Параметры сопоставления CSV с .NET.

Ответ 1

Вы пытались найти уже существующий .NET парсер CSV? Этот утверждает, что обрабатывает многострочные записи значительно быстрее, чем OLEDB.

Ответ 2

Я написал это некоторое время назад как легкий, автономный синтаксический анализатор CSV. Я считаю, что он отвечает всем вашим требованиям. Дайте ему попробовать, зная, что он, вероятно, не пуленепробиваемый.

Если это сработает для вас, не стесняйтесь изменять пространство имен и использовать без ограничений.

namespace NFC.Portability
{
    using System;
    using System.Collections.Generic;
    using System.Data;
    using System.IO;
    using System.Linq;
    using System.Text;

    /// <summary>
    /// Loads and reads a file with comma-separated values into a tabular format.
    /// </summary>
    /// <remarks>
    /// Parsing assumes that the first line will always contain headers and that values will be double-quoted to escape double quotes and commas.
    /// </remarks>
    public unsafe class CsvReader
    {
        private const char SEGMENT_DELIMITER = ',';
        private const char DOUBLE_QUOTE = '"';
        private const char CARRIAGE_RETURN = '\r';
        private const char NEW_LINE = '\n';

        private DataTable _table = new DataTable();

        /// <summary>
        /// Gets the data contained by the instance in a tabular format.
        /// </summary>
        public DataTable Table
        {
            get
            {
                // validation logic could be added here to ensure that the object isn't in an invalid state

                return _table;
            }
        }

        /// <summary>
        /// Creates a new instance of <c>CsvReader</c>.
        /// </summary>
        /// <param name="path">The fully-qualified path to the file from which the instance will be populated.</param>
        public CsvReader( string path )
        {
            if( path == null )
            {
                throw new ArgumentNullException( "path" );
            }

            FileStream fs = new FileStream( path, FileMode.Open );
            Read( fs );
        }

        /// <summary>
        /// Creates a new instance of <c>CsvReader</c>.
        /// </summary>
        /// <param name="stream">The stream from which the instance will be populated.</param>
        public CsvReader( Stream stream )
        {
            if( stream == null )
            {
                throw new ArgumentNullException( "stream" );
            }

            Read( stream );
        }

        /// <summary>
        /// Creates a new instance of <c>CsvReader</c>.
        /// </summary>
        /// <param name="bytes">The array of bytes from which the instance will be populated.</param>
        public CsvReader( byte[] bytes )
        {
            if( bytes == null )
            {
                throw new ArgumentNullException( "bytes" );
            }

            MemoryStream ms = new MemoryStream();
            ms.Write( bytes, 0, bytes.Length );
            ms.Position = 0;

            Read( ms );
        }

        private void Read( Stream s )
        {
            string lines;

            using( StreamReader sr = new StreamReader( s ) )
            {
                lines = sr.ReadToEnd();
            }

            if( string.IsNullOrWhiteSpace( lines ) )
            {
                throw new InvalidOperationException( "Data source cannot be empty." );
            }

            bool inQuotes = false;
            int lineNumber = 0;
            StringBuilder buffer = new StringBuilder( 128 );
            List<string> values = new List<string>();

            Action endSegment = () =>
            {
                values.Add( buffer.ToString() );
                buffer.Clear();
            };

            Action endLine = () =>
            {
                if( lineNumber == 0 )
                {
                    CreateColumns( values );
                    values.Clear();
                }
                else
                {
                    CreateRow( values );
                    values.Clear();
                }

                values.Clear();
                lineNumber++;
            };

            fixed( char* pStart = lines )
            {
                char* pChar = pStart;
                char* pEnd = pStart + lines.Length;

                while( pChar < pEnd ) // leave null terminator out
                {
                    if( *pChar == DOUBLE_QUOTE )
                    {
                        if( inQuotes )
                        {
                            if( Peek( pChar, pEnd ) == SEGMENT_DELIMITER )
                            {
                                endSegment();
                                pChar++;
                            }
                            else if( !ApproachingNewLine( pChar, pEnd ) )
                            {
                                buffer.Append( DOUBLE_QUOTE );
                            }
                        }

                        inQuotes = !inQuotes;
                    }
                    else if( *pChar == SEGMENT_DELIMITER )
                    {
                        if( !inQuotes )
                        {
                            endSegment();
                        }
                        else
                        {
                            buffer.Append( SEGMENT_DELIMITER );
                        }
                    }
                    else if( AtNewLine( pChar, pEnd ) )
                    {
                        if( !inQuotes )
                        {
                            endSegment();
                            endLine();
                            pChar++;
                        }
                        else
                        {
                            buffer.Append( *pChar );
                        }
                    }
                    else
                    {
                        buffer.Append( *pChar );
                    }

                    pChar++;
                }
            }

            // append trailing values at the end of the file
            if( values.Count > 0 )
            {
                endSegment();
                endLine();
            }
        }

        /// <summary>
        /// Returns the next character in the sequence but does not advance the pointer. Checks bounds.
        /// </summary>
        /// <param name="pChar">Pointer to current character.</param>
        /// <param name="pEnd">End of range to check.</param>
        /// <returns>
        /// Returns the next character in the sequence, or char.MinValue if range is exceeded.
        /// </returns>
        private char Peek( char* pChar, char* pEnd )
        {
            if( pChar < pEnd )
            {
                return *( pChar + 1 );
            }

            return char.MinValue;
        }

        /// <summary>
        /// Determines if the current character represents a newline. This includes lookahead for two character newline delimiters.
        /// </summary>
        /// <param name="pChar"></param>
        /// <param name="pEnd"></param>
        /// <returns></returns>
        private bool AtNewLine( char* pChar, char* pEnd )
        {
            if( *pChar == NEW_LINE )
            {
                return true;
            }

            if( *pChar == CARRIAGE_RETURN && Peek( pChar, pEnd ) == NEW_LINE )
            {
                return true;
            }

            return false;
        }

        /// <summary>
        /// Determines if the next character represents a newline, or the start of a newline.
        /// </summary>
        /// <param name="pChar"></param>
        /// <param name="pEnd"></param>
        /// <returns></returns>
        private bool ApproachingNewLine( char* pChar, char* pEnd )
        {
            if( Peek( pChar, pEnd ) == CARRIAGE_RETURN || Peek( pChar, pEnd ) == NEW_LINE )
            {
                // technically this cheats a little to avoid a two char peek by only checking for a carriage return or new line, not both in sequence
                return true;
            }

            return false;
        }

        private void CreateColumns( List<string> columns )
        {
            foreach( string column in columns )
            {
                DataColumn dc = new DataColumn( column );
                _table.Columns.Add( dc );
            }
        }

        private void CreateRow( List<string> values )
        {
            if( values.Where( (o) => !string.IsNullOrWhiteSpace( o ) ).Count() == 0 )
            {
                return; // ignore rows which have no content
            }

            DataRow dr = _table.NewRow();
            _table.Rows.Add( dr );

            for( int i = 0; i < values.Count; i++ )
            {
                dr[i] = values[i];
            }
        }
    }
}

Ответ 3

Взгляните на код, который я отправил на этот вопрос:

fooobar.com/info/390209/...

Он охватывает большинство ваших требований, и не потребуется многого для его обновления, чтобы поддерживать альтернативные разделители или текстовые классификаторы.