Scanner.hpp

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#pragma once
 
#include "AstGlobal.h"
#include "AstUtil/StringView.hpp"
#include <cstdio>
#include <string>
#include <fstream>
 
AST_NAMESPACE_BEGIN
 
class AST_SCRIPT_API Scanner
{
public:
    virtual ~Scanner() = default;
    
    virtual char consume() = 0;
    
    virtual char peek() const = 0;
    
    virtual char peekNext() const = 0;
    
    virtual bool atEnd() const = 0;
    
    virtual void skip() = 0;
    
 
};
 
class AST_SCRIPT_API StringScanner : public Scanner
{
public:
    explicit StringScanner(const std::string& str) 
        : str_(str), current_(0) 
    {}
    
    explicit StringScanner(StringView str) 
        : str_(str), current_(0) 
    {}
    
    char consume() override;
    char peek() const override;
    char peekNext() const override;
    bool atEnd() const override;
    void skip() override;
 
    
private:
    std::string str_;  
    size_t current_;   
};
 
class AST_SCRIPT_API FileScanner : public Scanner
{
public:
    explicit FileScanner(FILE* file)
        : file_(file), current_char_(0), next_char_(0), at_end_(false)
    {
        // 预读取两个字符
        current_char_ = std::fgetc(file_);
        next_char_ = std::fgetc(file_);
        at_end_ = (current_char_ == EOF);
    }
 
    FileScanner(const FileScanner&) = delete;
    FileScanner& operator=(const FileScanner&) = delete;
 
    ~FileScanner() override;
    
    char consume() override;
    char peek() const override;
    char peekNext() const override;
    bool atEnd() const override;
    void skip() override;
 
    
private:
    FILE* file_;         
    int current_char_;   
    int next_char_;      
    bool at_end_;        
};
 
class AST_SCRIPT_API StreamScanner : public Scanner
{
public:
    explicit StreamScanner(std::fstream& stream) 
        : stream_(stream), current_char_(0), next_char_(0), at_end_(false) 
    {
        // 预读取两个字符
        current_char_ = stream_.get();
        next_char_ = stream_.get();
        at_end_ = (current_char_ == EOF);
    }
    
    char consume() override;
    char peek() const override;
    char peekNext() const override;
    bool atEnd() const override;
    void skip() override;
    
private:
    std::fstream& stream_;  
    int current_char_;      
    int next_char_;         
    bool at_end_;           
};
 
AST_NAMESPACE_END