begriffs · February 13, 2021 20:28 · Feb 13, 2021
diff --git a/dict.c b/dict.c
@@ -0,0 +1,85 @@
+#include "dict.h"
+
+#include <stdlib.h>
+#include <search.h>
+
+/* XOPEN for strdup */
+#define _XOPEN_SOURCE 600
+#include <string.h>
+
+struct dict_entry
+{
+	const char *key;
+	char *val;
+};
+
+static int
+_key_cmp(const void *a, const void* b)
+{
+	const struct dict_entry *u = a, *v = b;
+	return strcmp(u->key, v->key);
+}
+
+static int
+_always_equal(const void *a, const void *b)
+{
+	(void) a;
+	(void) b;
+	return 0;
+}
+
+char *dict_get(void **d, const char *key)
+{
+	struct dict_entry  y   = { .key = (char *)key },
+	                 **elt = tfind(&y, d, _key_cmp);
+	return elt ? (*elt)->val : NULL;
+}
+
+bool dict_set(void **d, const char *key, const char *val)
+{
+	struct dict_entry *probe, **found;
+
+	if (!(probe = malloc(sizeof *probe)))
+		return false;
+	*probe = (struct dict_entry){.key=key};
+	if (!(found = tsearch(probe, d, _key_cmp)))
+		return false;
+
+	if (*found == probe) /* new entry */
+	{
+		char *newkey = strdup(key), *newval = strdup(val);
+		if (!newkey || !newval)
+		{
+			tdelete(probe, d, _always_equal);
+			free(probe);
+			return false;
+		}
+		/* probe used arg pointers; assign copies */
+		**found = (struct dict_entry){.key=newkey, .val=newval};
+	}
+	else  /* already existed */
+	{
+		char *newval = strdup(val);
+		if (!newval)
+		{
+			free(probe);
+			return false;
+		}
+		free((*found)->val);
+		(*found)->val = newval;
+		free(probe);
+	}
+	return true;
+}
+
+void dict_free(void **d)
+{
+	while (*d)
+	{
+		struct dict_entry *item = *(struct dict_entry **)*d;
+		tdelete(item, d, _always_equal);
+		free((char*)item->key);
+		free(item->val);
+		free(item);
+	}
+}
diff --git a/dict.h b/dict.h
@@ -0,0 +1,10 @@
+#ifndef GRIFFS_DICT_H
+#define GRIFFS_DICT_H
+
+#include <stdbool.h>
+
+char *dict_get(void **, const char *);
+bool dict_set(void **, const char *, const char *);
+void dict_free(void **);
+
+#endif