Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.SqlXml/System/Xml/Xsl/XsltOld/PrefixQname.cs

@@ -0,0 +1,71 @@
+//------------------------------------------------------------------------------
+// <copyright file="PrefixQName.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+// <owner current="true" primary="true">[....]</owner>
+//------------------------------------------------------------------------------
+
+namespace System.Xml.Xsl.XsltOld {
+    using Res = System.Xml.Utils.Res;
+    using System;
+    using System.Diagnostics; 
+    using System.Xml;
+
+    internal sealed class PrefixQName {
+        public string Prefix;
+        public string Name;
+        public string Namespace;
+
+        internal void ClearPrefix() {
+            Prefix = string.Empty;
+        }
+
+        internal void SetQName(string qname) {
+            PrefixQName.ParseQualifiedName(qname, out Prefix, out Name);
+        }
+
+        //
+        // Parsing qualified names
+        //
+
+        public static void ParseQualifiedName(string qname, out string prefix, out string local) {
+            Debug.Assert(qname != null);
+            prefix = string.Empty;
+            local = string.Empty;
+
+            // parse first NCName (prefix or local name)
+            int position = ValidateNames.ParseNCName(qname);
+            if (position == 0) {
+                throw XsltException.Create(Res.Xslt_InvalidQName, qname);
+            }
+            local = qname.Substring(0, position);
+            
+            // not at the end -> parse ':' and the second NCName (local name)
+            if (position < qname.Length) {
+                if (qname[position] == ':') {
+                    int startLocalNamePos = ++position;
+                    prefix = local;
+                    int len = ValidateNames.ParseNCName(qname, position);
+                    position += len;
+                    if (len == 0) {
+                        throw XsltException.Create(Res.Xslt_InvalidQName, qname);
+                    }
+                    local = qname.Substring(startLocalNamePos, len);
+                }
+
+                // still not at the end -> error
+                if (position < qname.Length) {
+                    throw XsltException.Create(Res.Xslt_InvalidQName, qname);
+                }
+            }
+        }
+
+        public static bool ValidatePrefix(string prefix) {
+            if (prefix.Length == 0) {
+                return false;
+            }
+            int endPos = ValidateNames.ParseNCName(prefix, 0);
+            return endPos == prefix.Length;
+        }
+    }
+}