mirror of
https://github.com/apple/swift.git
synced 2025-12-14 20:36:38 +01:00
2b61d4edbb
Swift syntax APIs lack an abstract way of accessing children. The client has to down-cast a syntax node to the leaf type to access any of its children. However, some children are common among different syntax kinds, e.g. DeclAttributeSyntax and DeclMembers. We should allow an abstract way to access and modify them, so that clients can avoid logic duplication. This patch adds a mechanism to define new traits and specify satisfied traits in specific syntax nodes. A trait is a set of common children and implemented in Swift as a protocol for syntax nodes to conform to. As a proof-of-concept, we added two traits for now including DeclGroupSyntax and BracedSyntax. Resolves: SR-6931 and SR-6916
72 lines
2.3 KiB
Python
72 lines
2.3 KiB
Python
from __future__ import print_function
|
|
import sys # noqa: I201
|
|
from kinds import SYNTAX_BASE_KINDS, kind_to_type, lowercase_first_word
|
|
|
|
|
|
def error(msg):
|
|
print('error: ' + msg, file=sys.stderr)
|
|
sys.exit(-1)
|
|
|
|
|
|
class Node(object):
|
|
"""
|
|
A Syntax node, possibly with children.
|
|
If the kind is "SyntaxCollection", then this node is considered a Syntax
|
|
Collection that will expose itself as a typedef rather than a concrete
|
|
subclass.
|
|
"""
|
|
|
|
def __init__(self, name, kind=None, traits=None, children=None,
|
|
element=None, element_name=None, element_choices=None):
|
|
self.syntax_kind = name
|
|
self.swift_syntax_kind = lowercase_first_word(name)
|
|
self.name = kind_to_type(self.syntax_kind)
|
|
|
|
self.traits = traits or []
|
|
self.children = children or []
|
|
self.base_kind = kind
|
|
self.base_type = kind_to_type(self.base_kind)
|
|
|
|
if self.base_kind not in SYNTAX_BASE_KINDS:
|
|
error("unknown base kind '%s' for node '%s'" %
|
|
(self.base_kind, self.syntax_kind))
|
|
|
|
self.collection_element = element or ""
|
|
# If there's a preferred name for the collection element that differs
|
|
# from its supertype, use that.
|
|
self.collection_element_name = element_name or self.collection_element
|
|
self.collection_element_type = kind_to_type(self.collection_element)
|
|
self.collection_element_choices = element_choices or []
|
|
|
|
def is_base(self):
|
|
"""
|
|
Returns `True` if this node declares one of the base syntax kinds.
|
|
"""
|
|
return self.syntax_kind in SYNTAX_BASE_KINDS
|
|
|
|
def is_syntax_collection(self):
|
|
"""
|
|
Returns `True` if this node is a subclass of SyntaxCollection.
|
|
"""
|
|
return self.base_kind == "SyntaxCollection"
|
|
|
|
def requires_validation(self):
|
|
"""
|
|
Returns `True` if this node should have a `valitate` method associated.
|
|
"""
|
|
return self.is_buildable()
|
|
|
|
def is_unknown(self):
|
|
"""
|
|
Returns `True` if this node is an `Unknown` syntax subclass.
|
|
"""
|
|
return "Unknown" in self.syntax_kind
|
|
|
|
def is_buildable(self):
|
|
"""
|
|
Returns `True` if this node should have a builder associated.
|
|
"""
|
|
return not self.is_base() and \
|
|
not self.is_unknown() and \
|
|
not self.is_syntax_collection()
|