Class MetadataVisitor

Parser/asdl_c.py:143–200

        self._metadata = value

class MetadataVisitor(asdl.VisitorBase):
    ROOT_TYPE = "AST"

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        # Metadata:
        #    - simple_sums: Tracks the list of compound type
        #                   names where all the constructors
        #                   belonging to that type lack of any
        #                   fields.
        #    - identifiers: All identifiers used in the AST declarations
        #    - singletons:  List of all constructors that originates from
        #                   simple sums.
        #    - types:       List of all top level type names
        #
        self.metadata = types.SimpleNamespace(
            simple_sums=set(),
            identifiers=set(),
            singletons=set(),
            types={self.ROOT_TYPE},
        )

    def visitModule(self, mod):
        for dfn in mod.dfns:
            self.visit(dfn)

    def visitType(self, type):
        self.visit(type.value, type.name)

    def visitSum(self, sum, name):
        self.metadata.types.add(name)

        simple_sum = is_simple(sum)
        if simple_sum:
            self.metadata.simple_sums.add(name)

        for constructor in sum.types:
            if simple_sum:
                self.metadata.singletons.add(constructor.name)
            self.visitConstructor(constructor)
        self.visitFields(sum.attributes)

    def visitConstructor(self, constructor):
        self.metadata.types.add(constructor.name)
        self.visitFields(constructor.fields)

    def visitProduct(self, product, name):
        self.metadata.types.add(name)
        self.visitFields(product.attributes)
        self.visitFields(product.fields)

    def visitFields(self, fields):
        for field in fields:
            self.visitField(field)

    def visitField(self, field):
        self.metadata.identifiers.add(field.name)