Shell: Move the Shell to a separate directory and let's call it "Shell" :^)

Shell/Parser.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <AK/AKString.h>
+#include <AK/Vector.h>
+
+struct Redirection {
+    enum Type { Pipe, FileWrite, FileRead, Rewire };
+    Type type;
+    int fd { -1 };
+    int rewire_fd { -1 };
+    String path { };
+};
+
+struct Subcommand {
+    Vector<String> args;
+    Vector<Redirection> redirections;
+};
+
+class Parser {
+public:
+    explicit Parser(const String& input) : m_input(input) { }
+
+    Vector<Subcommand> parse();
+
+private:
+    void commit_token();
+    void commit_subcommand();
+    void do_pipe();
+    void begin_redirect_read(int fd);
+    void begin_redirect_write(int fd);
+
+    enum State {
+        Free,
+        InSingleQuotes,
+        InDoubleQuotes,
+        InRedirectionPath,
+    };
+    State m_state { Free };
+    String m_input;
+
+    Vector<Subcommand> m_subcommands;
+    Vector<String> m_tokens;
+    Vector<Redirection> m_redirections;
+    Vector<char> m_token;
+};
+