Problem

Change this program (fa.cpp) with new DFA functions (follow my ** comments)

to accept the following tokens: [2pts per DFA] Your functions must match your DFAs.

function ident_token l ( l | d | _ )^* Give the DFA here with state numbers **

function real_token d^* . d^+ Give the DFA here with state numbers **

function int_token d^+ Give the DFA here with state numbers **

Code:

include

#include

#include

using namespace std;

//------------------------------------------------

// CS421 File fa.cpp for HW2B DFA->Scanner Function

// Your name: **

//------------------------------------------------

// ** Change this to fit the HW2B specification - look for **

// ** Must have the same types of tracing couts as mytoken.

// ** Must complete the ** comments with RE

// ---------- DFAs follow -------------------------

// MYTOKEN DFA done by Rika Sensei has a sample

// This FA is for a b^+

bool mytoken(string s)

{

int state = 0;

int charpos = 0;

cout << "Trying the mytoken machine..." << endl;

while (s[charpos] != '\0')

{

cout << "current state: " << state << endl;

cout << "character: " << s[charpos] << endl;

if (state == 0 && s[charpos] == 'a')

state = 1;

else

if (state == 1 && s[charpos] == 'b')

state = 2;

else

if (state == 2 && s[charpos] == 'b')

state = 2;

else

{

cout << "I am stuck in state " << state << endl;

return(false);

}

charpos++;

}//end of while

// where did I end up????

if (state == 2) return(true); // end in a final state

else return(false);

}// end of mytoken

// IDENT DFA

// This FA is for RE: **

bool ident_token(string s)

{

// ** complete this based on mytoken

}//end of ident

// REAL DFA

// This FA is for RE: **

bool real_token(string s)

{

// ** complete this based on mytoken

}//end of real

//INT DFA

// This FA is for RE: **

bool integer_token(string s)

{

// ** complete this based on mytoken

}// end of int

// -----------------------------------------------------

enum tokentype {ERROR, MYTOKEN, IDENT, REAL, INT};

int scanner(tokentype& , string& ); // to be called by main

fstream fin; // file stream to use

// The test-driver -- NO NEED TO CHANGE THIS

int main()

{ string fname;

cout << "Enter the input file name:";

cin >> fname;

fin.open( fname.c_str(), fstream::in);

string tokens[5] = {"ERROR", "MYTOKEN", "IDENT", "REAL", "INT"};

tokentype thetype;

string theword;

while (true) // keep on going

{

scanner(thetype, theword); // the paramers will be set by Scanner

if (theword == "EOF") break;

cout << ">>>>>Type is:" << tokens[thetype] << endl;

}

cout << ">>>>>End of File encountered" << endl;

fin.close();

}// end of main

// Scanner sets the_type and w - TO BE COMPLETED **

int scanner(tokentype& the_type, string& w)

{

// This goes through all machines one by one on the input string w

cout << endl;

cout << ".....Scanner was called..." << endl;

fin >> w; // grab next word from fain.txt

cout << ">>>>>Word is:" << w << endl;

if (mytoken(w))

{ the_type = MYTOKEN; }

// ** add other if-then's here in the right order to go through

// ** all FAs one by one and set the_type to be IDENT, REAL or INT.

else //none of the FAs returned TRUE

{ cout << ">>>>>Lexical Error: The string is not in my language" << endl;

the_type = ERROR; }

}//the very end of scanner

fain_mytoken.txt

abbb

ab

aabb

bb

EOF

Desired Output:

Enter the input file name:fain_mytoken.txt

hap

.....Scanner was called...

Word is:abbb

Trying the mytoken machine...

current state: 0

character: a

current state: 1

character: b

current state: 2

character: b

current state: 2

character: b

Type is:MYTOKEN

.....Scanner was called...

Word is:ab

Trying the mytoken machine...

current state: 0

character: a

current state: 1

character: b

Type is:MYTOKEN

.....Scanner was called...

Word is:aabb

Trying the mytoken machine...

current state: 0

character: a

current state: 1

character: a

I am stuck in state 1

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:bb

Trying the mytoken machine...

current state: 0

character: b

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:EOF

Trying the mytoken machine...

current state: 0

character: E

I am stuck in state 0

Lexical Error: The string is not in my language

Using File fain.txt

ab_2a

a_b_2_a

.23

23.3

23

ab&c

23.6

2a3

22..2

23.

EOF

Desired OutPut:

Enter the input file name:fain.txt

hap

.....Scanner was called...

Word is:ab_2a

Trying the mytoken machine...

current state: 0

character: a

current state: 1

character: b

current state: 2

character: _

I am stuck in state 2

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:a_b_2_a

Trying the mytoken machine...

current state: 0

character: a

current state: 1

character: _

I am stuck in state 1

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:.23

Trying the mytoken machine...

current state: 0

character: .

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:23.3

Trying the mytoken machine...

current state: 0

character: 2

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:23

Trying the mytoken machine...

current state: 0

character: 2

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:ab&c

Trying the mytoken machine...

current state: 0

character: a

current state: 1

character: b

current state: 2

character: &

I am stuck in state 2

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:23.6

Trying the mytoken machine...

current state: 0

character: 2

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:2a3

Trying the mytoken machine...

current state: 0

character: 2

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:22..2

Trying the mytoken machine...

current state: 0

character: 2

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:23.

Trying the mytoken machine...

current state: 0

character: 2

I am stuck in state 0

Lexical Error: The string is not in my language

Type is:ERROR

.....Scanner was called...

Word is:EOF

Trying the mytoken machine...

current state: 0

character: E

I am stuck in state 0

Lexical Error: The string is not in my language