
}