The fourth project involves modifying the semantic analyzer for the attached compiler by adding checks for semantic errors.

INSTRUCTIONS TO CANDIDATES

ANSWER ALL QUESTIONS

Modify the semantic analyzer for the attached compiler to check for semantic errors listed in the requirements.

 

 

The fourth project involves modifying the semantic analyzer for the attached compiler by adding

checks for semantic errors. The static semantic rules of this language are the following:

Variables and parameter names have local scope. The scope rules require that all names be

declared and prohibit duplicate names within the same scope. The type correspondence rules are

as follows:

 Boolean expressions cannot be used with arithmetic or relational operators.

 Arithmetic expressions cannot be used with logical operators.

 Reductions can only contain numeric types.

 Only integer operands can be used with the remainder operator.

 The two statements in an if statement must match in type. No coercion is performed.

 All the statements in a case statement must match in type. No coercion is performed.

 The type of the if expression must be Boolean.

 The type of the case expression must be Integer

 A narrowing variable initialization or function return occurs when a real value is being

forced into integer. Widening is permitted.

 Boolean types cannot be mixed with numeric types in variable initializations or function

returns.

Type coercion from an integer to a real type is performed within arithmetic expressions.

You must make the following semantic checks. Those highlighted in yellow are already

performed by the code that you have been provided, although you are must make minor

modifications to account for the addition of real types and the need to perform type coercion and

to handle the additional arithmetic and logical operators.

 Using Boolean Expressions with Arithmetic Operator

 Using Boolean Expressions with Relational Operator

 Using Arithmetic Expressions with Logical Operator

 Reductions containing nonnumeric types

 Remainder Operator Requires Integer Operands

 If-Then Type Mismatch

 Case Types Mismatch

 If Condition Not Boolean

 Case Expression Not Integer

 Narrowing Variable Initialization

 Variable Initialization Mismatch

 Undeclared Variable

 Duplicate Variable

 Narrowing Function Return

CMSC 30 Project 4

This project requires modification to the bison input file, so that it defines the additional

semantic checks necessary to produce these errors and addition of functions to the library of type

checking functions already provided in types.cc. You must also make some modifications to

the functions provided. You need to add a check to the checkAssignment function for

mismatched types in the case that Boolean and numeric types are mixed. You need to also add

code to the checkArithmetic function to coerce integers to reals when the types are mixed and

the error message must be modified to indicate that numeric rather than only integer types are

permitted.

The provided code includes a template class Symbols that defines the symbol table. It already

includes a check for undeclared identifiers. You need to add a check for duplicate identifiers.

Like the lexical and syntax errors, the compiler should display the semantic errors in the

compilation listing, after the line in which they occur. An example of compilation listing output

containing semantic errors is shown below:

 1 -- Test of Multiple Semantic Errors

 2

 3 function test a: integer returns integer;

 4 b: integer is

 5 if a + 5 then

 6 2;

 7 else

 8 5;

 9 endif;

Semantic Error, If Expression Must Be Boolean

 10 c: real is 9.8 - 2 + 8;

 11 d: boolean is 7 = f;

Semantic Error, Undeclared f

 12 begin

 13 case b is

 14 when 1 => 4.5 + c;

 15 when 2 => b;

Semantic Error, Case Types Mismatch

 16 others => c;

 17 endcase;

 18 end;

Lexical Errors 0

Syntax Errors 0

Semantic Errors 3

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, the bison file, which should

be a .y 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

Grading Rubric

Criteria Meets Does Not Meet

Functionality

70 points 0 points

Generates semantic error when a

remainder operator has non-integer

operands (10)

Does not generate semantic error

when a remainder operator has noninteger operands (0)

Generates semantic error when if and

then types don't match (10)

Does not generate semantic error

when if and then types don't match (0)

Generates semantic error when case

types don't match (10)

Does not generate semantic error

when case types don't match (0)

Generates semantic error when if

condition is not Boolean (10)

Does not generates semantic error

when if condition is not Boolean (0)

Generates semantic error when case

expression is not integer (10)

Does not generate semantic error

when case expression is not integer (0)

Generates semantic error on narrowing

initialization (10)

Does not generate semantic error on

narrowing initialization (0)

Generates semantic error for duplicate

variables (10)

Does not generate semantic error for

duplicate variables (0)

Test Cases

15 points 0 points

Includes test cases that test all type

checking errors (10)

Does not Include test cases that test all

type checking errors (0)

Includes test cases that test all symbol

table errors (3)

Does not include test cases that test all

symbol table errors (0)

Includes test case with multiple errors

(2)

Does not include test case with

multiple errors (0)

Documentation

15 points 0 points

Discussion of approach included (5) Discussion of approach not included (0)

Lessons learned included (5) Lessons learned not included (0)

Comment blocks with student name,

project, date and code description

included in each file (5)

Comment blocks with student name,

project, date and code description not

included in each file (0)

 

Attachments:

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