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package scala.xml.dtd ;
/** Parser for regexps (content models in DTD element declarations) */
object ContentModelParser extends Scanner { // a bit too permissive concerning #PCDATA
import ContentModel._ ;
/** parses the argument to a regexp */
def parse(s:String): ContentModel = { initScanner( s ); contentspec }
// zzz parser methods zzz
def accept( tok:int ) = {
if( token != tok ) {
if(( tok == STAR )&&( token == END )) // common mistake
error("in DTDs, \n"+
"mixed content models must be like (#PCDATA|Name|Name|...)*");
else
error("expected "+token2string(tok)+
", got unexpected token:"+token2string(token));
}
nextToken
}
// s [ '+' | '*' | '?' ]
def maybeSuffix(s:RegExp) = token match {
case STAR => nextToken; Star( s )
case PLUS => nextToken; Sequ( s, Star( s ))
case OPT => nextToken; Alt( Eps, s )
case _ => s
}
// contentspec ::= EMPTY | ANY | (#PCDATA) | "(#PCDATA|"regexp)
def contentspec: ContentModel = token match {
case NAME => value match {
case "ANY" => ANY
case "EMPTY" => EMPTY
case _ => error("expected ANY, EMPTY or '(' instead of " + value );
}
case LPAREN =>
nextToken;
sOpt;
if( token != TOKEN_PCDATA )
ELEMENTS(regexp);
else {
nextToken;
token match {
case RPAREN =>
PCDATA
case CHOICE =>
val res = MIXED(choiceRest(Eps));
sOpt;
accept( RPAREN );
accept( STAR );
res
case _ =>
error("unexpected token:" + token2string(token) );
}
}
case _ =>
error("unexpected token:" + token2string(token) );
}
// sopt ::= S?
def sOpt = if( token == S ) nextToken;
// (' S? mixed ::= '#PCDATA' S? ')'
// | '#PCDATA' (S? '|' S? atom)* S? ')*'
/*
def mixed = {
accept( TOKEN_PCDATA );
sOpt;
if( token == RPAREN )
PCDATA_
else {
val t = choiceRest( PCDATA_ );
if( !isMixed( t ) )
error("mixed content models must be like (#PCDATA.|.|.|.)*");
accept( RPAREN );
// lax: (workaround for buggy Java XML parser in JDK1.4.2)
if( token == STAR ) accept( STAR );
// strict:
// accept( STAR );
Star( t )
}
}
*/
// '(' S? regexp ::= cp S? [seqRest|choiceRest] ')' [ '+' | '*' | '?' ]
def regexp:RegExp = {
//Console.println("regexp, token = "+token2string(token));
val p = particle;
sOpt;
maybeSuffix( token match {
case RPAREN => nextToken; p
case CHOICE => val q = choiceRest( p );accept( RPAREN ); q
case COMMA => val q = seqRest( p ); accept( RPAREN ); q
})
}
// seqRest ::= (',' S? cp S?)+
def seqRest( p:RegExp ) = {
var k = List( p );
while( token == COMMA ) {
nextToken;
sOpt;
k = particle::k;
sOpt;
}
Sequ( k.reverse:_* )
}
// choiceRest ::= ('|' S? cp S?)+
def choiceRest( p:RegExp ) = {
var k = List( p );
while( token == CHOICE ) {
nextToken;
sOpt;
k = particle::k;
sOpt;
}
Alt( k.reverse:_* )
}
// particle ::= '(' S? regexp
// | name [ '+' | '*' | '?' ]
def particle = {
//Console.println("particle, token="+token2string(token));
token match {
case LPAREN => nextToken; sOpt; regexp;
case NAME => val a = Letter(ElemName(value)); nextToken; maybeSuffix( a )
case _ => error("expected '(' or Name, got:"+token2string( token ));
}
}
// atom ::= name
def atom = token match {
case NAME => val a = Letter(ElemName(value)); nextToken; a
case _ => error("expected Name, got:"+token2string( token ));
}
}
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