Add method to stringify a line struct, skipping first N elements

- adds an internal method _irc_line_to_string with current irc_line_to_string
  code, adding capability to skip the first N elements
- call this internal method from irc_line_to_string with N=0
- call this internal method from new irc_line_to_string_skip method

Signed-off-by: Loïc Gomez <bip@animanova.fr>

src/line.c

@@ -16,6 +16,8 @@
 #include "line.h"
 #include "util.h"
 
+char *_irc_line_to_string(struct line *l, int skip_first);
+
 // TODO resolve assuming signed overflow does not occur when changing X +- C1
 // cmp C2 to X cmp C2 -+ C1
 #pragma GCC diagnostic ignored "-Wstrict-overflow"
@@ -76,6 +78,19 @@ void irc_line_append(struct line *l, const char *s)
 }
 
 char *irc_line_to_string(struct line *l)
+{
+    return _irc_line_to_string(l, 0);
+}
+
+char *irc_line_to_string_skip(struct line *l, int skip_first)
+{
+    if (skip_first >= irc_line_count(l)) {
+        return NULL;
+    }
+    return _irc_line_to_string(l, skip_first);
+}
+
+char *_irc_line_to_string(struct line *l, int skip_first)
 {
 	size_t len = 0;
 	int i;
@@ -83,7 +98,7 @@ char *irc_line_to_string(struct line *l)
 
 	if (l->origin)
 		len = strlen(l->origin) + 2;
-	for (i = 0; i < array_count(&l->words); i++)
+	for (i = skip_first; i < array_count(&l->words); i++)
 		len += strlen(array_get(&l->words, i)) + 1;
 	len += 1; /* remove one trailing space and add \r\n */
 	len++;	  /* last args ":" */
@@ -95,7 +110,7 @@ char *irc_line_to_string(struct line *l)
 		strcat(ret, l->origin);
 		strcat(ret, " ");
 	}
-	for (i = 0; i < array_count(&l->words) - 1; i++) {
+	for (i = skip_first; i < array_count(&l->words) - 1; i++) {
 		strcat(ret, array_get(&l->words, i));
 		strcat(ret, " ");
 	}

src/line.h

@@ -90,6 +90,7 @@ void irc_line_write(struct line *l, connection_t *c);
 void irc_line_append(struct line *l, const char *s);
 struct line *irc_line_new_from_string(char *str);
 char *irc_line_to_string(struct line *l);
+char *irc_line_to_string_skip(struct line *l, int skip_first);
 char *irc_line_to_string_to(struct line *line, char *nick);
 void irc_line_free(struct line *l);
 struct line *irc_line_dup(struct line *line);