Lexer.hpp

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#pragma once
 
#include "AstGlobal.h"
#include "AstScript/Scanner.hpp"
#include "AstUtil/StringView.hpp"
 
 
AST_NAMESPACE_BEGIN
 
 
class Lexer
{
public:
    enum ETokenType
    {
        // 特殊令牌
        eEndOfFile,             
        eError,                 
 
        // 字面量           
        eNumber,                
        eString,                
        eIdentifier,            
        eTrue,                  
        eFalse,                 
        eNullLiteral,           
 
        // 运算符           
        ePlus,                  
        eMinus,                 
        eStar,                  
        eSlash,                 
        ePercent,               
        eCaret,                 
        eTilde,                 
 
        // 比较运算符           
        eEqual,                 
        eColonEqual,            
        eEqualAmpersand,        
        eEqualEqual,            
        eBang,                  
        eBangEqual,             
        eLess,                  
        eLessEqual,             
        eLessLess,              
        eGreater,               
        eGreaterEqual,          
        eGreaterGreater,        
        eGreaterGreaterGreater, 
        
        // 逻辑运算符
        eAmpersand,             
        ePipe,                  
        eXor,                   
        eAndAnd,                
        eOrOr,                  
        
        // 括号
        eLeftParen,             
        eRightParen,            
        eLeftBrace,             
        eRightBrace,            
 
        eLeftBracket,           
        eRightBracket,          
        
        // 其他
        eComma,                 
        eDot,                   
        eSemicolon,             
        eColon,                 
        eQuestion,              
 
        eNewline,               
        eAt,                    
        
        // 代码块关键字（参照Julia语言）
        eBegin,                 
        eEnd,                   
        
        // 条件语句关键字
        eIf,                    
        eElseif,                
        eElse,                  
        
        // 循环语句关键字
        eWhile,                 
        eFor,                   
        eIn,                    
    };
 
public:
    Lexer(Scanner* scanner) 
        : scanner_(scanner)
        // , line_(1)
        , current_lexeme_() 
    {}
    
    ETokenType getNextToken();
    
    StringView getCurrentLexeme() const { return current_lexeme_; }
    
    const char* getTokenStart() const { return nullptr; }
    
    const char* getTokenEnd() const { return nullptr; }
    
    // size_t getLine() const { return line_; }
    
    void skipWhitespace();
    
private:
    bool isAlpha(char c) const;
    
    bool isAlphaNumeric(char c) const;
    
    bool isDigit(char c) const;
    
    bool isWhitespace(char c) const;
    
    int parseIdentifier();
    
    Lexer::ETokenType scanNumber();
    
    Lexer::ETokenType scanString();
    
    bool match(char expected);
    
    bool match(const char* str);
    
    char advance();
    
    char peek() const;
    
    char peekNext() const;
    
    bool atEnd() const;
    
private:
    Scanner* scanner_;    
    // size_t line_;         ///< 当前行号
    std::string current_lexeme_; 
};
 
AST_NAMESPACE_END