663 lines
20 KiB
C#
663 lines
20 KiB
C#
using System.Text;
|
||
using Canon.Core.Abstractions;
|
||
using Canon.Core.Enums;
|
||
using Canon.Core.Exceptions;
|
||
|
||
namespace Canon.Core.LexicalParser;
|
||
|
||
public class Lexer : ILexer
|
||
{
|
||
// 记录token
|
||
private SemanticToken? _semanticToken;
|
||
private readonly StringBuilder _tokenBuilder = new();
|
||
private readonly List<SemanticToken> _tokens = [];
|
||
|
||
// 状态机
|
||
private StateType _state = StateType.Start;
|
||
private char _ch;
|
||
private bool _finish;
|
||
|
||
// 文件读取
|
||
private ISourceReader _reader;
|
||
private uint _line = 1;
|
||
private uint _chPos;
|
||
|
||
public IEnumerable<SemanticToken> Tokenize(ISourceReader reader)
|
||
{
|
||
_reader = reader;
|
||
_state = StateType.Start;
|
||
|
||
while (_state != StateType.Done)
|
||
{
|
||
switch (_state)
|
||
{
|
||
case StateType.Start:
|
||
HandleStartState();
|
||
break;
|
||
case StateType.Comment:
|
||
if (_ch == '{')
|
||
{
|
||
HandleCommentStateBig();
|
||
}
|
||
else if (_ch == '*')
|
||
{
|
||
HandleCommentStateSmall();
|
||
}
|
||
else
|
||
{
|
||
HandleCommentSingleLine();
|
||
}
|
||
|
||
break;
|
||
case StateType.Num:
|
||
HandleNumState();
|
||
break;
|
||
case StateType.Word:
|
||
HandleWordState();
|
||
break;
|
||
case StateType.Delimiter:
|
||
HandleDelimiterState();
|
||
break;
|
||
case StateType.Operator:
|
||
HandleOperatorState();
|
||
break;
|
||
case StateType.BreakPoint:
|
||
while (LexRules.IsBreakPoint(_ch))
|
||
{
|
||
GetChar();
|
||
}
|
||
|
||
Retract();
|
||
_state = StateType.Start;
|
||
break;
|
||
case StateType.Unknown:
|
||
throw new LexemeException(LexemeErrorType.UnknownCharacterOrString, _line, _chPos,
|
||
"Illegal lexeme.");
|
||
case StateType.Done:
|
||
break;
|
||
}
|
||
}
|
||
|
||
_tokens.Add(SemanticToken.End);
|
||
return _tokens;
|
||
}
|
||
|
||
private void HandleStartState()
|
||
{
|
||
// 初始化
|
||
ResetTokenBuilder();
|
||
|
||
// 读取首个字符
|
||
GetChar();
|
||
|
||
if (_finish)
|
||
{
|
||
_state = StateType.Done;
|
||
return;
|
||
}
|
||
|
||
// 根据首个字符判断可能的情况
|
||
if (_ch == '{') // 以 “{” 开头，为注释
|
||
{
|
||
_state = StateType.Comment;
|
||
}
|
||
else if (_ch == '(')
|
||
{
|
||
char nextChar = PeekNextChar();
|
||
if (nextChar == '*')
|
||
{
|
||
GetChar();
|
||
_state = StateType.Comment;
|
||
}
|
||
else
|
||
{
|
||
_state = StateType.Delimiter;
|
||
}
|
||
}
|
||
else if (_ch == '/')
|
||
{
|
||
char nextChar = PeekNextChar();
|
||
if (nextChar == '/')
|
||
{
|
||
GetChar();
|
||
_state = StateType.Comment;
|
||
}
|
||
else
|
||
{
|
||
_state = StateType.Operator;
|
||
}
|
||
}
|
||
else if (_ch == '.') // 以 “.” 开头，可能是数字或分隔符
|
||
{
|
||
char next = PeekNextChar();
|
||
if (next is >= '0' and <= '9')
|
||
{
|
||
_state = StateType.Num;
|
||
}
|
||
else
|
||
{
|
||
_state = StateType.Delimiter;
