Create 736-parse-lisp-expression.js

Author: everthis

736-parse-lisp-expression.js

@@ -0,0 +1,33 @@
+/**
+ * @param {string} expression
+ * @return {number}
+ */
+const evaluate = (x) =>
+  e(
+    JSON.parse(
+      x.replace(/[() ]|([a-z][a-z0-9]*)/g, (m) =>
+        m == '(' ? '[' : m == ')' ? ']' : m == ' ' ? ',' : `"${m}"`
+      )
+    )
+  )
+const e = (x, v = []) =>
+  ({
+    string: () => v.find((y) => y[0] === x)[1],
+    number: () => x,
+    object: () =>
+      ({
+        add: () => e(x[1], v) + e(x[2], v),
+        mult: () => e(x[1], v) * e(x[2], v),
+        let: () =>
+          e(
+            x[x.length - 1],
+            x
+              .slice(1, -1)
+              .reduce(
+                ({ v, t }, z) =>
+                  t ? { v: [[t, e(z, v)], ...v] } : { v, t: z },
+                { v }
+              ).v
+          ),
+      }[x[0]]()),
+  }[typeof x]())