System.Xml.Xsl.XsltOld.Compiler.CreateIfAction C# (CSharp) Method

        public virtual IfAction CreateIfAction(IfAction.ConditionType type)
        {
            IfAction action = new IfAction(type);
            action.Compile(this);
            return action;
        }

        private void CompileConditions(Compiler compiler) {
            NavigatorInput input = compiler.Input;
            bool when       = false;
            bool otherwise  = false;

            do {
                switch (input.NodeType) {
                case XPathNodeType.Element:
                    compiler.PushNamespaceScope();
                    string nspace = input.NamespaceURI;
                    string name   = input.LocalName;

                    if (Ref.Equal(nspace, input.Atoms.UriXsl)) {
                        IfAction action = null;
                        if (Ref.Equal(name, input.Atoms.When)) {
                            if (otherwise) {
                                throw XsltException.Create(Res.Xslt_WhenAfterOtherwise);
                            }
                            action = compiler.CreateIfAction(IfAction.ConditionType.ConditionWhen);
                            when = true;
                        }
                        else if (Ref.Equal(name, input.Atoms.Otherwise)) {
                            if (otherwise) {
                                throw XsltException.Create(Res.Xslt_DupOtherwise);
                            }
                            action = compiler.CreateIfAction(IfAction.ConditionType.ConditionOtherwise);
                            otherwise = true;
                        }
                        else {
                            throw compiler.UnexpectedKeyword();
                        }
                        AddAction(action);
                    }
                    else {
                        throw compiler.UnexpectedKeyword();
                    }
                    compiler.PopScope();
                    break;

                case XPathNodeType.Comment:
                case XPathNodeType.ProcessingInstruction:
                case XPathNodeType.Whitespace:
                case XPathNodeType.SignificantWhitespace:
                    break;

                default:
                    throw XsltException.Create(Res.Xslt_InvalidContents, "choose");
                }
            }
            while (compiler.Advance());
            if (! when) {
                throw XsltException.Create(Res.Xslt_NoWhen);
            }
        }