|
||
}
|
||
}
|
||
else if (LexRules.IsLetter(_ch)) // 以字母开头，为关键字或标识符
|
||
{
|
||
_state = StateType.Word;
|
||
}
|
||
else if (LexRules.IsDigit(_ch) || _ch == '$') // 以数字或 “$” 开头，为数值
|
||
{
|
||
_state = StateType.Num;
|
||
}
|
||
else if (LexRules.IsDelimiter(_ch)) // 为分隔符
|
||
{
|
||
_state = StateType.Delimiter;
|
||
}
|
||
else if (LexRules.IsOperator(_ch)) // 为运算符
|
||
{
|
||
_state = StateType.Operator;
|
||
}
|
||
else if (LexRules.IsBreakPoint(_ch))
|
||
{
|
||
_state = StateType.BreakPoint;
|
||
}
|
||
else
|
||
{
|
||
_state = StateType.Unknown;
|
||
}
|
||
}
|
||
|
||
private void HandleCommentStateBig()
|
||
{
|
||
while (_ch != '}')
|
||
{
|
||
GetChar();
|
||
|
||
if (_finish)
|
||
{
|
||
throw new LexemeException(LexemeErrorType.UnclosedComment, _line, _chPos,
|
||
"The comment is not closed.");
|
||
}
|
||
}
|
||
|
||
_state = StateType.Start;
|
||
}
|
||
|
||
private void HandleCommentStateSmall()
|
||
{
|
||
bool commentClosed = false;
|
||
while (!commentClosed)
|
||
{
|
||
GetChar();
|
||
while (_ch != '*')
|
||
{
|
||
GetChar();
|
||
if (_finish)
|
||
{
|
||
throw new LexemeException(LexemeErrorType.UnclosedComment, _line, _chPos,
|
||
"The comment is not closed.");
|
||
}
|
||
}
|
||
|
||
GetChar();
|
||
if (_finish)
|
||
{
|
||
throw new LexemeException(LexemeErrorType.UnclosedComment, _line, _chPos,
|
||
"The comment is not closed.");
|
||
}
|
||
|
||
if (_ch == ')') commentClosed = true;
|
||
}
|
||
|
||
_state = StateType.Start;
|
||
}
|
||
|
||
private void HandleCommentSingleLine()
|
||
{
|
||
while (_ch != '\n')
|
||
{
|
||
GetChar();
|
||
}
|
||
|
||
_state = StateType.Start;
|
||
}
|
||
|
||
private void HandleWordState()
|
||
{
|
||
while (LexRules.IsDigit(_ch) || LexRules.IsLetter(_ch))
|
||
{
|
||
Cat();
|
||
GetChar();
|
||
}
|
||
|
||
Retract();
|
||
|
||
string tokenString = GetCurrentTokenString();
|
||
if (LexRules.GetKeywordTypeByKeywprd(tokenString, out KeywordType keywordType))
|
||
{
|
||
|
||
_semanticToken = LexemeFactory.MakeToken(keywordType, tokenString, _line, _chPos);
|
||
}
|
||
else
|
||
{
|
||
_semanticToken = LexemeFactory.MakeToken(SemanticTokenType.Identifier, tokenString, _line, _chPos);
|
||
}
|
||
|
||
AddToTokens(_semanticToken);
|
||
_state = StateType.Start;
|
||
}
|
||
|
||
private void HandleNumState()
|
||
{
|
||
NumberType numberType = NumberType.Integer;
|
||
// 十六进制
|
||
if (_ch == '$')
|
||
{
|
||
ProcessHex();
|
||
numberType = NumberType.Hex;
|
||
}
|
||
// 非十六进制
|
||
else if (LexRules.IsDigit(_ch) || _ch == '.')
|
||
{
|
||
while (!NumberShouldBreak())
|
||
{
|
||
// 含小数部分
|
||
if (_ch == '.')
|
||
{
|
||
// 检查是否是符号 “..”
|
||
char next = PeekNextChar();
|
||
if (next == '.')
|
||
{
|
||
Retract();
|
||
_state = StateType.Delimiter;
|
||
break;
|
||
}
|
||
|
||
// 不是符号 “..”,进入小数点后的判断
|
||
Cat(); // 记录“.”
