/// <summary>
/// Reads the next available token.
/// </summary>
/// <returns></returns>
public Token ReadToken()
{
if (End)
{
_compiler.SyntaxError(Token.None, true, GetString("err-compiler-eof"));
return(Token.None);
}
return(_tokens[Position++]);
}
public static IEnumerable <Token> Lex(RantCompiler compiler, string input)
{
if (Util.IsNullOrWhiteSpace(input))
{
yield break;
}
int line = 1; // Pretty self-explanatory
int i = 0; // The iterator index
int len = input.Length; // The length of the input string
int li = len - 1; // The last character index available in the input string, precalculated for your pleasure
char c; // Currently scanned character
bool lineStart = true; // Indicates if all characters so far on this line have been whitespace
int lastLineStart = 0; // Index of last line start. Use to calculate columns lazily.
var text = new StringBuilder(64); // Buffer for text token content
var whitespace = new StringBuilder(16); // Buffer for whitespace
bool cycleWroteText = false; // Determines if the last loop cycle wrote to the text buffer
int lastTextIndex = 0; // The last initial character index recorded for the text buffer
int lastTextLine = 1; // The last initial line number recorded for the text buffer
int lastTextLineStart = 0; // The last initial line start character index recorded for the text buffer
while (i < len)
{
// No text was written on this cycle yet, so set this to false
cycleWroteText = false;
// Set the current scanned character
c = input[i];
// If a newline is detected, update all line state variables
if (c == '\n')
{
line++;
lastLineStart = i + 1;
lineStart = true;
whitespace.Length = 0;
goto iterate;
}
// Skip carriage returns too
if (c == '\r')
{
goto iterate;
}
// If whitespace, capture it all before moving on
if (char.IsWhiteSpace(c))
{
if (!lineStart)
{
whitespace.Append(input[i]);
}
goto iterate;
}
// At this point, a non-whitespace character has been read.
// Emit whitespace if queued
if (whitespace.Length > 0)
{
// If it's a line breaking character, a comment, or at the start of a line, skip it.
if (!lineStart && c != '#')
{
yield return(new Token(R.Whitespace, line, lastLineStart, i, whitespace.ToString()));
}
whitespace.Length = 0;
}
lineStart = false;
switch (c)
{
// Comment
case '#':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
// Just eat the line and ignore it
while (i < len && input[i] != '\n')
{
i++;
}
continue;
// Escape sequence
case '\\':
{
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
if (i == li)
{
// This is the last character! Blasphemy!
compiler.SyntaxError(line, lastLineStart, i, 1, false, "err-compiler-incomplete-escape");
yield break;
}
// At this point we know there's at least one character. Great!
int escStart = i++; // Skip the slash
// Verbose character
if (input[i] == '@')
{
int nameStart = ++i;
while (i < len)
{
if (input[i] == '@')
{
var name = input.Substring(nameStart, i - nameStart).Trim();
var unicode = Unicode.GetByName(name);
if (string.IsNullOrEmpty(unicode))
{
compiler.SyntaxError(line, lastLineStart, nameStart, i - nameStart, false, "err-compiler-invalid-vchar", name);
goto iterate;
}
yield return(new Token(R.Text, line, lastLineStart, nameStart, unicode));
goto iterate;
}
i++;
}
compiler.SyntaxError(line, lastLineStart, i - 1, 1, false, "err-compiler-incomplete-vchar");
break;
}
// No escaping whitespace.
if (char.IsWhiteSpace(input[i]))
{
compiler.SyntaxError(line, lastLineStart, i, 1, false, "err-compiler-incomplete-escape");
break;
}
// There's a quantifier here.
if (char.IsDigit(input[i]))
{
int qStart = i++; // Skip past the digit
while (i < len && char.IsDigit(input[i]))
{
i++;
}
if (i >= li)
{
compiler.SyntaxError(line, lastLineStart, escStart, i - escStart, false, "err-compiler-incomplete-escape");
break;
}
// We need a comma after a quantifier
if (input[i] != ',')
{
compiler.SyntaxError(line, lastLineStart, i, 1, false, "err-compiler-missing-quantity-comma");
break;
}
yield return(new Token(R.EscapeSequenceQuantifier, line, lastLineStart, qStart, input.Substring(qStart, i - qStart)));
i++; // Skip past the comma
}
// At this point we need to make sure that there are more characters
if (i >= len)
{
compiler.SyntaxError(line, lastLineStart, escStart, i - escStart, false, "err-compiler-incomplete-escape");
break;
}
switch (input[i])
{
case 'u': // Unicode code point
// This will require 4 characters
if (len - ++i < 4)
{
compiler.SyntaxError(line, lastLineStart, escStart, len - escStart, false, "err-compiler-incomplete-escape");
yield break;
}
yield return(new Token(R.EscapeSequenceUnicode, line, lastLineStart, escStart, input.Substring(i, 4)));
i += 4;
goto loop;
case 'U': // Unicode surrogate pair
// This will require 8 characters
if (len - ++i < 8)
{
compiler.SyntaxError(line, lastLineStart, escStart, len - escStart, false, "err-compiler-incomplete-escape");
yield break;
}
yield return(new Token(R.EscapeSequenceSurrogatePair, line, lastLineStart, escStart, input.Substring(i, 8)));
i += 8;
goto loop;
default:
// Spit out the escape char token
yield return(new Token(R.EscapeSequenceChar, line, lastLineStart, i, input[i]));
goto iterate;
}
}
// Verbatim string
case '\"':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
// Make sure we have at least a pair of quotes
if (len - i >= 2)
{
int vstrStart = ++i; // Skip past starting quote
var buffer = new StringBuilder();
while (i < len)
{
// Found a matching quote?
if (input[i] == '\"')
{
// Oh, it's just an escaped quote. (two in a row)
if (i < li && input[i + 1] == '\"')
{
buffer.Append('\"');
i += 2; // Skip past current and second quote
continue;
}
// Neato, looks like it's the end of the string literal.
