adding zephyr-im master branch

zwgc/string_dictionary_aux.c

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+/* This file is part of the Project Athena Zephyr Notification System.
+ * It is one of the source files comprising zwgc, the Zephyr WindowGram
+ * client.
+ *
+ *      Created by:     Marc Horowitz <marc@athena.mit.edu>
+ *
+ *      $Id$
+ *
+ *      Copyright (c) 1989 by the Massachusetts Institute of Technology.
+ *      For copying and distribution information, see the file
+ *      "mit-copyright.h".
+ */
+
+#if (!defined(lint) && !defined(SABER))
+static const char rcsid_string_dictionary_aux_c[] = "$Id$";
+#endif
+
+/*
+ * string_dictionary_aux - a module implementing convenience routines for use
+ *                         with string_dictionarys
+ *
+ * Overview:
+ *
+ *       This module implements Fetch and Set operations on
+ *    string_dictionaries which take the place of Define and Lookup for
+ *    most uses.  The importance difference between them and Define and
+ *    Lookup is that they maintain the invariant that all the value strings
+ *    in a string_dictionary are on the heap.  In particular, they do
+ *    free's and string_Copy's whenever needed.  Also implemented is
+ *    SafeDestroy which does a Destroy after freeing all the value strings
+ *    in a string_dictionary.
+ */
+
+#include <sysdep.h>
+#include "new_memory.h"
+#include "string_dictionary.h"
+#include "string_dictionary_aux.h"
+
+/*
+ *    void string_dictionary_Set(string_dictionary d, string key,string value):
+ *        Modifies: d
+ *        Effects: Binds key to value in d.  Automatically free's the
+ *                 previous value of key, if any.  Value is copied on the
+ *                 heap.
+ */
+
+void
+string__dictionary_Set(string_dictionary d,
+		       string key,
+		       string value)
+{
+    string_dictionary_binding *binding;
+    int already_exists;
+
+    binding = string_dictionary_Define(d, key, &already_exists);
+    if (already_exists)
+      free(binding->value);
+
+    binding->value = string_Copy(value);
+}
+
+/*
+ *    char *string_dictionary_Fetch(string_dictionary d, string key)
+ *        Effects: If key is not bound in d, returns 0.  Otherwise,
+ *                 returns the value that key is bound to.  
+ *                 Note that the returned string if any should not be
+ *                 freed or modified in any way.  Note also that it may
+ *                 disappear later if key is rebound.
+ */
+
+char *
+string_dictionary_Fetch(string_dictionary d,
+			string key)
+{
+    string_dictionary_binding *binding;
+
+    binding = string_dictionary_Lookup(d, key);
+    if (!binding)
+      return(0);
+
+    return(binding->value);
+}
+
+/*
+ *    void string_dictionary_SafeDestroy(string_dictionary d)
+ *        Modifies: d
+ *        Effects: Like string_dictionary_Destroy except first frees
+ *                 all value's in the dictionary.
+ */
+
+static void
+free_value_of_binding(string_dictionary_binding *b)
+{
+    free(b->value);
+}
+
+void
+string_dictionary_SafeDestroy(string_dictionary d)
+{
+    string_dictionary_Enumerate(d, free_value_of_binding);
+    string_dictionary_Destroy(d);
+}