%{
// XPath parser
//
// Author - Piers Haken <piersh@friskit.com>
//

using System;
using System.Xml;
using System.Xml.XPath;

namespace Mono.Xml.XPath
{
	public class XPathParser
	{
	
		internal System.Xml.Xsl.IStaticXsltContext Context;
		
		public XPathParser () : this (null) {}
		internal XPathParser (System.Xml.Xsl.IStaticXsltContext context)
		{
			Context = context;
			ErrorOutput = System.IO.TextWriter.Null;
		}
		
		internal Expression Compile (string xpath)
		{
			try {
				Tokenizer tokenizer = new Tokenizer (xpath);
				return (Expression) yyparse (tokenizer);
			} catch (XPathException e) {
				throw e;
			} catch (Exception e) {
				throw new XPathException ("Error during parse of " + xpath, e);
			}
		}
%}

%token ERROR
%token EOF

%token SLASH			"/"
%token SLASH2			"//"
%token DOT				"."
%token DOT2				".."
%token COLON2			"::"
%token COMMA			","
%token AT				"@"

%token FUNCTION_NAME

%token BRACKET_OPEN		"["
%token BRACKET_CLOSE	"]"
%token PAREN_OPEN		"("
%token PAREN_CLOSE		")"

%token AND				"and"
%token OR				"or"
%token DIV				"div"
%token MOD				"mod"
%token PLUS				"+"
%token MINUS			"-"
%token ASTERISK			"*"
%token DOLLAR			"$"
%token BAR				"|"
%token EQ				"="
%token NE				"!="
%token LE				"<="
%token GE				">="
%token LT				"<"
%token GT				">"

%token ANCESTOR					"ancestor"
%token ANCESTOR_OR_SELF			"ancstor-or-self"
%token ATTRIBUTE				"attribute"
%token CHILD					"child"
%token DESCENDANT				"descendant"
%token DESCENDANT_OR_SELF		"descendant-or-self"
%token FOLLOWING				"following"
%token FOLLOWING_SIBLING		"sibling"
%token NAMESPACE				"NameSpace"
%token PARENT					"parent"
%token PRECEDING				"preceding"
%token PRECEDING_SIBLING		"preceding-sibling"
%token SELF						"self"

%token COMMENT					"comment"
%token TEXT						"text"
%token PROCESSING_INSTRUCTION	"processing-instruction"
%token NODE						"node"

%token MULTIPLY			"*"

%token NUMBER
%token LITERAL
%token QName


%start Expr


%left AND
%left OR
%left EQ
%left NE
%left LE
%left GE
%left LT
%left GT

%left DIV
%left MOD
%left PLUS
%left MINUS

%%


Expr
	: OrExpr
	;
	
OrExpr
	: AndExpr 
	| OrExpr OR AndExpr
	{
		$$ = new ExprOR ((Expression) $1, (Expression) $3);
	}
	;

AndExpr
	: EqualityExpr 
	| AndExpr AND EqualityExpr 
	{
		$$ = new ExprAND ((Expression) $1, (Expression) $3);
	}
	;

EqualityExpr
	: RelationalExpr 
	| EqualityExpr EQ RelationalExpr 
	{
		$$ = new ExprEQ ((Expression) $1, (Expression) $3);
	}
	| EqualityExpr NE RelationalExpr 
	{
		$$ = new ExprNE ((Expression) $1, (Expression) $3);
	}
	;

RelationalExpr
	: AdditiveExpr 
	| RelationalExpr LT AdditiveExpr 
	{
		$$ = new ExprLT ((Expression) $1, (Expression) $3);
	}
	| RelationalExpr GT AdditiveExpr 
	{
		$$ = new ExprGT ((Expression) $1, (Expression) $3);
	}
	| RelationalExpr LE AdditiveExpr 
	{
		$$ = new ExprLE ((Expression) $1, (Expression) $3);
	}
	| RelationalExpr GE AdditiveExpr 
	{
		$$ = new ExprGE ((Expression) $1, (Expression) $3);
	}
	;

AdditiveExpr
	: MultiplicativeExpr 
	| AdditiveExpr PLUS MultiplicativeExpr
	{
		$$ = new ExprPLUS ((Expression) $1, (Expression) $3);
	}
	| AdditiveExpr MINUS MultiplicativeExpr
	{
		$$ = new ExprMINUS ((Expression) $1, (Expression) $3);
	}
	;

MultiplicativeExpr
	: UnaryExpr 
	| MultiplicativeExpr MULTIPLY UnaryExpr 
	{
		$$ = new ExprMULT ((Expression) $1, (Expression) $3);
	}
	| MultiplicativeExpr DIV UnaryExpr
	{
		$$ = new ExprDIV ((Expression) $1, (Expression) $3);
	}
	| MultiplicativeExpr MOD UnaryExpr
	{
		$$ = new ExprMOD ((Expression) $1, (Expression) $3);
	}
	;

UnaryExpr
	: UnionExpr 
	| MINUS UnaryExpr 
	{
		$$ = new ExprNEG ((Expression) $2);
	}
	;

UnionExpr
	: PathExpr 
	| UnionExpr BAR PathExpr
	{
		$$ = new ExprUNION ((Expression) $1, (Expression) $3);
	}
	;

PathExpr
	: LocationPath
	| FilterExpr
	| FilterExpr SLASH RelativeLocationPath
	{
		$$ = new ExprSLASH ((Expression) $1, (NodeSet) $3);
	}
	| FilterExpr SLASH2 RelativeLocationPath
	{
		$$ = new ExprSLASH2 ((Expression) $1, (NodeSet) $3);
	}
	;

