REPL/LineEdit to support "undo": part of JuliaLang#8447

The REPL now supports undo via Ctrl-^ or Ctrl-_.

This should very closely minic the behavior of other readline/emacs
shells, except it doesn't let the user goto a historical entry (A),
edit it, goto a different historical entry (B), return to the first
(A) and undo the edits.

NEWS.md

@@ -168,6 +168,11 @@ Deprecated or removed
  * `randbool` is deprecated. Use `rand(Bool)` to produce a random boolean value, and
  `bitrand` to produce a random BitArray ([#9105], [#9569]).
 
+REPL improvements
+-----------------
+
+ * Undo via Ctrl-/ and Ctrl-_
+
 Julia v0.3.0 Release Notes
 ==========================
 

base/LineEdit.jl

@@ -55,6 +55,7 @@ type PromptState <: ModeState
  terminal::TextTerminal
  p::Prompt
  input_buffer::IOBuffer
+ undo_buffers::Vector{IOBuffer}
  ias::InputAreaState
  indent::Int
 end
@@ -87,7 +88,8 @@ terminal(s::PromptState) = s.terminal
 
 for f in [:terminal, :edit_insert, :on_enter, :add_history, :buffer, :edit_backspace, :(Base.isempty),
  :replace_line, :refresh_multi_line, :input_string, :edit_move_left, :edit_move_right,
- :edit_move_word_left, :edit_move_word_right, :update_display_buffer]
+ :edit_move_word_left, :edit_move_word_right, :update_display_buffer,
+ :empty_undo, :push_undo, :pop_undo]
  @eval ($f)(s::MIState, args...) = $(f)(s.mode_state[s.current_mode], args...)
 end
 
@@ -146,16 +148,14 @@ function complete_line(s::PromptState, repeats)
  elseif length(completions) == 1
  # Replace word by completion
  prev_pos = position(s.input_buffer)
- seek(s.input_buffer, prev_pos-sizeof(partial))
- edit_replace(s, position(s.input_buffer), prev_pos, completions[1])
+ edit_replace(s, prev_pos-sizeof(partial), prev_pos, completions[1])
  else
  p = common_prefix(completions)
  if length(p) > 0 && p != partial
  # All possible completions share the same prefix, so we might as
  # well complete that
  prev_pos = position(s.input_buffer)
- seek(s.input_buffer, prev_pos-sizeof(partial))
- edit_replace(s, position(s.input_buffer), prev_pos, p)
+ edit_replace(s, prev_pos-sizeof(partial), prev_pos, p)
  elseif repeats > 0
  show_completions(s, completions)
  end
@@ -479,10 +479,12 @@ function splice_buffer!{T<:Integer}(buf::IOBuffer, r::UnitRange{T}, ins::Abstrac
 end
 
 function edit_replace(s, from, to, str)
+ push_undo(s)
  splice_buffer!(buffer(s), from:to-1, str)
 end
 
 function edit_insert(s::PromptState, c)
+ push_undo(s)
  str = string(c)
  edit_insert(s.input_buffer, str)
  if !('\n' in str) && eof(s.input_buffer) &&
@@ -503,9 +505,11 @@ function edit_insert(buf::IOBuffer, c)
 end
 
 function edit_backspace(s::PromptState)
+ push_undo(s)
  if edit_backspace(s.input_buffer)
  refresh_line(s)
  else
+ pop_undo(s)
  beep(terminal(s))
  end
 end
@@ -520,7 +524,15 @@ function edit_backspace(buf::IOBuffer)
  end
 end
 
