Solving an algorithm for a friend to be able to tell his emacs what window he wants to replace his current window when he closes it.

Readme.md

Solving an algorithm for a friend to be able to tell his emacs what window he wants to replace his current window when he closes it.

env.rb

def borderless(string)
  string.gsub(/^[-+|]/    , '')
        .gsub(/[-+|]$/    , '')
        .sub(/\A[-+|]*\n/ , '')
        .sub(/^[-+|]*\Z/  , '')
end

def leaf?(string)
  string !~ /[-+|]/
end

def split_cols(raw_cols)
  raw_cols[/\A.*$/].size
                   .times
                   .select { |index| raw_cols.each_line.all? { |line| '|+'.include? line[index] } }
                   .unshift(-1)
                   .push(0)
                   .each_cons(2)
                   .map { |left, right| raw_cols.each_line.map { |line| line[left+1..right-1].chomp } }
                   .map { |lines| lines.join "\n" }
end

def rows_for(raw_rows)
  raw_rows.split(/^[-+]*\n/)
          .map { |raw_cols| leaf?(raw_cols) ? raw_cols.strip : cols_for(raw_cols) }
          .unshift(:rows)
end

def cols_for(raw_cols)
  split_cols(raw_cols).map { |raw_rows| leaf?(raw_rows) ? raw_rows.strip : rows_for(raw_rows) }
                      .unshift(:cols)
end

def read_layout(string)
  rows_for borderless string
end

When 'I read the window layout:' do |s|
  @layout = read_layout(s.to_s)
end

Then 'the layout should be $struct' do |structure|
  structure.gsub!('(', '[')
  structure.gsub!(')', ']')
  structure.gsub!('] ', '], ')
  structure.gsub!(/(rows|cols) /, ':\1, ')
  structure.gsub!('" ', '", ')

  @layout.should == eval(structure)
end

read-layout.feature

Feature: Reading window layouts

  Scenario: one window
    When I read the window layout:
      """
      +---+
      | A |
      +---+
      """
    Then the layout should be (rows "A")

  Scenario: A|B
    When I read the window layout:
      """
      +---+---+
      | A | B |
      +---+---+
      """
    Then the layout should be (rows (cols "A" "B"))

  Scenario: A|B--C
    When I read the window layout:
      """
      +---+---+
      | A | B |
      +---+---+
      |   C   |
      +-------+
      """
    Then the layout should be (rows (cols "A" "B") "C")

  Scenario: A|B--C|D
    When I read the window layout:
      """
      +---+---+
      | A | B |
      +---+---+
      | C | D |
      +-------+
      """
    Then the layout should be (rows (cols "A" "B") (cols "C" "D"))

  Scenario: 3 rows
    When I read the window layout:
      """
      +---+
      | A |
      +---+
      | B |
      +---+
      | C |
      +---+
      """
    Then the layout should be (rows "A" "B" "C")

  Scenario: Inner horizontal split
    When I read the window layout:
      """
      +---+---+
      | A |   |
      +---+ B |
      | F |   |
      +---+---+
      |   C   |
      +-------+
      | D | E |
      +---+---+
      """
    Then the layout should be (rows (cols (rows "A" "F") "B") "C" (cols "D" "E"))

  Scenario: Inner vertical split
    When I read the window layout:
      """
      +---+---+---+
      |   | B | C |
      | A +---+---+
      |   |   D   |
      +---+---+---+
      |     E     |
      +-----------+
      """
    Then the layout should be (rows (cols "A" (rows (cols "B" "C") "D")) "E")

My friend's final version (in Elisp) https://github.com/pd/swallow-window.el/blob/master/swallow-window.el