string_list.h

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/*
 * Copyright (c) 2019 Roc Streaming authors
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
 
//! @file roc_core/string_list.h
//! @brief Dynamic list of strings.
 
#ifndef ROC_CORE_STRING_LIST_H_
#define ROC_CORE_STRING_LIST_H_
 
#include "roc_core/array.h"
#include "roc_core/attributes.h"
#include "roc_core/iarena.h"
#include "roc_core/noncopyable.h"
#include "roc_core/stddefs.h"
 
namespace roc {
namespace core {
 
//! Dynamic list of strings.
//!
//! Strings are stored in a countinous dynamically-growing array.
//! Each string is stored in a block with a header and footer,
//! which both store block length. This allow fast iteration
//! in both directions.
//!
//! @code
//!  ++--------+--------+---------+--------++-----------
//!  || Header | string | padding | Footer || Header ...
//!  ++--------+--------+---------+--------++-----------
//! @endcode
class StringList : public NonCopyable<> {
public:
    //! Initialize empty string list.
    explicit StringList(IArena& arena);
 
    //! Get number of elements.
    size_t size() const;
 
    //! Check if list is empty.
    bool is_empty() const;
 
    //! Get first string.
    //! @returns
    //!  the first string in the list or NULL if it is empty.
    const char* front() const;
 
    //! Get last string.
    //! @returns
    //!  the last string in the list or NULL if it is empty.
    const char* back() const;
 
    //! Get next string.
    //! @returns
    //!  the first string of the given string or NULL if it is the last string.
    //! @remarks
    //!  @p str should be a pointer returned by front(), nextof(), or prevof().
    //!  These pointers are invalidated by methods that modify the list.
    const char* nextof(const char* str) const;
 
    //! Get previous string.
    //! @returns
    //!  the last string of the given string or NULL if it is the first string.
    //! @remarks
    //!  @p str should be a pointer returned by back(), nextof(), or prevof().
    //!  These pointers are invalidated by methods that modify the list.
    const char* prevof(const char* str) const;
 
    //! Clear the list.
    void clear();
 
    //! Append string to the list.
    //! @remarks
    //!  Reallocates memory if necessary.
    //! @returns
    //!  false if allocation failed.
    ROC_ATTR_NODISCARD bool push_back(const char* str);
 
    //! Append string from a range to the list.
    //! @remarks
    //!  Reallocates memory if necessary.
    //! @returns
    //!  false if allocation failed.
    ROC_ATTR_NODISCARD bool push_back(const char* str_begin, const char* str_end);
 
    //! Find string in the list.
    //! @returns
    //!  the string in the list or NULL if it is not found.
    ROC_ATTR_NODISCARD const char* find(const char* str);
 
    //! Find string in the list.
    //! @returns
    //!  the string in the list or NULL if it is not found.
    ROC_ATTR_NODISCARD const char* find(const char* str_begin, const char* str_end);
 
private:
    enum { MinCapacity = 128 };
 
    struct Header {
        uint32_t len;
        char str[];
    };
 
    struct Footer {
        uint32_t len;
    };
 
    void check_member_(const char* str) const;
    bool grow_(size_t size);
 
    core::Array<char> data_;
    Header* front_;
    Header* back_;
    size_t size_;
};
 
} // namespace core
} // namespace roc
 
#endif // ROC_CORE_STRING_LIST_H_