|
||
|
||
// “.”后不应为空，至少应该有一位小数
|
||
GetChar();
|
||
if (NumberShouldBreak())
|
||
{
|
||
throw new LexemeException(LexemeErrorType.IllegalNumberFormat, _line, _chPos,
|
||
"Illegal numbers!");
|
||
}
|
||
|
||
// 读取小数点后的数字
|
||
while (!NumberShouldBreak())
|
||
{
|
||
if (LexRules.IsDigit(_ch))
|
||
{
|
||
Cat();
|
||
GetChar();
|
||
}
|
||
else if (_ch == 'e' || _ch == 'E')
|
||
{
|
||
ProcessE();
|
||
break;
|
||
}
|
||
else if (NumberShouldBreak())
|
||
{
|
||
break;
|
||
}
|
||
else
|
||
{
|
||
throw new LexemeException(LexemeErrorType.IllegalNumberFormat, _line, _chPos,
|
||
"Illegal number.");
|
||
}
|
||
}
|
||
|
||
numberType = NumberType.Real;
|
||
break;
|
||
}
|
||
|
||
// 不含小数部分，含科学计数法
|
||
if (_ch == 'e' || _ch == 'E')
|
||
{
|
||
ProcessE();
|
||
numberType = NumberType.Real;
|
||
break;
|
||
}
|
||
|
||
// 暂时为整数
|
||
if (LexRules.IsDigit(_ch))
|
||
{
|
||
Cat();
|
||
GetChar();
|
||
}
|
||
else if (NumberShouldBreak())
|
||
{
|
||
numberType = NumberType.Integer;
|
||
break;
|
||
}
|
||
else
|
||
{
|
||
throw new LexemeException(LexemeErrorType.IllegalNumberFormat, _line, _chPos, "Illegal number.");
|
||
}
|
||
}
|
||
}
|
||
|
||
_semanticToken = LexemeFactory.MakeToken(numberType, GetCurrentTokenString(),
|
||
_line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
_state = StateType.Start;
|
||
}
|
||
|
||
private void ProcessHex()
|
||
{
|
||
Cat();
|
||
GetChar();
|
||
|
||
while (!NumberShouldBreak())
|
||
{
|
||
// 假设IsHexDigit方法能够识别十六进制数字
|
||
if (LexRules.IsHexDigit(_ch))
|
||
{
|
||
Cat();
|
||
GetChar();
|
||
}
|
||
else if (NumberShouldBreak())
|
||
{
|
||
break;
|
||
}
|
||
else
|
||
{
|
||
throw new LexemeException(LexemeErrorType.IllegalNumberFormat, _line, _chPos,
|
||
"Illegal hex numbers!");
|
||
}
|
||
}
|
||
}
|
||
|
||
private void ProcessE()
|
||
{
|
||
Cat();
|
||
GetChar();
|
||
if (LexRules.IsDigit(_ch) || _ch == '+' || _ch == '-')
|
||
{
|
||
Cat();
|
||
}
|
||
else
|
||
{
|
||
throw new LexemeException(LexemeErrorType.IllegalNumberFormat, _line, _chPos, "Illegal number.");
|
||
}
|
||
|
||
// 读取e后的数字
|
||
GetChar();
|
||
while (!NumberShouldBreak())
|
||
{
|
||
if (LexRules.IsDigit(_ch))
|
||
{
|
||
Cat();
|
||
GetChar();
|
||
}
|
||
else
|
||
{
|
||
throw new LexemeException(LexemeErrorType.IllegalNumberFormat, _line, _chPos, "Illegal number.");
|
||
}
|
||
}
|
||
}
|
||
|
||
bool NumberShouldBreak()
|
||
{
|
||
if (_ch == ' ' || _ch == '\n' || _ch == '\t' || _ch == '\r' || (LexRules.IsDelimiter(_ch) && _ch != '.') ||
|
||
LexRules.IsOperator(_ch) || _finish)
|
||
{
|
||
Retract();
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
private bool IsDot()
|
||
{
|
||
if (_tokens.Count != 0)
|
||
{
|
||
SemanticToken tokenBefore = _tokens.Last();
|
||
if (tokenBefore.TokenType == SemanticTokenType.Identifier) return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
private void HandleDelimiterState()
|
||
{
|
||
Cat();
|
||
switch (_ch)
|
||
{
|
||
case '.':
|
||
{
|
||
GetChar();
|
||
if (_ch == '.')
