added the 'k' option to the 's' command in sed

qse/doc/page/sed-cmd.md

@@ -186,7 +186,9 @@ with *repl*. An ampersand(&) in *repl* refers to the matching substring.
    with *rex*
  - *p* prints pattern space if a successful replacement was made
  - *w* file writes pattern space to *file* if a successful replacement 
-      was made. It, if specified, should be the last option.
+   was made. It, if specified, should be the last option.
+ - *k* removes(kills) unmached portions from the pattern space. It is
+   useful for partial extraction.
 
 ### y/src/dst/ ###
 Replaces all occurrences of characters in *src* with characters in *dst*.
@@ -236,6 +238,18 @@ first and the first line last.
 ### s/[[:space:]]{2,}/ /g ###
 Compacts whitespaces if #QSE_SED_EXTENDEDREX is on.
 
+### s/[0-9]/&/gk ###
+Extract all digits.
+
+	$ echo "Q123Q456" | qsesed -r 's/[0-9]+/&/gk'
+	123456
+
+### s/[0-9]+/&/2k ###
+Extract the second number.
+
+	$ echo "Q123Q456" | qsesed -r 's/[0-9]+/&/2k'
+	456
+
 ### C/d:,f3,1/ ###
 Prints the third field and the first field from a colon separated text.
 

qse/include/qse/sed/sed.h

@@ -171,6 +171,7 @@ struct qse_sed_cmd_t
 			unsigned short g: 1; /* global */
 			unsigned short p: 1; /* print */
 			unsigned short i: 1; /* case insensitive */
+			unsigned short k: 1; /* kill unmatched portion */
 		} subst;
 
 		/* translation set for the y command */

qse/lib/sed/sed.c

@@ -1383,6 +1383,11 @@ static int get_subst (qse_sed_t* sed, qse_sed_cmd_t* cmd)
 			cmd->u.subst.g = 1;
 			NXTSC_GOTO (sed, c, oops);
 		}
+		else if (c == QSE_T('k')) 
+		{
+			cmd->u.subst.k = 1;
+			NXTSC_GOTO (sed, c, oops);
+		}
 		else if (c >= QSE_T('0') && c <= QSE_T('9'))
 		{
 			unsigned long occ;
@@ -2833,13 +2838,17 @@ static int do_subst (qse_sed_t* sed, qse_sed_cmd_t* cmd)
 
 		if (n == 0) 
 		{
-			/* no more match found */
+			/* no more match found or substitution occurrence matched.
-			if (qse_str_ncat (
+			 * copy the remaining portion and finish */
-				&sed->e.txt.scratch,
+			if (!cmd->u.subst.k)
-				cur.ptr, cur.len) == (qse_size_t)-1)
 			{
-				SETERR0 (sed, QSE_SED_ENOMEM, QSE_NULL);
+				/* copy the remaining portion */
-				return -1;
+				m = qse_str_ncat (&sed->e.txt.scratch, cur.ptr, cur.len);
+				if (m == (qse_size_t)-1)
+				{
+					SETERR0 (sed, QSE_SED_ENOMEM, QSE_NULL);
+					return -1;
+				}
 			}
 			break;
 		}
@@ -2854,11 +2863,16 @@ static int do_subst (qse_sed_t* sed, qse_sed_cmd_t* cmd)
 
 		if (max_count > 0 && sub_count + 1 != max_count)
 		{
-			if (cur.ptr < str_end)
+			/* substition occurrence specified.
+			 * but this is not the occurrence yet */
+
+			if (!cmd->u.subst.k && cur.ptr < str_end)
 			{
+				/* copy the unmatched portion and the matched portion
+				 * together as if the matched portion was not matched */
 				m = qse_str_ncat (
 					&sed->e.txt.scratch,
-					cur.ptr, mat.ptr-cur.ptr+mat.len
+					cur.ptr, mat.ptr - cur.ptr + mat.len
 				);
 				if (m == (qse_size_t)-1)
 				{
@@ -2869,12 +2883,14 @@ static int do_subst (qse_sed_t* sed, qse_sed_cmd_t* cmd)
 		}
 		else
 		{
+			/* perform actual substitution */
+
 			repl = 1;
 
-			if (cur.ptr < str_end)
+			if (!cmd->u.subst.k && cur.ptr < str_end)
 			{
 				m = qse_str_ncat (
-					&sed->e.txt.scratch, cur.ptr, mat.ptr-cur.ptr
+					&sed->e.txt.scratch, cur.ptr, mat.ptr - cur.ptr
 				);
 				if (m == (qse_size_t)-1)
 				{
@@ -2902,8 +2918,10 @@ static int do_subst (qse_sed_t* sed, qse_sed_cmd_t* cmd)
 					else
 					{
 #endif
-						/* the know speical characters have been escaped
+						/* Known speical characters have been escaped
-						 * in get_subst(). so i don't call trans_escaped() here */
+						 * in get_subst(). so i don't call trans_escaped() here. 
+						 * It's a normal character that's escaped. 
+						 * For example, \1 is just 1. and \M is just M. */
 						m = qse_str_ccat (&sed->e.txt.scratch, nc);
 #ifndef USE_REX
 					}