-edit_delete(s) = edit_delete(buffer(s)) ? refresh_line(s) : beep(terminal(s))
+function edit_delete(s)
+ push_undo(s)
+ if edit_delete(buffer(s))
+ refresh_line(s)
+ else
+ pop_undo(s)
+ beep(terminal(s))
+ end
+end
 function edit_delete(buf::IOBuffer)
  eof(buf) && return false
  oldpos = position(buf)
@@ -538,7 +550,8 @@ function edit_werase(buf::IOBuffer)
  true
 end
 function edit_werase(s)
- edit_werase(buffer(s)) && refresh_line(s)
+ push_undo(s)
+ edit_werase(buffer(s)) ? refresh_line(s) : pop_undo(s)
 end
 
 function edit_delete_prev_word(buf::IOBuffer)
@@ -550,7 +563,8 @@ function edit_delete_prev_word(buf::IOBuffer)
  true
 end
 function edit_delete_prev_word(s)
- edit_delete_prev_word(buffer(s)) && refresh_line(s)
+ push_undo(s)
+ edit_delete_prev_word(buffer(s)) ? refresh_line(s) : pop_undo(s)
 end
 
 function edit_delete_next_word(buf::IOBuffer)
@@ -562,15 +576,18 @@ function edit_delete_next_word(buf::IOBuffer)
  true
 end
 function edit_delete_next_word(s)
- edit_delete_next_word(buffer(s)) && refresh_line(s)
+ push_undo(s)
+ edit_delete_next_word(buffer(s)) ? refresh_line(s) : pop_undo(s)
 end
 
 function edit_yank(s::MIState)
+ push_undo(s)
  edit_insert(buffer(s), s.kill_buffer)
  refresh_line(s)
 end
 
 function edit_kill_line(s::MIState)
+ push_undo(s)
  buf = buffer(s)
  pos = position(buf)
  killbuf = readline(buf)
@@ -584,7 +601,10 @@ function edit_kill_line(s::MIState)
  refresh_line(s)
 end
 
-edit_transpose(s) = edit_transpose(buffer(s)) && refresh_line(s)
+function edit_transpose(s)
+ push_undo(s)
+ edit_transpose(buffer(s)) ? refresh_line(s) : pop_undo(s)
+end
 function edit_transpose(buf::IOBuffer)
  position(buf) == 0 && return false
  eof(buf) && char_move_left(buf)
@@ -599,15 +619,18 @@ end
 edit_clear(buf::IOBuffer) = truncate(buf, 0)
 
 function edit_clear(s::MIState)
+ push_undo(s)
  edit_clear(buffer(s))
  refresh_line(s)
 end
 
 function replace_line(s::PromptState, l::IOBuffer)
+ empty_undo(s)
  s.input_buffer = l
 end
 
 function replace_line(s::PromptState, l)
+ empty_undo(s)
  s.input_buffer.ptr = 1
  s.input_buffer.size = 0
  write(s.input_buffer, l)
@@ -1112,8 +1135,7 @@ function complete_line(s::SearchState, repeats)
  # For now only allow exact completions in search mode
  if length(completions) == 1
  prev_pos = position(s.query_buffer)
- seek(s.query_buffer, prev_pos-sizeof(partial))
- edit_replace(s, position(s.query_buffer), prev_pos, completions[1])
+ edit_replace(s, prev_pos-sizeof(partial), prev_pos, completions[1])
  end
 end
 
@@ -1345,6 +1367,9 @@ AnyDict(
  # Meta Enter
  "\e\r" => (s,o...)->(edit_insert(s, '\n')),
  "\e\n" => "\e\r",
+ # Undo: Ctrl-/ or Ctrl-_
+ "^/" => (s,o...)->(pop_undo(s) ? refresh_line(s) : beep(terminal(s))),
+ "^_" => "^/",
  # Simply insert it into the buffer by default
  "*" => (s,data,c)->(edit_insert(s, c)),
  "^U" => (s,o...)->edit_clear(s),
@@ -1483,6 +1508,7 @@ function reset_state(s::PromptState)
  s.input_buffer.size = 0
  s.input_buffer.ptr = 1
  end
+ empty_undo(s)
  s.ias = InputAreaState(0, 0)
 end
 
@@ -1512,7 +1538,7 @@ end
 
 run_interface(::Prompt) = nothing
 
-init_state(terminal, prompt::Prompt) = PromptState(terminal, prompt, IOBuffer(), InputAreaState(1, 1), length(prompt.prompt))
+init_state(terminal, prompt::Prompt) = PromptState(terminal, prompt, IOBuffer(), (IOBuffer)[], InputAreaState(1, 1), length(prompt.prompt))
 
 function init_state(terminal, m::ModalInterface)
  s = MIState(m, m.modes[1], false, Dict{Any,Any}())
@@ -1539,6 +1565,23 @@ buffer(s::PromptState) = s.input_buffer
 buffer(s::SearchState) = s.query_buffer
 buffer(s::PrefixSearchState) = s.response_buffer
 
