svn/view/buffer.rb

# buffer.rb: the class definition of Edmaru::Buffer
#
# Copyright (C) 2007 Takashi Nakamoto
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA.
#

require "exception.rb"

module Edmaru

  class EndOfBufferException < EdmaruException
    def initialize
      super("End of buffer.")
    end
  end
  
  #The instance of this class represents one string sequence.
  class Buffer
    
    #Create a new buffer.
    #
    #=== Argument
    #_name_ :: The unique title of this buffer.
    #_filename_ :: File name related to this buffer.
    #
    #=== Return
    #An initialized buffer.
    def initialize(name, filename = "")
      @name = name
      @lines = Array.new
      @lines.push("")

      @filename = filename

      @related_window = Array.new
    end

    #Link the specified window to this buffer.
    #
    #=== Argument
    #_window_ :: The window to display this buffer.
    def link(window)
      if @related_window.include?(window)
        return
      end

      @related_window.push(window)
    end

    #Unlink the specified window from this buffer.
    #
    #=== Argument
    #_window_ :: The window to be unlinked.
    def unlink(window)
      @related_window.delete(window)
    end

    #Make linked windows refresh
    def refresh_windows
      @related_window.each{ |window|
        window.refresh
      }
    end

    #The name of this buffer.
    #
    #=== Return
    #The name of this buffer.
    def name
      @name
    end

    #All lines in this buffer.
    #
    #=== Return
    #An array of string.
    #Each element represents one line of this buffer.
    def lines
      @lines
    end

    #File name related to this buffer.
    def filename
      @filename
    end

    #Check if the specified position is valid for this buffer.
    #
    #=== Arguments
    #
    #_row_ :: Row position or line number.
    #_col_ :: Column position.
    #
    #=== Return
    #_true_ if the specified position is valid for this buffer.
    #
    #=== Note
    #
    #The position is between two adjacent characters including line
    #feed character. Thus, this method returns true if _col_ is equal
    #to the size of the specified line, but false if _row_ is equal to
    #the size of Edmaru::Buffer#lines.
    def valid_position?(row, col)
      if row < 0 || row >= @lines.size
        # Invalid row position.
        return false
      elsif col < 0 || col > @lines[row].size
        # Invalid column position.
        return false
      else
        return true
      end
    end

    #Insert the specified string to the specified position
    #
    #=== Arguments
    #_row_ :: Row position or line number.
    #_col_ :: Column position.
    #_str_ :: A string to be inserted.
    def insert(row, col, str)
      if !valid_position?(row, col)
        raise "Invalid position was specified for 'insert' method."
      end

      return if str.empty? # Nothing to be inserted.

      if str.include?("\n")
        new_lines = str.split(/\n/, -1)
        new_lines[0] =
          @lines[row][0, col] + new_lines[0]
        new_lines[new_lines.size - 1] <<
          @lines[row][col .. -1]
        @lines[row] = new_lines
        @lines.flatten!
      else
        current_line = @lines[row]
        @lines[row] = ""
        if col > 0
          @lines[row] = current_line[0, col]
        end
        @lines[row] << str
        @lines[row] << current_line[col .. -1]
      end

      refresh_windows
    end

    #Delete one character at the specified position
    #
    #=== Arguments
    #_row_ :: Row position or line number.
    #_col_ :: Column position.
    def delete_at(row, col)
      if !valid_position?(row, col)
        raise "Invalid position was specified for 'delete' method."
      end

      if col >= @lines[row].size &&
          row == (lines.size - 1)
        raise EndOfBufferException.new
      elsif col >= @lines[row].size
        #Concatenate the next line behind the current line.
        @lines[row] << @lines[row + 1]
        @lines.delete_at(row + 1)

        refresh_windows
      else
        @lines[row] =
          @lines[row][0, col] + @lines[row][col + 1 .. -1]

        refresh_windows
      end
    end

    #Remove a string in the specified line behind the cursor.
    #
    #=== Arguments
    #_row_ :: Row position or line number.
    #_col_ :: Column position.
    #
    #=== Return
    #Deleted string.
    def delete_line(row, col)
      if !valid_position?(row, col)
        raise "Invalid position was specified for 'delete' method."
      end

      if col >= @lines[row].size &&
          row == (lines.size - 1)
        raise EndOfBufferException.new
      elsif col >= @lines[row].size
        #Concatenate the next line behind the current line.
        @lines[row] << @lines[row + 1]
        @lines.delete_at(row + 1)
        refresh_windows
        return "\n"
      else
        ret = @lines[row][col .. -1]
        @lines[row] = @lines[row][0, col]
        refresh_windows
        return ret
      end
    end

    #Append the specified string to the end of this buffer.
    #
    #=== Argument
    #
    #_str_ :: A string to be appended.
    def append(str)
      row = @lines.size - 1
      insert(row, @lines[row].size, str)

      refresh_windows
    end

    #Delete all characters in this buffer to make it empty.
    def clear
      @lines.clear
      @lines.push("")

      refresh_windows
    end
  end
end