feat: add hooks

integrity/__init__.py

@@ -2,6 +2,7 @@
 
 from .api import Integrity as _Integrity
 from .components import Components as _Components
+from .hooks import Hook as _Hook
 from .plugin import beet_default
 
 __all__ = ["Component", "beet_default"]

integrity/hooks.py

@@ -0,0 +1,63 @@
+from contextlib import contextmanager
+from dataclasses import dataclass, field, replace
+from typing import Dict, List
+from beet import Context
+from beet.core.utils import required_field
+from bolt import Runtime
+from mecha import AstChildren, AstNode, AstRoot, MutatingReducer, rule
+
+from .api import Integrity
+
+
+def beet_default(ctx: Context):
+    ctx.inject(Hook)
+
+
+@dataclass
+class Hook:
+    ctx: Context = field(repr=False)
+    api: Integrity = field(init=False, repr=False)
+    runtime: Runtime = field(init=False, repr=False)
+    commands: Dict[str, List[AstNode]] = field(default_factory=dict)
+
+    def __post_init__(self):
+        self.api = self.ctx.inject(Integrity)
+        self.runtime = self.api._runtime
+        mc = self.api._mc
+        mc.steps.insert(
+            mc.steps.index(self.runtime.evaluate) + 1, HookResolver(api=self)
+        )
+
+    def create(self, name: str):
+        node = AstHookLocation(name=name)
+        self.runtime.commands.append(node)
+
+    @contextmanager
+    def at(self, name: str):
+        with self.runtime.scope() as commands:
+            yield
+        self.commands.setdefault(name, []).extend(commands)
+
+
+@dataclass(frozen=True)
+class AstHookLocation(AstNode):
+    name: str = required_field()
+
+
+@dataclass
+class HookResolver(MutatingReducer):
+    api: Hook = required_field()
+
+    @rule(AstRoot)
+    def root(self, node: AstRoot):
+        if not any(isinstance(child, AstHookLocation) for child in node):
+            return node
+        commands = []
+        for child in node:
+            if isinstance(child, AstHookLocation):
+                hook_commands = self.api.commands.get(child.name, ())
+                child_node = self.invoke(AstRoot(commands=AstChildren(hook_commands)))
+                commands.extend(child_node)
+            else:
+                commands.append(child)
+        return replace(node, commands=AstChildren(commands))

integrity/plugin.py

@@ -5,5 +5,6 @@
 
 def beet_default(ctx: Context):
     integ.Component = ctx.inject(integ._Components)
+    integ.Hook = ctx.inject(integ._Hook)
     yield
     integ.Component.generate_tags()