accept empty input

bobo-z · Dec 23, 2020 · 2254bf1 · 2254bf1
1 parent fd71daf
commit 2254bf1
Showing 1 changed file with 24 additions and 21 deletions.
diff --git a/turing-project/turing_machine.cpp b/turing-project/turing_machine.cpp
@@ -4,7 +4,7 @@
  * @Author: ybzhang
  * @Date: 2020-12-21 19:52:33
  * @LastEditors: ybzhang
- * @LastEditTime: 2020-12-24 01:52:09
+ * @LastEditTime: 2020-12-24 03:35:55
  */
 #include"common.h"
 #include"turing_machine.h"
@@ -557,29 +557,32 @@ void TuringMachine::run(string input)
  tapes.push_back(tape);
  heads.push_back(tapes[i].begin());
  }
- tapes[0].clear();
- int index = 0;
- for (auto i = input.begin(); i != input.end();i++)
+ if(input!="")
  {
- auto it = input_char.find(*i);
- if(it == input_char.end())
+ tapes[0].clear();
+ int index = 0;
+ for (auto i = input.begin(); i != input.end(); i++)
  {
- string tmp = "";
- tmp = tmp + *i;
- int pos = input.find_first_of(*i);
- string head_pos = " ";
- for (int i = 0; i < pos;i++)
- head_pos = head_pos + ' ';
- head_pos = head_pos + '^';
- Error({tmp,
- input,
- head_pos},
- INVALID_INPUT);
- }
- tapes[0].push_back(Cell(index, *i));
- index += 1;
+ auto it = input_char.find(*i);
+ if (it == input_char.end())
+ {
+ string tmp = "";
+ tmp = tmp + *i;
+ int pos = input.find_first_of(*i);
+ string head_pos = " ";
+ for (int i = 0; i < pos; i++)
+ head_pos = head_pos + ' ';
+ head_pos = head_pos + '^';
+ Error({tmp,
+ input,
+ head_pos},
+ INVALID_INPUT);
+ }
+ tapes[0].push_back(Cell(index, *i));
+ index += 1;
+ }
+ heads[0] = tapes[0].begin();
  }
- heads[0]=tapes[0].begin();
  string current_state = start_state;
  int step = 0;
  if(verbose)