Add incremental search to less. 2013-06-19-02

less.diff

===================================================================
RCS file: RCS/command.c,v
retrieving revision 1.92
diff -u -r1.92 command.c
--- command.c	2012/07/03 20:10:42	1.92
+++ command.c	2013/06/19 19:37:59
@@ -47,6 +47,8 @@
 extern int shift_count;
 extern int oldbot;
 extern int forw_prompt;
+extern int incremental_search;
+extern int same_pos_bell;
 
 #if SHELL_ESCAPE
 static char *shellcmd = NULL;	/* For holding last shell command for "!!" */
@@ -61,6 +63,7 @@
 static int optgetname;
 static POSITION bottompos;
 static int save_hshift;
+static struct mark searchstack[CMDBUF_SIZE];
 #if PIPEC
 static char pipec;
 #endif
@@ -203,7 +206,7 @@
 	{
 	case A_F_SEARCH:
 	case A_B_SEARCH:
-		multi_search(cbuf, (int) number);
+		multi_search(cbuf, (int) number, 0);
 		break;
 #if HILITE_SEARCH
 	case A_FILTER:
@@ -516,6 +519,7 @@
 mca_char(c)
 	int c;
 {
+	char *cbuf;
 	int ret;
 
 	switch (mca)
@@ -606,6 +610,43 @@
 		return (MCA_DONE);
 	}
 
+	if (incremental_search && (mca == A_F_SEARCH || mca == A_B_SEARCH))
+	{
+		/*
+		 * Special case for incremental search.
+		 * Run multi_search with incremental=1
+		 * and repaint prompt after each char in search.
+		 * Don't ring the same-position bell while typing.
+		 */
+		same_pos_bell = 0;
+		if (is_erase_char(c))
+		{
+			/* Return to previous incremental search position. */
+			struct mark *m = &searchstack[len_cmdbuf()];
+			if (edit_ifile(m->m_ifile))
+				return (MCA_DONE);
+			jump_loc(m->m_scrpos.pos, m->m_scrpos.ln);
+			forw_prompt = 0;
+		} else if (len_cmdbuf() > 0)
+		{
+		    /* Remember this position for later erase_char. */
+		    struct mark *m = &searchstack[len_cmdbuf()-1];
+		    struct scrpos scrpos;
+		    get_scrpos(&scrpos);
+		    m->m_scrpos = scrpos;
+		    m->m_ifile = curr_ifile;
+		}
+		cbuf = get_cmdbuf();
+		if (len_cmdbuf() == 0)
+			undo_search();
+		else if (valid_pattern(cbuf))
+			multi_search(cbuf, (int) number, 1);
+		same_pos_bell = 1;
+		/* Repaint search prompt and pattern. */
+		mca_search();
+		cmd_putstr(cbuf);
+	}
+
 	/*
 	 * Need another character.
 	 */
@@ -771,7 +812,7 @@
 		 * We have just run out of ungotten chars.
 		 */
 		unget_end = 0;
-		if (len_cmdbuf() == 0 || !empty_screen())
+		if (len_cmdbuf() == 0)
 			return (getchr());
 		/*
 		 * Command is incomplete, so try to complete it.
@@ -856,9 +897,10 @@
  * If SRCH_PAST_EOF is set, continue the search thru multiple files.
  */
 	static void
-multi_search(pattern, n)
+multi_search(pattern, n, incremental)
 	char *pattern;
 	int n;
+	int incremental;
 {
 	register int nomore;
 	IFILE save_ifile;
@@ -933,7 +975,7 @@
 	 * Didn't find it.
 	 * Print an error message if we haven't already.
 	 */
-	if (n > 0)
+	if (n > 0 && !incremental)
 		error("Pattern not found", NULL_PARG);
 
 	if (changed_file)
@@ -1376,7 +1418,7 @@
 			if (number <= 0) number = 1;	\
 			mca_search();			\
 			cmd_exec();			\
-			multi_search((char *)NULL, (int) number);
+			multi_search((char *)NULL, (int) number, 0);
 
 
 		case A_F_SEARCH:
===================================================================
RCS file: RCS/forwback.c,v
retrieving revision 1.35
diff -u -r1.35 forwback.c
--- forwback.c	2012/05/21 17:23:54	1.35
+++ forwback.c	2013/06/19 19:08:22
@@ -13,6 +13,7 @@
 public int squished;
 public int no_back_scroll = 0;
 public int forw_prompt;
+public int same_pos_bell = 1;
 
 extern int sigs;
 extern int top_scroll;
@@ -264,7 +265,7 @@
 		forw_prompt = 1;
 	}
 
