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Copy pathPythonTokenizer.cs
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1040 lines (902 loc) · 32.2 KB
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using System.Globalization;
using System.Text;
using DotPython.Language.Diagnostics;
using DotPython.Language.Text;
namespace DotPython.Language.Syntax;
public static class PythonTokenizer
{
public static TokenizationResult Tokenize(SourceText source)
{
ArgumentNullException.ThrowIfNull(source);
return new Lexer(source).Tokenize();
}
private sealed class Lexer
{
private const int TabWidth = 8;
private readonly List<Diagnostic> _diagnostics = [];
private readonly Stack<Delimiter> _delimiters = [];
private readonly List<IndentationLevel> _indentation = [new(0, 0)];
private readonly SourceText _source;
private readonly string _text;
private readonly List<SyntaxToken> _tokens = [];
private bool _atBeginningOfLine = true;
private bool _logicalLineHasCode;
private int _position;
internal Lexer(SourceText source)
{
_source = source;
_text = source.Content;
}
internal TokenizationResult Tokenize()
{
while (_position < _text.Length)
{
if (_atBeginningOfLine)
{
if (_delimiters.Count == 0)
{
if (ReadBeginningOfLine())
{
continue;
}
}
else
{
_atBeginningOfLine = false;
}
}
if (IsHorizontalWhitespace(Current))
{
_position++;
continue;
}
if (Current == '#')
{
ReadComment();
continue;
}
if (IsNewLine(Current))
{
ReadNewLine(_delimiters.Count == 0);
continue;
}
if (Current == '\\' && IsNewLine(Peek(1)))
{
ReadExplicitLineJoining();
continue;
}
if (TryReadString())
{
_logicalLineHasCode = true;
continue;
}
if (char.IsAsciiDigit(Current) || Current == '.' && char.IsAsciiDigit(Peek(1)))
{
ReadNumber();
_logicalLineHasCode = true;
continue;
}
if (IsIdentifierStartAt(_position))
{
ReadIdentifier();
_logicalLineHasCode = true;
continue;
}
if (TryReadOperator())
{
_logicalLineHasCode = true;
continue;
}
ReadBadToken();
_logicalLineHasCode = true;
}
FinishTokenization();
return new TokenizationResult(_source, _tokens, _diagnostics);
}
private char Current => Peek(0);
private bool ReadBeginningOfLine()
{
var whitespaceStart = _position;
var column = 0;
var alternateColumn = 0;
while (_position < _text.Length && IsHorizontalWhitespace(Current))
{
switch (Current)
{
case ' ':
column++;
alternateColumn++;
break;
case '\t':
column = (column / TabWidth + 1) * TabWidth;
alternateColumn++;
break;
case '\f':
column = 0;
alternateColumn = 0;
break;
}
_position++;
}
if (Current == '#')
{
ReadComment();
}
if (IsNewLine(Current))
{
ReadNewLine(significant: false);
return true;
}
if (_position >= _text.Length)
{
return true;
}
ApplyIndentation(whitespaceStart, column, alternateColumn);
_atBeginningOfLine = false;
return false;
}
private void ApplyIndentation(int whitespaceStart, int column, int alternateColumn)
{
var current = _indentation[^1];
var span = TextSpan.FromBounds(whitespaceStart, _position);
if (column == current.Column)
{
if (alternateColumn != current.AlternateColumn)
{
ReportInconsistentTabsAndSpaces(span);
}
return;
}
if (column > current.Column)
{
if (alternateColumn <= current.AlternateColumn)
{
ReportInconsistentTabsAndSpaces(span);
}
_indentation.Add(new IndentationLevel(column, alternateColumn));
AddToken(SyntaxTokenKind.Indent, whitespaceStart, _position);
return;
}
while (_indentation.Count > 1 && column < _indentation[^1].Column)
{
_indentation.RemoveAt(_indentation.Count - 1);
AddToken(SyntaxTokenKind.Dedent, _position, _position);
}
current = _indentation[^1];
if (column != current.Column)
{
Report("DPY1002", "Unindent does not match any outer indentation level.", span);
}
else if (alternateColumn != current.AlternateColumn)
{
ReportInconsistentTabsAndSpaces(span);
}
}
private void ReadComment()
{
while (_position < _text.Length && !IsNewLine(Current))
{
_position++;
}
}
private void ReadNewLine(bool significant)
{
var start = _position;