LocationPath
	: RelativeLocationPath
	| AbsoluteLocationPath
	;

AbsoluteLocationPath
	: SLASH
	{
		$$ = new ExprRoot ();
	}
	| SLASH RelativeLocationPath
	{
		$$ = new ExprSLASH (new ExprRoot (), (NodeSet) $2);
	}
	| SLASH2 RelativeLocationPath
	{
		$$ = new ExprSLASH2 (new ExprRoot (), (NodeSet) $2);
	}
	;

RelativeLocationPath
	: Step
	| RelativeLocationPath SLASH Step 
	{
		$$ = new ExprSLASH ((NodeSet) $1, (NodeSet) $3);
	}
	| RelativeLocationPath SLASH2 Step 
	{
		$$ = new ExprSLASH2 ((NodeSet) $1, (NodeSet) $3);
	}
	;

Step
	: PredicatedStep
	| DOT
	{
		$$ = new NodeTypeTest (Axes.Self, XPathNodeType.All);
	}
	| DOT2
	{
		$$ = new NodeTypeTest (Axes.Parent, XPathNodeType.All);
	}
	;

PredicatedStep
	: AxisTest
	| PredicatedStep Predicate
	{
		$$ = new ExprFilter ((NodeSet) $1, (Expression) $2);
	}
	;

AxisTest
	: AxisSpecifier QName
	{
		$$ = new NodeNameTest ((Axes) $1, (XmlQualifiedName) $2, Context);
	}
	| AxisSpecifier ASTERISK
	{
		$$ = new NodeTypeTest ((Axes) $1);
	}
	| AxisSpecifier NodeType PAREN_OPEN OptionalLiteral PAREN_CLOSE
	{
		$$ = new NodeTypeTest ((Axes) $1, (XPathNodeType) $2, (String) $4);
	}
	;

AxisSpecifier
	: /* empty */
	{
		$$ = Axes.Child;
	}
	| AT
	{
		$$ = Axes.Attribute;
	}
	| AxisName COLON2
	{
		$$ = $1;
	}
	;

NodeType
	: COMMENT					{ $$ = XPathNodeType.Comment; }
	| TEXT						{ $$ = XPathNodeType.Text; }
	| PROCESSING_INSTRUCTION	{ $$ = XPathNodeType.ProcessingInstruction; }
	| NODE						{ $$ = XPathNodeType.All; }
	;


FilterExpr
	: PrimaryExpr 
	| FilterExpr Predicate 
	{
		$$ = new ExprFilter ((Expression) $1, (Expression) $2);
	}
	;

PrimaryExpr
	: DOLLAR QName
	{
		Expression ret = null;
		if (Context != null)
			ret = Context.TryGetVariable (((XmlQualifiedName) $2).ToString ());
		
		if (ret == null)
			ret = new ExprVariable ((XmlQualifiedName) $2, Context);
			
		$$ = ret;
	}
	| PAREN_OPEN Expr PAREN_CLOSE
	{
		$$ = new ExprParens ((Expression) $2);
	}
	| LITERAL
	{
		$$ = new ExprLiteral ((String) $1);
	}
	| NUMBER
	{
		$$ = new ExprNumber ((double) $1);
	}
	| FunctionCall
	;

FunctionCall
	: FUNCTION_NAME PAREN_OPEN OptionalArgumentList PAREN_CLOSE
	{
		Expression ret = null;
		if (Context != null)
			ret = Context.TryGetFunction ((XmlQualifiedName) $1, (FunctionArguments) $3);
		if (ret == null)
			ret = ExprFunctionCall.Factory ((XmlQualifiedName) $1, (FunctionArguments) $3, Context);
		
		$$ = ret;
	}
	;

OptionalArgumentList
	: /* empty */
	| Expr OptionalArgumentListTail
	{
		$$ = new FunctionArguments ((Expression) $1, (FunctionArguments) $2);
	}
	;

OptionalArgumentListTail
	: /* empty */
	| COMMA Expr OptionalArgumentListTail
	{
		$$ = new FunctionArguments ((Expression) $2, (FunctionArguments) $3);
	}
	;

Predicate
	: BRACKET_OPEN Expr BRACKET_CLOSE
	{
		$$ = $2;
	}
	;

AxisName
	: ANCESTOR				{ $$ = Axes.Ancestor; }
	| ANCESTOR_OR_SELF		{ $$ = Axes.AncestorOrSelf; }
	| ATTRIBUTE				{ $$ = Axes.Attribute; }
	| CHILD					{ $$ = Axes.Child; }
	| DESCENDANT			{ $$ = Axes.Descendant; }
	| DESCENDANT_OR_SELF	{ $$ = Axes.DescendantOrSelf; }
	| FOLLOWING				{ $$ = Axes.Following; }
	| FOLLOWING_SIBLING		{ $$ = Axes.FollowingSibling; }
	| NAMESPACE				{ $$ = Axes.Namespace; }
	| PARENT				{ $$ = Axes.Parent; }
	| PRECEDING				{ $$ = Axes.Preceding; }
	| PRECEDING_SIBLING		{ $$ = Axes.PrecedingSibling; }
	| SELF					{ $$ = Axes.Self; }
	;

OptionalLiteral
	: /* empty */
	| LITERAL
	;

%%
	}