TextAdept outline module

-- File outline (functions, globals, sections...) for TextAdept
--
-- Copyright 2018 Google LLC.
-- SPDX-License-Identifier: Apache 2.0
--
-- Usage: put the following somewhere in init.lua:
--     keys[CURSES and 'mo' or 'ao'] = require('outline').show
-- You can customize per-lexer patterns using outline.patters table

local textredux = require 'textredux'
local outline = {}
outline.patterns = {
  lua      = {"^function", "^local", "^[%w%d%._]+%s*="},
  go       = {"^import", "^func", "^type"},
  python   = {"^%s*def%s", "^%s*class%s", "^%s*[A-Z_]+%s*=", "^[%w_]+%s*="},
  protobuf = {"^%s*message", "^%s*enum", "^%s*service", "^%s*rpc"},
}
local function matches(str, patterns)
  if type(patterns) ~= "table" then patterns = {patterns} end
  local matched
  for _,p in ipairs(patterns) do
    matched = str:match(p); if matched then break end
  end
  if not matched then return false end
  if patterns.blacklist then
    for _,b in ipairs(patterns.blacklist) do
      if matched:match(b) then return false end
    end
  end
  return true
end
function outline.show()
  if not buffer.filename then return end
  local lines = {}
  local patterns = outline.patterns[buffer:get_lexer()]
  if patterns then
    -- find matching lines
    for i=0,buffer.line_count-1 do
      local line = buffer:get_line(i):sub(1,-2)
      if matches(line, patterns) then
        lines[#lines + 1] = {line, i}
      end
    end
  end
  if #lines == 0 then return end
  -- create the list
  local list = textredux.core.list.new(
    'Outline of ' .. buffer.filename:match('[^/]+$'),
    lines, -- list items
    function (list, item) -- on selection callback
      list:close()
      buffer:goto_line(item[2])
      buffer:vertical_centre_caret()
    end
  )
  list.keys.esc = function() list:close() end
  list:show()
end
return outline