AdvanceNewLine();
AddToken(
significant ? SyntaxTokenKind.NewLine : SyntaxTokenKind.NonSignificantNewLine,
start,
_position
);
_atBeginningOfLine = true;
if (significant)
{
_logicalLineHasCode = false;
}
}
private void ReadExplicitLineJoining()
{
_position++;
AdvanceNewLine();
_atBeginningOfLine = false;
}
private bool TryReadString()
{
var start = _position;
var prefixLength = GetStringPrefixLength(start);
var quotePosition = start + prefixLength;
if (quotePosition >= _text.Length || !IsQuote(_text[quotePosition]))
{
return false;
}
var prefix = _text.AsSpan(start, prefixLength);
var kind = GetStringKind(prefix);
_position = quotePosition;
if (
kind
is SyntaxTokenKind.FormattedStringLiteral
or SyntaxTokenKind.TemplateStringLiteral
)
{
ReadInterpolatedString(start);
}
else
{
ReadOrdinaryString(start);
}
AddToken(kind, start, _position);
return true;
}
private void ReadOrdinaryString(int tokenStart)
{
var quote = Current;
var quoteLength = HasRepeatedQuote(_position, quote) ? 3 : 1;
_position += quoteLength;
while (_position < _text.Length)
{
if (MatchesQuote(_position, quote, quoteLength))
{
_position += quoteLength;
return;
}
if (IsNewLine(Current) && quoteLength == 1)
{
ReportUnterminatedString(tokenStart);
return;
}
if (Current == '\\')
{
_position++;
if (_position < _text.Length)
{
if (IsNewLine(Current))
{
AdvanceNewLine();
}
else
{
AdvanceCodePoint();
}
}
continue;
}
AdvanceCodePoint();
}
ReportUnterminatedString(tokenStart);
}
private void ReadInterpolatedString(int tokenStart)
{
var quote = Current;
var quoteLength = HasRepeatedQuote(_position, quote) ? 3 : 1;
var replacementDepth = 0;
_position += quoteLength;
while (_position < _text.Length)
{
if (replacementDepth == 0 && MatchesQuote(_position, quote, quoteLength))
{
_position += quoteLength;
return;
}
if (replacementDepth == 0)
{
if (Current == '{')
{
if (Peek(1) == '{')
{
_position += 2;
}
else
{
replacementDepth = 1;
_position++;
}
continue;
}
if (Current == '}' && Peek(1) == '}')
{
_position += 2;
continue;
}
if (IsNewLine(Current) && quoteLength == 1)
{
ReportUnterminatedString(tokenStart);
return;
}
AdvanceStringCharacter();
continue;
}
if (Current == '#')
{
ReadComment();
continue;
}
if (TrySkipNestedString())
{
continue;
}
if (Current == '{')
{
replacementDepth++;
_position++;
continue;
}
if (Current == '}')
{
replacementDepth--;
_position++;
continue;
}
AdvanceCodePoint();
}
ReportUnterminatedString(tokenStart);
}
private bool TrySkipNestedString()
{
var start = _position;
var prefixLength = GetStringPrefixLength(start);
var quotePosition = start + prefixLength;
if (quotePosition >= _text.Length || !IsQuote(_text[quotePosition]))
{
return false;
}
_position = quotePosition;
var nestedKind = GetStringKind(_text.AsSpan(start, prefixLength));
if (
nestedKind
is SyntaxTokenKind.FormattedStringLiteral
or SyntaxTokenKind.TemplateStringLiteral
)
{
ReadInterpolatedString(start);
}
else
{
ReadOrdinaryString(start);
}
return true;
}
private void AdvanceStringCharacter()
{
if (Current != '\\')
{
AdvanceCodePoint();
return;
}
_position++;
if (_position >= _text.Length)
{
return;
}
if (IsNewLine(Current))
{
AdvanceNewLine();
}
else
{
AdvanceCodePoint();
}
}
private void ReadNumber()
{
var start = _position;
var kind = SyntaxTokenKind.IntegerLiteral;
var valid = true;
if (Current == '.')
{
kind = SyntaxTokenKind.FloatLiteral;
_position++;
valid &= ReadDigitPart(IsDecimalDigit, allowLeadingUnderscore: false);
}
else if (Current == '0' && IsBasePrefix(Peek(1)))
{
var prefix = char.ToLowerInvariant(Peek(1));
_position += 2;
Func<char, bool> digitPredicate = prefix switch
{
'b' => IsBinaryDigit,
'o' => IsOctalDigit,
_ => IsHexadecimalDigit,
};
valid &= ReadDigitPart(digitPredicate, allowLeadingUnderscore: true);
while (char.IsAsciiLetterOrDigit(Current) || Current == '_')
{
valid = false;
_position++;
}
}
else
{
valid &= ReadDigitPart(IsDecimalDigit, allowLeadingUnderscore: false);
if (Current == '.')
