Added treemap example

examples/treemap/README.md

@@ -1,3 +1,3 @@
 # Treemap examples
 
-Currently none
+* pseudo_multiset.c - An example of how to make a multiset using a map.

examples/treemap/pseudo_multiset.c

@@ -0,0 +1,90 @@
+/**
+ * pseudo_multiset.c
+ *
+ * Creation Date: 03/04/2019
+ *
+ * Authors:
+ * Leonardo Vencovsky (https://github.com/LeoVen)
+ *
+ */
+
+// How to make a multiset using a map
+
+#include "treemap.h"
+#include <stdio.h>
+
+// Mapping an integer by size_t which will represent the key's multiplicity
+// (key could be anything and multiplicity could be an integer, preferably
+// unsigned)
+TREEMAP_GENERATE(tm, tmap, , int, size_t)
+
+// Compare function used by the treemap
+int intcmp(int a, int b)
+{
+    return (a > b) - (a < b);
+}
+
+// Little helper to print the tree
+void print_tree(tmap_node *root, int height)
+{
+    if (!root)
+        return;
+
+    print_tree(root->right, height + 1);
+
+    for (int i = 0; i < height; i++)
+        printf("|------- ");
+
+    // Key:Multiplicity
+    printf("%d:%llu\n", root->key, root->value);
+
+    print_tree(root->left, height + 1);
+}
+
+int main(int argc, char const *argv[])
+{
+    tmap *map = tm_new(intcmp);
+
+    // Start adding elements
+    for (int i = 0; i < 100; i++)
+    {
+        // Modulo of 8 so we get some repetition
+        int key = i % 8;
+
+        // Get the reference to a value in the map with the key
+        size_t *rvalue = tm_get_ref(map, key);
+
+        // If the key exists, rvalue is not null
+        if (rvalue != NULL)
+        {
+            // Incrementing it means we have added another key to the set
+            // The value represents the multiplicity, that is, how many times
+            // we have added the key in the set
+            (*rvalue)++;
+        }
+        else
+            // Create a new entry with key with an initial multiplicity of 1
+            tm_insert(map, key, 1);
+    }
+
+    print_tree(map->root, 0);
+
+    // Summary
+    printf("\n---------- SUMMARY ----------\n\n");
+
+    // Print using iterator
+    tmap_iter iter;
+    int key;
+    size_t mult, _;
+
+    for (tm_iter_new(&iter, map); !tm_iter_end(&iter); /* empty */)
+    {
+        // Map[key] = multiplicity
+        tm_iter_next(&iter, &key, &mult, &_);
+        printf("Map[%2d] = %llu\n", key, mult);
+    }
+
+    tm_free(map);
+
+    return 0;
+}