ed

commit f7835588a3b9d7411ecbbdbe133191ccec714e50
parent 7283f7b7e396bbdc8f6ac0e77a41ec2faae67e0d
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Sun, 13 Dec 2015 20:41:01 +0100

Use a better allocation schema for undo

We were using a realloc by one schema in
undo data, which can be really inefficient.
This commits use a 10 items at time allocation
schema and creates a struct for the undo data.

Diffstat:
M
ed.c
 | 
49
++++++++++++++++++++++++++++++-------------------

1 file changed, 30 insertions(+), 19 deletions(-)
diff --git a/ed.c b/ed.c
@@ -24,12 +24,15 @@ struct hline {
 	int   next, prev;
 };
 
-struct editop {
-	int to1, from1;
-	int to2, from2;
+struct undo {
+	int curln;
+	size_t nr, cap;
+	struct link {
+		int to1, from1;
+		int to2, from2;
+	} *vec;
 };
 
-
 char *prompt = "*";
 regex_t *pattern;
 regmatch_t matchs[10];
@@ -56,8 +59,7 @@ size_t cmdsiz, cmdcap;
 int repidx;
 char *rhs;
 char *lastmatch;
-struct editop *undoptr;
-int nr_undo;
+struct undo udata;
 
 static void
 error(char *msg)
@@ -226,36 +228,45 @@ setglobal(int i, int v)
 static void
 relink(int to1, int from1, int from2, int to2)
 {
-	struct editop *p;
+	struct link *p;
 
-	if ((p = realloc(undoptr, sizeof(*p) * (nr_undo + 1))) == NULL)
-		error("out of memory");
-	undoptr = p;
-	p += nr_undo;
+	if (udata.nr >= udata.cap) {
+		size_t siz = (udata.cap + 10) * sizeof(struct link);
+		if ((p = realloc(udata.vec, siz)) == NULL)
+			error("out of memory");
+		udata.vec = p;
+		udata.cap = udata.cap + 10;
+	}
+	p = &udata.vec[udata.nr++];
 	p->from1 = from1;
 	p->to1 = zero[from1].next;
-	p->to2 = zero[from2].prev;
 	p->from2 = from2;
+	p->to2 = zero[from2].prev;
 
 	zero[from1].next = to1;
 	zero[from2].prev = to2;
 	modflag = 1;
-	++nr_undo;
+	fprintf(stderr, "linking %d <- %d, %d -> %d\n", to2, from2, from1, to1);
 }
 
 static void
 undo(void)
 {
 	int i;
-	struct editop *p;
+	struct link *p;
 
-	for (p = &undoptr[nr_undo]; p-- > undoptr; ) {
+	if (udata.nr == 0)
+		error("nothing to undo");
+	for (p = &udata.vec[udata.nr-1]; udata.nr--; --p) {
 		zero[p->from1].next = p->to1;
-		zero[p->from2].next = p->to2;
+		zero[p->from2].prev = p->to2;
+		fprintf(stderr,
+		        "linking %d <- %d, %d -> %d\n",
+		        p->to2, p->from2, p->from1, p->to1);
 	}
-	free(undoptr);
-	nr_undo = 0;
-	undoptr = NULL;
+	free(udata.vec);
+	udata.vec = NULL;
+	udata.cap = 0;
 }
 
 static void