|
||
{
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.DoubleDots, "..", _line, _chPos);
|
||
break;
|
||
}
|
||
|
||
Retract();
|
||
if (IsDot())
|
||
{
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.Dot, ".", _line, _chPos);
|
||
}
|
||
else
|
||
{
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.Period, ".", _line, _chPos);
|
||
}
|
||
}
|
||
break;
|
||
case '\'':
|
||
case '\"':
|
||
{
|
||
// 重置_token，准备收集字符串内容
|
||
ResetTokenBuilder();
|
||
|
||
GetChar(); // 移动到下一个字符，即字符串的第一个字符
|
||
while (_ch != '\'' && _ch != '\"')
|
||
{
|
||
Cat(); // 收集字符
|
||
GetChar(); // 移动到下一个字符
|
||
if (_ch == '\n' || _finish)
|
||
{
|
||
throw new LexemeException(LexemeErrorType.UnclosedStringLiteral, _line, _chPos,
|
||
"The String is not closed.");
|
||
}
|
||
}
|
||
|
||
_semanticToken = LexemeFactory.MakeToken(SemanticTokenType.Character,
|
||
GetCurrentTokenString(), _line, _chPos);
|
||
|
||
ResetTokenBuilder();
|
||
|
||
if (!(_ch == '\'' || _ch == '\"'))
|
||
{
|
||
throw new LexemeException(LexemeErrorType.UnclosedStringLiteral, _line, _chPos,
|
||
"The String is not closed.");
|
||
}
|
||
}
|
||
break;
|
||
case ',':
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.Comma, ",", _line, _chPos);
|
||
|
||
break;
|
||
case ':':
|
||
char nextChar = PeekNextChar();
|
||
if (nextChar == '=')
|
||
{
|
||
GetChar();
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Assign, ":=", _line, _chPos);
|
||
}
|
||
else
|
||
{
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.Colon, ":", _line, _chPos);
|
||
}
|
||
|
||
break;
|
||
case ';':
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.Semicolon, ";", _line, _chPos);
|
||
|
||
break;
|
||
case '(':
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.LeftParenthesis, "(", _line, _chPos);
|
||
break;
|
||
case ')':
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.RightParenthesis, ")", _line, _chPos);
|
||
|
||
break;
|
||
case '[':
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.LeftSquareBracket, "[", _line, _chPos);
|
||
|
||
break;
|
||
case ']':
|
||
_semanticToken = LexemeFactory.MakeToken(DelimiterType.RightSquareBracket, "]", _line, _chPos);
|
||
break;
|
||
}
|
||
|
||
if (_semanticToken is null)
|
||
{
|
||
throw new InvalidOperationException();
|
||
}
|
||
_tokens.Add(_semanticToken);
|
||
_state = StateType.Start;
|
||
}
|
||
|
||
private void HandleOperatorState()
|
||
{
|
||
switch (_ch)
|
||
{
|
||
case '+': // 识别 +
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Plus, "+", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
break;
|
||
case '-': // 识别 -
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Minus, "-", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
break;
|
||
case '*': // 识别 *
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Multiply, "*", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
break;
|
||
case '/': // 识别 /
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Divide, "/", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
break;
|
||
case '=':
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Equal, "=", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
break;
|
||
case '<':
|
||
Cat();
|
||
GetChar();
|
||
if (_ch == '=')
|
||
{
|
||
// 识别 <=
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.LessEqual, "<=", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
}
|
||
else if (_ch == '>')
|
||
{
|
||
// 识别 <>
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.NotEqual, ">", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
}
|
||
else
|
||
{
|
||
// 识别 <
|
||
Retract();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Less, "<", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
}
|
||
|
||
break;
|
||
case '>':
|
||
Cat();
|
||
GetChar();
|
||
if (_ch == '=')
|
||
{
|
||
// 识别 >=
|
||
Cat();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.GreaterEqual, ">=", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
}
|
||
else
|
||
{
|
||
// 识别 >
|
||
Retract();
|
||
_semanticToken = LexemeFactory.MakeToken(OperatorType.Greater, ">", _line, _chPos);
|
||
AddToTokens(_semanticToken);
|
||
}
|
||
|
||
break;
|
||
default:
|
||
throw new LexemeException(LexemeErrorType.UnknownCharacterOrString, _line, _chPos, "Illegal lexeme.");
|
||
}
|
||
|
||
_state = StateType.Start;
|
||
}
|
||
|
||
private void AddToTokens(SemanticToken semanticToken)
|
||
{
|
||
_tokens.Add(semanticToken);
|
||
}
|
||
|
||
private void Cat()
|
||
{
|
||
_tokenBuilder.Append(_ch); // 使用StringBuilder追加字符
|
||
}
|
||
|
||
private string GetCurrentTokenString()
|
||
{
|
||
return _tokenBuilder.ToString(); // 从StringBuilder获取当前记号的字符串
|
||
}
|
||
|
||
private void ResetTokenBuilder()
|
||
{
|
||
_tokenBuilder.Clear(); // 清空StringBuilder以复用
|
||
}
|
||
|
||
private char PeekNextChar()
|
||
{
|
||
// 确认下一个位置是否仍在buffer的范围内
|
||
if (_reader.TryPeekChar(out char? c))
|
||
{
|
||
return c.Value;
|
||
}
|
||
else
|
||
{
|
||
return char.MinValue;
|
||
}
|
||
}
|
||
|
||
void GetChar()
|
||
{
|
||
if (_finish)
|
||
{
|
||
return;
|
||
}
|
||
|
||
_finish = !_reader.MoveNext();
|
||
|
||
if (_finish)
|
||
{
|
||
_ch = char.MinValue;
|
||
return;
|
||
}
|
||
|
||
_ch = _reader.Current;
|
||
_line = _reader.Line;
|
||
_chPos = _reader.Pos;
|
||
}
|
||
|
||
void Retract()
|
||
{
|
||
_reader.Retract();
|
||
}
|
||
}
|