+function empty_undo(s::PromptState)
+ empty!(s.undo_buffers)
+end
+empty_undo(s) = nothing
+
+function push_undo(s::PromptState)
+ push!(s.undo_buffers, copy(s.input_buffer))
+end
+push_undo(s) = nothing
+
+function pop_undo(s::PromptState)
+ length(s.undo_buffers) > 0 || return false
+ s.input_buffer = pop!(s.undo_buffers)
+ true
+end
+pop_undo(s) = nothing
+
 keymap(s::PromptState, prompt::Prompt) = prompt.keymap_dict
 keymap_data(s::PromptState, prompt::Prompt) = prompt.keymap_func_data
 keymap(ms::MIState, m::ModalInterface) = keymap(ms.mode_state[ms.current_mode], ms.current_mode)

doc/manual/interacting-with-julia.rst

@@ -159,7 +159,7 @@ The Julia REPL makes great use of key bindings. Several control-key bindings we
 +------------------------+----------------------------------------------------+
 | ``^T`` | Transpose the characters about the cursor |
 +------------------------+----------------------------------------------------+
-| Delete, ``^D`` | Forward delete one character (when buffer has text)|
+| ``^/``, ``^_`` | Undo |
 +------------------------+----------------------------------------------------+
 
 Customizing keybindings

test/lineedit.jl

@@ -395,3 +395,96 @@ term = TestHelpers.FakeTerminal(IOBuffer(), IOBuffer(), IOBuffer())
 s = LineEdit.refresh_multi_line(termbuf, term, buf,
  Base.LineEdit.InputAreaState(0,0), "julia> ", indent = 7)
 @test s == Base.LineEdit.InputAreaState(3,1)
+
+# test Undo
+let
+ term = TestHelpers.FakeTerminal(IOBuffer(), IOBuffer(), IOBuffer())
+ s = LineEdit.init_state(term, ModalInterface([Prompt("test> ")]))
+ function bufferdata(s)
+ buf = LineEdit.buffer(s)
+ bytestring(buf.data[1:buf.size])
+ end
+
+ LineEdit.edit_insert(s, "one two three")
+
+ LineEdit.edit_delete_prev_word(s)
+ @test bufferdata(s) == "one two "
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.edit_insert(s, " four")
+ LineEdit.edit_insert(s, " five")
+ @test bufferdata(s) == "one two three four five"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three four"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.edit_clear(s)
+ @test bufferdata(s) == ""
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.edit_move_left(s)
+ LineEdit.edit_move_left(s)
+ LineEdit.edit_transpose(s)
+ @test bufferdata(s) == "one two there"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.move_line_start(s)
+ LineEdit.edit_kill_line(s)
+ @test bufferdata(s) == ""
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.move_line_start(s)
+ LineEdit.edit_kill_line(s)
+ LineEdit.edit_yank(s)
+ LineEdit.edit_yank(s)
+ @test bufferdata(s) == "one two threeone two three"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == ""
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.move_line_end(s)
+ LineEdit.edit_backspace(s)
+ LineEdit.edit_backspace(s)
+ LineEdit.edit_backspace(s)
+ @test bufferdata(s) == "one two th"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two thr"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two thre"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.edit_replace(s, 4, 7, "stott")
+ @test bufferdata(s) == "one stott three"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.edit_move_left(s)
+ LineEdit.edit_move_left(s)
+ LineEdit.edit_move_left(s)
+ LineEdit.edit_delete(s)
+ @test bufferdata(s) == "one two thee"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ LineEdit.edit_move_word_left(s)
+ LineEdit.edit_werase(s)
+ LineEdit.edit_delete_next_word(s)
+ @test bufferdata(s) == "one "
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one three"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == "one two three"
+
+ # pop initial insert of "one two three"
+ LineEdit.pop_undo(s)
+ @test bufferdata(s) == ""
+end