# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0 # For details: https://bitbucket.org/ned/coveragepy/src/default/NOTICE.txt """Code parsing for coverage.py.""" import ast import collections import dis import os import re import token import tokenize from coverage import env from coverage.backward import range # pylint: disable=redefined-builtin from coverage.backward import bytes_to_ints, string_class from coverage.bytecode import ByteCodes, CodeObjects from coverage.misc import contract, nice_pair, join_regex from coverage.misc import CoverageException, NoSource, NotPython from coverage.phystokens import compile_unicode, generate_tokens, neuter_encoding_declaration class PythonParser(object): """Parse code to find executable lines, excluded lines, etc.""" @contract(text='unicode|None') def __init__(self, text=None, filename=None, exclude=None): """ Source can be provided as `text`, the text itself, or `filename`, from which the text will be read. Excluded lines are those that match `exclude`, a regex. """ assert text or filename, "PythonParser needs either text or filename" self.filename = filename or "" self.text = text if not self.text: from coverage.python import get_python_source try: self.text = get_python_source(self.filename) except IOError as err: raise NoSource( "No source for code: '%s': %s" % (self.filename, err) ) self.exclude = exclude # The text lines of the parsed code. self.lines = self.text.split('\n') # The normalized line numbers of the statements in the code. Exclusions # are taken into account, and statements are adjusted to their first # lines. self.statements = set() # The normalized line numbers of the excluded lines in the code, # adjusted to their first lines. self.excluded = set() # The raw_* attributes are only used in this class, and in # lab/parser.py to show how this class is working. # The line numbers that start statements, as reported by the line # number table in the bytecode. self.raw_statements = set() # The raw line numbers of excluded lines of code, as marked by pragmas. self.raw_excluded = set() # The line numbers of class and function definitions. self.raw_classdefs = set() self.raw_funcdefs = set() # The line numbers of docstring lines. self.raw_docstrings = set() # Internal detail, used by lab/parser.py. self.show_tokens = False # A dict mapping line numbers to (lo,hi) for multi-line statements. self._multiline = {} # Lazily-created ByteParser and arc data. self._byte_parser = None self._all_arcs = None @property def byte_parser(self): """Create a ByteParser on demand.""" if not self._byte_parser: self._byte_parser = ByteParser(self.text, filename=self.filename) return self._byte_parser def lines_matching(self, *regexes): """Find the lines matching one of a list of regexes. Returns a set of line numbers, the lines that contain a match for one of the regexes in `regexes`. The entire line needn't match, just a part of it. """ combined = join_regex(regexes) if env.PY2: combined = combined.decode("utf8") regex_c = re.compile(combined) matches = set() for i, ltext in enumerate(self.lines, start=1): if regex_c.search(ltext): matches.add(i) return matches def _raw_parse(self): """Parse the source to find the interesting facts about its lines. A handful of attributes are updated. """ # Find lines which match an exclusion pattern. if self.exclude: self.raw_excluded = self.lines_matching(self.exclude) # Tokenize, to find excluded suites, to find docstrings, and to find # multi-line statements. indent = 0 exclude_indent = 0 excluding = False excluding_decorators = False prev_toktype = token.INDENT first_line = None empty = True first_on_line = True tokgen = generate_tokens(self.text) for toktype, ttext, (slineno, _), (elineno, _), ltext in tokgen: if self.show_tokens: # pragma: not covered print("%10s %5s %-20r %r" % ( tokenize.tok_name.get(toktype, toktype), nice_pair((slineno, elineno)), ttext, ltext )) if toktype == token.INDENT: indent += 1 elif toktype == token.DEDENT: indent -= 1 elif toktype == token.NAME: if ttext == 'class': # Class definitions look like branches in