#!/usr/bin/env python

"""

Result abstractions.

Copyright (C) 2016, 2017 Paul Boddie <paul@boddie.org.uk>

This program is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free Software

Foundation; either version 3 of the License, or (at your option) any later

version.

This program is distributed in the hope that it will be useful, but WITHOUT

ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more

details.

You should have received a copy of the GNU General Public License along with

this program.  If not, see <http://www.gnu.org/licenses/>.

"""

from referencing import Reference

# Classes representing inspection and translation observations.

class Result:

    "An abstract expression result."

    def is_name(self):

        return False

    def is_global_name(self):

        return False

    def reference(self):

        return None

    def references(self):

        return None

    def access_location(self):

        return None

    def access_locations(self):

        return None

    def context(self):

        return None

    def context_verified(self):

        return None

    def discards_temporary(self, test=True):

        return None

    def get_name(self):

        return None

    def get_origin(self):

        return None

    def static(self):

        return None

    def final(self):

        return None

    def has_kind(self, kinds):

        return False

class AccessRef(Result):

    """

    A reference to an attribute access that is generally only returned from a

    processed access for possible initialiser resolution for assignments.

    """

    def __init__(self, original_name, attrnames, number):

        self.original_name = original_name

        self.attrnames = attrnames

        self.number = number

    def __repr__(self):

        return "AccessRef(%r, %r, %r)" % (self.original_name, self.attrnames, self.number)

class InvocationRef(Result):

    "An invocation of a name reference."

    def __init__(self, name_ref):

        self.name_ref = name_ref

    def reference(self):

        origin = self.name_ref.get_origin()

        if origin:

            return Reference("<invoke>", origin)

        else:

            return Reference("<var>")

    def __repr__(self):

        return "InvocationRef(%r)" % self.name_ref

class NameRef(Result):

    "A reference to a name."

    def __init__(self, name, expr=None, is_global=False):

        self.name = name

        self.expr = expr

        self.is_global = is_global

    def is_name(self):

        return True

    def is_global_name(self):

        return self.is_global

    def final(self):

        return None

    def __repr__(self):

        return "NameRef(%r, %r, %r)" % (self.name, self.expr, self.is_global)

class LocalNameRef(NameRef):

    "A reference to a local name."

    def __init__(self, name, number):

        NameRef.__init__(self, name, is_global=False)

        self.number = number

    def __repr__(self):

        return "LocalNameRef(%r, %r)" % (self.name, self.number)

class ResolvedRef:

    "A resolved reference mix-in."

    def __init__(self, ref):

        self.ref = ref

    def reference(self):

        return self.ref

    def references(self):

        return [self.ref]

    def get_name(self):

        return self.ref and self.ref.get_name() or None

    def get_origin(self):

        return self.ref and self.ref.get_origin() or None

    def static(self):

        return self.ref and self.ref.static() or None

    def final(self):

        return self.ref and self.ref.final() or None

    def has_kind(self, kinds):

        return self.ref and self.ref.has_kind(kinds)

    def is_constant_alias(self):

        return self.ref and self.ref.is_constant_alias()

class ResolvedNameRef(ResolvedRef, NameRef):

    "A resolved name-based reference."

    def __init__(self, name, ref, expr=None, is_global=False):

        NameRef.__init__(self, name, expr, is_global)

        ResolvedRef.__init__(self, ref)

    def __repr__(self):

        return "ResolvedNameRef(%r, %r, %r, %r)" % (self.name, self.ref, self.expr, self.is_global)

class ConstantValueRef(ResolvedNameRef):

    "A constant reference representing a single literal value."

    def __init__(self, name, ref, value, number=None):

        ResolvedNameRef.__init__(self, name, ref)

        self.value = value

        self.number = number

    def __repr__(self):

        return "ConstantValueRef(%r, %r, %r, %r)" % (self.name, self.ref, self.value, self.number)

class InstanceRef(ResolvedRef, Result):

    "An instance reference."

    def reference(self):

        return self.ref

    def __repr__(self):

        return "InstanceRef(%r)" % self.ref

class LiteralSequenceRef(ResolvedNameRef):

    "A reference representing a sequence of values."

    def __init__(self, name, ref, node, items=None):

        ResolvedNameRef.__init__(self, name, ref)

        self.node = node

        self.items = items

    def __repr__(self):

        return "LiteralSequenceRef(%r, %r, %r, %r)" % (self.name, self.ref, self.node, self.items)

class MultipleRef(Result):

    "A multiple outcome result."

    def __init__(self, results):

        self.results = results

    def reference(self):

        refs = set(self.references())

        ref = len(refs) == 1 and list(refs)[0] or Reference("<var>")

    def references(self):

        refs = []

        for result in self.results:

            refs.append(result.reference())

        return refs

    def __repr__(self):

        return "MultipleRef(%r)" % self.results

class VariableRef(Result):

    "A variable reference."

    def __repr__(self):

        return "VariableRef()"

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