// We don't need a new token for this, so just add it to the text buffer.
if (text.Length == 0)
{
lastTextLine = line;
lastTextIndex = i;
lastTextLineStart = lastLineStart;
}
text.Append(buffer);
cycleWroteText = true;
i++;
goto loop;
}
buffer.Append(input[i]);
i++;
}
compiler.SyntaxError(line, lastLineStart, vstrStart - 1, i - vstrStart, false, "err-compiler-incomplete-verbatim");
}
else
{
compiler.SyntaxError(line, lastLineStart, i, 1, false, "err-compiler-incomplete-verbatim");
}
break;
// Regular expression
case '`':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
// Make sure we have at least a pair of apostrophes
if (li - i >= 2)
{
int regStart = ++i; // Skip past starting apostrophe
var buffer = new StringBuilder();
while (i < len)
{
// Found an escape sequence in the regex?
if (input[i] == '\\')
{
buffer.Append('\\');
// Make sure there's room for an escape code and the end of the literal
if (li - i >= 2)
{
if (input[i + 1] == '`')
{
buffer.Append('`');
i += 2; // Skip past current and second quote
continue;
}
i++;
continue;
}
// If we don't have enough room for an escape char and an ending apostrophe, error.
compiler.SyntaxError(line, lastLineStart, regStart - 1, i - regStart + 1, false, "err-compiler-incomplete-regex");
break;
}
// Found another apostrophe that isn't escaped?
if (input[i] == '`')
{
yield return(new Token(R.Regex, line, lastLineStart, regStart - 1, buffer.ToString()));
// Read flags
if (++i < len && char.IsLetter(input[i]))
{
int flagsStart = i++;
while (i < len && char.IsLetter(input[i]))
{
i++;
}
yield return(new Token(R.RegexFlags, line, lastLineStart, flagsStart, input.Substring(flagsStart, i - flagsStart)));
}
goto loop;
}
// Add character to buffer
buffer.Append(input[i]);
i++;
}
// Reached EOF
compiler.SyntaxError(line, lastLineStart, regStart, i - regStart, false, "err-compiler-incomplete-regex");
}
else
{
// Impossible to create regex here because there are too few characters remaining
compiler.SyntaxError(line, lastLineStart, i, len - i, false, "err-compiler-incomplete-regex");
}
break;
case '[':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.LeftSquare, line, lastLineStart, i, c));
break;
case ']':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.RightSquare, line, lastLineStart, i, c));
break;
case '{':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.LeftCurly, line, lastLineStart, i, c));
break;
case '}':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.RightCurly, line, lastLineStart, i, c));
break;
case '(':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.LeftParen, line, lastLineStart, i, c));
break;
case ')':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.RightParen, line, lastLineStart, i, c));
break;
case '<':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.LeftAngle, line, lastLineStart, i, c));
break;
case '>':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.RightAngle, line, lastLineStart, i, c));
break;
case '|':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Pipe, line, lastLineStart, i, c));
break;
case '?':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
if (li - i > 0 && input[i + 1] == '!')
{
yield return(new Token(R.Without, line, lastLineStart, i, "?!"));
i++;
break;
}
yield return(new Token(R.Question, line, lastLineStart, i, c));
break;
case '!':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Exclamation, line, lastLineStart, i, c));
break;
case '@':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.At, line, lastLineStart, i, c));
break;
case '-':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Hyphen, line, lastLineStart, i, c));
break;
case '$':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Dollar, line, lastLineStart, i, c));
break;
case '=':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Equal, line, lastLineStart, i, c));
break;
case '&':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Ampersand, line, lastLineStart, i, c));
break;
case '+':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Plus, line, lastLineStart, i, c));
break;
case '.':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Period, line, lastLineStart, i, c));
break;
case ':':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
// Check for double-colon
if (li - i > 0 && input[i + 1] == ':')
{
yield return(new Token(R.DoubleColon, line, lastLineStart, i, "::"));
i += 2;
goto loop;
}
yield return(new Token(R.Colon, line, lastLineStart, i, c));
break;
case ';':
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
yield return(new Token(R.Semicolon, line, lastLineStart, i, c));
break;
default:
if (text.Length == 0)
{
lastTextLine = line;
lastTextIndex = i;
lastTextLineStart = lastLineStart;
}
text.Append(c);
cycleWroteText = true;
break;
}
// Iterates the index
iterate:
i++;
loop: // Skips iteration of the index
// Emit text token if appropriate
if (!cycleWroteText && text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
text.Length = 0;
}
}
// Spit out any last text that remains
if (text.Length > 0)
{
yield return(new Token(R.Text, lastTextLine, lastTextLineStart, lastTextIndex, text.ToString()));
}
}