add createFn

1 files changed, 46 insertions, 0 deletions

diff --git a/src/lang/js-lang/core/lexer.ts b/src/lang/js-lang/core/lexer.ts
new file mode 100644
index 0000000..95e0e19
--- /dev/null
+++ b/src/lang/js-lang/core/lexer.ts
@@ -0,0 +1,46 @@
+import { TokenType, Lex, Token } from "../../ts-lang";
+
+const WHITESPACE_TOKENS = [
+  TokenType.SPACE,
+  TokenType.COMMA,
+  TokenType.SEMICOLON,
+] as string[];
+
+export const lex = <const Raw extends string>(raw: Raw): Lex<Raw> => {
+  let _raw: string = raw;
+  let nameCollection = "";
+  const tokens: Token[] = [];
+
+  while (_raw) {
+    const head = _raw[0];
+    _raw = _raw.slice(1);
+
+    const processNameCollection = () => {
+      if (nameCollection) {
+        tokens.push({ type: TokenType.NAME, name: nameCollection });
+        nameCollection = "";
+      }
+    };
+
+    if (WHITESPACE_TOKENS.includes(head)) {
+      processNameCollection();
+      continue;
+    }
+
+    if (head === TokenType.OPEN_PAREN) {
+      processNameCollection();
+      tokens.push({ type: TokenType.OPEN_PAREN, name: "" });
+      continue;
+    }
+
+    if (head === TokenType.CLOSE_PAREN) {
+      processNameCollection();
+      tokens.push({ type: TokenType.CLOSE_PAREN, name: "" });
+      continue;
+    }
+
+    nameCollection += head;
+  }
+
+  return tokens as Lex<Raw>;
+};