-	if (nlines == 0)
+	if (nlines == 0 && same_pos_bell)
 		eof_bell();
 	else if (do_repaint)
 		repaint();
@@ -315,7 +316,7 @@
 		}
 	}
 
-	if (nlines == 0)
+	if (nlines == 0 && same_pos_bell)
 		eof_bell();
 	else if (do_repaint)
 		repaint();
===================================================================
RCS file: RCS/less.h,v
retrieving revision 1.64
diff -u -r1.64 less.h
--- less.h	2012/05/21 17:23:54	1.64
+++ less.h	2013/06/18 23:14:35
@@ -288,6 +288,15 @@
 	int ln;
 };
 
+/*
+ * A mark is an ifile (input file) plus a position within the file.
+ */
+struct mark 
+{
+	IFILE m_ifile;
+	struct scrpos m_scrpos;
+};
+
 typedef union parg
 {
 	char *p_string;
===================================================================
RCS file: RCS/mark.c,v
retrieving revision 1.17
diff -u -r1.17 mark.c
--- mark.c	2012/05/21 17:23:54	1.17
+++ mark.c	2013/06/19 19:08:22
@@ -8,14 +8,6 @@
 extern int jump_sline;
 
 /*
- * A mark is an ifile (input file) plus a position within the file.
- */
-struct mark {
-	IFILE m_ifile;
-	struct scrpos m_scrpos;
-};
-
-/*
  * The table of marks.
  * Each mark is identified by a lowercase or uppercase letter.
  * The final one is lmark, for the "last mark"; addressed by the apostrophe.
===================================================================
RCS file: RCS/opttbl.c,v
retrieving revision 1.58
diff -u -r1.58 opttbl.c
--- opttbl.c	2012/12/08 22:15:26	1.58
+++ opttbl.c	2013/06/19 19:09:06
@@ -46,6 +46,7 @@
 public int follow_mode;		/* F cmd Follows file desc or file name? */
 public int oldbot;		/* Old bottom of screen behavior {{REMOVE}} */
 public int opt_use_backslash;	/* Use backslash escaping in option parsing */
+public int incremental_search;	/* Display search results after each char in pattern */
 #if HILITE_SEARCH
 public int hilite_search;	/* Highlight matched search patterns? */
 #endif
@@ -101,6 +102,7 @@
 static struct optname x_optname      = { "tabs",                 NULL };
 static struct optname X__optname     = { "no-init",              NULL };
 static struct optname y_optname      = { "max-forw-scroll",      NULL };
+static struct optname Y__optname     = { "incremental-search",   NULL };
 static struct optname z_optname      = { "window",               NULL };
 static struct optname quote_optname  = { "quotes",               NULL };
 static struct optname tilde_optname  = { "tilde",                NULL };
@@ -385,6 +387,14 @@
 			NULL
 		}
 	},
+	{ 'Y', &Y__optname,
+		BOOL, OPT_OFF, &incremental_search, NULL,
+		{
+			"Normal search (press Enter to search)",
+			"Incremental search",
+			NULL
+		}
+	},
 	{ 'z', &z_optname,
 		NUMBER, -1, &swindow, NULL,
 		{
===================================================================
RCS file: RCS/pattern.c,v
retrieving revision 1.9
diff -u -r1.9 pattern.c
--- pattern.c	2012/06/17 00:03:32	1.9
+++ pattern.c	2013/06/19 19:26:57
@@ -13,10 +13,11 @@
  * Compile a search pattern, for future use by match_pattern.
  */
 	static int
-compile_pattern2(pattern, search_type, comp_pattern)
+compile_pattern2(pattern, search_type, comp_pattern, show_error)
 	char *pattern;
 	int search_type;
 	void **comp_pattern;
+	int show_error;
 {
 	if (search_type & SRCH_NO_REGEX)
 		return (0);
@@ -30,7 +31,8 @@
 	if (re_compile_pattern(pattern, strlen(pattern), comp))
 	{
 		free(comp);
-		error("Invalid pattern", NULL_PARG);
+		if (show_error)
+			error("Invalid pattern", NULL_PARG);
 		return (-1);
 	}
 	if (*pcomp != NULL)
@@ -43,7 +45,8 @@
 	if (regcomp(comp, pattern, REGCOMP_FLAG))
 	{
 		free(comp);
-		error("Invalid pattern", NULL_PARG);
+		if (show_error)
+			error("Invalid pattern", NULL_PARG);
 		return (-1);
 	}
 	if (*pcomp != NULL)
@@ -61,7 +64,8 @@
 	if (comp == NULL)
 	{
 		parg.p_string = (char *) errstring;
-		error("%s", &parg);
+		if (show_error)
+			error("%s", &parg);
 		return (-1);
 	}
 	*pcomp = comp;
@@ -71,7 +75,8 @@
 	int *pcomp = (int *) comp_pattern;
 	if ((parg.p_string = re_comp(pattern)) != NULL)
 	{
-		error("%s", &parg);
+		if (show_error)
+			error("%s", &parg);
 		return (-1);
 	}
 	*pcomp = 1;
@@ -81,7 +86,8 @@
 	char **pcomp = (char **) comp_pattern;
 	if ((comp = regcmp(pattern, 0)) == NULL)
 	{
-		error("Invalid pattern", NULL_PARG);
+		if (show_error)
+			error("Invalid pattern", NULL_PARG);
 		return (-1);
 	}
 	if (pcomp != NULL)
@@ -91,7 +97,10 @@
 #if HAVE_V8_REGCOMP
 	struct regexp *comp;
 	struct regexp **pcomp = (struct regexp **) comp_pattern;
-	if ((comp = regcomp(pattern)) == NULL)
+	reg_show_error = show_error;
+	comp = regcomp(pattern);
+	reg_show_error = 1;
+	if (comp == NULL)
 	{
 		/*
 		 * regcomp has already printed an error message 
@@ -126,7 +135,7 @@
 		cvt_pattern = (char*) ecalloc(1, cvt_length(strlen(pattern), CVT_TO_LC));
 		cvt_text(cvt_pattern, pattern, (int *)NULL, (int *)NULL, CVT_TO_LC);
 	}
-	result = compile_pattern2(cvt_pattern, search_type, comp_pattern);
+	result = compile_pattern2(cvt_pattern, search_type, comp_pattern, 1);
 	if (cvt_pattern != pattern)
 		free(cvt_pattern);
 	return (result);
@@ -176,6 +185,24 @@
 }
 
