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|
class PParser extends Parser;
{
public void traceOut(String rname) throws TokenStreamException {
System.out.println("exit "+rname+"; LT(1)="+LT(1));
}
public void traceIn(String rname) throws TokenStreamException {
System.out.println("enter "+rname+"; LT(1)="+LT(1));
}
/*
public void consume() throws IOException {
try {
System.out.println(LT(1));
}
catch (IOException ignore) {}
super.consume();
}
*/
}
startRule
: ( decl )+
;
decl: INT a:ID {System.out.println("decl "+a.getText());}
( COMMA b:ID {System.out.println("decl "+b.getText());} )*
SEMI
;
{
import java.io.*;
}
class PLexer extends Lexer;
options {
charVocabulary = '\3'..'\377';
k=2;
}
tokens {
INT="int";
}
{
public void uponEOF() throws TokenStreamException, CharStreamException {
if ( Main.selector.getCurrentStream() != Main.mainLexer ) {
// don't allow EOF until main lexer. Force the
// selector to retry for another token.
Main.selector.pop(); // return to old lexer/stream
Main.selector.retry();
}
else {
System.out.println("Hit EOF of main file");
}
}
}
SEMI: ';'
;
COMMA
: ','
;
ID
: ('a'..'z')+
;
INCLUDE
: "#include" (WS)? f:STRING
{
// create lexer to handle include
String name = f.getText();
DataInputStream input=null;
try {
FileInputStream fi = new FileInputStream(name);
input = new DataInputStream(fi);
}
catch (FileNotFoundException fnf) {
System.err.println("cannot find file "+name);
}
PLexer sublexer = new PLexer(input);
// make sure errors are reported in right file
sublexer.setFilename(name);
Main.parser.setFilename(name);
// you can't just call nextToken of sublexer
// because you need a stream of tokens to
// head to the parser. The only way is
// to blast out of this lexer and reenter
// the nextToken of the sublexer instance
// of this class.
Main.selector.push(sublexer);
// ignore this as whitespace; ask selector to try
// to get another token. It will call nextToken()
// of the new instance of this lexer.
Main.selector.retry(); // throws TokenStreamRetryException
}
;
STRING
: '"'! ( ~'"' )* '"'!
;
WS : ( ' '
| '\t'
| '\f'
// handle newlines
| ( options {generateAmbigWarnings=false;}
: "\r\n" // Evil DOS
| '\r' // Macintosh
| '\n' // Unix (the right way)
)
{ newline(); }
)+
{ $setType(Token.SKIP); }
;
|
