Better reindenting for Sublime Text

Default.sublime-keymap

// Excerpt
    { "keys": ["tab"], "command": "sane_reindent", "context":
        [
            { "key": "setting.auto_indent", "operator": "equal", "operand": true },
            { "key": "selection_empty", "operator": "equal", "operand": true, "match_all": true },
            { "key": "preceding_text", "operator": "regex_match", "operand": "^$", "match_all": true },
            { "key": "following_text", "operator": "regex_match", "operand": "^$", "match_all": true }
        ]
    }

sane_reindent.py

import sublime
import sublime_plugin


class SaneReindentCommand(sublime_plugin.TextCommand):
    def run(self, edit):
        view = self.view

        max_index = view.size()
        to_reindent = {}

        sel = view.sel()
        regions = sorted(sel, key=lambda r: r.a, reverse=True)
        for region in regions:
            if not region.empty():
                return  # Don't have a spec for non-empty selections
            cursor = region.a
            cur_line = view.line(cursor)
            if not cur_line.empty():
                return  # Don't have a spec for non-empty lines
            index = cursor
            next_line = cur_line
            while next_line.empty() and index < max_index:
                index += 1
                next_line = view.line(index)
            if index == max_index:
                continue
            length = view.find_by_class(
                index - 1,  # Using the index itself seemed to act weird.
                True,
                # Just get anything, I don't care
                sublime.CLASS_WORD_START
                | sublime.CLASS_WORD_END
                | sublime.CLASS_PUNCTUATION_START
                | sublime.CLASS_PUNCTUATION_END
                | sublime.CLASS_SUB_WORD_START
                | sublime.CLASS_SUB_WORD_END
                | sublime.CLASS_LINE_END
            ) - index
            if length:
                to_reindent[cursor] = length * " "
        for region in regions:
            cursor = region.a
            view.insert(edit, cursor, to_reindent.get(cursor, "\t"))

I don't even use Sublime Text much any more. I just pinned this to flex on the builtin reindent logic, at least as far as Python development goes.