xml path expressions and a (not yet working) pa...

xml path expressions and a (not yet working) parser for them

4 files changed, 131 insertions, 2 deletions

diff --git a/sources/scala/xml/path/Expression.scala b/sources/scala/xml/path/Expression.scala
index 4fec113a9b..d9f81d5836 100644
--- a/sources/scala/xml/path/Expression.scala
+++ b/sources/scala/xml/path/Expression.scala
@@ -10,6 +10,7 @@ object Expression {
 
 abstract class Expression ;
 
+/*
 case class Node[T<:Element]( conds:Condition* ) extends Expression {
         type t = T;
 
@@ -17,6 +18,8 @@ case class Node[T<:Element]( conds:Condition* ) extends Expression {
                 x.isInstanceOf[t];
         }
 };
+*/
+case class Node( label:String, cond:Option[List[List[Expression]]] ) extends Expression ;
 
 case class Attribute( name:String ) extends Expression;
 
@@ -24,7 +27,7 @@ case object Wildcard extends Expression;
 
 case object Descendant extends Expression;
 
-abstract class Condition ;
-
+/*
 case class Present(attr:Attribute) extends Condition;
 case class Equals(attr:Attribute, str:String) extends Condition;
+*/
diff --git a/sources/scala/xml/path/Parser.scala b/sources/scala/xml/path/Parser.scala
new file mode 100644
index 0000000000..e7828fe716
--- /dev/null
+++ b/sources/scala/xml/path/Parser.scala
@@ -0,0 +1,55 @@
+package scala.xml.path ;
+
+class Parser( it:Iterator[char] ) with Scanner( it ) {
+
+  def acc( tok:int ) = {
+    if( token != tok ) error("unexpected token") else {};
+    nextToken
+  }
+
+  def parseString( xpath:String ) = {
+    //initScanner( new IterableString( xpath ));
+    expr
+  }
+
+ def expr:List[Expression] = {
+    var es : List[Expression] = Nil;
+    while( token != ENDTOK ) token.match {
+
+      case AT =>
+	nextToken; es = Attribute( ident ) :: es;
+
+      case DOT =>
+	nextToken; acc( SLASH );
+
+      case IDENT =>
+	val label = value; nextToken; val cs = conds; es = Node( label, cs ) :: es ;
+
+      case SLASH =>
+	nextToken;
+
+      case SLASHSLASH =>
+	nextToken; es = Descendant :: es ;
+
+      case STAR =>
+	nextToken; es = Wildcard :: es;
+
+    }
+    es.reverse;
+  }
+
+  def conds = token match  {
+    case LBRACKET =>
+      nextToken;
+      var cond :List[List[Expression]] = List( expr );
+      while( COMMA == token ) { cond = expr :: cond }
+      acc( RBRACKET );
+      Some( cond.reverse )
+    case _ =>
+      None
+  }
+
+  def ident = {
+    val label = value; acc(IDENT); label
+  }
+}
diff --git a/sources/scala/xml/path/Scanner.scala b/sources/scala/xml/path/Scanner.scala
new file mode 100644
index 0000000000..81c251d055
--- /dev/null
+++ b/sources/scala/xml/path/Scanner.scala
@@ -0,0 +1,48 @@
+package scala.xml.path ;
+
+class Scanner( it:Iterator[char] ) with Tokens {
+
+  val ENDCH : char = (-1).asInstanceOf[char];
+
+  var c : char = '%';
+  var token : int = 0;
+  var value : String = "";
+
+  def next = if( it.hasNext ) { c = it.next } else { c = ENDCH };
+
+  def nextToken = if( ENDCH == c ) ENDTOK else c match {
+    case '@' => AT
+    case ',' => COMMA
+    case '.' =>{
+      next;
+      if ( '.' == c ) { next; token = DOTDOT } else { token = DOT }
+    }
+    case '=' =>next; token = EQUALS
+    case '[' =>next; token = LBRACKET
+    case ']' =>next; token = RBRACKET
+    case '/' =>{
+      next;
+      if ( '/' == c ) { next; token = SLASHSLASH } else { token = SLASH }
+    }
+    case '*' =>next; token = STAR
+    case _  =>getIdentOrKeyword;
+  }
+
+  def isIdentChar = ('a' <= c && c <= 'z');
+
+  def getIdentOrKeyword = {
+    val str = getIdent; token = IDENT /*
+    keywords.get( str ) match {
+      case Some( tok ) => value=""; token = tok
+      case None => token = IDENT
+    }*/
+  }
+
+  def getIdent:String = {
+    var cs = List(c);
+    next;
+    while ( isIdentChar ) { cs = c::cs; next }
+    cs.foldLeft ("") { (c,s) => s+c }
+  }
+
+}
diff --git a/sources/scala/xml/path/Tokens.scala b/sources/scala/xml/path/Tokens.scala
new file mode 100644
index 0000000000..d88b372335
--- /dev/null
+++ b/sources/scala/xml/path/Tokens.scala
@@ -0,0 +1,23 @@
+package scala.xml.path ;
+
+/** Tokens for XPath expressions
+ */
+
+class Tokens {
+
+  final val AT         = 0;
+  final val COMMA      = AT + 1;
+  final val DOT        = COMMA + 1;
+  final val DOTDOT     = DOT + 1;
+  final val EQUALS     = DOTDOT + 1;
+  final val IDENT      = EQUALS + 1;
+  final val LBRACKET   = IDENT + 1;
+  final val RBRACKET   = LBRACKET + 1;
+  final val SLASH      = RBRACKET + 1;
+  final val SLASHSLASH = SLASH + 1;
+  final val STAR       = SLASHSLASH + 1;
+
+  final val ENDTOK     = STAR + 1;
+
+
+}