//------------------------------------------------------------------------------
// <copyright file="Avt.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
 
namespace System.Xml.Xsl.XsltOld {
    using Res = System.Xml.Utils.Res;
    using System;
    using System.Diagnostics;
    using System.Collections;
    using System.Xml;
    using System.Xml.XPath;
    using System.Text;
 
    internal sealed class Avt {
        private string      constAvt;
        private TextEvent[] events;
 
        private Avt(string constAvt) {
            Debug.Assert(constAvt != null);
            this.constAvt = constAvt;
        }
 
        private Avt(ArrayList eventList) {
            Debug.Assert(eventList != null);
            this.events = new TextEvent[eventList.Count];
            for(int i = 0; i < eventList.Count; i ++) {
                this.events[i] = (TextEvent) eventList[i];
            }
        }
 
        public bool IsConstant {
            get {return this.events == null;}
        }
 
        internal string Evaluate(Processor processor, ActionFrame frame) {
            if (IsConstant) {
                Debug.Assert(constAvt != null);
                return constAvt;
            }
            else {
                Debug.Assert(processor != null && frame != null);
 
                StringBuilder builder = processor.GetSharedStringBuilder();
 
                for(int i = 0; i < events.Length; i ++) {
                    builder.Append(events[i].Evaluate(processor, frame));
                }
                processor.ReleaseSharedStringBuilder();
                return builder.ToString();
            }
        }
 
        internal static Avt CompileAvt(Compiler compiler, string avtText) {
            Debug.Assert(compiler != null);
            Debug.Assert(avtText != null);
 
            bool constant;
            ArrayList list = compiler.CompileAvt(avtText, out constant);
            return constant ? new Avt(avtText) : new Avt(list);
        }
    }
}