Add array_grow function

Makefile.am

@@ -3,9 +3,10 @@
 AM_CPPFLAGS = -Ilib -Isrc
 
 noinst_LIBRARIES = \
-		libcore.a 
+		libcore.a
 
 libcore_a_SOURCES = \
+		src/coreutil.c \
 		src/coreutil.h \
 		src/hash.h \
 		src/hashset.c \

src/coreutil.c

@@ -0,0 +1,19 @@
+#include <assert.h>
+#include "coreutil.h"
+
+
+size_t array_grow(size_t count, size_t capacity, size_t delta,
+		  size_t capacity_max)
+{
+	assert(count <= capacity);
+	assert(capacity <= capacity_max);
+	assert(delta <= capacity_max - count);
+
+	size_t capacity_min = count + delta;
+	while (capacity < capacity_min) {
+		capacity = ARRAY_GROW1(capacity, capacity_max);
+	}
+
+	return capacity;
+}
+

src/coreutil.h

@@ -1,6 +1,9 @@
 #ifndef CORE_COREUTIL_H
 #define CORE_COREUTIL_H
 
+#include <stddef.h>
+
+
 #define MAX(x,y) ((y) > (x) ? (y) : (x))
 #define MIN(x,y) ((y) < (x) ? (y) : (x))
 
@@ -9,13 +12,16 @@
 
 
 /* 0, 5, 11, 20, 34, 55, 86, 133, 203, 308, ... */
-#define ARRAY_DELTA(n) \
+#define ARRAY_DELTA1(n) \
 	((n) ? ((n) >> 1) + 4 : 5)
 
-#define ARRAY_GROW(n,nmax) \
-	(((n) <= (nmax) - ARRAY_DELTA(n)) \
-	 ? (n) + ARRAY_DELTA(n) \
+#define ARRAY_GROW1(n,nmax) \
+	(((n) <= (nmax) - ARRAY_DELTA1(n)) \
+	 ? (n) + ARRAY_DELTA1(n) \
 	 : (nmax))
 
+size_t array_grow(size_t count, size_t capacity, size_t delta,
+		  size_t capacity_max);
+
 
 #endif /* CORE_COREUTIL_H */

src/pqueue.c

@@ -85,7 +85,7 @@ int pqueue_ensure_capacity(struct pqueue *q, size_t n)
 
 static void pqueue_grow(struct pqueue *q)
 {
-	q->capacity = ARRAY_GROW(q->capacity, SIZE_MAX);
+	q->capacity = ARRAY_GROW1(q->capacity, SIZE_MAX);
 	q->base = xrealloc(q->base, q->capacity * q->width);
 }