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# linelog - efficient cache for annotate data
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#
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# Copyright 2018 Google LLC.
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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"""linelog is an efficient cache for annotate data inspired by SCCS Weaves.
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SCCS Weaves are an implementation of
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https://en.wikipedia.org/wiki/Interleaved_deltas. See
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mercurial/helptext/internals/linelog.txt for an exploration of SCCS weaves
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and how linelog works in detail.
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Here's a hacker's summary: a linelog is a program which is executed in
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the context of a revision. Executing the program emits information
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about lines, including the revision that introduced them and the line
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number in the file at the introducing revision. When an insertion or
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deletion is performed on the file, a jump instruction is used to patch
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in a new body of annotate information.
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"""
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from __future__ import absolute_import, print_function
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import abc
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import struct
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from .thirdparty import attr
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from . import pycompat
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_llentry = struct.Struct(b'>II')
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class LineLogError(Exception):
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"""Error raised when something bad happens internally in linelog."""
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@attr.s
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class lineinfo(object):
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# Introducing revision of this line.
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rev = attr.ib()
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# Line number for this line in its introducing revision.
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linenum = attr.ib()
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# Private. Offset in the linelog program of this line. Used internally.
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_offset = attr.ib()
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@attr.s
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class annotateresult(object):
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rev = attr.ib()
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lines = attr.ib()
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_eof = attr.ib()
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def __iter__(self):
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return iter(self.lines)
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class _llinstruction(object): # pytype: disable=ignored-metaclass
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__metaclass__ = abc.ABCMeta
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@abc.abstractmethod
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def __init__(self, op1, op2):
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pass
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@abc.abstractmethod
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def __str__(self):
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pass
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def __repr__(self):
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return str(self)
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@abc.abstractmethod
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def __eq__(self, other):
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pass
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@abc.abstractmethod
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def encode(self):
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"""Encode this instruction to the binary linelog format."""
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@abc.abstractmethod
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def execute(self, rev, pc, emit):
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"""Execute this instruction.
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Args:
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rev: The revision we're annotating.
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pc: The current offset in the linelog program.
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emit: A function that accepts a single lineinfo object.
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Returns:
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The new value of pc. Returns None if exeuction should stop
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(that is, we've found the end of the file.)
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"""
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class _jge(_llinstruction):
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"""If the current rev is greater than or equal to op1, jump to op2."""
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def __init__(self, op1, op2):
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self._cmprev = op1
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self._target = op2
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def __str__(self):
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return 'JGE %d %d' % (self._cmprev, self._target)
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def __eq__(self, other):
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return (
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type(self) == type(other)
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and self._cmprev == other._cmprev
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and self._target == other._target
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)
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def encode(self):
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return _llentry.pack(self._cmprev << 2, self._target)
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def execute(self, rev, pc, emit):
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if rev >= self._cmprev:
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return self._target
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return pc + 1
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class _jump(_llinstruction):
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"""Unconditional jumps are expressed as a JGE with op1 set to 0."""
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def __init__(self, op1, op2):
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if op1 != 0:
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raise LineLogError(b"malformed JUMP, op1 must be 0, got %d" % op1)
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self._target = op2
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def __str__(self):
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return 'JUMP %d' % (self._target)
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def __eq__(self, other):
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return type(self) == type(other) and self._target == other._target
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def encode(self):
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return _llentry.pack(0, self._target)
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def execute(self, rev, pc, emit):
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return self._target
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class _eof(_llinstruction):
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"""EOF is expressed as a JGE that always jumps to 0."""
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def __init__(self, op1, op2):
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if op1 != 0:
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raise LineLogError(b"malformed EOF, op1 must be 0, got %d" % op1)
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if op2 != 0:
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raise LineLogError(b"malformed EOF, op2 must be 0, got %d" % op2)
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def __str__(self):
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return r'EOF'
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def __eq__(self, other):
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return type(self) == type(other)
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def encode(self):
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return _llentry.pack(0, 0)
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def execute(self, rev, pc, emit):
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return None
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class _jl(_llinstruction):
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"""If the current rev is less than op1, jump to op2."""
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def __init__(self, op1, op2):
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self._cmprev = op1
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self._target = op2
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def __str__(self):
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return 'JL %d %d' % (self._cmprev, self._target)
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def __eq__(self, other):
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return (
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type(self) == type(other)
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and self._cmprev == other._cmprev
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and self._target == other._target
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)
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def encode(self):
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return _llentry.pack(1 | (self._cmprev << 2), self._target)
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def execute(self, rev, pc, emit):
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if rev < self._cmprev:
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return self._target
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return pc + 1
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class _line(_llinstruction):
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"""Emit a line."""
