Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Xml/System/Xml/XPath/Internal/BooleanFunctions.cs

@@ -0,0 +1,90 @@
+//------------------------------------------------------------------------------
+// <copyright file="BooleanFunctions.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+// <owner current="true" primary="true">[....]</owner>
+//------------------------------------------------------------------------------
+
+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();
+        }
+    }
+}