Add rtree.h.md

rtree.h.md

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+# Tree example
+
+Was written a long while ago. But it's probably ok.
+
+## Source code:
+```c
+#ifndef RTREE_H
+#define RTREE_H
+#include "rmalloc.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct rtree_t {
+    struct rtree_t *next;
+    struct rtree_t *children;
+    char c;
+    void *data;
+} rtree_t;
+
+rtree_t *rtree_new() {
+    rtree_t *b = (rtree_t *)rmalloc(sizeof(rtree_t));
+    b->next = NULL;
+    b->children = NULL;
+    b->c = 0;
+    b->data = NULL;
+    return b;
+}
+
+rtree_t *rtree_set(rtree_t *b, char *c, void *data) {
+    while (b) {
+        if (b->c == 0) {
+            b->c = *c;
+            c++;
+            if (*c == 0) {
+                b->data = data;
+                // printf("SET1 %c\n", b->c);
+                return b;
+            }
+        } else if (b->c == *c) {
+            c++;
+            if (*c == 0) {
+                b->data = data;
+                return b;
+            }
+            if (b->children) {
+                b = b->children;
+            } else {
+                b->children = rtree_new();
+                b = b->children;
+            }
+        } else if (b->next) {
+            b = b->next;
+        } else {
+            b->next = rtree_new();
+            b = b->next;
+            b->c = *c;
+            c++;
+            if (*c == 0) {
+                b->data = data;
+                return b;
+            } else {
+                b->children = rtree_new();
+                b = b->children;
+            }
+        }
+    }
+    return NULL;
+}
+
+rtree_t *rtree_find(rtree_t *b, char *c) {
+    while (b) {
+        if (b->c == *c) {
+            c++;
+            if (*c == 0) {
+                return b;
+            }
+            b = b->children;
+            continue;
+        }
+        b = b->next;
+    }
+    return NULL;
+}
+
+void rtree_free(rtree_t *b) {
+    if (!b)
+        return;
+    rtree_free(b->children);
+    rtree_free(b->next);
+    rfree(b);
+}
+
+void *rtree_get(rtree_t *b, char *c) {
+    rtree_t *t = rtree_find(b, c);
+    if (t) {
+        return t->data;
+    }
+    return NULL;
+}
+
+```