Refactor configuration file parsing

Now the time for importing the kitty.config module has been halved, from
16ms from 32ms on my machine. Also, the new architecture will eventually
allow for auto generating a bunch of python-to-C boilerplate code.

kittens/diff/config.py

@@ -3,21 +3,16 @@
 # License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
 
 import os
-from typing import Any, Dict, FrozenSet, Iterable, Optional, Tuple, Type, Union
+from typing import Any, Dict, Iterable, Optional
 
 from kitty.cli_stub import DiffCLIOptions
-from kitty.conf.definition import config_lines
 from kitty.conf.utils import (
-    init_config as _init_config, key_func, load_config as _load_config,
-    merge_dicts, parse_config_base, parse_kittens_key, resolve_config
+    load_config as _load_config, parse_config_base, resolve_config
 )
 from kitty.constants import config_dir
-from kitty.options_stub import DiffOptions
 from kitty.rgb import color_as_sgr
 
-from .config_data import all_options
-
-defaults: Optional[DiffOptions] = None
+from .options.types import Options as DiffOptions, defaults
 
 formats: Dict[str, str] = {
     'title': '',
@@ -42,97 +37,27 @@ def set_formats(opts: DiffOptions) -> None:
     formats['added_highlight'] = '48' + color_as_sgr(opts.highlight_added_bg)
 
 
-func_with_args, args_funcs = key_func()
-
-
-@func_with_args('scroll_by')
-def parse_scroll_by(func: str, rest: str) -> Tuple[str, int]:
-    try:
-        return func, int(rest)
-    except Exception:
-        return func, 1
-
-
-@func_with_args('scroll_to')
-def parse_scroll_to(func: str, rest: str) -> Tuple[str, str]:
-    rest = rest.lower()
-    if rest not in {'start', 'end', 'next-change', 'prev-change', 'next-page', 'prev-page', 'next-match', 'prev-match'}:
-        rest = 'start'
-    return func, rest
-
-
-@func_with_args('change_context')
-def parse_change_context(func: str, rest: str) -> Tuple[str, Union[int, str]]:
-    rest = rest.lower()
-    if rest in {'all', 'default'}:
-        return func, rest
-    try:
-        amount = int(rest)
-    except Exception:
-        amount = 5
-    return func, amount
-
-
-@func_with_args('start_search')
-def parse_start_search(func: str, rest: str) -> Tuple[str, Tuple[bool, bool]]:
-    rest_ = rest.lower().split()
-    is_regex = bool(rest_ and rest_[0] == 'regex')
-    is_backward = bool(len(rest_) > 1 and rest_[1] == 'backward')
-    return func, (is_regex, is_backward)
-
-
-def special_handling(key: str, val: str, ans: Dict) -> bool:
-    if key == 'map':
-        x = parse_kittens_key(val, args_funcs)
-        if x is not None:
-            action, key_def = x
-            ans['key_definitions'][key_def] = action
-            return True
-    return False
-
-
-def parse_config(lines: Iterable[str], check_keys: bool = True) -> Dict[str, Any]:
-    ans: Dict[str, Any] = {'key_definitions': {}}
-    defs: Optional[FrozenSet] = None
-    if check_keys:
-        defs = frozenset(defaults._fields)  # type: ignore
-
-    parse_config_base(
-        lines,
-        defs,
-        all_options,
-        special_handling,
-        ans,
-    )
-    return ans
-
-
-def merge_configs(defaults: Dict, vals: Dict) -> Dict:
-    ans = {}
-    for k, v in defaults.items():
-        if isinstance(v, dict):
-            newvals = vals.get(k, {})
-            ans[k] = merge_dicts(v, newvals)
-        else:
-            ans[k] = vals.get(k, v)
-    return ans
-
-
-def parse_defaults(lines: Iterable[str], check_keys: bool = False) -> Dict[str, Any]:
-    return parse_config(lines, check_keys)
-
-
-x = _init_config(config_lines(all_options), parse_defaults)
-Options: Type[DiffOptions] = x[0]
-defaults = x[1]
+SYSTEM_CONF = '/etc/xdg/kitty/diff.conf'
+defconf = os.path.join(config_dir, 'diff.conf')
 
 
 def load_config(*paths: str, overrides: Optional[Iterable[str]] = None) -> DiffOptions:
-    return _load_config(Options, defaults, parse_config, merge_configs, *paths, overrides=overrides)
+    from .options.parse import (
+        create_result_dict, merge_result_dicts, parse_conf_item
+    )
 
+    def parse_config(lines: Iterable[str]) -> Dict[str, Any]:
+        ans: Dict[str, Any] = create_result_dict()
+        parse_config_base(
+            lines,
+            parse_conf_item,
+            ans,
+        )
+        return ans
 
-SYSTEM_CONF = '/etc/xdg/kitty/diff.conf'
-defconf = os.path.join(config_dir, 'diff.conf')
+    opts_dict = _load_config(defaults, parse_config, merge_result_dicts, *paths, overrides=overrides)
+    opts = DiffOptions(opts_dict)
+    return opts
 
 
 def init_config(args: DiffCLIOptions) -> DiffOptions:
@@ -140,4 +65,6 @@ def init_config(args: DiffCLIOptions) -> DiffOptions:
     overrides = (a.replace('=', ' ', 1) for a in args.override or ())
     opts = load_config(*config, overrides=overrides)
     set_formats(opts)
+    for (sc, action) in opts.map:
+        opts.key_definitions[sc] = action
     return opts