Compiler Theory

CMSC 430 Project 1

The first project involves modifying the attached lexical analyzer and the compilation listing

generator code. You need to make the following modifications to the lexical analyzer,

scanner.l:

1. The following reserved words should be added:

else, elsif, endfold, endif, fold, if, left, real, right, then

Each reserved words should be a separate token. The token name should be the same as

the lexeme, but in all upper case.

2. Two additional logical operators should be added. The lexeme for the first should be |

and its token should be OROP. The second logical operator added should be ! and its token

should be NOTOP.

3. Five relational operators should be added. They are =, <>, >, >= and <=. All of the

lexemes should be represented by the single token RELOP.

4. One additional lexeme should be added for the ADDOP token. It is binary operator – that is

the subtraction operator.

5. One additional lexeme should be added for the MULOP token. It is/ that is the division

operator.

6. A new token REMOP should be added for the remainder operator. Its lexeme should be %.

7. A new token EXPOP should be added for the exponentiation operator. Its lexeme should

be ^.

8. A new token NEGOP should be added for the unary minus operator. Its lexeme should be

~.

9. A second type of comment should be added that begins with -- and ends with the end of

line. As with the existing comment, no token should be returned.

10. The definition for the identifiers should be modified so that underscores can be included,

however, no more than two consecutive underscores are permitted, but leading and

trailing underscores should not be permitted.

11. One additional type of integer literal should be added, which are hexadecimal integers.

The begin with the # character followed by one of more decimal digits, or the letter A-F,

in either upper or lower case.

12. A real literal token should be added. It should begin with a sequence of zero or more

digits following by a decimal point followed by one or more additional digits. It may

optionally end with an exponent. If present, the exponent should begin with an e or E,

followed by an optional plus or minus sign followed by one or more digits.

13. The definition for the character literals should be modified so that five additional escape

characters are also allowed: '\b', '\t', '\n', '\b' and '\f'.

You must also modify the header file tokens.h to include each the new tokens mentioned

above.

The compilation listing generator code should be modified as follows:

1. The lastLine function should be modified to compute the total number of errors. If any

errors occurred the number of lexical, syntactic and semantic errors should be displayed.

If no errors occurred, it should display Compiled Successfully. It should return the

total number of errors.

2. The appendError function should be modified to count the number of lexical, syntactic

and semantic errors. The error message passed to it should be added to a queue of

messages that occurred on that line.

3. The displayErrors function should be modified to display all the error messages that

have occurred on the previous line and then clear the queue of messages.

An example of the output of a program with no lexical errors is shown below:

1 // Function with Arithmetic Expression

2

3 function main returns integer;

4 begin

5 7 + 2 * (5 + 4);

6 end;

Compiled Successfully

Here is the required output for a program that contains more than one lexical error on the same

line:

1 // Function with Two Lexical Errors

2

3 function main returns integer;

4 begin

5 7 $ 2 ? (2 + 4);

Lexical Error, Invalid Character $

Lexical Error, Invalid Character ?

6 end;

Lexical Errors 2

Syntax Errors 0

Semantic Errors 0

You are to submit two files.

1. The first is a .zip file that contains all the source code for the project. The .zip file

should contain the flex input file, which should be a .l file, all .cc and .h files and a

makefile that builds the project.

2. The second is a Word document (PDF or RTF is also acceptable) that contains the

documentation for the project, which should include the following:

a. A discussion of how you approached the project

b. A test plan that includes test cases that you have created indicating what aspects

of the program each one is testing and a screen shot of your compiler run on that

test case

c. A discussion of lessons learned from the project and any improvements that could

be made