/// <summary>
/// This method tries to process given line according to given set of parameters.
/// </summary>
/// <remarks>
/// This method processes given line by splitting it into its pieces and then by
/// trying to convert each element into its type-safe object expression.
/// </remarks>
/// <param name="line">
/// The line to be processed.
/// </param>
/// <param name="separator">
/// The separator to be used to split given line at.
/// </param>
/// <param name="exactly">
/// An exception of type 'FormatException' is throw if this parameter is 'true' and
/// converting one of the values has failed. Otherwise, each variable is set to a
/// default value. Which default value will be used in such a failure case depends
/// on current data type. For example, strings using <null> as default value,
/// 'false' is used as default for Boolean types, and the corresponding max-value is
/// used for all other types.
/// </param>
/// <param name="culture">
/// The culture information to be used for data conversion.
/// </param>
/// <param name="mapping">
/// The value mappings to be used for an extended data interpretation.
/// </param>
/// <param name="descriptors">
/// A list of data type descriptor items that help interpreting data.
/// </param>
/// <returns>
/// An instance of class of type <typeparamref name="TInstance"/>.
/// </returns>
/// <exception cref="InvalidOperationException">
/// This exception is thrown for example if <typeparamref name="TInstance"/> does not
/// provide a default constructor.
/// </exception>
/// <exception cref="FormatException">
/// This exception is thrown for example if 'exactly' is set to 'true' and one of the
/// data items could not be converted.
/// </exception>
/// <exception cref="NotSupportedException">
/// This exception is thrown as soon as a class of type <typeparamref name="TInstance"/>
/// wants to use an unsupported data type.
/// </exception>
private static TInstance ProcessLine(String line, Char separator, Boolean exactly, CultureInfo culture, CsvMappings mapping, List <ItemDescriptor> descriptors)
{
TInstance result = CsvImporter <TInstance> .Construct(); // throws
List <String> values = ProcessHelper.SplitIntoCells(line, separator);
for (Int32 index = 0; index < values.Count; index++)
{
// A simple break is possible because of column validation has been done already.
if (index >= descriptors.Count)
{
break;
}
String value = values[index];
PropertyInfo property = descriptors[index].Origin;
Type type = property.PropertyType;
property.SetValue(result, TypeConverter.IntoObject(value, type, exactly, culture, mapping)); // throws
}
return(result);
}
/// <summary>
/// This method tries to write a particular line into given stream according
/// to given parameter set.
/// </summary>
/// <remarks>
/// This method may throw exceptions which must be handled by the caller.
/// </remarks>
/// <param name="writer">
/// The stream writer to be used to push data.
/// </param>
/// <param name="separator">
/// The delimiter to be used to separate each column.
/// </param>
/// <param name="textual">
/// The flag indicating how strings have to be handled. If true then all string
/// are enclosed in double-quotes. If false then only the necessary strings are
/// enclosed in double-quotes.
/// </param>
/// <param name="culture">
/// The culture to be used for data conversion.
/// </param>
/// <param name="mapping">
/// The mapping to be used for value transformation.
/// </param>
/// <param name="values">
/// A list of values representing a single line of the CSV file.
/// </param>
private static void WriteLine(StreamWriter writer, Char separator, Boolean textual, CultureInfo culture, CsvMappings mapping, IEnumerable <Object> values)
{
StringBuilder builder = new StringBuilder(1024);
if (values != null && values.Any())
{
foreach (Object value in values)
{
String current = ProcessHelper.ConvertToString(value, culture, mapping);
builder.Append(ProcessHelper.ConvertToOutput(current, separator, textual));
}
}
writer.WriteLine(ProcessHelper.FixupOutput(builder, separator).ToString());
}
/// <summary>
/// This method tries to load all values from given stream using given
/// settings.
/// </summary>
/// <remarks>
/// The settings parameter describes how the data within given file should be
/// processed. For example, users may define the expected culture, the expected
/// file encoding, which separator is used and so on.
/// </remarks>
/// <param name="stream">
/// The stream to read data from.
/// </param>
/// <param name="settings">
/// The settings to be used to process stream data.
/// </param>
/// <returns>
/// A list of classes of <typeparamref name="TInstance"/>.
/// </returns>
/// <exception cref="ArgumentNullException">
/// This exception is thrown either if given stream or if given settings is
/// invalid.
/// </exception>
/// <exception cref="ArgumentException">
/// This exception is thrown in case of given stream does not have read access.
/// </exception>
public static IEnumerable <TInstance> Load(Stream stream, CsvSettings settings)
{
List <TInstance> values = new List <TInstance>();
if (stream == null)
{
throw new ArgumentNullException(nameof(stream), $"The stream to read the data from is invalid.");
}
if (!stream.CanRead)
{
throw new ArgumentException("No read access to given stream.", nameof(stream));
}
if (settings == null)
{
throw new ArgumentNullException(nameof(settings), "The CSV settings are invalid.");
}
TypeDescriptor descriptor = TypeProcessor.LoadDescriptor <TInstance>();
// NOTE: Keep in mind! All item descriptors are confirmed and ordered already.
// This means they are in the right (which means expected) order! Therefore,
// something like "search for right column" is absolutely redundant.
List <ItemDescriptor> items = descriptor.Settings.ToList();
List <String> lines = new List <String>();
using (StreamReader reader = new StreamReader(stream, settings.Encoding))
{
while (!reader.EndOfStream)
{
String line = reader.ReadLine();
if (!String.IsNullOrWhiteSpace(line))
{
lines.Add(line);
}
}
}
if (lines.Count > 0)
{
Char separator = settings.Separator;
Boolean exactly = settings.Exactly;
CultureInfo culture = settings.Culture;
Boolean heading = settings.Heading;
CsvMappings mapping = settings.Mappings;
CsvImporter <TInstance> .ValidateColumns(lines, separator, exactly, items); // throws
Int32 index = 0;
List <String> cells = ProcessHelper.SplitIntoCells(lines[index], separator);
if (CsvImporter <TInstance> .IsHeaderLine(cells, items))
{
// An exact header validation is performed, but only if the first
// line represents a header and Heading and Exactly are both enabled.
// In such a case a Format Exception is thrown as soon as the header
// does not exactly fit! In this conjunction, the validation must pass
// the case-sensitive check as well as the position check.
if (heading && exactly)
{
CsvImporter <TInstance> .ValidateHeader(cells, items); // throws
}
index++;
}
for (; index < lines.Count; index++)
{
values.Add(CsvImporter <TInstance> .ProcessLine(lines[index], separator, exactly, culture, mapping, items));
}
}
return(values);
}
