Starting with the lexer, i'm starting to comprehend better what pratt parsing is and how to apply it. For now just declaring basic structure and functions

src/parser.c

@@ -0,0 +1,27 @@
+#include "parser.h"
+#include "lexer.h"
+#include <stdlib.h>
+
+size_t node_lbp(Operator op) {
+    switch (op) {
+        case OP_ADD:
+        case OP_SUB:
+            return 10;
+            break;
+        case OP_DIV:
+        case OP_MUL:
+            return 20;
+    }
+}
+
+size_t node_rbp(Operator op) {
+    switch (op) {
+        case OP_ADD:
+        case OP_SUB:
+            return 10;
+            break;
+        case OP_DIV:
+        case OP_MUL:
+            return 20;
+    }
+}