mesa: Add iterate method for string_to_uint_map

The upcoming shader cache needs this to be able to cache hash data
from the gl_shader_program structure.

Edited-by: Carl Worth <cworth@cworth.org>:

There is an internal implementation detail that the hash table
underlying the struct string_to_uint_map stores each value internally
as (value+1). The user needn't be very concerned with this (other than
knowing that a value of UINT_MAX cannot be stored) since put() adds 1
and get() subtracts 1.

So in this commit, rather than call the user's function directly with
hash_table_call_foreach, we call through a wrapper that fixes up the
off-by-one values before the caller's callback sees them.

And with this wrapper in place, we also give a better signature to the
callback function being passed to iterate(), so that this callback
function can actually expect a char* and an unsigned argument, (rather
than a couple of void* ).

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>

src/mesa/program/hash_table.h

@@ -198,6 +198,11 @@ string_to_uint_map_dtor(struct string_to_uint_map *);
 #ifdef __cplusplus
 }
 
+struct string_map_iterate_wrapper_closure {
+   void (*callback)(const char *key, unsigned value, void *closure);
+   void *closure;
+};
+
 /**
  * Map from a string (name) to an unsigned integer value
  *
@@ -228,6 +233,24 @@ public:
       hash_table_clear(this->ht);
    }
 
+   /**
+    * Runs a passed callback for the hash
+    */
+   void iterate(void (*func)(const char *, unsigned, void *), void *closure)
+   {
+      struct string_map_iterate_wrapper_closure *wrapper;
+
+      wrapper = (struct string_map_iterate_wrapper_closure *)
+         malloc(sizeof(struct string_map_iterate_wrapper_closure));
+      if (wrapper == NULL)
+         return;
+
+      wrapper->callback = func;
+      wrapper->closure = closure;
+
+      hash_table_call_foreach(this->ht, subtract_one_wrapper, wrapper);
+   }
+
    /**
     * Get the value associated with a particular key
     *
@@ -281,6 +304,17 @@ private:
       free((char *)key);
    }
 
+   static void subtract_one_wrapper(const void *key, void *data, void *closure)
+   {
+      struct string_map_iterate_wrapper_closure *wrapper =
+         (struct string_map_iterate_wrapper_closure *) closure;
+      unsigned value = (intptr_t) data;
+
+      value -= 1;
+
+      wrapper->callback((const char *) key, value, wrapper->closure);
+   }
+
    struct hash_table *ht;
 };