Shell: Implement specifying fds in file redirection

Shell/Parser.cpp

@@ -1,6 +1,7 @@
 #include "Parser.h"
 #include <stdio.h>
 #include <unistd.h>
+#include <ctype.h>
 
 void Parser::commit_token()
 {
@@ -102,6 +103,28 @@ Vector<Command> Parser::parse()
  m_state = State::InDoubleQuotes;
  break;
  }
+ if (isdigit(ch)) {
+ if (i != m_input.length() - 1) {
+ char next_ch = m_input.characters()[i + 1];
+ if (next_ch == '>') {
+ commit_token();
+ begin_redirect_write(ch - '0');
+ ++i;
+
+ // Search for another > for append.
+ m_state = State::InWriteAppendOrRedirectionPath;
+ break;
+ }
+ if (next_ch == '<') {
+ commit_token();
+ begin_redirect_read(ch - '0');
+ ++i;
+
+ m_state = State::InRedirectionPath;
+ break;
+ }
+ }
+ }
  m_token.append(ch);
  break;
  case State::InWriteAppendOrRedirectionPath: