Enable pasted lines to switch to pkg, shell and help repl modes

[IanButterworth]

Currently it's possible to paste julia> 1+1 into the repl, and julia> will be stripped, and the 1+1 evaluated, etc.

This adds the handling of pkg> , shell> , and help?> prefixes, which are stripped and the mode changed.

With this PR, for instance if I copy this

julia> 1 + 1

shell> pwd

help?> trues

pkg> st

and paste it into the julia> repl mode, I get:

julia> 1 + 1
2

shell> pwd
/Users/ian/Documents/GitHub/julia

help?> trues
search: trues truncate InterruptException promote_rule isstructtype AbstractUnitRange

  trues(dims)

  Create a BitArray with all values set to true.

  Examples
  ≡≡≡≡≡≡≡≡≡≡

  julia> trues(2,3)
  2×3 BitMatrix:
   1  1  1
   1  1  1

(@v1.7) pkg> st
      Status `~/.julia/environments/v1.7/Project.toml`
  [6e4b80f9] BenchmarkTools v0.7.0
  [295af30f] Revise v3.1.15

(@v1.7) pkg> 

Note that this only works for pasted text. Typing pkg> st into the julia> repl won't trigger the same behavior as it is paste-specific like the existing julia> prefix handling

[IanButterworth]

If this lands, perhaps Pkg should use this const for constructing the prefix

[KristofferC]

Can I paste in

julia> 1+1
2

(@v1.7) pkg> st
      Status `~/.julia/environments/v1.7/Project.toml`
  [d2c73de3] GR_jll v0.57.2+0

shell> echo foo
foo

?

[IanButterworth]

Ah no, good point. That one needs to be a regex

[IanButterworth]

@KristofferC I've fixed the pkg prompt with env prefixes, but I didn't see the shell issue coming..

This is the result of pasting in your example. Why isn't the newline executing the echo??

julia> 1+1
2

(@v1.7) pkg> st
      Status `~/.julia/environments/v1.7/Project.toml`
  [6e4b80f9] BenchmarkTools v0.7.0
  [3da002f7] ColorTypes v0.10.12
  [295af30f] Revise v3.1.15

shell> echo foo
       foo

If I then press return I get

shell> echo foo
       foo
foo foo

[simeonschaub]

If I then press return I get

shell> echo foo
       foo
foo foo

Pretty sure that is the expected behavior for multiline commands. Not great, I agree, but it is what it is.

[IanButterworth]

I think the thing to do is to check if the next line is indented to the prompt start, and if so, treat it like a multiline command and add a return at the end to execute it

[IanButterworth]

Multiline shell commands are now handled by identifying them if they are indented in alignment with the prompt.

Also, the indented prompts in the docstrings that might show in help mode are ignored until the next non-indented prompt. So indented prompts are still handled as before, just not within a a help?>.

So pasting this in looks identical after execution

julia> 1 + 1
2

shell> echo foo
       foo
foo foo

shell> echo foo
foo

help?> trues
search: trues truncate InterruptException promote_rule isstructtype AbstractUnitRange

  trues(dims)

  Create a BitArray with all values set to true.

  Examples
  ≡≡≡≡≡≡≡≡≡≡

  julia> trues(2,3)
  2×3 BitMatrix:
   1  1  1
   1  1  1

(@v1.7) pkg> st
      Status `~/.julia/environments/v1.7/Project.toml`
  [6e4b80f9] BenchmarkTools v0.7.0
  [295af30f] Revise v3.1.15

(@v1.7) pkg> 

[IanButterworth]

Good to merge?