REPL: add an Options type to handle REPL options

It was previously not practical to disable the "align"
feature of backspace: overwriting the '\b' binding with:
`'\b' => (s,o...) -> Base.LineEdit.edit_backspace(s, false)`
worked to a certain extent, but for example it was disabling
the feature that '\b' must get you out of shell/help mode.

A new experimental Options type is introduced here, which is
meant to conveniently allow users to pass options controlling
the REPL behavior. For example:

atreplinit() do repl
    repl.options = Base.REPL.Options(backspace_align = false)
end

base/repl/LineEdit.jl

@@ -27,7 +27,7 @@ mutable struct Prompt <: TextInterface
  # Same as prefix except after the prompt
  prompt_suffix::Union{String,Function}
  keymap_dict::Dict{Char}
- keymap_func_data # ::AbstractREPL
+ repl # ::AbstractREPL
  complete # ::REPLCompletionProvider
  on_enter::Function
  on_done::Function
@@ -75,6 +75,8 @@ mutable struct PromptState <: ModeState
  indent::Int
 end
 
+options(s::PromptState) = isdefined(s.p, :repl) ? s.p.repl.options : Base.REPL.Options()
+
 setmark(s) = mark(buffer(s))
 
 # the default mark is 0
@@ -116,7 +118,7 @@ terminal(s::PromptState) = s.terminal
 
 for f in [:terminal, :on_enter, :add_history, :buffer, :(Base.isempty),
  :replace_line, :refresh_multi_line, :input_string, :update_display_buffer,
- :empty_undo, :push_undo, :pop_undo]
+ :empty_undo, :push_undo, :pop_undo, :options]
  @eval ($f)(s::MIState, args...) = $(f)(state(s), args...)
 end
 
@@ -549,7 +551,8 @@ end
 # align: delete up to 4 spaces to align to a multiple of 4 chars
 # adjust: also delete spaces on the right of the cursor to try to keep aligned what is
 # on the right
-function edit_backspace(s::PromptState, align::Bool=false, adjust=align)
+function edit_backspace(s::PromptState, align::Bool=options(s).backspace_align,
+ adjust=options(s).backspace_adjust)
  push_undo(s)
  if edit_backspace(buffer(s), align, adjust)
  refresh_line(s)
@@ -571,7 +574,7 @@ function endofline(buf, pos=position(buf))
  eol == 0 ? buf.size : pos + eol - 1
 end
 
-function edit_backspace(buf::IOBuffer, align::Bool=false, adjust::Bool=align)
+function edit_backspace(buf::IOBuffer, align::Bool=false, adjust::Bool=false)
  !align && adjust &&
  throw(DomainError((align, adjust),
  "if `adjust` is `true`, `align` must be `true`"))
@@ -1649,7 +1652,7 @@ AnyDict(
  end,
  '\n' => KeyAlias('\r'),
  # Backspace/^H
- '\b' => (s,o...)->edit_backspace(s, true),
+ '\b' => (s,o...)->edit_backspace(s),
  127 => KeyAlias('\b'),
  # Meta Backspace
  "\e\b" => (s,o...)->edit_delete_prev_word(s),
@@ -1860,14 +1863,14 @@ function Prompt(prompt;
  prompt_prefix = "",
  prompt_suffix = "",
  keymap_dict = default_keymap_dict,
- keymap_func_data = nothing,
+ repl = nothing,
  complete = EmptyCompletionProvider(),
  on_enter = default_enter_cb,
  on_done = ()->nothing,
  hist = EmptyHistoryProvider(),
  sticky = false)
 
- Prompt(prompt, prompt_prefix, prompt_suffix, keymap_dict, keymap_func_data,
+ Prompt(prompt, prompt_prefix, prompt_suffix, keymap_dict, repl,
  complete, on_enter, on_done, hist, sticky)
 end
 
