intmap: implement uintmap_last/sintmap_last.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/intmap/intmap.c

@@ -197,6 +197,24 @@ void *intmap_after_(const struct intmap *map, intmap_index_t *indexp)
 	return intmap_first_(&prev->u.n->child[1], indexp);
 }
 
+void *intmap_last_(const struct intmap *map, intmap_index_t *indexp)
+{
+	const struct intmap *n;
+
+	if (intmap_empty_(map)) {
+		errno = ENOENT;
+		return NULL;
+	}
+
+	n = map;
+	/* Anything with NULL value is a node. */
+	while (!n->v)
+		n = &n->u.n->child[1];
+	errno = 0;
+	*indexp = n->u.i;
+	return n->v;
+}
+
 static void clear(struct intmap n)
 {
 	if (!n.v) {

ccan/intmap/intmap.h

@@ -309,6 +309,32 @@ void *intmap_after_(const struct intmap *map, intmap_index_t *indexp);
 	tcon_cast((smap), sintmap_canary,				\
 		  sintmap_after_(sintmap_unwrap_(smap), (indexp)))
 
+/**
+ * uintmap_last - get last value in an unsigned intmap
+ * @umap: the typed intmap to iterate through.
+ * @indexp: a pointer to store the index.
+ *
+ * Returns NULL if the map is empty, otherwise populates *@indexp and
+ * returns the highest entry.
+ */
+#define uintmap_last(umap, indexp)					\
+	tcon_cast((umap), uintmap_canary,				\
+		  intmap_last_(uintmap_unwrap_(umap), (indexp)))
+
+void *intmap_last_(const struct intmap *map, intmap_index_t *indexp);
+
+/**
+ * sintmap_last - get last value in a signed intmap
+ * @smap: the typed intmap to iterate through.
+ * @indexp: a pointer to store the index.
+ *
+ * Returns NULL if the map is empty, otherwise populates *@indexp and
+ * returns the highest entry.
+ */
+#define sintmap_last(smap, indexp)					\
+	tcon_cast((smap), sintmap_canary,				\
+		  sintmap_last_(sintmap_unwrap_(smap), (indexp)))
+
 /* TODO: We could implement intmap_prefix. */
 
 /* These make sure it really is a uintmap/sintmap */
@@ -339,4 +365,14 @@ static inline void *sintmap_after_(const struct intmap *map,
 	*indexp = SINTMAP_UNOFF(i);
 	return ret;
 }
+
+static inline void *sintmap_last_(const struct intmap *map,
+				  sintmap_index_t *indexp)
+{
+	intmap_index_t i;
+	void *ret = intmap_last_(map, &i);
+	*indexp = SINTMAP_UNOFF(i);
+	return ret;
+
+}
 #endif /* CCAN_INTMAP_H */

ccan/intmap/test/run-order-smallsize.c

@@ -14,8 +14,9 @@ static bool check_umap(const umap *map)
 {
 	/* This is a larger type than unsigned, and allows negative */
 	int64_t prev;
-	intmap_index_t i;
+	intmap_index_t i, last_idx;
 	uint8_t *v;
+	bool last = true;
 
 	/* Must be in order, must contain value. */
 	prev = -1;
@@ -25,16 +26,18 @@ static bool check_umap(const umap *map)
 		if (*v != i)
 			return false;
 		prev = i;
+		last = (uintmap_last(map, &last_idx) == v);
 	}
-	return true;
+	return last;
 }
 
 static bool check_smap(const smap *map)
 {
 	/* This is a larger type than int, and allows negative */
 	int64_t prev;
-	sintmap_index_t i;
+	sintmap_index_t i, last_idx;
 	int8_t *v;
+	bool last = true;
 
 	/* Must be in order, must contain value. */
 	prev = -0x80000001ULL;
@@ -44,8 +47,9 @@ static bool check_smap(const smap *map)
 		if (*v != i)
 			return false;
 		prev = i;
+		last = (sintmap_last(map, &last_idx) == v);
 	}
-	return true;
+	return last;
 }
 
 int main(void)

ccan/intmap/test/run-order.c

@@ -11,8 +11,9 @@ static bool check_umap(const umap *map)
 {
 	/* This is a larger type than unsigned, and allows negative */
 	int64_t prev;
-	uint64_t i;
+	uint64_t i, last_idx;
 	unsigned int *v;
+	bool last = true;
 