the byte code, so # we need to exclude them. The simplest way is to note the # lines with the 'class' keyword. self.raw_classdefs.add(slineno) elif ttext == 'def': self.raw_funcdefs.add(slineno) elif toktype == token.OP: if ttext == ':': should_exclude = (elineno in self.raw_excluded) or excluding_decorators if not excluding and should_exclude: # Start excluding a suite. We trigger off of the colon # token so that the #pragma comment will be recognized on # the same line as the colon. self.raw_excluded.add(elineno) exclude_indent = indent excluding = True excluding_decorators = False elif ttext == '@' and first_on_line: # A decorator. if elineno in self.raw_excluded: excluding_decorators = True if excluding_decorators: self.raw_excluded.add(elineno) elif toktype == token.STRING and prev_toktype == token.INDENT: # Strings that are first on an indented line are docstrings. # (a trick from trace.py in the stdlib.) This works for # 99.9999% of cases. For the rest (!) see: # http://stackoverflow.com/questions/1769332/x/1769794#1769794 self.raw_docstrings.update(range(slineno, elineno+1)) elif toktype == token.NEWLINE: if first_line is not None and elineno != first_line: # We're at the end of a line, and we've ended on a # different line than the first line of the statement, # so record a multi-line range. for l in range(first_line, elineno+1): self._multiline[l] = first_line first_line = None first_on_line = True if ttext.strip() and toktype != tokenize.COMMENT: # A non-whitespace token. empty = False if first_line is None: # The token is not whitespace, and is the first in a # statement. first_line = slineno # Check whether to end an excluded suite. if excluding and indent <= exclude_indent: excluding = False if excluding: self.raw_excluded.add(elineno) first_on_line = False prev_toktype = toktype # Find the starts of the executable statements. if not empty: self.raw_statements.update(self.byte_parser._find_statements()) def first_line(self, line): """Return the first line number of the statement including `line`.""" first_line = self._multiline.get(line) if first_line: return first_line else: return line def first_lines(self, lines): """Map the line numbers in `lines` to the correct first line of the statement. Returns a set of the first lines. """ return set(self.first_line(l) for l in lines) def translate_lines(self, lines): """Implement `FileReporter.translate_lines`.""" return self.first_lines(lines) def translate_arcs(self, arcs): """Implement `FileReporter.translate_arcs`.""" return [(self.first_line(a), self.first_line(b)) for (a, b) in arcs] def parse_source(self): """Parse source text to find executable lines, excluded lines, etc. Sets the .excluded and .statements attributes, normalized to the first line of multi-line statements. """ try: self._raw_parse() except (tokenize.TokenError, IndentationError) as err: if hasattr(err, "lineno"): lineno = err.lineno # IndentationError else: lineno = err.args[1][0] # TokenError raise NotPython( u"Couldn't parse '%s' as Python source: '%s' at line %d" % ( self.filename, err.args[0], lineno ) ) self.excluded = self.first_lines(self.raw_excluded) ignore = self.excluded | self.raw_docstrings starts = self.raw_statements - ignore self.statements = self.first_lines(starts) - ignore def old_arcs(self): """Get information about the arcs available in the code. Returns a set of line number pairs. Line numbers have been normalized to the first line of multi-line statements. """ if self._all_arcs is None: self._all_arcs = set() for l1, l2 in self.byte_parser._all_arcs(): fl1 = self.first_line(l1) fl2 = self.first_line(l2) if fl1 != fl2: self._all_arcs.add((fl1, fl2)) return self._all_arcs def arcs(self): if self._all_arcs is None: aaa = AstArcAnalyzer(self.text, self.raw_funcdefs, self.raw_classdefs) arcs = aaa.collect_arcs() self._all_arcs = set() for l1, l2 in arcs: fl1 = self.first_line(l1) fl2 = self.first_line(l2) if fl1 != fl2: self._all_arcs.add((fl1, fl2)) return self._all_arcs def exit_counts(self): """Get a count of exits from that each line. Excluded lines are excluded. """ exit_counts = collections.defaultdict(int) for l1, l2 in self.arcs(): if l1 < 0: # Don't ever report -1 as a line number continue if l1 in self.excluded: # Don't report excluded lines as line numbers. continue if l2 in self.excluded: # Arcs to excluded lines shouldn't count. continue exit_counts[l1] += 1 # Class definitions have one extra exit, so remove one for each: for l in self.raw_classdefs: # Ensure key is there: class definitions can include excluded lines. if l in exit_counts: exit_counts[l] -= 1 return exit_counts class LoopBlock(object): def __init__(self, start): self.start = start self.break_exits = set() class FunctionBlock(object): def __init__(self, start): self.start = start class TryBlock(object): def __init__(self, handler_start=None, final_start=None): self.handler_start = handler_start # TODO: is this used? self.final_start = final_start # TODO: is this used? self.break_from = set() self.continue_from = set() self.return_from = set() self.raise_from = set() class AstArcAnalyzer(object): @contract(text='unicode', funcdefs=set, classdefs=set) def __init__(self, text, funcdefs, classdefs): self.root_node = ast.parse(neuter_encoding_declaration(text)) self.funcdefs = funcdefs self.classdefs = classdefs if int(os.environ.get("COVERAGE_ASTDUMP", 0)): # pragma: debugging # Dump the AST so that failing tests have helpful output. ast_dump(self.root_node) self.arcs = None self.block_stack = [] def collect_arcs(self): self.arcs = set() self.add_arcs_for_code_objects(self.root_node) return self.arcs def blocks(self): """Yield the blocks in nearest-to-farthest order.""" return reversed(self.block_stack) def line_for_node(self, node): """What is the right line number to use for this node?""" node_name = node.__class__.__name__ handler = getattr(self, "line_" + node_name, None) if handler is not None: return handler(node) else: return node.lineno def line_Assign(self, node): return self.line_for_node(node.value) def line_Dict(self, node): # Python 3.5 changed how dict literals are made. if env.PYVERSION >= (3, 5) and node.keys: return node.keys[0].lineno else: return node.lineno def line_List(self, node): if node.elts: return self.line_for_node(node.elts[0]) else: return node.lineno def line_Module(self, node): if node.body: return self.line_for_node(node.body[0]) else: # Modules have no line number, they always start at 1. return 1 OK_TO_DEFAULT = set([ "Assign", "Assert", "AugAssign", "Delete", "Exec", "Expr", "Global", "Import", "ImportFrom", "Pass", "Print", ]) def add_arcs(self, node): """Add the arcs for `node`. Return a set of line numbers, exits from this node to the next. """ # Yield-froms and awaits can appear anywhere. # TODO: this is probably over-doing it, and too expensive. Can we # instrument the ast walking to see how many nodes we are revisiting? if isinstance(node, ast.stmt): for _, value in ast.iter_fields(node): if isinstance(value, ast.expr) and self.contains_return_expression(value): self.process_return_exits([self.line_for_node(node)]) break node_name = node.__class__.__name__ handler = getattr(self, "handle_" + node_name, None) if handler is not None: return handler(node) if 0: node_name = node.__class__.__name__ if node_name not in self.OK_TO_DEFAULT: print("*** Unhandled: {0}".format(node)) return set([self.line_for_node(node)]) def add_body_arcs(self, body, from_line=None, prev_lines=None): if prev_lines is None: prev_lines = set([from_line]) for body_node in body: lineno = self.line_for_node(body_node) for prev_lineno in prev_lines: self.arcs.add((prev_lineno, lineno)) prev_lines = self.add_arcs(body_node) return prev_lines def is_constant_expr(self, node): """Is this a compile-time constant?""" node_name = node.__class__.