🔧 Add typing of rule functions (#283)

Rule functions signature is specific to the state it acts on.

Author: chrisjsewell

docs/conf.py

@@ -53,7 +53,6 @@
         ".*Literal.*",
         ".*_Result",
         "EnvType",
-        "RuleFunc",
         "Path",
         "Ellipsis",
     )

markdown_it/parser_block.py

@@ -2,7 +2,7 @@
 from __future__ import annotations
 
 import logging
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Callable
 
 from . import rules_block
 from .ruler import Ruler
@@ -16,7 +16,13 @@
 LOGGER = logging.getLogger(__name__)
 
 
-_rules: list[tuple[str, Any, list[str]]] = [
+RuleFuncBlockType = Callable[[StateBlock, int, int, bool], bool]
+"""(state: StateBlock, startLine: int, endLine: int, silent: bool) -> matched: bool)
+
+`silent` disables token generation, useful for lookahead.
+"""
+
+_rules: list[tuple[str, RuleFuncBlockType, list[str]]] = [
     # First 2 params - rule name & source. Secondary array - list of rules,
     # which can be terminated by this one.
     ("table", rules_block.table, ["paragraph", "reference"]),
@@ -45,7 +51,7 @@ class ParserBlock:
     """
 
     def __init__(self) -> None:
-        self.ruler = Ruler()
+        self.ruler = Ruler[RuleFuncBlockType]()
         for name, rule, alt in _rules:
             self.ruler.push(name, rule, {"alt": alt})
 

markdown_it/parser_core.py

@@ -6,7 +6,9 @@
 """
 from __future__ import annotations
 
-from .ruler import RuleFunc, Ruler
+from typing import Callable
+
+from .ruler import Ruler
 from .rules_core import (
     block,
     inline,
@@ -18,7 +20,9 @@
 )
 from .rules_core.state_core import StateCore
 
-_rules: list[tuple[str, RuleFunc]] = [
+RuleFuncCoreType = Callable[[StateCore], None]
+
+_rules: list[tuple[str, RuleFuncCoreType]] = [
     ("normalize", normalize),
     ("block", block),
     ("inline", inline),
@@ -31,7 +35,7 @@
 
 class ParserCore:
     def __init__(self) -> None:
-        self.ruler = Ruler()
+        self.ruler = Ruler[RuleFuncCoreType]()
         for name, rule in _rules:
             self.ruler.push(name, rule)
 

markdown_it/parser_inline.py

@@ -2,19 +2,25 @@
 """
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Callable
 
 from . import rules_inline
-from .ruler import RuleFunc, Ruler
+from .ruler import Ruler
 from .rules_inline.state_inline import StateInline
 from .token import Token
 from .utils import EnvType
 
 if TYPE_CHECKING:
     from markdown_it import MarkdownIt
 
+
 # Parser rules
-_rules: list[tuple[str, RuleFunc]] = [
+RuleFuncInlineType = Callable[[StateInline, bool], bool]
+"""(state: StateInline, silent: bool) -> matched: bool)
+
+`silent` disables token generation, useful for lookahead.
+"""
+_rules: list[tuple[str, RuleFuncInlineType]] = [
     ("text", rules_inline.text),
     ("linkify", rules_inline.linkify),
     ("newline", rules_inline.newline),
@@ -34,7 +40,8 @@
 #
 # Don't use this for anything except pairs (plugins working with `balance_pairs`).
 #
-_rules2: list[tuple[str, RuleFunc]] = [
+RuleFuncInline2Type = Callable[[StateInline], None]
+_rules2: list[tuple[str, RuleFuncInline2Type]] = [
     ("balance_pairs", rules_inline.link_pairs),
     ("strikethrough", rules_inline.strikethrough.postProcess),
     ("emphasis", rules_inline.emphasis.postProcess),
@@ -46,11 +53,11 @@
 
 class ParserInline:
     def __init__(self) -> None:
-        self.ruler = Ruler()
+        self.ruler = Ruler[RuleFuncInlineType]()
         for name, rule in _rules:
             self.ruler.push(name, rule)
         # Second ruler used for post-processing (e.g. in emphasis-like rules)
-        self.ruler2 = Ruler()
+        self.ruler2 = Ruler[RuleFuncInline2Type]()
         for name, rule2 in _rules2:
             self.ruler2.push(name, rule2)
 

