std json parser

std/str.zr

@@ -29,7 +29,7 @@ func u8.to_str[c: u8] : str
     return s
 
 func str.free[s: str] : void
-    mem.free(s)
+    (s as ptr)->free()
 
 func str.len[s: str] : i64
     i := 0
@@ -103,7 +103,7 @@ func str.format_into[..] : i64
                 n += 1
                 i += 1
             else if s[0] == 'f'
-                // TODO: fix when we implement f64 params
+                // TODO: use arrow when we implement f64 params
                 f64.to_str_buf(_var_arg(i), tmp as ptr)
                 tmp_len := tmp->len()
                 remaining := size - n - 1
@@ -166,7 +166,7 @@ func str.find[haystack: str, needle: str] : i64
             return i
     return -1
 
-func str.substr[s: str, start: i64, length: i64] : str
+func str.substr_n[s: str, start: i64, length: i64] : str
     out := mem.alloc(length + 1) as str
     mem.copy(s as ptr + start, out as ptr, length)
     out[length] = 0
@@ -188,7 +188,7 @@ func str.trim[s: str] : str
     while end >= start && s[end]->is_whitespace()
         end -= 1
 
-    return s->substr(start, end - start + 1)
+    return s->substr_n(start, end - start + 1)
 
 func str.reverse[s: str] : str
     len := s->len()
@@ -286,7 +286,12 @@ func str.Builder.build[b: str.Builder] : str
     s[b->size] = 0
     return s
 
-func str.Builder.destroy[b: str.Builder] : void
+func str.Builder.build_and_free_buffer[b: str.Builder] : str
+    s := b->build()
+    b->free_buffer()
+    return s
+
+func str.Builder.free_buffer[b: str.Builder] : void
     if b->data != 0
         b->data->free()
     b->size = 0