__name__ if node_name in ["NameConstant", "Num"]: return True elif node_name == "Name": if env.PY3 and node.id in ["True", "False", "None"]: return True return False # tests to write: # TODO: while EXPR: # TODO: while False: # TODO: listcomps hidden deep in other expressions # TODO: listcomps hidden in lists: x = [[i for i in range(10)]] # TODO: nested function definitions def process_break_exits(self, exits): for block in self.blocks(): if isinstance(block, LoopBlock): block.break_exits.update(exits) break elif isinstance(block, TryBlock) and block.final_start: block.break_from.update(exits) break def process_continue_exits(self, exits): for block in self.blocks(): if isinstance(block, LoopBlock): for xit in exits: self.arcs.add((xit, block.start)) break elif isinstance(block, TryBlock) and block.final_start: block.continue_from.update(exits) break def process_raise_exits(self, exits): for block in self.blocks(): if isinstance(block, TryBlock): if block.handler_start: for xit in exits: self.arcs.add((xit, block.handler_start)) break elif block.final_start: block.raise_from.update(exits) break elif isinstance(block, FunctionBlock): for xit in exits: self.arcs.add((xit, -block.start)) break def process_return_exits(self, exits): for block in self.blocks(): if isinstance(block, TryBlock) and block.final_start: block.return_from.update(exits) break elif isinstance(block, FunctionBlock): for xit in exits: self.arcs.add((xit, -block.start)) break ## Handlers def handle_Break(self, node): here = self.line_for_node(node) self.process_break_exits([here]) return set() def handle_ClassDef(self, node): return self.process_decorated(node, self.classdefs) def process_decorated(self, node, defs): last = self.line_for_node(node) if node.decorator_list: for dec_node in node.decorator_list: dec_start = self.line_for_node(dec_node) if dec_start != last: self.arcs.add((last, dec_start)) last = dec_start # The definition line may have been missed, but we should have it in # `defs`. body_start = self.line_for_node(node.body[0]) for lineno in range(last+1, body_start): if lineno in defs: self.arcs.add((last, lineno)) last = lineno # the body is handled in add_arcs_for_code_objects. return set([last]) def handle_Continue(self, node): here = self.line_for_node(node) self.process_continue_exits([here]) return set() def handle_For(self, node): start = self.line_for_node(node.iter) self.block_stack.append(LoopBlock(start=start)) exits = self.add_body_arcs(node.body, from_line=start) for xit in exits: self.arcs.add((xit, start)) my_block = self.block_stack.pop() exits = my_block.break_exits if node.orelse: else_exits = self.add_body_arcs(node.orelse, from_line=start) exits |= else_exits else: # no else clause: exit from the for line. exits.add(start) return exits handle_AsyncFor = handle_For def handle_FunctionDef(self, node): return self.process_decorated(node, self.funcdefs) handle_AsyncFunctionDef = handle_FunctionDef def handle_If(self, node): start = self.line_for_node(node.test) exits = self.add_body_arcs(node.body, from_line=start) exits |= self.add_body_arcs(node.orelse, from_line=start) return exits def handle_Raise(self, node): # `raise` statement jumps away, no exits from here. here = self.line_for_node(node) self.process_raise_exits([here]) return set() def handle_Return(self, node): here = self.line_for_node(node) self.process_return_exits([here]) return set() def handle_Try(self, node): # try/finally is tricky. If there's a finally clause, then we need a # FinallyBlock to track what flows might go through the finally instead # of their normal flow. if node.handlers: handler_start = self.line_for_node(node.handlers[0]) else: handler_start = None if node.finalbody: final_start = self.line_for_node(node.finalbody[0]) else: final_start = None self.block_stack.append(TryBlock(handler_start=handler_start, final_start=final_start)) start = self.line_for_node(node) exits = self.add_body_arcs(node.body, from_line=start) try_block = self.block_stack.pop() handler_exits = set() last_handler_start = None if node.handlers: for handler_node in node.handlers: handler_start = self.line_for_node(handler_node) if last_handler_start is not None: self.arcs.add((last_handler_start, handler_start)) last_handler_start = handler_start handler_exits |= self.add_body_arcs(handler_node.body, from_line=handler_start) if handler_node.type is None: # "except:" doesn't jump to subsequent handlers, or # "finally:". last_handler_start = None # TODO: should we break here? Handlers after "except:" # won't be run. Should coverage know that code can't be # run, or should it flag it as not run? if node.orelse: exits = self.add_body_arcs(node.orelse, prev_lines=exits) exits |= handler_exits if node.finalbody: final_from = ( # You can get to the `finally` clause from: exits | # the exits of the body or `else` clause, try_block.break_from | # or a `break` in the body, try_block.continue_from | # or a `continue` in the body, try_block.return_from # or a `return` in the body. ) if node.handlers and last_handler_start is not None: # If there was an "except X:" clause, then a "raise" in the # body goes to the "except X:" before the "finally", but the # "except" go to the finally. final_from.add(last_handler_start) else: final_from |= try_block.raise_from exits = self.add_body_arcs(node.finalbody, prev_lines=final_from) if try_block.break_from: self.process_break_exits(exits) if try_block.continue_from: self.process_continue_exits(exits) if try_block.raise_from: self.process_raise_exits(exits) if try_block.return_from: self.process_return_exits(exits) return exits def handle_TryExcept(self, node): # Python 2.7 uses separate TryExcept and TryFinally nodes. If we get # TryExcept, it means there was no finally, so fake it, and treat as # a general Try node. node.finalbody = [] return self.handle_Try(node) def handle_TryFinally(self, node): # Python 2.7 uses separate TryExcept and TryFinally nodes. If we get # TryFinally, see if there's a TryExcept nested inside. If so, merge # them. Otherwise, fake fields to complete a Try node. node.handlers = [] node.orelse = [] first = node.body[0] if first.__class__.__name__ == "TryExcept" and node.lineno == first.lineno: assert len(node.body) == 1 node.body = first.body node.handlers = first.handlers node.orelse = first.orelse return self.handle_Try(node) def handle_While(self, node): constant_test = self.is_constant_expr(node.test) start = to_top = self.line_for_node(node.test) if constant_test: to_top = self.line_for_node(node.body[0]) self.block_stack.append(LoopBlock(start=start)) exits = self.add_body_arcs(node.body, from_line=start) for xit in exits: self.arcs.add((xit, to_top)) exits = set() my_block = self.block_stack.pop() exits.update(my_block.break_exits) if node.orelse: else_exits = self.add_body_arcs(node.orelse, from_line=start) exits |= else_exits else: # No `else` clause: you can exit from the start. if not constant_test: exits.add(start) return exits def handle_With(self, node): start = self.line_for_node(node) exits = self.add_body_arcs(node.body, from_line=start) return exits handle_AsyncWith = handle_With def add_arcs_for_code_objects(self, root_node): for node in ast.walk(root_node): node_name = node.__class__.__name__ code_object_handler = getattr(self, "code_object_" + node_name, None) if code_object_handler is not None: code_object_handler(node) def code_object_Module(self, node): start = self.line_for_node(node) if node.body: exits = self.add_body_arcs(node.body, from_line=-1) for xit in exits: self.arcs.add((xit, -start)) else: # Empty module. self.arcs.add((-1, start)) self.arcs.add((start, -1)) def code_object_FunctionDef(self, node): start = self.line_for_node(node) self.block_stack.append(FunctionBlock(start=start)) exits = self.add_body_arcs(node.body, from_line=-1) self.block_stack.pop() for xit in exits: self.arcs.add((xit, -start)) code_object_AsyncFunctionDef = code_object_FunctionDef def code_object_ClassDef(self, node): start = self.line_for_node(node) self.arcs.add((-1, start)) exits = self.add_body_arcs(node.body, from_line=start) for xit in exits: self.arcs.add((xit, -start)) def do_code_object_comprehension(self, node): start = self.line_for_node(node) self.arcs.add((-1, start)) self.arcs.add((start, -start)) code_object_GeneratorExp = do_code_object_comprehension code_object_DictComp = do_code_object_comprehension code_object_SetComp = do_code_object_comprehension if env.PY3: code_object_ListComp = do_code_object_comprehension def code_object_Lambda(self, node): start = self.line_for_node(node) self.arcs.add((-1, start)) self.arcs.add((start, -start)) # TODO: test multi-line lambdas def contains_return_expression(self, node): """Is there a yield-from or await in `node` someplace?""" for child in ast.walk(node): if child.