Clean up AST code

gtkblueprinttool/ast_utils.py

@@ -17,7 +17,99 @@
 #
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
+import typing as T
+from collections import ChainMap, defaultdict
+
 from .errors import *
+from .utils import lazy_prop
+from .xml_emitter import XmlEmitter
+
+
+class Children:
+    """ Allows accessing children by type using array syntax. """
+    def __init__(self, children):
+        self._children = children
+    def __iter__(self):
+        return iter(self._children)
+    def __getitem__(self, key):
+        return [child for child in self._children if isinstance(child, key)]
+
+
+class AstNode:
+    """ Base class for nodes in the abstract syntax tree. """
+
+    completers: T.List = []
+
+    def __init__(self, group, children, tokens, incomplete=False):
+        self.group = group
+        self.children = Children(children)
+        self.tokens = ChainMap(tokens, defaultdict(lambda: None))
+        self.incomplete = incomplete
+
+        self.parent = None
+        for child in self.children:
+            child.parent = self
+
+    def __init_subclass__(cls):
+        cls.completers = []
+
+
+    @property
+    def root(self):
+        if self.parent is None:
+            return self
+        else:
+            return self.parent.root
+
+    @lazy_prop
+    def errors(self):
+        return list(self._get_errors())
+
+    def _get_errors(self):
+        for name, attr in self._attrs_by_type(Validator):
+            try:
+                getattr(self, name)
+            except AlreadyCaughtError:
+                pass
+            except CompileError as e:
+                yield e
+
+        for child in self.children:
+            yield from child._get_errors()
+
+    def _attrs_by_type(self, attr_type):
+        for name in dir(type(self)):
+            item = getattr(type(self), name)
+            if isinstance(item, attr_type):
+                yield name, item
+
+    def generate(self) -> str:
+        """ Generates an XML string from the node. """
+        xml = XmlEmitter()
+        self.emit_xml(xml)
+        return xml.result
+
+    def emit_xml(self, xml: XmlEmitter):
+        """ Emits the XML representation of this AST node to the XmlEmitter. """
+        raise NotImplementedError()
+
+    def get_docs(self, idx: int) -> T.Optional[str]:
+        for name, attr in self._attrs_by_type(Docs):
+            if attr.token_name:
+                token = self.group.tokens.get(attr.token_name)
+                if token and token.start <= idx < token.end:
+                    return getattr(self, name)
+            else:
+                return getattr(self, name)
+
+        for child in self.children:
+            if child.group.start <= idx < child.group.end:
+                docs = child.get_docs(idx)
+                if docs is not None:
+                    return docs
+
+        return None
+
 
 class Validator:
     def __init__(self, func, token_name=None, end_token_name=None):