Description
The second project involves modifying the syntactic analyzer for the attached compiler by
adding to the existing grammar. The full grammar of the language is shown below. The
highlighted portions of the grammar show what you must either modify or add to the existing
grammar.
function:
function_header {variable} body
function_header:
FUNCTION IDENTIFIER [parameters] RETURNS type ;
variable:
IDENTIFIER : type IS statement
parameters:
parameter {, parameter}
parameter:
IDENTIFIER : type
type:
INTEGER | REAL | BOOLEAN
body:
BEGIN statement END ;
statement:
expression ; |
REDUCE operator {statement} ENDREDUCE ; |
IF expression THEN statement ELSE statement ENDIF ; |
CASE expression IS {case} OTHERS ARROW statement ; ENDCASE ;
operator:
ADDOP | MULOP
case:
WHEN INT_LITERAL ARROW statement
expression:
( expression ) |
expression binary_operator expression |
NOT expression |
INT_LITERAL | REAL_LITERAL | BOOL_LITERAL |
IDENTIFIER
binary_operator: ADDOP | MULOP | REMOP | EXPOP | RELOP | ANDOP | OROP
In the above grammar, the red symbols are nonterminals, the blue symbols are terminals and the
black punctuation are EBNF metasymbols. The braces denote repetition 0 or more times and the
brackets denote optional.
You must rewrite the grammar to eliminate the EBNF brace and bracket metasymbols and to
incorporate the significance of parentheses, operator precedence and associativity for all
operators. Among arithmetic operators the exponentiation operator has highest precedence
following by the multiplying operators and then the adding operators. All relational operators
have the same precedence. Among the binary logical operators, and has higher precedence than
or. Of the categories of operators, the unary logical operator has highest precedence, the
arithmetic operators have next highest precedence, followed by the relational operators and
finally the binary logical operators. All operators except the exponentiation operator are left
associative. The directives to specify precedence and associativity, such as %prec and %left,
may not be used
Your parser should be able to correctly parse any syntactically correct program without any
problem.
You must modify the syntactic analyzer to detect and recover from additional syntax errors using
the semicolon as the synchronization token. To accomplish detecting additional errors an error
production must be added to the function header and another to the variable declaration.
Your bison input file should not produce any shift/reduce or reduce/reduce errors. Eliminating
them can be difficult so the best strategy is not introduce any. That is best achieved by making
small incremental additions to the grammar and ensuring that no addition introduces any such
errors.
An example of compilation listing output containing syntax errors is shown below:
1 — Multiple errors
2
3 function main a integer returns real;
Syntax Error, Unexpected INTEGER, expecting ‘:’
4 b: integer is * 2;
Syntax Error, Unexpected MULOP
5 c: real is 6.0;
6 begin
7 if a > c then
8 b 3.0;
Syntax Error, Unexpected REAL_LITERAL, expecting ‘;’
9 else
10 b = 4.;
11 endif;
12 ;
Syntax Error, Unexpected ‘;’, expecting END
Lexical Errors 0
Syntax Errors 4
Semantic Errors 0
You are to submit two files.
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.
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
Parses all syntactically correct
programs (25)
Does not parse all syntactically correct
programs (0)
Productions correctly implement
precedence and associativity (10)
Productions do not correctly
implement precedence and
associativity (0)
Grammar contains no shift/reduce or
reduce/reduce errors (5)
Grammar contains shift/reduce or
reduce/reduce errors (0)
Detects and recovers from all programs
with single syntax errors (20)
Does not detect and recover from
errors in the function header (0)
Detects and recovers from a program
with multiple syntax errors (10)
Does not detect and recover from
multiple errors (0)
Test Cases
15 points 0 points
Includes test cases that test all
grammar productions (6)
Does not include test cases that test all
grammar productions (0)
Includes test cases that test errors in all
productions (6)
Does not include test cases that test
errors in all productions (0)
Includes test case with multiple errors
(3)
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)
