Download Lexical and Syntax Analyzer (PA1)

Md. Zahurul Islam
CRBLP, BRAC University
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You will construct a lexer and a parser for Clanguage, a subset of the C language.
Portions
◦ Lexical Analyzer (lexer)
◦ Syntax Analyzer (parser)
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Tools
◦ JLex
◦ JCUP
CRBLP, BRAC University
Md. Zahurul Islam
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A lexical analyzer breaks an input stream of
characters into tokens. Writing lexical analyzers
by hand can be a tedious process, so software
tools have been developed to ease this task.
The JLex utility is based upon the Lex lexical
analyzer generator model. Jlex creates a Java
source file for the corresponding lexical
analyzer.
CRBLP, BRAC University
Md. Zahurul Islam
user code
%%
JLex directives
%%
regular expression rules
CRBLP, BRAC University
Md. Zahurul Islam
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User Code
◦ The user code section - the first section of the
specification file - is copied directly into the
resulting output file. This area of the specification
provides space for the implementation of utility
classes or return types.
CRBLP, BRAC University
Md. Zahurul Islam

JLex Directives
◦ The JLex directives section is the second part of the
input file. Here, macros definitions are given and
state names are declared.
 Example
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%implements
%class
%function
%type
CRBLP, BRAC University
Md. Zahurul Islam
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Regular expression rule
◦ The third section contains the rules of lexical
analysis, each of which consists of three parts: an
optional state list, a regular expression, and an
action.
CRBLP, BRAC University
Md. Zahurul Islam
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CUP is written in Java, uses specifications
including embedded Java code, and produces
parsers which are implemented in Java.
CRBLP, BRAC University
Md. Zahurul Islam
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Package and import specification
User code components
Symbol lists
Precedence and associativity declaration
The grammar
CRBLP, BRAC University
Md. Zahurul Islam
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Package and Import Specification
◦ A specification begins with optional package and
import declarations. These have the same syntax,
and play the same role, as the package and import
declarations found in a normal Java program. A
package declaration is of the form:
package name;
import package_name.*;
CRBLP, BRAC University
Md. Zahurul Islam
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User Code Components
◦ Optional declarations that allow user code to be
included as part of the generated parser.
action code {: ... :};
parser code {: ... :};
CRBLP, BRAC University
Md. Zahurul Islam

Symbol List
◦ These declarations are responsible for naming and
supplying a type for each terminal and nonterminal symbol that appears in the grammar.
terminal classname name1, name2, ...; non terminal
classname name1, name2, ...;
CRBLP, BRAC University
Md. Zahurul Islam
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Precedence and Associativity Declaration
◦ The third section, which is optional, specifies the
precedence and associativity of terminals. This is
useful for parsing with ambiguous grammar.
precedence left terminal [, terminal1…];
precedence right terminal [,terminal1…];
precedence nonassoc terminal [,terminal…];
CRBLP, BRAC University
Md. Zahurul Islam
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The Grammar
◦ The final section of a CUP declaration provides the
Grammar.
CRBLP, BRAC University
Md. Zahurul Islam
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Project Details
JLex
JCUP
CRBLP, BRAC University
Md. Zahurul Islam