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def __init__(self, op1, op2):
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# This line was introduced by this revision number.
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self._rev = op1
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# This line had the specified line number in the introducing revision.
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self._origlineno = op2
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def __str__(self):
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return 'LINE %d %d' % (self._rev, self._origlineno)
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def __eq__(self, other):
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return (
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type(self) == type(other)
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and self._rev == other._rev
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and self._origlineno == other._origlineno
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)
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def encode(self):
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return _llentry.pack(2 | (self._rev << 2), self._origlineno)
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def execute(self, rev, pc, emit):
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emit(lineinfo(self._rev, self._origlineno, pc))
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return pc + 1
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def _decodeone(data, offset):
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"""Decode a single linelog instruction from an offset in a buffer."""
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try:
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op1, op2 = _llentry.unpack_from(data, offset)
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except struct.error as e:
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raise LineLogError(b'reading an instruction failed: %r' % e)
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opcode = op1 & 0b11
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op1 = op1 >> 2
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if opcode == 0:
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if op1 == 0:
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if op2 == 0:
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return _eof(op1, op2)
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return _jump(op1, op2)
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return _jge(op1, op2)
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elif opcode == 1:
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return _jl(op1, op2)
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elif opcode == 2:
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return _line(op1, op2)
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raise NotImplementedError(b'Unimplemented opcode %r' % opcode)
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class linelog(object):
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"""Efficient cache for per-line history information."""
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def __init__(self, program=None, maxrev=0):
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if program is None:
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# We pad the program with an extra leading EOF so that our
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# offsets will match the C code exactly. This means we can
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# interoperate with the C code.
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program = [_eof(0, 0), _eof(0, 0)]
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self._program = program
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self._lastannotate = None
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self._maxrev = maxrev
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def __eq__(self, other):
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return (
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type(self) == type(other)
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and self._program == other._program
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and self._maxrev == other._maxrev
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)
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def __repr__(self):
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return '<linelog at %s: maxrev=%d size=%d>' % (
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hex(id(self)),
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self._maxrev,
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len(self._program),
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)
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def debugstr(self):
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fmt = '%%%dd %%s' % len(str(len(self._program)))
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return pycompat.sysstr(b'\n').join(
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fmt % (idx, i) for idx, i in enumerate(self._program[1:], 1)
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)
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@classmethod
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def fromdata(cls, buf):
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if len(buf) % _llentry.size != 0:
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raise LineLogError(
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b"invalid linelog buffer size %d (must be a multiple of %d)"
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% (len(buf), _llentry.size)
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)
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expected = len(buf) / _llentry.size
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fakejge = _decodeone(buf, 0)
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if isinstance(fakejge, _jump):
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maxrev = 0
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elif isinstance(fakejge, (_jge, _jl)):
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maxrev = fakejge._cmprev
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else:
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raise LineLogError(
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'Expected one of _jump, _jge, or _jl. Got %s.'
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% type(fakejge).__name__
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)
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assert isinstance(fakejge, (_jump, _jge, _jl)) # help pytype
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numentries = fakejge._target
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if expected != numentries:
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raise LineLogError(
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b"corrupt linelog data: claimed"
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b" %d entries but given data for %d entries"
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% (expected, numentries)
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)
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instructions = [_eof(0, 0)]
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for offset in pycompat.xrange(1, numentries):
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instructions.append(_decodeone(buf, offset * _llentry.size))
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return cls(instructions, maxrev=maxrev)
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def encode(self):
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hdr = _jge(self._maxrev, len(self._program)).encode()
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return hdr + b''.join(i.encode() for i in self._program[1:])
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def clear(self):
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self._program = []
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self._maxrev = 0
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self._lastannotate = None
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def replacelines_vec(self, rev, a1, a2, blines):
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return self.replacelines(
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rev, a1, a2, 0, len(blines), _internal_blines=blines
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)
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def replacelines(self, rev, a1, a2, b1, b2, _internal_blines=None):
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"""Replace lines [a1, a2) with lines [b1, b2)."""
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if self._lastannotate:
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# TODO(augie): make replacelines() accept a revision at
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# which we're editing as well as a revision to mark
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# responsible for the edits. In hg-experimental it's
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# stateful like this, so we're doing the same thing to
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# retain compatibility with absorb until that's imported.
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ar = self._lastannotate
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else:
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ar = self.annotate(rev)
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# ar = self.annotate(self._maxrev)
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if a1 > len(ar.lines):
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raise LineLogError(
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b'%d contains %d lines, tried to access line %d'
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% (rev, len(ar.lines), a1)
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)
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elif a1 == len(ar.lines):
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# Simulated EOF instruction since we're at EOF, which
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# doesn't have a "real" line.