{
kind = SyntaxTokenKind.FloatLiteral;
_position++;
if (IsDecimalDigitPartCharacter(Current))
{
valid &= ReadDigitPart(IsDecimalDigit, allowLeadingUnderscore: false);
}
}
if (Current is 'e' or 'E')
{
kind = SyntaxTokenKind.FloatLiteral;
_position++;
if (Current is '+' or '-')
{
_position++;
}
valid &= ReadDigitPart(IsDecimalDigit, allowLeadingUnderscore: false);
}
if (Current is 'j' or 'J')
{
kind = SyntaxTokenKind.ImaginaryLiteral;
_position++;
}
}
AddToken(kind, start, _position);
if (!valid)
{
Report(
"DPY1006",
"Invalid numeric literal.",
TextSpan.FromBounds(start, _position)
);
}
}
private bool ReadDigitPart(Func<char, bool> isDigit, bool allowLeadingUnderscore)
{
var sawDigit = false;
var previousWasUnderscore = false;
var isValid = true;
if (allowLeadingUnderscore && Current == '_')
{
previousWasUnderscore = true;
_position++;
}
while (isDigit(Current) || Current == '_')
{
if (Current == '_')
{
if (!sawDigit || previousWasUnderscore)
{
isValid = false;
previousWasUnderscore = true;
_position++;
continue;
}
previousWasUnderscore = true;
}
else
{
sawDigit = true;
previousWasUnderscore = false;
}
_position++;
}
return isValid && sawDigit && !previousWasUnderscore;
}
private void ReadIdentifier()
{
var start = _position;
AdvanceCodePoint();
while (IsIdentifierContinueAt(_position))
{
AdvanceCodePoint();
}
AddToken(SyntaxTokenKind.Identifier, start, _position);
}
private bool TryReadOperator()
{
var start = _position;
SyntaxTokenKind kind;
var length = 1;
switch (Current)
{
case '(':
kind = SyntaxTokenKind.LeftParenthesis;
break;
case ')':
kind = SyntaxTokenKind.RightParenthesis;
break;
case '[':
kind = SyntaxTokenKind.LeftBracket;
break;
case ']':
kind = SyntaxTokenKind.RightBracket;
break;
case '{':
kind = SyntaxTokenKind.LeftBrace;
break;
case '}':
kind = SyntaxTokenKind.RightBrace;
break;
case ':':
kind = Peek(1) == '=' ? SyntaxTokenKind.ColonEqual : SyntaxTokenKind.Colon;
length = kind == SyntaxTokenKind.ColonEqual ? 2 : 1;
break;
case ',':
kind = SyntaxTokenKind.Comma;
break;
case ';':
kind = SyntaxTokenKind.Semicolon;
break;
case '.':
kind =
Peek(1) == '.' && Peek(2) == '.'
? SyntaxTokenKind.Ellipsis
: SyntaxTokenKind.Dot;
length = kind == SyntaxTokenKind.Ellipsis ? 3 : 1;
break;
case '@':
kind = Peek(1) == '=' ? SyntaxTokenKind.AtEqual : SyntaxTokenKind.At;
length = kind == SyntaxTokenKind.AtEqual ? 2 : 1;
break;
case '+':
kind = Peek(1) == '=' ? SyntaxTokenKind.PlusEqual : SyntaxTokenKind.Plus;
length = kind == SyntaxTokenKind.PlusEqual ? 2 : 1;
break;
case '-':
kind = Peek(1) switch
{
'=' => SyntaxTokenKind.MinusEqual,
'>' => SyntaxTokenKind.Arrow,
_ => SyntaxTokenKind.Minus,
};
length = kind == SyntaxTokenKind.Minus ? 1 : 2;
break;
case '*':
(kind, length) = ReadRepeatedOperator(
SyntaxTokenKind.Star,
SyntaxTokenKind.StarEqual,
SyntaxTokenKind.DoubleStar,
SyntaxTokenKind.DoubleStarEqual
);
break;
case '/':
(kind, length) = ReadRepeatedOperator(
SyntaxTokenKind.Slash,
SyntaxTokenKind.SlashEqual,
SyntaxTokenKind.DoubleSlash,
SyntaxTokenKind.DoubleSlashEqual
);
break;
case '|':
kind =
Peek(1) == '='
? SyntaxTokenKind.VerticalBarEqual
: SyntaxTokenKind.VerticalBar;
length = kind == SyntaxTokenKind.VerticalBarEqual ? 2 : 1;
break;
case '&':
kind =
Peek(1) == '=' ? SyntaxTokenKind.AmpersandEqual : SyntaxTokenKind.Ampersand;
length = kind == SyntaxTokenKind.AmpersandEqual ? 2 : 1;
break;
case '<':
(kind, length) = ReadComparisonOperator(
SyntaxTokenKind.LessThan,
