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Add String.Format #12

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merged 4 commits into from
Jun 15, 2018
Merged

Add String.Format #12

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bcffecd
Add String.Format
ishvedov Jun 1, 2018
775bbad
Remove excess access to string.this[]
ishvedov Jun 1, 2018
884d269
Add alignment support
ishvedov Jun 4, 2018
f8bfad4
Improvments for PadLeft, PadRight
ishvedov Jun 13, 2018
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241 changes: 241 additions & 0 deletions source/System/String.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -532,5 +532,246 @@ public static String IsInterned(String str)
return str;
}

/// <summary>
/// Replaces the format items in a string with the string representations of corresponding objects in a specified array.
/// </summary>
/// <param name="format">A composite format string</param>
/// <param name="args">An object array that contains zero or more objects to format.</param>
/// <returns>A copy of format in which the format items have been replaced by the string representation of the corresponding objects in args.</returns>
public static string Format(string format, params object[] args)
{
var index = 0;
var alignment = 0;
var chr = '\0';
var len = format.Length;
var fmt = Empty;
var token = Empty;
var output = Empty;

if (format is null)
{
throw new ArgumentNullException("format can't be null");
}

for (var i = 0; i < len; i++)
{
token = Empty;
chr = format[i];

if (chr == '{')
{
if (i + 1 == len)
{
throw new ArgumentException("Format error: no closed brace, column " + i);
}

if (format[i + 1] == '{')
{
output += chr;
i++;
continue;
}
else
{
alignment = 0;
fmt = Empty;

for (i++; i < len; i++)
{
chr = format[i];

if (chr >= '0' && chr <= '9')
{
token += chr;
}
else if (chr == ',' || chr == ':' || chr == '}')
{
break;
}
else
{
throw new ArgumentException("Format error: wrong symbol at {}, column " + i);
}
}

if (token.Length > 0)
{
index = int.Parse(token);
}
else
{
throw new ArgumentException("Format error: empty {}, column " + i);
}

if (chr == ',')
{
if (format[i + 1] == '-')
{
token = "-";
i++;
}
else
{
token = Empty;
}

for (i++; i < len; i++)
{
chr = format[i];

if (chr >= '0' && chr <= '9')
{
token += chr;
}
else if (chr == ':' || chr == '}')
{
break;
}
else
{
throw new ArgumentException("Format error: wrong symbol at alignment, column " + i);
}
}

if (token.Length > 0)
{
alignment = int.Parse(token);
}
else
{
throw new ArgumentException("Format error: empty alignment, column " + i);
}
}

if (chr == ':')
{
token = Empty;
for (i++; i < len; i++)
{
chr = format[i];

if (chr == '}')
{
break;
}
else
{
token += chr;
}
}

if (token.Length > 0)
{
fmt = token;
}
else
{
throw new ArgumentException("Format error: empty format after ':', column " + i);
}
}
}

if (chr != '}')
{
throw new ArgumentException("Format error: no closed brace, column " + i);
}

if (fmt.Length > 0)
{
var method = args[index].GetType().GetMethod("ToString", new Type[] { typeof(string) });
token = (method is null)
? args[index].ToString()
: method.Invoke(args[index], new object[] { token }).ToString();
}
else
{
token = args[index].ToString();
}

if (alignment > 0)
{
output += token.PadLeft(alignment);
}
else if (alignment < 0)
{
output += token.PadRight(Math.Abs(alignment));
}
else
{
output += token;
}
}
else if (chr == '}')
{
if (i + 1 == len)
{
throw new ArgumentException("Format error: no closed brace, column " + i);
}

if (format[i + 1] == '}')
{
output += chr;
i++;
}
else
{
throw new ArgumentException("Format error: no closed brace, column " + i);
}
}
else
{
output += chr;
}
}

return output;
}

/// <summary>
/// Returns a new string that right-aligns the characters in this instance by padding them on the left with a specified Unicode character, for a specified total length.
/// </summary>
/// <param name="totalWidth">The number of characters in the resulting string, equal to the number of original characters plus any additional padding characters.</param>
/// <param name="paddingChar">A Unicode padding character.</param>
/// <returns></returns>
public String PadLeft(int totalWidth, char paddingChar = ' ')
{
if (totalWidth < 0)
{
throw new ArgumentOutOfRangeException("totalWidth can't be less than 0");
}

if (Length >= totalWidth)
{
return this;
}
else
{
return new String(paddingChar, totalWidth - Length) + this;
}
}

/// <summary>
/// Returns a new string that left-aligns the characters in this string by padding them on the right with a specified Unicode character, for a specified total length.
/// </summary>
/// <param name="totalWidth">The number of characters in the resulting string, equal to the number of original characters plus any additional padding characters.</param>
/// <param name="paddingChar">A Unicode padding character.</param>
/// <returns></returns>
public String PadRight(int totalWidth, char paddingChar = ' ')
{
if (totalWidth < 0)
{
throw new ArgumentOutOfRangeException("totalWidth can't be less than 0");
}

if (Length >= totalWidth)
{
return this;
}
else
{
return this + new String(paddingChar, totalWidth - Length);
}
}

}
}