StringConcat.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / XmlUtils / System / Xml / Xsl / Runtime / StringConcat.cs / 1305376 / StringConcat.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
using System; 
using System.Collections.Generic; 
using System.Diagnostics;
using System.ComponentModel; 

namespace System.Xml.Xsl.Runtime {

    ///  
    /// Efficiently concatenates strings when the number of string is not known beforehand, and
    /// yet it is common for only one string to be concatenated.  StringBuilder is not good for 
    /// this purpose, since it *always* allocates objects, even if only one string is appended. 
    /// 
    [EditorBrowsable(EditorBrowsableState.Never)] 
    public struct StringConcat {
        private string s1, s2, s3, s4;
        private string delimiter;
        private List strList; 
        int idxStr;
 
        ///  
        /// Clear the result string.
        ///  
        public void Clear() {
            this.idxStr = 0;
            this.delimiter = null;
        } 

        ///  
        /// Gets or sets the string that delimits concatenated strings. 
        /// 
        public string Delimiter { 
            get { return this.delimiter; }
            set { this.delimiter = value; }
        }
 
        /// 
        /// Return the number of concatenated strings, including delimiters. 
        ///  
        internal int Count {
            get { return this.idxStr; } 
        }

        /// 
        /// Concatenate a new string to the result. 
        /// 
        public void Concat(string value) { 
            Debug.Assert(value != null); 

            if (this.delimiter != null && this.idxStr != 0) { 
                // Add delimiter
                ConcatNoDelimiter(this.delimiter);
            }
 
            ConcatNoDelimiter(value);
        } 
 
        /// 
        /// Get the result string. 
        /// 
        public string GetResult() {
            switch (this.idxStr) {
                case 0: return string.Empty; 
                case 1: return this.s1;
                case 2: return string.Concat(this.s1, this.s2); 
                case 3: return string.Concat(this.s1, this.s2, this.s3); 
                case 4: return string.Concat(this.s1, this.s2, this.s3, this.s4);
            } 
            return string.Concat(this.strList.ToArray());
        }

        ///  
        /// Concatenate a new string to the result without adding a delimiter.
        ///  
        internal void ConcatNoDelimiter(string s) { 
            switch (this.idxStr) {
                case 0: this.s1 = s; break; 
                case 1: this.s2 = s; break;
                case 2: this.s3 = s; break;
                case 3: this.s4 = s; break;
                case 4: 
                    // Calling Clear() is expensive, allocate a new List instead
                    int capacity = (this.strList == null) ? 8 : this.strList.Count; 
                    List strList = this.strList = new List(capacity); 
                    strList.Add(this.s1);
                    strList.Add(this.s2); 
                    strList.Add(this.s3);
                    strList.Add(this.s4);
                    goto default;
                default: 
                    this.strList.Add(s);
                    break; 
            } 

            this.idxStr++; 
        }
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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