feat(lsm): possibly implemented trie insert

lsm/src/str/lsm_str.c

@@ -5,6 +5,8 @@
 #include "lsm.h"
 #include "lsm/str_internal.h"
 
+#define MIN(x, y) (((x) < (y)) ? (x) : (y))
+
 lsm_error lsm_str_init_zero(lsm_str **ptr) {
   lsm_str *str = calloc(1, sizeof(lsm_str));
 
@@ -59,3 +61,100 @@ void lsm_str_free(lsm_str *str) {
 }
 
 uint64_t lsm_str_len(lsm_str *str) { return str->len; }
+
+const char *lsm_str_ptr(lsm_str *str) {
+  if (str->len <= 8) {
+    return str->data.val;
+  } else {
+    return str->data.ptr;
+  }
+}
+
+char lsm_str_char(lsm_str *str, uint64_t index) {
+  if (str->len <= 8) {
+    return str->data.val[index];
+  } else {
+    return str->data.ptr[index];
+  }
+}
+
+lsm_error lsm_str_substr(lsm_str *out, lsm_str *str, uint64_t start,
+                         uint64_t end) {
+  // A substring that starts past the string's length will have length 0
+  uint64_t len = start < str->len ? end - start : 0;
+  const char *str_ptr = lsm_str_ptr(str);
+
+  if (len <= 8) {
+    lsm_str_zero(out);
+    memcpy(out->data.val, &str_ptr[start], len);
+  } else {
+    char *buf = malloc(len * sizeof(char));
+
+    if (buf == NULL) {
+      return lsm_error_failed_alloc;
+    }
+
+    memcpy(buf, &str_ptr[start], len);
+
+    lsm_str_zero(out);
+    out->data.ptr = buf;
+  }
+
+  out->len = len;
+
+  return lsm_error_ok;
+}
+
+uint64_t lsm_str_cmp(lsm_str *s1, uint64_t s1_offset, lsm_str *s2,
+                     uint64_t s2_offset) {
+  uint64_t index = 0;
+  uint64_t max_len = MIN(s1->len - s1_offset, s2->len - s2_offset);
+
+  while ((index < max_len) && (lsm_str_char(s1, s1_offset + index) ==
+                               lsm_str_char(s2, s2_offset + index))) {
+    index++;
+  }
+
+  return index;
+}
+
+lsm_error lsm_str_truncate(lsm_str *s, uint64_t new_len) {
+  if (new_len >= s->len) {
+    return lsm_error_ok;
+  }
+
+  if (new_len <= 8) {
+    char *s_buf = s->data.ptr;
+
+    memcpy(s->data.val, lsm_str_ptr(s), new_len);
+
+    if (s->len > 8) {
+      free(s_buf);
+    }
+  } else {
+    char *buf = malloc(new_len * sizeof(char));
+
+    if (buf == NULL) {
+      return lsm_error_failed_alloc;
+    }
+
+    memcpy(buf, s->data.ptr, new_len);
+    free(s->data.ptr);
+
+    s->data.ptr = buf;
+  }
+
+  s->len = new_len;
+
+  return lsm_error_ok;
+}
+
+lsm_error lsm_str_split(lsm_str *s, lsm_str *s2, uint64_t index) {
+  lsm_error res = lsm_str_substr(s2, s, index, s->len);
+
+  if (res != lsm_error_ok) {
+    return res;
+  }
+
+  return lsm_str_truncate(s, index);
+}