49 lines
2.1 KiB
Python
49 lines
2.1 KiB
Python
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# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, You can obtain one at http://mozilla.org/MPL/2.0/.
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import gdb
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import itertools
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from gdbpp import GeckoPrettyPrinter
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# mfbt's LinkedList<T> is a doubly-linked list where the items in the list store
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# the next/prev pointers as part of themselves rather than the list structure be
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# its own independent data structure. This means:
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# - Every item may belong to at most one LinkedList instance.
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# - For our pretty printer, we only want to pretty-print the LinkedList object
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# itself. We do not want to start printing every item in the list whenever
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# we run into a LinkedListElement<T>.
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@GeckoPrettyPrinter('mozilla::LinkedList', '^mozilla::LinkedList<.*>$')
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class linkedlist_printer(object):
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def __init__(self, value):
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self.value = value
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# mfbt's LinkedList has the elements of the linked list subclass from
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# LinkedListElement<T>. We want its pointer type for casting purposes.
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#
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# (We want to list pointers since we expect all of these objects to be
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# complex enough that we don't want to automatically expand them. The
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# LinkedListElement type itself isn't small.)
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self.t_ptr_type = value.type.template_argument(0).pointer()
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def children(self):
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# Walk mNext until we loop back around to the sentinel. The sentinel
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# item always exists and in the zero-length base-case mNext == sentinel,
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# so extract that immediately and update it throughout the loop.
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sentinel = self.value['sentinel']
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pSentinel = sentinel.address
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pNext = sentinel['mNext']
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i = 0
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while pSentinel != pNext:
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list_elem = pNext.dereference()
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list_value = pNext.cast(self.t_ptr_type)
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yield ('%d' % i, list_value)
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pNext = list_elem['mNext']
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i += 1
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def to_string(self):
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return str(self.value.type)
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def display_hint(self):
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return 'array'
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