@@ -1968,7 +1971,7 @@ end
 edit_redo!(s) = nothing
 
 keymap(s::PromptState, prompt::Prompt) = prompt.keymap_dict
-keymap_data(s::PromptState, prompt::Prompt) = prompt.keymap_func_data
+keymap_data(s::PromptState, prompt::Prompt) = prompt.repl
 keymap(ms::MIState, m::ModalInterface) = keymap(state(ms), mode(ms))
 keymap_data(ms::MIState, m::ModalInterface) = keymap_data(state(ms), mode(ms))
 

base/repl/REPL.jl

@@ -241,6 +241,16 @@ function run_frontend(repl::BasicREPL, backend::REPLBackendRef)
  dopushdisplay && popdisplay(d)
 end
 
+## Custom Options
+
+mutable struct Options
+ backspace_align::Bool
+ backspace_adjust::Bool
+end
+
+Options(; backspace_align=true, backspace_adjust=backspace_align) =
+ Options(backspace_align, backspace_adjust)
+
 ## LineEditREPL ##
 
 mutable struct LineEditREPL <: AbstractREPL
@@ -257,11 +267,12 @@ mutable struct LineEditREPL <: AbstractREPL
  envcolors::Bool
  waserror::Bool
  specialdisplay::Union{Void,Display}
+ options::Options
  interface::ModalInterface
  backendref::REPLBackendRef
  LineEditREPL(t,hascolor,prompt_color,input_color,answer_color,shell_color,help_color,history_file,in_shell,in_help,envcolors) =
  new(t,true,prompt_color,input_color,answer_color,shell_color,help_color,history_file,in_shell,
- in_help,envcolors,false,nothing)
+ in_help,envcolors,false,nothing, Options())
 end
 outstream(r::LineEditREPL) = r.t
 specialdisplay(r::LineEditREPL) = r.specialdisplay
@@ -741,7 +752,7 @@ function setup_interface(
  prompt_prefix = hascolor ? repl.prompt_color : "",
  prompt_suffix = hascolor ?
  (repl.envcolors ? Base.input_color : repl.input_color) : "",
- keymap_func_data = repl,
+ repl = repl,
  complete = replc,
  on_enter = return_callback)
 
@@ -750,7 +761,7 @@ function setup_interface(
  prompt_prefix = hascolor ? repl.help_color : "",
  prompt_suffix = hascolor ?
  (repl.envcolors ? Base.input_color : repl.input_color) : "",
- keymap_func_data = repl,
+ repl = repl,
  complete = replc,
  # When we're done transform the entered line into a call to help("$line")
  on_done = respond(Docs.helpmode, repl, julia_prompt))
@@ -760,7 +771,7 @@ function setup_interface(
  prompt_prefix = hascolor ? repl.shell_color : "",
  prompt_suffix = hascolor ?
  (repl.envcolors ? Base.input_color : repl.input_color) : "",
- keymap_func_data = repl,
+ repl = repl,
  complete = ShellCompletionProvider(),
  # Transform "foo bar baz" into `foo bar baz` (shell quoting)
  # and pass into Base.repl_cmd for processing (handles `ls` and `cd`

test/lineedit.jl

@@ -330,7 +330,7 @@ let buf = IOBuffer()
  @test position(buf) == 0
  LineEdit.edit_move_right(buf)
  @test nb_available(buf) == 0
- LineEdit.edit_backspace(buf)
+ LineEdit.edit_backspace(buf, false, false)
  @test content(buf) == "a"
 end
 
@@ -699,9 +699,9 @@ end
  @test edit!(edit_undo!) == "one two three"
 
  LineEdit.move_line_end(s)
- LineEdit.edit_backspace(s)
- LineEdit.edit_backspace(s)
- @test edit!(LineEdit.edit_backspace) == "one two th"
+ LineEdit.edit_backspace(s, false, false)
+ LineEdit.edit_backspace(s, false, false)
+ @test edit!(s->LineEdit.edit_backspace(s, false, false)) == "one two th"
  @test edit!(edit_undo!) == "one two thr"
  @test edit!(edit_undo!) == "one two thre"
  @test edit!(edit_undo!) == "one two three"