SyntaxTokenKind.LessThanOrEqual,
SyntaxTokenKind.LeftShift,
SyntaxTokenKind.LeftShiftEqual
);
break;
case '>':
(kind, length) = ReadComparisonOperator(
SyntaxTokenKind.GreaterThan,
SyntaxTokenKind.GreaterThanOrEqual,
SyntaxTokenKind.RightShift,
SyntaxTokenKind.RightShiftEqual
);
break;
case '=':
kind = Peek(1) == '=' ? SyntaxTokenKind.EqualEqual : SyntaxTokenKind.Equal;
length = kind == SyntaxTokenKind.EqualEqual ? 2 : 1;
break;
case '%':
kind = Peek(1) == '=' ? SyntaxTokenKind.PercentEqual : SyntaxTokenKind.Percent;
length = kind == SyntaxTokenKind.PercentEqual ? 2 : 1;
break;
case '~':
kind = SyntaxTokenKind.Tilde;
break;
case '^':
kind = Peek(1) == '=' ? SyntaxTokenKind.CaretEqual : SyntaxTokenKind.Caret;
length = kind == SyntaxTokenKind.CaretEqual ? 2 : 1;
break;
case '!':
kind = Peek(1) == '=' ? SyntaxTokenKind.NotEqual : SyntaxTokenKind.Exclamation;
length = kind == SyntaxTokenKind.NotEqual ? 2 : 1;
break;
default:
return false;
}
_position += length;
AddToken(kind, start, _position);
UpdateDelimiterStack(kind, start);
return true;
}
private (SyntaxTokenKind Kind, int Length) ReadRepeatedOperator(
SyntaxTokenKind single,
SyntaxTokenKind singleEqual,
SyntaxTokenKind repeated,
SyntaxTokenKind repeatedEqual
)
{
if (Peek(1) == Current)
{
return Peek(2) == '=' ? (repeatedEqual, 3) : (repeated, 2);
}
return Peek(1) == '=' ? (singleEqual, 2) : (single, 1);
}
private (SyntaxTokenKind Kind, int Length) ReadComparisonOperator(
SyntaxTokenKind single,
SyntaxTokenKind singleEqual,
SyntaxTokenKind shift,
SyntaxTokenKind shiftEqual
)
{
if (Peek(1) == Current)
{
return Peek(2) == '=' ? (shiftEqual, 3) : (shift, 2);
}
return Peek(1) == '=' ? (singleEqual, 2) : (single, 1);
}
private void UpdateDelimiterStack(SyntaxTokenKind kind, int start)
{
if (
kind
is SyntaxTokenKind.LeftParenthesis
or SyntaxTokenKind.LeftBracket
or SyntaxTokenKind.LeftBrace
)
{
_delimiters.Push(new Delimiter(kind, start));
return;
}
if (
kind
is not (
SyntaxTokenKind.RightParenthesis
or SyntaxTokenKind.RightBracket
or SyntaxTokenKind.RightBrace
)
)
{
return;
}
if (_delimiters.Count == 0)
{
Report(
"DPY1004",
"Closing delimiter has no matching opening delimiter.",
new TextSpan(start, 1)
);
return;
}
var opening = _delimiters.Pop();
if (!DelimitersMatch(opening.Kind, kind))
{
Report(
"DPY1004",
"Closing delimiter does not match the opening delimiter.",
new TextSpan(start, 1)
);
}
}
private void ReadBadToken()
{
var start = _position;
AdvanceCodePoint();
AddToken(SyntaxTokenKind.BadToken, start, _position);
Report(
"DPY1001",
$"Unexpected character {FormatCharacter(_text.AsSpan(start, _position - start))}.",
TextSpan.FromBounds(start, _position)
);
}
private void FinishTokenization()
{
if (_logicalLineHasCode)
{
AddToken(SyntaxTokenKind.NewLine, _position, _position);
}
while (_indentation.Count > 1)
{
_indentation.RemoveAt(_indentation.Count - 1);
AddToken(SyntaxTokenKind.Dedent, _position, _position);
}
foreach (var delimiter in _delimiters)
{
Report(
"DPY1005",
"Opening delimiter is not closed.",
new TextSpan(delimiter.Position, 1)
);
}
AddToken(SyntaxTokenKind.EndOfFile, _position, _position);
}
private void AddToken(SyntaxTokenKind kind, int start, int end)
{
var span = TextSpan.FromBounds(start, end);
_tokens.Add(new SyntaxToken(kind, span, _source.GetText(span)));
}
private void Report(string code, string message, TextSpan span) =>
_diagnostics.Add(new Diagnostic(code, message, DiagnosticSeverity.Error, span));