__class__.__name__ in ["YieldFrom", "Await"]: return True return False ## Opcodes that guide the ByteParser. def _opcode(name): """Return the opcode by name from the dis module.""" return dis.opmap[name] def _opcode_set(*names): """Return a set of opcodes by the names in `names`.""" s = set() for name in names: try: s.add(_opcode(name)) except KeyError: pass return s # Opcodes that leave the code object. OPS_CODE_END = _opcode_set('RETURN_VALUE') # Opcodes that unconditionally end the code chunk. OPS_CHUNK_END = _opcode_set( 'JUMP_ABSOLUTE', 'JUMP_FORWARD', 'RETURN_VALUE', 'RAISE_VARARGS', 'BREAK_LOOP', 'CONTINUE_LOOP', ) # Opcodes that unconditionally begin a new code chunk. By starting new chunks # with unconditional jump instructions, we neatly deal with jumps to jumps # properly. OPS_CHUNK_BEGIN = _opcode_set('JUMP_ABSOLUTE', 'JUMP_FORWARD') # Opcodes that push a block on the block stack. OPS_PUSH_BLOCK = _opcode_set( 'SETUP_LOOP', 'SETUP_EXCEPT', 'SETUP_FINALLY', 'SETUP_WITH', 'SETUP_ASYNC_WITH', ) # Block types for exception handling. OPS_EXCEPT_BLOCKS = _opcode_set('SETUP_EXCEPT', 'SETUP_FINALLY') # Opcodes that pop a block from the block stack. OPS_POP_BLOCK = _opcode_set('POP_BLOCK') OPS_GET_AITER = _opcode_set('GET_AITER') # Opcodes that have a jump destination, but aren't really a jump. OPS_NO_JUMP = OPS_PUSH_BLOCK # Individual opcodes we need below. OP_BREAK_LOOP = _opcode('BREAK_LOOP') OP_END_FINALLY = _opcode('END_FINALLY') OP_COMPARE_OP = _opcode('COMPARE_OP') COMPARE_EXCEPTION = 10 # just have to get this constant from the code. OP_LOAD_CONST = _opcode('LOAD_CONST') OP_RETURN_VALUE = _opcode('RETURN_VALUE') class ByteParser(object): """Parse byte codes to understand the structure of code.""" @contract(text='unicode') def __init__(self, text, code=None, filename=None): self.text = text if code: self.code = code else: try: self.code = compile_unicode(text, filename, "exec") except SyntaxError as synerr: raise NotPython( u"Couldn't parse '%s' as Python source: '%s' at line %d" % ( filename, synerr.msg, synerr.lineno ) ) # Alternative Python implementations don't always provide all the # attributes on code objects that we need to do the analysis. for attr in ['co_lnotab', 'co_firstlineno', 'co_consts', 'co_code']: if not hasattr(self.code, attr): raise CoverageException( "This implementation of Python doesn't support code analysis.\n" "Run coverage.py under CPython for this command." ) def child_parsers(self): """Iterate over all the code objects nested within this one. The iteration includes `self` as its first value. """ children = CodeObjects(self.code) return (ByteParser(self.text, code=c) for c in children) def _bytes_lines(self): """Map byte offsets to line numbers in `code`. Uses co_lnotab described in Python/compile.c to map byte offsets to line numbers. Produces a sequence: (b0, l0), (b1, l1), ... Only byte offsets that correspond to line numbers are included in the results. """ # Adapted from dis.py in the standard library. byte_increments = bytes_to_ints(self.code.co_lnotab[0::2]) line_increments = bytes_to_ints(self.code.co_lnotab[1::2]) last_line_num = None line_num = self.code.co_firstlineno byte_num = 0 for byte_incr, line_incr in zip(byte_increments, line_increments): if byte_incr: if line_num != last_line_num: yield (byte_num, line_num) last_line_num = line_num byte_num += byte_incr line_num += line_incr if line_num != last_line_num: yield (byte_num, line_num) def _find_statements(self): """Find the statements in `self.code`. Produce a sequence of line numbers that start statements. Recurses into all code objects reachable from `self.code`. """ for bp in self.child_parsers(): # Get all of the lineno information from this code. for _, l in bp._bytes_lines(): yield l def _block_stack_repr(self, block_stack): # pragma: debugging """Get a string