The document presents Java code for two compilations using ANTLR for parsing a programming language. It includes grammar definitions and parser implementations for handling basic constructs like constants, variables, procedures, and mathematical expressions. Additionally, the code structures are encapsulated within classes that execute simple operations and display results.

1. java compiler/Compiler1.javajava compiler/Compiler1.java
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CharStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.TokenStream;
publicclassTest1{
publicstaticvoid main(String[] args)throwsRecognitionExceptio
n{
CharStream stream =
newANTLRStringStream("program XLSample1 =rn"+
"/*rn"+
" constant one : Integer := 1;rn"+
" constant two : Integer := 2 * 3;rn"+
" var x, y, z : Integer := 42;rn"+
"*/rn"+
"rn"+
" procedure foo() =rn"+
" var x : Integer := 2;rn"+
" beginrn"+
" end foo.rn"+
" procedure fee(y : Integer) =rn"+
" var x : Integer := 2;rn"+
" beginrn"+
" end fee.rn"+
" function fie(y : Integer) : Integer =rn"+
" var x : Integer := 2;rn"+
" beginrn"+
" return y;rn"+
" end fie.rn"+
"beginrn"+
"end XLSample1.");

2. SampleLexer lexer =newSampleLexer(stream);
TokenStream tokenStream =newCommonTokenStream(lexer);
SampleParser parser =newSampleParser(tokenStream);
parser.program();
System.out.println("ok");
}
}
java compiler/Compiler2.javajava compiler/Compiler2.java
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CharStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.TokenStream;
publicclassTest2{
publicstaticvoid main(String[] args)throwsRecognitionExceptio
n{
CharStream stream =
newANTLRStringStream("3 * (2 + 4) * 3");
Sample2Lexer lexer =newSample2Lexer(stream);
TokenStream tokenStream =newCommonTokenStream(lexer);
Sample2Parser parser =newSample2Parser(tokenStream);
int result = parser.evaluator();
System.out.println("ok - result is "+ result);
}
}
java compiler/src1.g4
grammar scr1;
options {

3. language = Java;
}
@header {
package a.b.c;
}
@lexer::header {
package a.b.c;
}
program
: 'program' IDENT '='
(constant | variable | function | procedure | typeDecl)*
'begin'
statement*
'end' IDENT '.'
;

4. constant
: 'constant' IDENT ':' type ':=' expression ';'
;
variable
: 'var' IDENT (',' IDENT)* ':' type (':=' expression)? ';'
;
type
: 'Integer'
| 'Boolean'
| 'String'
| 'Char'
| IDENT
| typeSpec
;

5. typeDecl
: 'type' IDENT '=' typeSpec ';'
;
typeSpec
: arrayType
| recordType
| enumType
;
arrayType
: 'array' '[' INTEGER '..' INTEGER ']' 'of' type
;
recordType
: 'record' field* 'end' 'record'
;

6. field
: IDENT ':' type ';'
;
enumType
: '<' IDENT (',' IDENT)* '>'
;
statement
: assignmentStatement
| ifStatement
| loopStatement
| whileStatement
| procedureCallStatement
;
procedureCallStatement
: IDENT '(' actualParameters? ')' ';'

7. ;
actualParameters
: expression (',' expression)*
;
ifStatement
: 'if' expression 'then' statement+
('elsif' expression 'then' statement+)*
('else' statement+)?
'end' 'if' ';'
;
assignmentStatement
: IDENT ':=' expression ';'
;
exitStatement

8. : 'exit' 'when' expression ';'
;
whileStatement
: 'while' expression 'loop'
(statement|exitStatement)*
'end' 'loop' ';'
;
loopStatement
: 'loop' (statement|exitStatement)* 'end' 'loop' ';'
;
returnStatement
: 'return' expression ';'
;
procedure

9. : 'procedure' IDENT '(' parameters? ')' '='
(constant | variable)*
'begin'
statement*
'end' IDENT '.'
;
function
: 'function' IDENT '(' parameters? ')' ':' type '='
(constant | variable)*
'begin'
(statement|returnStatement)*
'end' IDENT '.'
;
parameters
: parameter (',' parameter)*
;

10. parameter
: 'var'? IDENT ':' type
;
// expressions -- fun time!
term
: IDENT
| '(' expression ')'
| INTEGER
| STRING_LITERAL
| CHAR_LITERAL
| IDENT '(' actualParameters ')'
;
negation
: 'not'* term

11. ;
unary
: ('+' | '-')* negation
;
mult
: unary (('*' | '/' | 'mod') unary)*
;
add
: mult (('+' | '-') mult)*
;
relation
: add (('=' | '/=' | '<' | '<=' | '>=' | '>') add)*
;

12. expression
: relation (('and' | 'or') relation)*
;
MULTILINE_COMMENT : '/*' .* '*/' {$channel = HIDDEN;} ;
STRING_LITERAL
: '"'
{ StringBuilder b = new StringBuilder(); }
( '"' '"' { b.appendCodePoint('"');}
| c=~('"'|'r'|'n') { b.appendCodePoint(c);}
)*
'"'
{ setText(b.toString()); }
;
CHAR_LITERAL

13. : ''' . ''' {setText(getText().substring(1,2));}
;
fragment LETTER : ('a'..'z' | 'A'..'Z') ;
fragment DIGIT : '0'..'9';
INTEGER : DIGIT+ ;
IDENT : LETTER (LETTER | DIGIT)*;
WS : (' ' | 't' | 'n' | 'r' | 'f')+ {$channel = HIDDEN;};
COMMENT : '//' .* ('n'|'r') {$channel = HIDDEN;};
java compiler/src2.g4
grammar src2;
options {
language = Java;
}
@header {

14. package a.b.c;
}
@lexer::header {
package a.b.c;
}
evaluator returns [int result]
: expression EOF { $result = $expression.result; }
;
// expressions -- fun time!
term returns [int result]
: IDENT {$result = 0;}
| '(' expression ')' {$result = $expression.result;}
| INTEGER {$result =
Integer.parseInt($INTEGER.text);}
;

15. unary returns [int result]
: { boolean positive = true; }
('+' | '-' { positive = !positive; })* term
{
$result = $term.result;
if (!positive)
$result = -$result;
}
;
mult returns [int result]
: op1=unary { $result = $op1.result; }
( '*' op2=unary { $result = $result * $op2.result; }
| '/' op2=unary { $result = $result / $op2.result; }
| 'mod' op2=unary { $result = $result %
$op2.result; }
)*

16. ;
expression returns [int result]
: op1=mult { $result = $op1.result; }
( '+' op2=mult { $result = $result + $op2.result; }
| '-' op2=mult { $result = $result - $op2.result; }
)*
;
MULTILINE_COMMENT : '/*' .* '*/' {$channel = HIDDEN;} ;
STRING_LITERAL
: '"'
{ StringBuilder b = new StringBuilder(); }
( '"' '"' { b.appendCodePoint('"');}
| c=~('"'|'r'|'n') { b.appendCodePoint(c);}
)*

17. '"'
{ setText(b.toString()); }
;
CHAR_LITERAL
: ''' . ''' {setText(getText().substring(1,2));}
;
fragment LETTER : ('a'..'z' | 'A'..'Z') ;
fragment DIGIT : '0'..'9';
INTEGER : DIGIT+ ;
IDENT : LETTER (LETTER | DIGIT)*;
WS : (' ' | 't' | 'n' | 'r' | 'f')+ {$channel = HIDDEN;};
COMMENT : '//' .* ('n'|'r') {$channel = HIDDEN;};