Handle markdown from LSP data

[w0rp]

Related to #2922, it would be nice to handle markdown data from LSP responses for features like hover information, so the relevant languages can be loaded for syntax highlighting, and certain markdown format markers or whatever LSP sends can be turned into Vim highlights.

Here's an example from a project I work on, with output taken from pyright:

Ideally that can be rendered in a popup or preview window like this:

DEFAULTS: dict[str, Literal[False]]

I'd like to write a function that accepts markup data and returns [clean_string, highlights], where highlights is a List of highlights to render using Vim/NeoVim highlight functions.

[w0rp]

I've implemented basic handling for markdown formatting. Just code fences with syntax highlights for the preview window and \_ for now. There's more we can handle later, but those are the two most important things.

[blayz3r]

I still have the off-white color in the popup

[w0rp]

Could you provide a screenshot? Maybe I can figure out what that is.

[blayz3r]

Expecting

[blayz3r]

I have pyright and flake8 as my linters
let g:ale_hover_to_preview and let g:ale_hover_cursor don't seem to change anything

Current Filetype: python
Available Linters: ['bandit', 'flake8', 'mypy', 'prospector', 'pycodestyle', 'pydocstyle', 'pyflakes', 'pylama', 'pylint', 'pyls', 'pyre', 'pyright', 'vulture']
Enabled Linters: ['flake8', 'pyright']
Suggested Fixers:
'add_blank_lines_for_python_control_statements' - Add blank lines before control statements.
'autopep8' - Fix PEP8 issues with autopep8.
'black' - Fix PEP8 issues with black.
'isort' - Sort Python imports with isort.
'remove_trailing_lines' - Remove all blank lines at the end of a file.
'reorder-python-imports' - Sort Python imports with reorder-python-imports.
'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
'yapf' - Fix Python files with yapf.
Linter Variables:

let g:ale_python_auto_pipenv = 0
let g:ale_python_autopep8_options = '--aggressive'
let g:ale_python_flake8_auto_pipenv = 0
let g:ale_python_flake8_change_directory = 1
let g:ale_python_flake8_executable = 'flake8'
let g:ale_python_flake8_options = ''
let g:ale_python_flake8_use_global = 0
let g:ale_python_pyright_config = {}
let g:ale_python_pyright_executable = 'pyright-langserver'
Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = v:null
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '[%linter%] %s [%severity%]'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {'r': ['styler'], 'java': ['uncrustify', 'google_java_format'], 'python': ['black', 'isort', 'autopep8']}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 1
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'normal'
let g:ale_linter_aliases = {}
let g:ale_linters = {'zsh': ['shellcheck'], 'r': ['lintr'], 'sh': ['shellcheck'], 'bash': ['shellcheck'], 'javascript': ['jshint', 'eslint'], 'python': ['flake8', 'pyright']}
let g:ale_linters_explicit = 0
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '[%linter%] %s [%severity%]'
let g:ale_lsp_root = {}
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_set_balloons = 1
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 0
let g:ale_sign_error = '✗'
let g:ale_sign_info = '💡'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '✗'
let g:ale_sign_style_warning = ''
let g:ale_sign_warning = ''
let g:ale_sign_highlight_linenrs = 0
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
Command History:

(executable check - success) flake8
(finished - exit code 0) 'cmd /s/c "flake8 --version"'

<<>>
3.8.3 (mccabe: 0.6.1, pycodestyle: 2.6.0, pyflakes: 2.2.0) CPython 3.8.5 on
Windows
<<>>

(executable check - success) pyright-langserver
(started) 'cmd /s/c "pyright-langserver --stdio"'
(finished - exit code 1) 'cmd /s/c "cd /d D:\Library\Datascience\machine-learning-course\code\supervised\Logistic_Regression && flake8 --format=default --stdin-display-name D:\Library\Datascience\machine-learning-course\code\supervised\Logistic_Regression\logistic_ex1.py - < C:\Users\Tate\AppData\Local\Temp\VIC6601.tmp\logistic_ex1.py"'

<<>>
D:\Library\Datascience\machine-learning-course\code\supervised\Logistic_Regression\logistic_ex1.py:23:80: E501 line too long (84 > 79 characters)
<<>>

[w0rp]

That's not a bug, that's the difference between Vim popups and balloons. There's an open PR for popups here: #2925

It's held up because the author tried to implement two different uses of popups at once. One is somewhat ready to merge, the other I think will break things.

You can get syntax highlighting in the preview window with :ALEHover for long messages. You won't get documentation for symbols without installing type stubs that provide the documentation. Consult pyright documentation for that.