zeek/src/ZeekString.h

// See the file "COPYING" in the main distribution directory for copyright.

#pragma once

#include <sys/types.h>
#include <iosfwd>
#include <string>
#include <string_view>
#include <vector>

namespace zeek {

// Forward declaration, for helper functions that convert (sub)string vectors
// to and from policy-level representations.
//
class VectorVal;

using byte_vec = u_char*;

/**
 * A container type for holding blocks of byte data. This can be used for
 * character strings, but is not limited to that alone. This class provides
 * methods for rendering byte data into character strings, including
 * conversions of non-printable characters into other representations.
 */
class String {
public:
    using Vec = std::vector<String*>;
    using VecIt = Vec::iterator;
    using VecCIt = Vec::const_iterator;

    using CVec = std::vector<const String*>;
    using CVecIt = Vec::iterator;
    using CVecCIt = Vec::const_iterator;

    // IdxVecs are vectors of indices of characters in a string.
    using IdxVec = std::vector<int>;
    using IdxVecIt = IdxVec::iterator;
    using IdxVecCIt = IdxVec::const_iterator;

    // Constructors creating internal copies of the data passed in.
    String(const u_char* str, int arg_n, bool add_NUL);
    String(std::string_view str);
    String(const String& bs);

    // Constructor that takes ownership of the vector passed in.
    String(bool arg_final_NUL, byte_vec str, int arg_n);

    // Move constructor
    String(String&& s) noexcept;

    String();
    ~String() { Reset(); }

    const String& operator=(const String& bs);
    String& operator=(String&& bs) noexcept;
    bool operator==(const String& bs) const;
    bool operator<(const String& bs) const;
    bool operator==(std::string_view s) const;
    bool operator!=(std::string_view s) const;

    byte_vec Bytes() const { return b; }
    int Len() const { return n; }

    // Releases the string's current contents, if any, and
    // adopts the byte vector of given length.  The string will
    // manage the memory occupied by the string afterwards.
    //
    void Adopt(byte_vec bytes, int len);

    // Various flavors of methods that release the string's
    // current contents, if any, and then set the string's
    // contents to a copy of the string given by the arguments.
    //
    void Set(const u_char* str, int len, bool add_NUL = true);
    void Set(std::string_view str);
    void Set(const String& str);

    void SetUseFreeToDelete(int use_it) { use_free_to_delete = use_it; }

    /**
     * Returns a character-string representation of the stored bytes. This
     * method doesn't do any extra rendering or character conversions. If
     * null characters are found in the middle of the data or if the data
     * is missing a closing null character, an error string is returned and
     * a error is reported.
     */
    const char* CheckString() const;

    /**
     * Like @c CheckString(), but also returns the length of the string.
     */
    std::pair<const char*, size_t> CheckStringWithSize() const;

    /**
     * Returns the string data as a std::string. This makes a copy of the
     * string data.
     */
    std::string ToStdString() const;

    /**
     * Returns the string data as a std::string_view.
     */
    std::string_view ToStdStringView() const;

    enum render_style {
        ESC_NONE = 0,
        ESC_ESC = (1 << 1),  // '\' -> "\\"
        ESC_QUOT = (1 << 2), // '"' -> "\"", ''' -> "\'"
        ESC_HEX = (1 << 3),  // Not in [32, 126]? -> "\xXX"
        ESC_DOT = (1 << 4),  // Not in [32, 126]? -> "."

        // For serialization: '<string len> <string>'
        ESC_SER = (1 << 7),
    };

    static constexpr int EXPANDED_STRING = // the original style
        ESC_HEX;

    static constexpr int ZEEK_STRING_LITERAL = // as in a Zeek string literal
        ESC_ESC | ESC_QUOT | ESC_HEX;

    // Renders a string into a newly allocated character array that
    // you have to delete[].  You can combine the render styles given
    // above to achieve the representation you desire.  If you pass a
    // pointer to an integer as the final argument, you'll receive the
    // entire length of the resulting char* in it.
    //
    // Note that you need to delete[] the resulting string.
    //
    char* Render(int format = EXPANDED_STRING, int* len = nullptr) const;

    // Similar to the above, but useful for output streams.
    // Also more useful for debugging purposes since no deallocation
    // is required on your part here.
    //
    std::ostream& Render(std::ostream& os, int format = ESC_SER) const;

    // Reads a string from an input stream.  Unless you use a render
    // style combination that uses ESC_SER, note that the streams
    // will consider whitespace as a field delimiter.
    //
    std::istream& Read(std::istream& is, int format = ESC_SER);

    // XXX Fix redundancy: strings.bif implements both to_lower
    // XXX and to_upper; the latter doesn't use String::ToUpper().
    void ToUpper();

    // Returns new string containing the substring of this string,
    // starting at @start >= 0 for going up to @length elements,
    // A negative @length means "until end of string".  Other invalid
    // values result in a return value of 0.
    //
    String* GetSubstring(int start, int length) const;

    // Returns the start index of s in this string, counting from 0.
    // If s is not found, -1 is returned.
    //
    int FindSubstring(const String* s) const;

    // Splits the string into substrings, taking all the indices in
    // the given vector as cutting points.  The vector does not need
    // to be sorted, and can have multiple entries.  Out-of-bounds
    // indices are ignored.  All returned strings are newly allocated.
    //
    Vec* Split(const IdxVec& indices) const;

    // Helper functions for vectors:
    static VectorVal* VecToPolicy(Vec* vec);
    static Vec* VecFromPolicy(VectorVal* vec);
    static char* VecToString(const Vec* vec);

protected:
    void Reset();

    byte_vec b;
    int n;
    bool final_NUL;          // whether we have added a final NUL
    bool use_free_to_delete; // free() vs. operator delete
};

// A comparison class that sorts pointers to String's according to
// the length of the pointed-to strings. Sort order can be specified
// through the constructor.
//
class StringLenCmp {
public:
    explicit StringLenCmp(bool increasing = true) { _increasing = increasing; }
    bool operator()(String* const& bst1, String* const& bst2);

private:
    unsigned int _increasing;
};

// Default output stream operator, using rendering mode EXPANDED_STRING.
std::ostream& operator<<(std::ostream& os, const String& bs);

extern int Bstr_eq(const String* s1, const String* s2);
extern int Bstr_cmp(const String* s1, const String* s2);

// A data_chunk_t specifies a length-delimited constant string. It is
// often used for substrings of other String's to avoid memory copy,
// which would be necessary if String were used. Unlike String,
// the string should not be deallocated on destruction.
//
// "ZeekConstString" might be a better name here.

struct data_chunk_t {
    int length;
    const char* data;
};

extern String* concatenate(std::vector<data_chunk_t>& v);
extern String* concatenate(String::Vec& v);
extern String* concatenate(String::CVec& v);
extern void delete_strings(std::vector<const String*>& v);

} // namespace zeek