private void ReportInconsistentTabsAndSpaces(TextSpan span) =>
Report("DPY1003", "Inconsistent use of tabs and spaces in indentation.", span);
private void ReportUnterminatedString(int start) =>
Report(
"DPY1007",
"String literal is not terminated.",
TextSpan.FromBounds(start, _position)
);
private int GetStringPrefixLength(int start)
{
if (start >= _text.Length)
{
return 0;
}
if (IsQuote(_text[start]))
{
return 0;
}
if (
start + 2 < _text.Length
&& IsValidTwoCharacterStringPrefix(_text[start], _text[start + 1])
&& IsQuote(_text[start + 2])
)
{
return 2;
}
return
start + 1 < _text.Length
&& IsValidOneCharacterStringPrefix(_text[start])
&& IsQuote(_text[start + 1])
? 1
: 0;
}
private char Peek(int offset)
{
var index = _position + offset;
return index >= 0 && index < _text.Length ? _text[index] : '\0';
}
private void AdvanceCodePoint()
{
if (Rune.TryGetRuneAt(_text, _position, out var rune))
{
_position += rune.Utf16SequenceLength;
}
else
{
_position++;
}
}
private void AdvanceNewLine()
{
if (Current == '\r' && Peek(1) == '\n')
{
_position += 2;
}
else
{
_position++;
}
}
private bool IsIdentifierStartAt(int position) =>
TryGetRune(position, out var rune) && IsIdentifierStart(rune);
private bool IsIdentifierContinueAt(int position) =>
TryGetRune(position, out var rune) && IsIdentifierContinue(rune);
private bool TryGetRune(int position, out Rune rune)
{
if (position >= 0 && position < _text.Length)
{
return Rune.TryGetRuneAt(_text, position, out rune);
}
rune = default;
return false;
}
private static bool IsIdentifierStart(Rune rune)
{
if (rune.Value == '_')
{
return true;
}
var category = Rune.GetUnicodeCategory(rune);
return category
is UnicodeCategory.UppercaseLetter
or UnicodeCategory.LowercaseLetter
or UnicodeCategory.TitlecaseLetter
or UnicodeCategory.ModifierLetter
or UnicodeCategory.OtherLetter
or UnicodeCategory.LetterNumber
|| rune.Value is 0x1885 or 0x1886 or 0x2118 or 0x212E or 0x309B or 0x309C;
}
private static bool IsIdentifierContinue(Rune rune)
{
if (IsIdentifierStart(rune))
{
return true;
}
var category = Rune.GetUnicodeCategory(rune);
return category
is UnicodeCategory.NonSpacingMark
or UnicodeCategory.SpacingCombiningMark
or UnicodeCategory.DecimalDigitNumber
or UnicodeCategory.ConnectorPunctuation
|| rune.Value is 0x00B7 or 0x0387 or 0x19DA
|| rune.Value is >= 0x1369 and <= 0x1371;
}
private static bool IsValidOneCharacterStringPrefix(char value) =>
char.ToLowerInvariant(value) is 'b' or 'f' or 'r' or 't' or 'u';
private static bool IsValidTwoCharacterStringPrefix(char first, char second)
{
first = char.ToLowerInvariant(first);
second = char.ToLowerInvariant(second);
return (first, second)
is
('b', 'r')
or
('r', 'b')
or
('f', 'r')
or
('r', 'f')
or
('t', 'r')
or
('r', 't');
}
private static SyntaxTokenKind GetStringKind(ReadOnlySpan<char> prefix)
{
foreach (var character in prefix)
{
switch (char.ToLowerInvariant(character))
{
case 'b':
return SyntaxTokenKind.BytesLiteral;
case 'f':
return SyntaxTokenKind.FormattedStringLiteral;
case 't':
return SyntaxTokenKind.TemplateStringLiteral;
}
}
return SyntaxTokenKind.StringLiteral;
}
private static bool IsQuote(char value) => value is '\'' or '"';
private bool HasRepeatedQuote(int position, char quote) =>
position + 2 < _text.Length
&& _text[position + 1] == quote
&& _text[position + 2] == quote;
private bool MatchesQuote(int position, char quote, int quoteLength)
{
if (position >= _text.Length || _text[position] != quote)
{
return false;
}