diff --git a/parser.js b/parser.js
index 96368c1..ad2babd 100644
--- a/parser.js
+++ b/parser.js
@@ -29,6 +29,7 @@ const ATTR_TYPE = {
   POSITIONAL: "positional",
   OPTION: "option",
   FLAG: "flag",
+  REST: "rest",
 };
 const CONTEXT = {
   POS_COUNT: "pos_count",
@@ -98,6 +99,11 @@ function parse_spec_entry(raw_entry, context) {
           },
         })[attribute](attribute_value);
       });
+
+      // Set default values
+      if (!attributes[ATTR.MAP]) {
+        attributes[ATTR.MAP] = entry.aliases[0]; // alias 0 is always the larger format
+      }
       return attributes;
     },
   }[entry.type]();
@@ -126,12 +132,11 @@ function parse_spec(spec, command = null) {
   const context = {
     ...ctx_defaults,
     reset() {
-      Object.assing(this, defaults);
+      Object.assign(this, ctx_defaults);
     },
   };
   for (const raw_entry of spec) {
     const entry = parse_spec_entry(raw_entry, context);
-    console.log(entry.type);
     const exit = {
       [ENTRY.COMMAND]: () => {
         // Previous command was populated
@@ -164,26 +169,90 @@ function parse_spec(spec, command = null) {
         spec_data[`${cmd_id}.${entry.id}`] = entry;
         entry.aliases.forEach((alias) => {
           if (entry.attr.type === ATTR_TYPE.POSITIONAL) {
-            spec_aliases[`${cmd_id}.${entry.attr[ATTR.POSITION]}`] = entry.id;
-          } else {
-            spec_aliases[`${cmd_id}.${alias}`] = entry.id;
+            const alias_id = `${cmd_id}.${entry.attr[ATTR.POSITION]}`;
+            spec_aliases[alias_id] = `${cmd_id}.${entry.id}`;
+          } else if (
+            entry.attr.type === ATTR_TYPE.OPTION ||
+            entry.attr.type === ATTR_TYPE.FLAG
+          ) {
+            const alias_id = `${cmd_id}.${alias}`;
+            spec_aliases[alias_id] = `${cmd_id}.${entry.id}`;
+          } else if (entry.attr.type === ATTR_TYPE.REST) {
+            const alias_id = `${cmd_id}._rest`;
+            spec_aliases[alias_id] = `${cmd_id}.${entry.id}`;
           }
         });
       },
     }[entry.type]();
+    context.reset();
     if (exit) break;
   }
 
-  return { spec_data, spec_aliases };
+  if (command && cmd_id === null) {
+    throw new Error(`Invalid command: ${command}`);
+  }
+
+  return {
+    data: spec_data,
+    aliases: spec_aliases,
+    cmd_id: command ? cmd_id : null,
+  };
 }
 
-const r = parse_spec(SPEC, "build");
-console.log(JSON.stringify(r, null, 2));
+const r = parse_spec(SPEC);
+// console.log(JSON.stringify(r, null, 2));
 
 /**
- * INPUT: build -i tm0:node mybox
- *
- * spec_aliases[build] -> "0"
- * -i -> option/flag short -> spec_aliases["0.i"] -> "1"
- *
+ * @return {<variable_name>:<value>}
  */
+const inspect = (v) => console.log(JSON.stringify(v, null, 2));
+function parse_args(spec, args_raw) {
+  const vars = {};
+  const args = args_raw.split(" ");
+  args.shift(); // script name
+  const cmd = args.shift();
+
+  const get_next = () => args[0];
+  const consume = () => args.shift();
+  const consume_all = () => args.splice(0);
+
+  const cmd_spec = parse_spec(spec, cmd);
+  const cmd_info = cmd_spec.data[cmd_spec.cmd_id];
+  let positional_count = 0;
+  while (args.length > 0) {
+    const next = get_next();
+    const [type, next_arg] = (() => {
+      if (next === "--") {
+        return [ATTR_TYPE.REST, "_rest"]; // check if spec if expecing a rest arg
+      } else if (next.startsWith("--")) {
+        return [ATTR_TYPE.OPTION, next.slice(2)]; // invalid type. use only to know if to search per key or whole string
+      } else if (next.startsWith("-")) {
+        return [ATTR_TYPE.FLAG, next.slice(1)]; // same
+      } else {
+        return [ATTR_TYPE.POSITIONAL, positional_count++];
+      }
+    })();
+    const alias_id = `${cmd_info.id}.${next_arg}`;
+    const next_arg_id = cmd_spec.aliases[alias_id];
+    if (typeof next_arg_id !== "undefined") {
+      consume();
+      const next_arg_info = cmd_spec.data[next_arg_id];
+      if (next_arg_info.attr.type === ATTR_TYPE.OPTION) {
+        vars[next_arg_info.attr.map] = consume();
+      } else if (next_arg_info.attr.type === ATTR_TYPE.FLAG) {
+        vars[next_arg_info.attr.map] = true;
+      } else if (next_arg_info.attr.type === ATTR_TYPE.REST) {
+        vars[next_arg_info.attr.map] = consume_all();
+      } else if (next_arg_info.attr.type === ATTR_TYPE.POSITIONAL) {
+        vars[next_arg_info.attr.map] = next;
+      }
+    } else {
+      inspect(vars);
+      throw new Error(`Invalid argument: '${next_arg}'`);
+    }
+  }
+  return vars;
+}
+
+const args = "dev build -q -v --image tm0:node mybox -v -- bla1 bla2";
+inspect(parse_args(SPEC, args));