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a1inst = _eof(0, 0)
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a1info = lineinfo(0, 0, ar._eof)
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else:
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a1info = ar.lines[a1]
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a1inst = self._program[a1info._offset]
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programlen = self._program.__len__
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oldproglen = programlen()
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appendinst = self._program.append
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# insert
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blineinfos = []
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bappend = blineinfos.append
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if b1 < b2:
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# Determine the jump target for the JGE at the start of
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# the new block.
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tgt = oldproglen + (b2 - b1 + 1)
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# Jump to skip the insert if we're at an older revision.
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appendinst(_jl(rev, tgt))
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for linenum in pycompat.xrange(b1, b2):
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if _internal_blines is None:
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bappend(lineinfo(rev, linenum, programlen()))
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appendinst(_line(rev, linenum))
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else:
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newrev, newlinenum = _internal_blines[linenum]
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bappend(lineinfo(newrev, newlinenum, programlen()))
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appendinst(_line(newrev, newlinenum))
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# delete
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if a1 < a2:
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if a2 > len(ar.lines):
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raise LineLogError(
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b'%d contains %d lines, tried to access line %d'
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% (rev, len(ar.lines), a2)
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)
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elif a2 == len(ar.lines):
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endaddr = ar._eof
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else:
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endaddr = ar.lines[a2]._offset
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if a2 > 0 and rev < self._maxrev:
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# If we're here, we're deleting a chunk of an old
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# commit, so we need to be careful and not touch
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# invisible lines between a2-1 and a2 (IOW, lines that
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# are added later).
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endaddr = ar.lines[a2 - 1]._offset + 1
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appendinst(_jge(rev, endaddr))
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# copy instruction from a1
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a1instpc = programlen()
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appendinst(a1inst)
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# if a1inst isn't a jump or EOF, then we need to add an unconditional
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# jump back into the program here.
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if not isinstance(a1inst, (_jump, _eof)):
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appendinst(_jump(0, a1info._offset + 1))
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# Patch instruction at a1, which makes our patch live.
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self._program[a1info._offset] = _jump(0, oldproglen)
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# Update self._lastannotate in place. This serves as a cache to avoid
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# expensive "self.annotate" in this function, when "replacelines" is
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# used continuously.
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if len(self._lastannotate.lines) > a1:
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self._lastannotate.lines[a1]._offset = a1instpc
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else:
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assert isinstance(a1inst, _eof)
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self._lastannotate._eof = a1instpc
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self._lastannotate.lines[a1:a2] = blineinfos
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self._lastannotate.rev = max(self._lastannotate.rev, rev)
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if rev > self._maxrev:
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self._maxrev = rev
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def annotate(self, rev):
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pc = 1
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lines = []
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executed = 0
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# Sanity check: if instructions executed exceeds len(program), we
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# hit an infinite loop in the linelog program somehow and we
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# should stop.
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while pc is not None and executed < len(self._program):
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inst = self._program[pc]
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lastpc = pc
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pc = inst.execute(rev, pc, lines.append)
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executed += 1
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if pc is not None:
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raise LineLogError(
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r'Probably hit an infinite loop in linelog. Program:\n'
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+ self.debugstr()
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)
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ar = annotateresult(rev, lines, lastpc)
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self._lastannotate = ar
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return ar
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@property
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def maxrev(self):
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return self._maxrev
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# Stateful methods which depend on the value of the last
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# annotation run. This API is for compatiblity with the original
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# linelog, and we should probably consider refactoring it.
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@property
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def annotateresult(self):
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"""Return the last annotation result. C linelog code exposed this."""
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return [(l.rev, l.linenum) for l in self._lastannotate.lines]
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def getoffset(self, line):
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return self._lastannotate.lines[line]._offset
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def getalllines(self, start=0, end=0):
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"""Get all lines that ever occurred in [start, end).
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Passing start == end == 0 means "all lines ever".
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This works in terms of *internal* program offsets, not line numbers.
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"""
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pc = start or 1
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lines = []
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# only take as many steps as there are instructions in the
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# program - if we don't find an EOF or our stop-line before
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# then, something is badly broken.
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for step in pycompat.xrange(len(self._program)):
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inst = self._program[pc]
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nextpc = pc + 1
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if isinstance(inst, _jump):
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nextpc = inst._target
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elif isinstance(inst, _eof):
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return lines
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elif isinstance(inst, (_jl, _jge)):
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pass
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elif isinstance(inst, _line):
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lines.append((inst._rev, inst._origlineno))
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else:
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raise LineLogError(b"Illegal instruction %r" % inst)
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if nextpc == end:
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return lines
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pc = nextpc
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raise LineLogError(b"Failed to perform getalllines")
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