private static bool TryParseTerminalInputSequence(char[] buffer, TerminalFormatStrings terminalFormatStrings, out ConsoleKeyInfo parsed, ref int startIndex, int endIndex)
{
ReadOnlySpan <char> input = buffer.AsSpan(startIndex, endIndex - startIndex);
parsed = default;
// sequences start with either "^[[" or "^[O". "^[" stands for Escape (27).
if (input.Length < MinimalSequenceLength || input[0] != Escape || (input[1] != '[' && input[1] != 'O'))
{
return(false);
}
Dictionary <ReadOnlyMemory <char>, ConsoleKeyInfo> terminfoDb = terminalFormatStrings.KeyFormatToConsoleKey; // the most important source of truth
ConsoleModifiers modifiers = 0;
ConsoleKey key;
// Is it a three character sequence? (examples: '^[[H' (Home), '^[OP' (F1))
if (input[1] == 'O' || char.IsAsciiLetter(input[2]) || input.Length == MinimalSequenceLength)
{
if (!terminfoDb.TryGetValue(buffer.AsMemory(startIndex, MinimalSequenceLength), out parsed))
{
// All terminals which use "^[O{letter}" escape sequences don't define conflicting mappings.
// Example: ^[OH either means Home or simply is not used by given terminal.
// But with "^[[{character}" sequences, there are conflicts between rxvt and SCO.
// Example: "^[[a" is Shift+UpArrow for rxvt and Shift+F3 for SCO.
(key, modifiers) = input[1] == 'O' || terminalFormatStrings.IsRxvtTerm
? MapKeyIdOXterm(input[2], terminalFormatStrings.IsRxvtTerm)
: MapSCO(input[2]);
if (key == default)
{
return(false); // it was not a known sequence
}
char keyChar = key switch
{
ConsoleKey.Enter => '\r', // "^[OM" should produce new line character (was not previously mapped this way)
ConsoleKey.Add => '+',
ConsoleKey.Subtract => '-',
ConsoleKey.Divide => '/',
ConsoleKey.Multiply => '*',
_ => default
};
parsed = Create(keyChar, key, modifiers);
}
startIndex += MinimalSequenceLength;
return(true);
}
// Is it a four character sequence used by Linux Console or PuTTy configured to emulate it? (examples: '^[[[A' (F1), '^[[[B' (F2))
if (input[1] == '[' && input[2] == '[' && char.IsBetween(input[3], 'A', 'E'))
{
if (!terminfoDb.TryGetValue(buffer.AsMemory(startIndex, 4), out parsed))
{
parsed = new ConsoleKeyInfo(default, ConsoleKey.F1 + input[3] - 'A', false, false, false);
internal static ConsoleKeyInfo Parse(char[] buffer, TerminalFormatStrings terminalFormatStrings, byte posixDisableValue, byte veraseCharacter, ref int startIndex, int endIndex)
{
MapBufferToConsoleKey(buffer, terminalFormatStrings, posixDisableValue, veraseCharacter, out ConsoleKey key,
out char ch, out bool isShift, out bool isAlt, out bool isCtrl, ref startIndex, endIndex);
// Replace the '\n' char for Enter by '\r' to match Windows behavior.
if (key == ConsoleKey.Enter && ch == '\n')
{
ch = '\r';
}
return(new ConsoleKeyInfo(ch, key, isShift, isAlt, isCtrl));
}
private static bool MapBufferToConsoleKey(char[] buffer, TerminalFormatStrings terminalFormatStrings, byte posixDisableValue, byte veraseCharacter,
out ConsoleKey key, out char ch, out bool isShift, out bool isAlt, out bool isCtrl, ref int startIndex, int endIndex)
{
// Try to get the special key match from the TermInfo static information.
if (TryGetSpecialConsoleKey(buffer, startIndex, endIndex, terminalFormatStrings, posixDisableValue, veraseCharacter, out ConsoleKeyInfo keyInfo, out int keyLength))
{
key = keyInfo.Key;
isShift = (keyInfo.Modifiers & ConsoleModifiers.Shift) != 0;
isAlt = (keyInfo.Modifiers & ConsoleModifiers.Alt) != 0;
isCtrl = (keyInfo.Modifiers & ConsoleModifiers.Control) != 0;
ch = ((keyLength == 1) ? buffer[startIndex] : '\0'); // ignore keyInfo.KeyChar
startIndex += keyLength;
return(true);
}
// Check if we can match Esc + combination and guess if alt was pressed.
if (buffer[startIndex] == (char)0x1B && // Alt is send as an escape character
endIndex - startIndex >= 2) // We have at least two characters to read
{
startIndex++;
if (MapBufferToConsoleKey(buffer, terminalFormatStrings, posixDisableValue, veraseCharacter, out key, out ch, out isShift, out _, out isCtrl, ref startIndex, endIndex))
{
isAlt = true;
return(true);
}
else
{
// We could not find a matching key here so, Alt+ combination assumption is in-correct.
