static bool NextCharacterIsFullWidthAndWillWrap(int width, int currentLineLength, ReadOnlySpan <char> chunk, int i) => chunk.Length > i + 1 && UnicodeWidth.GetWidth(chunk[i + 1]) > 1 && currentLineLength + 1 == width;
/// <summary>
/// Wraps editable input, contained in the string builder, to the supplied width.
/// The caret index (as the input is a 1 dimensional string of text) is converted
/// to a 2 dimensional coordinate in the wrapped text.
/// </summary>
public static WordWrappedText WrapEditableCharacters(ReadOnlyStringBuilder input, int caret, int width)
{
Debug.Assert(caret >= 0 && caret <= input.Length);
if (input.Length == 0)
{
return(new WordWrappedText(
new[] { WrappedLine.Empty(startIndex: 0) },
new ConsoleCoordinate(0, caret)));
}
var lines = new List <WrappedLine>();
int currentLineLength = 0;
var line = new StringBuilder(width);
int textIndex = 0;
int cursorColumn = 0;
int cursorRow = 0;
foreach (ReadOnlyMemory <char> chunkMemory in input.GetChunks())
{
var chunk = chunkMemory.Span;
for (var i = 0; i < chunk.Length; i++)
{
char character = chunk[i];
line.Append(character);
bool isCursorPastCharacter = caret > textIndex;
Debug.Assert(character != '\t', "tabs should be replaced by spaces");
int unicodeWidth = UnicodeWidth.GetWidth(character);
if (unicodeWidth < 1)
{
Debug.Fail("such character should not be present");
continue;
}
currentLineLength += unicodeWidth;
textIndex++;
if (isCursorPastCharacter && !char.IsControl(character))
{
cursorColumn++;
}
if (character == '\n' || currentLineLength == width ||
NextCharacterIsFullWidthAndWillWrap(width, currentLineLength, chunk, i))
{
if (isCursorPastCharacter)
{
cursorRow++;
cursorColumn = 0;
}
lines.Add(new WrappedLine(textIndex - line.Length, line.ToString()));
line = new StringBuilder();
currentLineLength = 0;
}
}
}
if (currentLineLength > 0 || input[^ 1] == '\n')
{
lines.Add(new WrappedLine(textIndex - line.Length, line.ToString()));
}
Debug.Assert(textIndex == input.Length);
if (cursorRow >= lines.Count)
{
Debug.Assert(cursorRow == lines.Count);
lines.Add(WrappedLine.Empty(startIndex: textIndex));
}
return(new WordWrappedText(lines, new ConsoleCoordinate(cursorRow, cursorColumn)));