jes/src/core/PieceTable.h

#ifndef PIECETABLE_H
#define PIECETABLE_H

#include <stdint.h>
#include "PagedBuffer.h"
#include <utility>
#include <memory>
#include <list>
#include "Encoding.h"

class PieceTable
{
public:
    enum
    {
        INTERNAL_EOL = '\n',
    };

    struct Piece
    {
        /** The previous piece in the chain. */
        Piece * prev;

        /** The next piece in the chain. */
        Piece * next;

        /** Text that the piece describes. */
        uint8_t * start;

        /** Length of the text (in bytes). */
        uint32_t length;

        /** Get whether this piece is the end of a line. */
        bool eol() { return (length > 0u) && (start[length - 1u] == INTERNAL_EOL); }
    };

    struct Iterator
    {
        /** The piece table the cursor belongs to. */
        PieceTable * piece_table;

        /** The piece. */
        Piece * piece;

        /** Byte offset within the piece. */
        uint32_t offset;

        Iterator(PieceTable * pt);

        /** Get the character pointed to by the cursor. */
        uint32_t operator*() const
        {
            if (has_char())
            {
                return Encoding::decode(piece_table->encoding, &piece->start[offset]);
            }
            else
            {
                return 0xFFFFFFFFu;
            }
        }

        uint8_t num_bytes_in_code_point() const;

        void go_next_position();
        void go_prev_position();
        void go_end_of_piece();
        void go_next_piece();
        void go_prev_piece();

        bool valid() const
        {
            return (piece != piece_table->start_piece) &&
                (piece != piece_table->end_piece);
        }

        bool has_char() const
        {
            return valid() && (offset < piece->length);
        }

        bool operator==(const Iterator & other) const
        {
            return (other.piece == piece) && (other.offset == offset);
        }

        bool operator!=(const Iterator & other) const
        {
            return !(*this == other);
        }
    };

    struct Cursor
    {
        Iterator iterator;

        uint32_t line;

        uint32_t column;

        /** Get the character pointed to by the cursor. */
        uint32_t operator*() const
        {
            return *iterator;
        }

        Cursor(PieceTable * pt);

        void go_start_of_line();
        void go_end_of_line(bool allow_on_eol);
        void go_up(int n, uint32_t desired_column);
        void go_down(int n, uint32_t desired_column);
        void go_left(int n);
        void go_right(int n, bool allow_on_eol);

        bool check_go_start_of_line();
        bool check_go_end_of_line(bool allow_on_eol);
        bool check_go_up(int n, uint32_t desired_column);
        bool check_go_down(int n, uint32_t desired_column);
        bool check_go_left(int n);
        bool check_go_right(int n, bool allow_on_eol);

        bool operator==(const Cursor & c) const
        {
            return (c.line == line) && (c.column == column);
        }
        bool operator!=(const Cursor & c) const
        {
            return !(*this == c);
        }
        void warp_to_inserted_piece(Piece * piece);

    protected:
        bool is_start_of_line();
        bool is_end_of_line();
        Piece * prev_line() const;
        Piece * next_line() const;
        void init_column();
        void calculate_column();
        void forward_to_column(uint32_t c);
    };

    struct Change
    {
        Piece * before;
        Piece * after;
        Piece * chains[2][2];
    };

    Piece * start_piece;
    Piece * end_piece;
    uint8_t tabstop;
    Encoding::Type encoding;

    PieceTable();

    uint32_t get_num_lines() { return m_num_lines; }

    void append_initial_line_piece(uint8_t * start, uint32_t length, bool eol);

    std::shared_ptr<Cursor> add_cursor();

    void begin_insert(const Cursor & cursor, bool before);
    void insert_code_point(uint32_t code_point);
    void end_insert();
    void insertion_test(Cursor & c);

    void undo();

protected:
    Piece * add_piece()
    {
        return &m_pieces[m_piece_index++];
    }

    Piece & operator[](uint32_t index)
    {
        return m_pieces[index];
    }

    Change * add_change()
    {
        return &m_changes[m_changes_index++];
    }

    void apply_change(Change * change, uint8_t forward);

    uint32_t m_num_lines;

    PagedBuffer<uint8_t> m_append_buffer;
    uint32_t m_append_buffer_index;
    PagedBuffer<Piece> m_pieces;
    /** Next available piece index. */
    uint32_t m_piece_index;
    PagedBuffer<Change> m_changes;
    uint32_t m_changes_index;
    Piece * m_insert_before_piece;
    Piece * m_inserting_piece;

    std::list<std::shared_ptr<Cursor>> m_cursors;
};

#endif