/// <summary>
/// <seealso cref="T:System.String.Format"/>. This version takes a string builder and outputs to that instead of returning a new string.
/// </summary>
public static void Format(IFormatProvider provider, string format, IDictionary<string, object> context, MissingValueHandler handler, StringBuilder result)
{
if (format == null)
throw new ArgumentNullException("format");
// Nothing to see here. Move along.
if (format.IndexOf('{') < 0)
{
result.Append(format);
return;
}
if (context == null)
{
throw new ArgumentNullException("context");
}
int ptr = 0;
int start = ptr;
while (ptr < format.Length)
{
char c = format[ptr++];
if (c == '{')
{
result.Append(format, start, ptr - start - 1);
// check for escaped open bracket or whitespace
if (format[ptr] == '{' || Char.IsWhiteSpace(format[ptr]))
{
start = ptr++;
continue;
}
// parse specifier
int width, formatStart = ptr;
bool left_align;
string arg_format, arg_name;
ParseFormatSpecifier(format, ref ptr, out arg_name, out width, out left_align, out arg_format);
object arg = null;
if (!context.ContainsKey(arg_name))
{
if (handler == null)
{
throw new FormatException(String.Format("The named argument {{{0}}} must exist in the context.", arg_name));
}
else
{
arg = handler(arg_name, format, formatStart, ptr);
}
}
else
arg = context[arg_name];
string str;
if (arg == null)
str = "";
else if (arg is IFormattable)
str = ((IFormattable)arg).ToString(arg_format, provider);
else
str = arg.ToString();
// pad formatted string and append to result
if (width > (str == null ? 0 : str.Length))
{
string pad = new String(' ', width - str.Length);
if (left_align)
{
result.Append(str);
result.Append(pad);
}
else
{
result.Append(pad);
result.Append(str);
}
}
else
result.Append(str);
start = ptr;
}
else if (c == '}' && ptr < format.Length && format[ptr] == '}')
{
result.Append(format, start, ptr - start - 1);
start = ptr++;
}
else if (c == '}')
{
throw new FormatException("Input string was not in a correct format.");
}
}
if (start < format.Length)
result.Append(format.Substring(start));
}
/// <summary>
/// <seealso cref="T:System.String.Format"/>
/// </summary>
public static string Format(IFormatProvider provider, string format, IDictionary<string, object> context, MissingValueHandler handler)
{
if (format == null)
throw new ArgumentNullException("format");
// Nothing to see here. Move along.
if (format.IndexOf('{') < 0)
return format;
StringBuilder result = new StringBuilder(format.Length);
Format(provider, format, context, handler, result);
return result.ToString();
}
