JD2022-TU1/main/tools/framework/JD.Collections/Utilities/CollectionPrinter.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using JD.Kernel.StaticHelpers;

namespace JD.Collections.Utilities
{
    /// <summary>
    /// Used to get a string representation of the elements in a collection.
    /// Each item in the collection is converted to a string by calling its 
    /// ToString method (null is represented by "null").
    /// </summary>
    public class CollectionPrinter
    {
        #region Constants

        private const string NullString = "null";

        #endregion

        #region Variables

        private bool m_recursive = true;
        private string m_startToken = "{";
        private string m_endToken = "}";
        private string m_separator = ", ";

        #endregion

        #region Properties

        /// <summary>
        /// If true, contained collections (except strings) are converted to strings by a 
        /// recursive call to the printer, instead of calling ToString.
        /// </summary>
        public bool Recursive
        {
            get { return m_recursive; }
            set
            {
                m_recursive = value;
            }
        }

        /// <summary>
        /// The string that delimits the beginning of the output string.
        /// </summary>
        public string StartToken
        {
            get { return m_startToken; }
            set
            {
                Throw.IfEmpty(value, "StartToken");
                m_startToken = value;
            }
        }

        /// <summary>
        /// The string that delimits the end of the output string.
        /// </summary>
        public string EndToken
        {
            get { return m_endToken; }
            set
            {
                Throw.IfEmpty(value, "EndToken");
                m_endToken = value;
            }
        }

        /// <summary>
        /// The string that delimits each item in the collection.
        /// </summary>
        public string Separator
        {
            get { return m_separator; }
            set
            {
                Throw.IfEmpty(value, "Separator");
                m_separator = value;
            }
        }

        #endregion

        #region Methods

        public string Print(IEnumerable collection)
        {
            if (collection == null)
            {
                return NullString;
            }

            StringBuilder builder = new StringBuilder();

            builder.Append(StartToken);

            PrintCollection(builder, collection);

            builder.Append(EndToken);
            return builder.ToString();
        }

        private void PrintCollection(StringBuilder builder, IEnumerable collection)
        {
            bool firstItem = true;

            foreach (object item in collection)
            {
                if (!firstItem)
                {
                    builder.Append(Separator);
                }
                firstItem = false;

                PrintObject(builder, item);
            }
        }

        private void PrintObject(StringBuilder builder, object item)
        {
            if (ReferenceEquals(item, null))
            {
                builder.Append(NullString);
            }
            else if (Recursive && item.GetType().IsGenericType && item.GetType().GetGenericTypeDefinition() == typeof(KeyValuePair<,>))
            {
                Type itemType = item.GetType();
                object key = itemType.GetProperty("Key").GetValue(item, null);
                object value = itemType.GetProperty("Value").GetValue(item, null);

                PrintObject(builder, key);
                builder.Append(" = ");
                PrintObject(builder, value);
            }
            else if (Recursive && item is IEnumerable && !(item is string))
            {
                builder.Append(Print((IEnumerable)item));
            }
            else if (item is IFormattable)
            {
                builder.Append(((IFormattable)item).ToString(string.Empty, System.Globalization.CultureInfo.InvariantCulture));
            }
            else
            {
                builder.Append(item);
            }
        }

        #endregion
    }
}