svn/view/mini_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 ReadOnlyException < EdmaruException
    def initialize
      super("Text is read-only.")
    end
  end

  #The instance of this class represents one string sequence that doesn't
  #contain line feeds.
  class MiniBuffer < Buffer

    #Create a new buffer.
    #
    #=== Argument
    #_name_ :: The unique title of this buffer.
    #
    #=== Return
    #An initialized buffer.
    def initialize(name)
      @name = name
      @line = String.new
      @prefix = ""

      @related_window = Array.new
    end

    #All lines in this buffer.
    #
    #=== Return
    #An array of string including only one element (line).
    def lines
      [@line]
    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
        # Invalid row position.
        return false
      elsif col < 0 || col > @line.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")
        str = str.split(/\n/, -1)[0]
      end

      if !@prefix.empty? && col < @prefix.size
          raise ReadOnlyException.new        
      end

      pre = @line.clone
      @line = pre[0, col]
      @line << str
      @line << pre[col .. -1]

      refresh_windows
    end

    #Delete one character at the specified position
    #
    #=== Arguments
    #_row_ :: Row position or line number. This must be 1 for mini buffer.
    #_col_ :: Column position.
    def delete_at(row, col)
      if !valid_position?(row, col)
        raise "Invalid position was specified for 'delete' method."
      end

      if col >= @line.size
        raise EndOfBufferException.new
      elsif col < @prefix.size
        raise ReadOnlyException.new
      else
        @line = @line[0, col] + @line[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 >= @line.size
        raise EndOfBufferException.new
      else
        if col < @prefix.size
          raise ReadOnlyException.new
        end

        ret = @line[col .. -1]
        @line = @line[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)
      insert(0, @line.size, str)
    end
    
    #Delete all characters in this buffer to make it empty but prefix
    #will be remained.
    def clear
      @line = @prefix
      
      refresh_windows
    end

    #Set prefix for this buffer. Prefix cannot be changed by users.
    #
    #=== Argument
    #_new_prefix_ :: New prefix to be set.
    def prefix=(new_prefix)
      @prefix = new_prefix

      if @line[0, @prefix.size] != @prefix
        @line = @prefix + @line
      end
    end

    #Get prefix for this buffer.
    def prefix
      @prefix
    end

    #Get text in this buffer excluding prefix.
    def text_without_prefix
      @line[@prefix.size .. -1]
    end
  end
end