// The current key needs to be marked as Esc key.
// Also, we do not increment _startIndex as we already did it.
key = ConsoleKey.Escape;
ch = (char)0x1B;
isAlt = false;
return(true);
}
}
// Try reading the first char in the buffer and interpret it as a key.
ch = buffer[startIndex++];
key = GetKeyFromCharValue(ch, out isShift, out isCtrl);
isAlt = false;
return(key != default(ConsoleKey));
}
private static bool TryGetSpecialConsoleKey(char[] givenChars, int startIndex, int endIndex,
TerminalFormatStrings terminalFormatStrings, byte posixDisableValue, byte veraseCharacter, out ConsoleKeyInfo key, out int keyLength)
{
int unprocessedCharCount = endIndex - startIndex;
// First process special control character codes. These override anything from terminfo.
if (unprocessedCharCount > 0)
{
// Is this an erase / backspace?
char c = givenChars[startIndex];
if (c != posixDisableValue && c == veraseCharacter)
{
key = new ConsoleKeyInfo(c, ConsoleKey.Backspace, shift: false, alt: false, control: false);
keyLength = 1;
return(true);
}
}
// Then process terminfo mappings.
int minRange = terminalFormatStrings.MinKeyFormatLength;
if (unprocessedCharCount >= minRange)
{
int maxRange = Math.Min(unprocessedCharCount, terminalFormatStrings.MaxKeyFormatLength);
for (int i = maxRange; i >= minRange; i--)
{
var currentString = new ReadOnlyMemory <char>(givenChars, startIndex, i);
// Check if the string prefix matches.
if (terminalFormatStrings.KeyFormatToConsoleKey.TryGetValue(currentString, out key))
{
keyLength = currentString.Length;
return(true);
}
}
}
// Otherwise, not a known special console key.
key = default(ConsoleKeyInfo);
keyLength = 0;
return(false);
}
private const int SequencePrefixLength = 2; // ^[[ ("^[" stands for Escape)
internal static ConsoleKeyInfo Parse(char[] buffer, TerminalFormatStrings terminalFormatStrings, byte posixDisableValue, byte veraseCharacter, ref int startIndex, int endIndex)
{
int length = endIndex - startIndex;
Debug.Assert(length > 0);
// VERASE overrides anything from Terminfo. Both settings can be different for Linux and macOS.
if (buffer[startIndex] != posixDisableValue && buffer[startIndex] == veraseCharacter)
{
// the original char is preserved on purpose (backward compat + consistency)
return(new ConsoleKeyInfo(buffer[startIndex++], ConsoleKey.Backspace, false, false, false));
}
// Escape Sequences start with Escape. But some terminals like PuTTY and rxvt prepend Escape to express that for given sequence Alt was pressed.
if (length >= MinimalSequenceLength + 1 && buffer[startIndex] == Escape && buffer[startIndex + 1] == Escape)
{
startIndex++;
if (TryParseTerminalInputSequence(buffer, terminalFormatStrings, out ConsoleKeyInfo parsed, ref startIndex, endIndex))
{
return(new ConsoleKeyInfo(parsed.KeyChar, parsed.Key, (parsed.Modifiers & ConsoleModifiers.Shift) != 0, alt: true, (parsed.Modifiers & ConsoleModifiers.Control) != 0));
}
startIndex--;
}
else if (length >= MinimalSequenceLength && TryParseTerminalInputSequence(buffer, terminalFormatStrings, out ConsoleKeyInfo parsed, ref startIndex, endIndex))
{
return(parsed);
}
if (length == 2 && buffer[startIndex] == Escape && buffer[startIndex + 1] != Escape)
{
startIndex++; // skip the Escape
return(ParseFromSingleChar(buffer[startIndex++], isAlt: true));
}
return(ParseFromSingleChar(buffer[startIndex++], isAlt: false));
}