BooleanFunctions.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Xml / System / Xml / XPath / Internal / BooleanFunctions.cs / 1 / BooleanFunctions.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
 
namespace MS.Internal.Xml.XPath { 
    using System;
    using System.Xml; 
    using System.Xml.XPath;
    using System.Diagnostics;
    using System.Globalization;
    using System.Xml.Xsl; 
    using FT = MS.Internal.Xml.XPath.Function.FunctionType;
 
    internal sealed class BooleanFunctions : ValueQuery { 
        Query arg;
        FT    funcType; 

        public BooleanFunctions(FT funcType, Query arg) {
            this.arg      = arg;
            this.funcType = funcType; 
        }
        private BooleanFunctions(BooleanFunctions other) : base(other) { 
            this.arg      = Clone(other.arg); 
            this.funcType = other.funcType;
        } 

        public override void SetXsltContext(XsltContext context) {
            if (arg != null) {
                arg.SetXsltContext(context); 
            }
        } 
 
        public override object Evaluate(XPathNodeIterator nodeIterator) {
            switch (funcType) { 
            case FT.FuncBoolean : return toBoolean(nodeIterator);
            case FT.FuncNot     : return Not(nodeIterator);
            case FT.FuncTrue    : return true;
            case FT.FuncFalse   : return false; 
            case FT.FuncLang    : return Lang(nodeIterator);
            } 
            return false; 
        }
 
        internal static bool toBoolean(double number) {
            return number != 0 && ! double.IsNaN(number);
        }
        internal static bool toBoolean(string str) { 
            return str.Length > 0;
        } 
 
        internal bool toBoolean(XPathNodeIterator nodeIterator) {
            object result = arg.Evaluate(nodeIterator); 
            if (result is XPathNodeIterator) return arg.Advance() != null;
            if (result is string           ) return toBoolean((string)result);
            if (result is double           ) return toBoolean((double)result);
            if (result is bool             ) return (bool)result; 
            Debug.Assert(result is XPathNavigator, "Unknown value type");
            return true; 
        } 

        public override XPathResultType StaticType { get { return XPathResultType.Boolean; } } 

        private bool Not(XPathNodeIterator nodeIterator) {
            return ! (bool) arg.Evaluate(nodeIterator);
        } 

        private bool Lang(XPathNodeIterator nodeIterator) { 
            string str  = arg.Evaluate(nodeIterator).ToString(); 
            string lang = nodeIterator.Current.XmlLang;
            return ( 
               lang.StartsWith(str, StringComparison.OrdinalIgnoreCase) &&
               (lang.Length == str.Length || lang[str.Length] == '-')
            );
        } 

        public override XPathNodeIterator Clone() { return new BooleanFunctions(this); } 
 
        public override void PrintQuery(XmlWriter w) {
            w.WriteStartElement(this.GetType().Name); 
            w.WriteAttributeString("name", funcType.ToString());
            if (arg != null) {
                arg.PrintQuery(w);
            } 
            w.WriteEndElement();
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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