1 files changed, 132 insertions, 0 deletions
diff --git a/src/js-lang/core/parser.ts b/src/js-lang/core/parser.ts
new file mode 100644
index 0000000..f193d6a
--- /dev/null
+++ b/src/js-lang/core/parser.ts
@@ -0,0 +1,132 @@
+import { Token, Parse, TokenType, ASTNode, NodeType } from "../../ts-lang";
+import { lex } from "./lexer";
+
+const resolveNodeFromToken = (token: Token): ASTNode => {
+  // FIXME not correct
+  if (!isNaN(Number(token.name))) {
+    return {
+      type: NodeType.INT,
+      name: "",
+      value: Number(token.name),
+      children: [],
+    };
+  }
+  if (token.name[0] === '"' && token.name[token.name.length - 1] === '"') {
+    return {
+      type: NodeType.INT,
+      name: "",
+      value: token.name.slice(1, token.name.length - 1),
+      children: [],
+    };
+  }
+  return {
+    type: NodeType.EXT,
+    name: token.name,
+    value: null,
+    children: [],
+  };
+};
+
+const _parse = ({
+  remainingTokens,
+  lastToken,
+  stack,
+}: {
+  remainingTokens: Token[];
+  lastToken: Token | null;
+  stack: ASTNode[];
+}): ASTNode | null => {
+  const head = remainingTokens.shift();
+  if (!head) {
+    if (lastToken) {
+      (stack[stack.length - 1].children as ASTNode[]).push(
+        resolveNodeFromToken(lastToken)
+      );
+
+      return _parse({
+        lastToken: null,
+        remainingTokens: [],
+        stack,
+      });
+    }
+
+    return stack[0] ?? null;
+  }
+
+  if (lastToken) {
+    if (head.type === TokenType.NAME) {
+      (stack[stack.length - 1].children as ASTNode[]).push(
+        resolveNodeFromToken(lastToken)
+      );
+      return _parse({
+        lastToken: head,
+        remainingTokens,
+        stack,
+      });
+    }
+
+    if (head.type === TokenType.CLOSE_PAREN) {
+      const top = stack.pop()!;
+      (top.children as ASTNode[]).push(resolveNodeFromToken(lastToken));
+      (stack[stack.length - 1].children as ASTNode[]).push(top);
+
+      return _parse({
+        lastToken: null,
+        remainingTokens,
+        stack,
+      });
+    }
+
+    if (head.type === TokenType.OPEN_PAREN) {
+      return _parse({
+        lastToken: null,
+        remainingTokens,
+        stack: [...stack, resolveNodeFromToken(lastToken)],
+      });
+    }
+
+    throw new Error(
+      `${JSON.stringify({
+        lastToken,
+        remainingTokens,
+        stack,
+      })} Was not expecting ${head.type}`
+    );
+  }
+
+  if (head.type === TokenType.NAME) {
+    return _parse({
+      lastToken: head,
+      remainingTokens,
+      stack,
+    });
+  }
+
+  if (head.type === TokenType.CLOSE_PAREN) {
+    const top = stack.pop()!;
+    (stack[stack.length - 1].children as ASTNode[]).push(top);
+
+    return _parse({
+      lastToken: null,
+      remainingTokens,
+      stack,
+    });
+  }
+
+  throw new Error(
+    `${JSON.stringify({
+      lastToken,
+      remainingTokens,
+      stack,
+    })} Expected nextToken to be a name or close paren at ${head.type}`
+  );
+};
+
+export const parse = <const Raw extends readonly Token[]>(
+  raw: Raw
+): Parse<Raw> =>
+  _parse({
+    remainingTokens: raw as unknown as Token[],
+    lastToken: null,
+    stack: [{ type: NodeType.EXT, name: "arr", value: null, children: [] }],
+  }) as Parse<Raw>;