markdown_it/ruler.py

@@ -17,9 +17,9 @@ class Ruler
 """
 from __future__ import annotations
 
-from collections.abc import Callable, Iterable
+from collections.abc import Iterable
 from dataclasses import dataclass, field
-from typing import TYPE_CHECKING, TypedDict
+from typing import TYPE_CHECKING, Generic, TypedDict, TypeVar
 import warnings
 
 from markdown_it._compat import DATACLASS_KWARGS
@@ -57,33 +57,30 @@ def srcCharCode(self) -> tuple[int, ...]:
         return self._srcCharCode
 
 
-# The first positional arg is always a subtype of `StateBase`. Other
-# arguments may or may not exist, based on the rule's type (block,
-# core, inline). Return type is either `None` or `bool` based on the
-# rule's type.
-RuleFunc = Callable  # type: ignore
-
-
 class RuleOptionsType(TypedDict, total=False):
     alt: list[str]
 
 
+RuleFuncTv = TypeVar("RuleFuncTv")
+"""A rule function, whose signature is dependent on the state type."""
+
+
 @dataclass(**DATACLASS_KWARGS)
-class Rule:
+class Rule(Generic[RuleFuncTv]):
     name: str
     enabled: bool
-    fn: RuleFunc = field(repr=False)
+    fn: RuleFuncTv = field(repr=False)
     alt: list[str]
 
 
-class Ruler:
+class Ruler(Generic[RuleFuncTv]):
     def __init__(self) -> None:
         # List of added rules.
-        self.__rules__: list[Rule] = []
+        self.__rules__: list[Rule[RuleFuncTv]] = []
         # Cached rule chains.
         # First level - chain name, '' for default.
         # Second level - diginal anchor for fast filtering by charcodes.
-        self.__cache__: dict[str, list[RuleFunc]] | None = None
+        self.__cache__: dict[str, list[RuleFuncTv]] | None = None
 
     def __find__(self, name: str) -> int:
         """Find rule index by name"""
@@ -112,7 +109,7 @@ def __compile__(self) -> None:
                 self.__cache__[chain].append(rule.fn)
 
     def at(
-        self, ruleName: str, fn: RuleFunc, options: RuleOptionsType | None = None
+        self, ruleName: str, fn: RuleFuncTv, options: RuleOptionsType | None = None
     ) -> None:
         """Replace rule by name with new function & options.
 
@@ -133,7 +130,7 @@ def before(
         self,
         beforeName: str,
         ruleName: str,
-        fn: RuleFunc,
+        fn: RuleFuncTv,
         options: RuleOptionsType | None = None,
     ) -> None:
         """Add new rule to chain before one with given name.
@@ -148,14 +145,16 @@ def before(
         options = options or {}
         if index == -1:
             raise KeyError(f"Parser rule not found: {beforeName}")
-        self.__rules__.insert(index, Rule(ruleName, True, fn, options.get("alt", [])))
+        self.__rules__.insert(
+            index, Rule[RuleFuncTv](ruleName, True, fn, options.get("alt", []))
+        )
         self.__cache__ = None
 
     def after(
         self,
         afterName: str,
         ruleName: str,
-        fn: RuleFunc,
+        fn: RuleFuncTv,
         options: RuleOptionsType | None = None,
     ) -> None:
         """Add new rule to chain after one with given name.
@@ -171,12 +170,12 @@ def after(
         if index == -1:
             raise KeyError(f"Parser rule not found: {afterName}")
         self.__rules__.insert(
-            index + 1, Rule(ruleName, True, fn, options.get("alt", []))
+            index + 1, Rule[RuleFuncTv](ruleName, True, fn, options.get("alt", []))
         )
         self.__cache__ = None
 
     def push(
-        self, ruleName: str, fn: RuleFunc, options: RuleOptionsType | None = None
+        self, ruleName: str, fn: RuleFuncTv, options: RuleOptionsType | None = None
     ) -> None:
         """Push new rule to the end of chain.
 