 /*
+ * Can a pattern be successfully compiled?
+ */
+	public int
+valid_pattern(pattern)
+	char *pattern;
+{
+	void *comp_pattern;
+	int result;
+
+	CLEAR_PATTERN(comp_pattern);
+	result = compile_pattern2(pattern, 0, &comp_pattern, 0);
+	if (result != 0)
+		return (0);
+	uncompile_pattern(&comp_pattern);
+	return (1);
+}
+
+/*
  * Is a compiled pattern null?
  */
 	public int
===================================================================
RCS file: RCS/search.c,v
retrieving revision 1.97
diff -u -r1.97 search.c
--- search.c	2012/06/23 23:48:33	1.97
+++ search.c	2013/06/19 18:52:06
@@ -1236,12 +1236,16 @@
  * This function is called by the V8 regcomp to report 
  * errors in regular expressions.
  */
+public int reg_show_error = 1;
+
 	void 
 regerror(s) 
 	char *s; 
 {
 	PARG parg;
 
+	if (!reg_show_error)
+		return;
 	parg.p_string = s;
 	error("%s", &parg);
 }

With this patch installed, search history doesn't work any more for me.

Try this:

• Open some file.
• Type "/and" (no quotes)
• Less now searches for "and", which is good.
• Type to get out of search mode
• Now, type "/or"
• Less now searches for "or", so far so good
• Press up arrow

Current result:

• Screen flashes a bit, nothing else happens

Expected result:

• Should have reverted to searching for "and" since "and" should be before "or" in the search history.

@walles would you mind re-filing your bug report at https://github.com/matthewlmcclure/less/issues ? Because this seems to be a one-off gist, and the main development seems to be done at the above linked Git repository. 😅