version of `block_stack`, for debugging.""" blocks = ", ".join( "(%s, %r)" % (dis.opname[b[0]], b[1]) for b in block_stack ) return "[" + blocks + "]" def _split_into_chunks(self): """Split the code object into a list of `Chunk` objects. Each chunk is only entered at its first instruction, though there can be many exits from a chunk. Returns a list of `Chunk` objects. """ # The list of chunks so far, and the one we're working on. chunks = [] chunk = None # A dict mapping byte offsets of line starts to the line numbers. bytes_lines_map = dict(self._bytes_lines()) # The block stack: loops and try blocks get pushed here for the # implicit jumps that can occur. # Each entry is a tuple: (block type, destination) block_stack = [] # Some op codes are followed by branches that should be ignored. This # is a count of how many ignores are left. ignore_branch = 0 ignore_pop_block = 0 # We have to handle the last two bytecodes specially. ult = penult = None # Get a set of all of the jump-to points. jump_to = set() bytecodes = list(ByteCodes(self.code.co_code)) for bc in bytecodes: if bc.jump_to >= 0: jump_to.add(bc.jump_to) chunk_lineno = 0 # Walk the byte codes building chunks. for bc in bytecodes: # Maybe have to start a new chunk. start_new_chunk = False first_chunk = False if bc.offset in bytes_lines_map: # Start a new chunk for each source line number. start_new_chunk = True chunk_lineno = bytes_lines_map[bc.offset] first_chunk = True elif bc.offset in jump_to: # To make chunks have a single entrance, we have to make a new # chunk when we get to a place some bytecode jumps to. start_new_chunk = True elif bc.op in OPS_CHUNK_BEGIN: # Jumps deserve their own unnumbered chunk. This fixes # problems with jumps to jumps getting confused. start_new_chunk = True if not chunk or start_new_chunk: if chunk: chunk.exits.add(bc.offset) chunk = Chunk(bc.offset, chunk_lineno, first_chunk) if not chunks: # The very first chunk of a code object is always an # entrance. chunk.entrance = True chunks.append(chunk) # Look at the opcode. if bc.jump_to >= 0 and bc.op not in OPS_NO_JUMP: if ignore_branch: # Someone earlier wanted us to ignore this branch. ignore_branch -= 1 else: # The opcode has a jump, it's an exit for this chunk. chunk.exits.add(bc.jump_to) if bc.op in OPS_CODE_END: # The opcode can exit the code object. chunk.exits.add(-self.code.co_firstlineno) if bc.op in OPS_PUSH_BLOCK: # The opcode adds a block to the block_stack. block_stack.append((bc.op, bc.jump_to)) if bc.op in OPS_POP_BLOCK: # The opcode pops a block from the block stack. if ignore_pop_block: ignore_pop_block -= 1 else: block_stack.pop() if bc.op in OPS_CHUNK_END: # This opcode forces the end of the chunk. if bc.op == OP_BREAK_LOOP: # A break is implicit: jump where the top of the # block_stack points. chunk.exits.add(block_stack[-1][1]) chunk = None if bc.op == OP_END_FINALLY: # For the finally clause we need to find the closest exception # block, and use its jump target as an exit. for block in reversed(block_stack): if block[0] in OPS_EXCEPT_BLOCKS: chunk.exits.add(block[1]) break if bc.op == OP_COMPARE_OP and bc.arg == COMPARE_EXCEPTION: # This is an except clause. We want to overlook the next # branch, so that except's don't count as branches. ignore_branch += 1 if bc.op in OPS_GET_AITER: # GET_AITER is weird: First, it seems to generate one more # POP_BLOCK than SETUP_*, so we have to prepare to ignore one # of the POP_BLOCKS. Second, we don't have a clear branch to # the exit of the loop, so we peek into the block stack to find # it. ignore_pop_block += 1 chunk.exits.add(block_stack[-1][1]) penult = ult ult = bc if chunks: # The last two bytecodes could be a dummy "return None" that # shouldn't be counted as real code. Every Python code object seems # to end with a return, and a "return None" is inserted if there # isn't an explicit return in the source. if ult and penult: if penult.op == OP_LOAD_CONST and ult.op == OP_RETURN_VALUE: if self.code.co_consts[penult.arg] is None: # This is "return None", but is it dummy? A real line # would be a last chunk all