/// <summary>
/// Creates a <see cref="TextLine"/> instance.
/// </summary>
/// <param name="text">The source text.</param>
/// <param name="span">The span of the line.</param>
/// <returns>An instance of <see cref="TextLine"/>.</returns>
/// <exception cref="ArgumentOutOfRangeException">The span does not represent a text line.</exception>
public static TextLine FromSpan(SourceText text, TextSpan span)
{
if (text == null)
{
throw new ArgumentNullException(nameof(text));
}
if (span.Start > text.Length || span.Start < 0 || span.End > text.Length)
{
throw new ArgumentOutOfRangeException(nameof(span));
}
if (text.Length > 0)
{
// check span is start of line
if (span.Start > 0 && !TextUtilities.IsAnyLineBreakCharacter(text[span.Start - 1]))
{
throw new ArgumentOutOfRangeException(nameof(span), CodeAnalysisResources.SpanDoesNotIncludeStartOfLine);
}
bool endIncludesLineBreak = false;
if (span.End > span.Start)
{
endIncludesLineBreak = TextUtilities.IsAnyLineBreakCharacter(text[span.End - 1]);
}
if (!endIncludesLineBreak && span.End < text.Length)
{
var lineBreakLen = TextUtilities.GetLengthOfLineBreak(text, span.End);
if (lineBreakLen > 0)
{
// adjust span to include line breaks
endIncludesLineBreak = true;
span = new TextSpan(span.Start, span.Length + lineBreakLen);
}
}
// check end of span is at end of line
if (span.End < text.Length && !endIncludesLineBreak)
{
throw new ArgumentOutOfRangeException(nameof(span), CodeAnalysisResources.SpanDoesNotIncludeEndOfLine);
}
return(new TextLine(text, span.Start, span.End));
}
else
{
return(new TextLine(text, 0, 0));
}
}
private int[] ParseLineStarts()
{
// Corner case check
if (0 == this.Length)
{
return(new[] { 0 });
}
var lineStarts = ArrayBuilder <int> .GetInstance();
lineStarts.Add(0); // there is always the first line
var lastWasCR = false;
// The following loop goes through every character in the text. It is highly
// performance critical, and thus inlines knowledge about common line breaks
// and non-line breaks.
EnumerateChars((int position, char[] buffer, int length) =>
{
var index = 0;
if (lastWasCR)
{
if (length > 0 && buffer[0] == '\n')
{
index++;
}
lineStarts.Add(position + index);
lastWasCR = false;
}
while (index < length)
{
char c = buffer[index];
index++;
// Common case - ASCII & not a line break
// if (c > '\r' && c <= 127)
// if (c >= ('\r'+1) && c <= 127)
const uint bias = '\r' + 1;
if (unchecked (c - bias) <= (127 - bias))
{
continue;
}
// Assumes that the only 2-char line break sequence is CR+LF
if (c == '\r')
{
if (index < length && buffer[index] == '\n')
{
index++;
}
else if (index >= length)
{
lastWasCR = true;
continue;
}
}
else if (!TextUtilities.IsAnyLineBreakCharacter(c))
{
continue;
}
// next line starts at index
lineStarts.Add(position + index);
}
});
return(lineStarts.ToArrayAndFree());
}