 	/* Must be in order, must contain value. */
 	prev = -1;
@@ -22,15 +23,17 @@ static bool check_umap(const umap *map)
 		if (*v != i)
 			return false;
 		prev = i;
+		last = (uintmap_last(map, &last_idx) == v);
 	}
-	return true;
+	return last;
 }
 
 static bool check_smap(const smap *map)
 {
 	/* This is a larger type than int, and allows negative */
-	int64_t prev, i;
+	int64_t prev, i, last_idx;
 	int *v;
+	bool last = true;
 
 	/* Must be in order, must contain value. */
 	prev = -0x80000001ULL;
@@ -39,9 +42,10 @@ static bool check_smap(const smap *map)
 			return false;
 		if (*v != i)
 			return false;
+		last = (sintmap_last(map, &last_idx) == v);
 		prev = i;
 	}
-	return true;
+	return last;
 }
 
 int main(void)

ccan/intmap/test/run-signed-int.c

@@ -9,13 +9,14 @@ int main(void)
 	int64_t s;
 
 	/* This is how many tests you plan to run */
-	plan_tests(35);
+	plan_tests(38);
 
 	sintmap_init(&map);
 	/* Test boundaries. */
 	ok1(!sintmap_get(&map, 0x7FFFFFFFFFFFFFFFLL));
 	ok1(!sintmap_get(&map, -0x8000000000000000LL));
 	ok1(sintmap_first(&map, &s) == NULL);
+	ok1(sintmap_last(&map, &s) == NULL);
 	ok1(errno == ENOENT);
 	s = 0x7FFFFFFFFFFFFFFFLL;
 	ok1(sintmap_after(&map, &s) == NULL);
@@ -29,12 +30,14 @@ int main(void)
 	ok1(sintmap_add(&map, 0x7FFFFFFFFFFFFFFFLL, first));
 	ok1(sintmap_get(&map, 0x7FFFFFFFFFFFFFFFLL) == first);
 	ok1(sintmap_first(&map, &s) == first && s == 0x7FFFFFFFFFFFFFFFLL);
+	ok1(sintmap_last(&map, &s) == first && s == 0x7FFFFFFFFFFFFFFFLL);
 	ok1(errno == 0);
 	ok1(sintmap_add(&map, -0x8000000000000000LL, second));
 	ok1(sintmap_get(&map, 0x7FFFFFFFFFFFFFFFLL) == first);
 	ok1(sintmap_get(&map, -0x8000000000000000LL) == second);
 	ok1(sintmap_first(&map, &s) == second && s == -0x8000000000000000LL);
 	ok1(sintmap_after(&map, &s) == first && s == 0x7FFFFFFFFFFFFFFFLL);
+	ok1(sintmap_last(&map, &s) == first && s == 0x7FFFFFFFFFFFFFFFLL);
 	ok1(errno == 0);
 	s = 0x7FFFFFFFFFFFFFFELL;
 	ok1(sintmap_after(&map, &s) == first && s == 0x7FFFFFFFFFFFFFFFLL);

ccan/intmap/test/run.c

@@ -7,9 +7,10 @@ int main(void)
 	UINTMAP(char *) map;
 	const char val[] = "there";
 	const char none[] = "";
+	uint64_t idx;
 
 	/* This is how many tests you plan to run */
-	plan_tests(28);
+	plan_tests(40);
 
 	uintmap_init(&map);
 
@@ -21,11 +22,19 @@ int main(void)
 	ok1(errno == ENOENT);
 	ok1(!uintmap_del(&map, 0));
 	ok1(errno == ENOENT);
+	ok1(!uintmap_first(&map, &idx));
+	ok1(errno == ENOENT);
+	ok1(!uintmap_last(&map, &idx));
+	ok1(errno == ENOENT);
 
 	ok1(uintmap_add(&map, 1, val));
 	ok1(uintmap_get(&map, 1) == val);
 	ok1(!uintmap_get(&map, 0));
 	ok1(errno == ENOENT);
+	ok1(uintmap_first(&map, &idx) == val);
+	ok1(idx == 1);
+	ok1(uintmap_last(&map, &idx) == val);
+	ok1(idx == 1);
 
 	/* Add a duplicate should fail. */
 	ok1(!uintmap_add(&map, 1, val));
@@ -43,6 +52,10 @@ int main(void)
 	ok1(uintmap_add(&map, 1, val));
 	ok1(uintmap_get(&map, 1) == val);
 	ok1(uintmap_get(&map, 0) == none);
+	ok1(uintmap_first(&map, &idx) == none);
+	ok1(idx == 0);
+	ok1(uintmap_last(&map, &idx) == val);
+	ok1(idx == 1);
 	ok1(!uintmap_del(&map, 2));
 	ok1(uintmap_del(&map, 0) == none);
 	ok1(uintmap_get(&map, 1) == val);