scala.xml.dtd.ContentModelParser.scala Maven / Gradle / Ivy
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2002-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://www.scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
package xml
package 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 }
def accept(tok: Int) = {
if (token != tok) {
if ((tok == STAR) && (token == END)) // common mistake
scala.sys.error("in DTDs, \n" +
"mixed content models must be like (#PCDATA|Name|Name|...)*")
else
scala.sys.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 _ => scala.sys.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 _ =>
scala.sys.error("unexpected token:" + token2string(token))
}
}
case _ =>
scala.sys.error("unexpected token:" + token2string(token))
}
// sopt ::= S?
def sOpt() = if (token == S) nextToken()
// (' S? mixed ::= '#PCDATA' S? ')'
// | '#PCDATA' (S? '|' S? atom)* S? ')*'
// '(' S? regexp ::= cp S? [seqRest|choiceRest] ')' [ '+' | '*' | '?' ]
def regexp: RegExp = {
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 = token match {
case LPAREN =>
nextToken(); sOpt(); regexp
case NAME =>
val a = Letter(ElemName(value)); nextToken(); maybeSuffix(a)
case _ => scala.sys.error("expected '(' or Name, got:" + token2string(token))
}
// atom ::= name
def atom = token match {
case NAME =>
val a = Letter(ElemName(value)); nextToken(); a
case _ => scala.sys.error("expected Name, got:" + token2string(token))
}
}