strmap: add functions facilitating use as a string->int map

Although strmap could be used as a string->int map, one either had to
allocate an int for every entry and then deallocate later, or one had to
do a bunch of casting between (void*) and (intptr_t).

Add some special functions that do the casting.  Also, rename put->set
for such wrapper functions since 'put' implied there may be some
deallocation needed if the string was already found in the map, which
isn't the case when we're storing an int value directly in the void*
slot instead of using the void* slot as a pointer to data.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

strmap.c

@@ -123,3 +123,14 @@ void strmap_remove(struct strmap *map, const char *str, int free_value)
 		free((char*)ret->key);
 	free(ret);
 }
+
+void strintmap_incr(struct strintmap *map, const char *str, intptr_t amt)
+{
+	struct strmap_entry *entry = find_strmap_entry(&map->map, str);
+	if (entry) {
+		intptr_t *whence = (intptr_t*)&entry->value;
+		*whence += amt;
+	}
+	else
+		strintmap_set(map, str, map->default_value + amt);
+}

strmap.h

@@ -23,6 +23,10 @@ int cmp_strmap_entry(const void *hashmap_cmp_fn_data,
 			.map = HASHMAP_INIT(cmp_strmap_entry, NULL),  \
 			.strdup_strings = 1,                          \
 		    }
+#define STRINTMAP_INIT { \
+			.map = STRMAP_INIT,   \
+			.default_value = 0,   \
+		       }
 
 /*
  * Initialize the members of the strmap.  Any keys added to the strmap will
@@ -102,4 +106,94 @@ static inline int strmap_empty(struct strmap *map)
 #define strmap_for_each_entry(mystrmap, iter, var)	\
 	hashmap_for_each_entry(&(mystrmap)->map, iter, var, ent)
 
+
+/*
+ * strintmap:
+ *    A map of string -> int, typecasting the void* of strmap to an int.
+ *
+ * Primary differences:
+ *    1) Since the void* value is just an int in disguise, there is no value
+ *       to free.  (Thus one fewer argument to strintmap_clear)
+ *    2) strintmap_get() returns an int, or returns the default_value if the
+ *       key is not found in the strintmap.
+ *    3) No strmap_put() equivalent; strintmap_set() and strintmap_incr()
+ *       instead.
+ */
+
+struct strintmap {
+	struct strmap map;
+	int default_value;
+};
+
+#define strintmap_for_each_entry(mystrmap, iter, var)	\
+	strmap_for_each_entry(&(mystrmap)->map, iter, var)
+
+static inline void strintmap_init(struct strintmap *map, int default_value)
+{
+	strmap_init(&map->map);
+	map->default_value = default_value;
+}
+
+static inline void strintmap_init_with_options(struct strintmap *map,
+					       int default_value,
+					       int strdup_strings)
+{
+	strmap_init_with_options(&map->map, strdup_strings);
+	map->default_value = default_value;
+}
+
+static inline void strintmap_clear(struct strintmap *map)
+{
+	strmap_clear(&map->map, 0);
+}
+
+static inline void strintmap_partial_clear(struct strintmap *map)
+{
+	strmap_partial_clear(&map->map, 0);
+}
+
+static inline int strintmap_contains(struct strintmap *map, const char *str)
+{
+	return strmap_contains(&map->map, str);
+}
+
+static inline void strintmap_remove(struct strintmap *map, const char *str)
+{
+	return strmap_remove(&map->map, str, 0);
+}
+
+static inline int strintmap_empty(struct strintmap *map)
+{
+	return strmap_empty(&map->map);
+}
+
+static inline unsigned int strintmap_get_size(struct strintmap *map)
+{
+	return strmap_get_size(&map->map);
+}
+
+/*
+ * Returns the value for str in the map.  If str isn't found in the map,
+ * the map's default_value is returned.
+ */
+static inline int strintmap_get(struct strintmap *map, const char *str)
+{
+	struct strmap_entry *result = strmap_get_entry(&map->map, str);
+	if (!result)
+		return map->default_value;
+	return (intptr_t)result->value;
+}
+
+static inline void strintmap_set(struct strintmap *map, const char *str,
+				 intptr_t v)
+{
+	strmap_put(&map->map, str, (void *)v);
+}
+
+/*
+ * Increment the value for str by amt.  If str isn't in the map, add it and
+ * set its value to default_value + amt.
+ */
+void strintmap_incr(struct strintmap *map, const char *str, intptr_t amt);
+
 #endif /* STRMAP_H */