@@ -185,7 +184,9 @@ def push(
         :param options: new rule options (not mandatory).
 
         """
-        self.__rules__.append(Rule(ruleName, True, fn, (options or {}).get("alt", [])))
+        self.__rules__.append(
+            Rule[RuleFuncTv](ruleName, True, fn, (options or {}).get("alt", []))
+        )
         self.__cache__ = None
 
     def enable(
@@ -252,7 +253,7 @@ def disable(
         self.__cache__ = None
         return result
 
-    def getRules(self, chainName: str) -> list[RuleFunc]:
+    def getRules(self, chainName: str = "") -> list[RuleFuncTv]:
         """Return array of active functions (rules) for given chain name.
         It analyzes rules configuration, compiles caches if not exists and returns result.
 

markdown_it/rules_block/lheading.py

@@ -1,7 +1,6 @@
 # lheading (---, ==)
 import logging
 
-from ..ruler import Ruler
 from .state_block import StateBlock
 
 LOGGER = logging.getLogger(__name__)
@@ -12,7 +11,7 @@ def lheading(state: StateBlock, startLine: int, endLine: int, silent: bool) -> b
 
     level = None
     nextLine = startLine + 1
-    ruler: Ruler = state.md.block.ruler
+    ruler = state.md.block.ruler
     terminatorRules = ruler.getRules("paragraph")
 
     if state.is_code_block(startLine):

markdown_it/rules_block/paragraph.py

@@ -1,7 +1,6 @@
 """Paragraph."""
 import logging
 
-from ..ruler import Ruler
 from .state_block import StateBlock
 
 LOGGER = logging.getLogger(__name__)
@@ -13,7 +12,7 @@ def paragraph(state: StateBlock, startLine: int, endLine: int, silent: bool) ->
     )
 
     nextLine = startLine + 1
-    ruler: Ruler = state.md.block.ruler
+    ruler = state.md.block.ruler
     terminatorRules = ruler.getRules("paragraph")
     endLine = state.lineMax
 

tests/test_api/test_plugin_creation.py

@@ -6,26 +6,27 @@
 
 def inline_rule(state, silent):
     print("plugin called")
+    return False
 
 
 def test_inline_after(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.inline.ruler.after("text", "new_rule", inline_rule)
 
     MarkdownIt().use(_plugin).parse("[")
     assert "plugin called" in capsys.readouterr().out
 
 
 def test_inline_before(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.inline.ruler.before("text", "new_rule", inline_rule)
 
     MarkdownIt().use(_plugin).parse("a")
     assert "plugin called" in capsys.readouterr().out
 
 
 def test_inline_at(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.inline.ruler.at("text", inline_rule)
 
     MarkdownIt().use(_plugin).parse("a")
@@ -34,26 +35,27 @@ def _plugin(_md):
 
 def block_rule(state, startLine, endLine, silent):
     print("plugin called")
+    return False
 
 
 def test_block_after(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.block.ruler.after("hr", "new_rule", block_rule)
 
     MarkdownIt().use(_plugin).parse("a")
     assert "plugin called" in capsys.readouterr().out
 
 
 def test_block_before(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.block.ruler.before("hr", "new_rule", block_rule)
 
     MarkdownIt().use(_plugin).parse("a")
     assert "plugin called" in capsys.readouterr().out
 
 
 def test_block_at(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.block.ruler.at("hr", block_rule)
 
     MarkdownIt().use(_plugin).parse("a")
@@ -65,23 +67,23 @@ def core_rule(state):
 
 
 def test_core_after(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.core.ruler.after("normalize", "new_rule", core_rule)
 
     MarkdownIt().use(_plugin).parse("a")
     assert "plugin called" in capsys.readouterr().out
 
 
 def test_core_before(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.core.ruler.before("normalize", "new_rule", core_rule)
 
     MarkdownIt().use(_plugin).parse("a")
     assert "plugin called" in capsys.readouterr().out
 
 
 def test_core_at(capsys):
-    def _plugin(_md):
+    def _plugin(_md: MarkdownIt) -> None:
         _md.core.ruler.at("normalize", core_rule)
 
     MarkdownIt().use(_plugin).parse("a")