by itself. if chunks[-1].byte != penult.offset: ex = -self.code.co_firstlineno # Split the last chunk last_chunk = chunks[-1] last_chunk.exits.remove(ex) last_chunk.exits.add(penult.offset) chunk = Chunk( penult.offset, last_chunk.line, False ) chunk.exits.add(ex) chunks.append(chunk) # Give all the chunks a length. chunks[-1].length = bc.next_offset - chunks[-1].byte for i in range(len(chunks)-1): chunks[i].length = chunks[i+1].byte - chunks[i].byte #self.validate_chunks(chunks) return chunks def validate_chunks(self, chunks): # pragma: debugging """Validate the rule that chunks have a single entrance.""" # starts is the entrances to the chunks starts = set(ch.byte for ch in chunks) for ch in chunks: assert all((ex in starts or ex < 0) for ex in ch.exits) def _arcs(self): """Find the executable arcs in the code. Yields pairs: (from,to). From and to are integer line numbers. If from is < 0, then the arc is an entrance into the code object. If to is < 0, the arc is an exit from the code object. """ chunks = self._split_into_chunks() # A map from byte offsets to the chunk starting at that offset. byte_chunks = dict((c.byte, c) for c in chunks) # Traverse from the first chunk in each line, and yield arcs where # the trace function will be invoked. for chunk in chunks: if chunk.entrance: yield (-1, chunk.line) if not chunk.first: continue chunks_considered = set() chunks_to_consider = [chunk] while chunks_to_consider: # Get the chunk we're considering, and make sure we don't # consider it again. this_chunk = chunks_to_consider.pop() chunks_considered.add(this_chunk) # For each exit, add the line number if the trace function # would be triggered, or add the chunk to those being # considered if not. for ex in this_chunk.exits: if ex < 0: yield (chunk.line, ex) else: next_chunk = byte_chunks[ex] if next_chunk in chunks_considered: continue # The trace function is invoked if visiting the first # bytecode in a line, or if the transition is a # backward jump. backward_jump = next_chunk.byte < this_chunk.byte if next_chunk.first or backward_jump: if next_chunk.line != chunk.line: yield (chunk.line, next_chunk.line) else: chunks_to_consider.append(next_chunk) def _all_chunks(self): """Returns a list of `Chunk` objects for this code and its children. See `_split_into_chunks` for details. """ chunks = [] for bp in self.child_parsers(): chunks.extend(bp._split_into_chunks()) return chunks def _all_arcs(self): """Get the set of all arcs in this code object and its children. See `_arcs` for details. """ arcs = set() for bp in self.child_parsers(): arcs.update(bp._arcs()) return arcs class Chunk(object): """A sequence of byte codes with a single entrance. To analyze byte code, we have to divide it into chunks, sequences of byte codes such that each chunk has only one entrance, the first instruction in the block. This is almost the CS concept of `basic block`_, except that we're willing to have many exits from a chunk, and "basic block" is a more cumbersome term. .. _basic block: http://en.wikipedia.org/wiki/Basic_block `byte` is the offset to the bytecode starting this chunk. `line` is the source line number containing this chunk. `first` is true if this is the first chunk in the source line. An exit < 0 means the chunk can leave the code (return). The exit is the negative of the starting line number of the code block. The `entrance` attribute is a boolean indicating whether the code object can be entered at this chunk. """ def __init__(self, byte, line, first): self.byte = byte self.line = line self.first = first self.length = 0 self.entrance = False self.exits = set() def __repr__(self): return "<%d+%d @%d%s%s %r>" % ( self.byte, self.length, self.line, "!" if self.first else "", "v" if self.entrance else "", list(self.exits), ) SKIP_DUMP_FIELDS = ["ctx"] def is_simple_value(value): return ( value in [None, [], (), {}, set()] or isinstance(value, (string_class, int, float)) ) def ast_dump(node, depth=0): indent = " " * depth if not isinstance(node, ast.AST): print("{0}<{1} {2!r}>".format(indent, node.__class__.__name__, node)) return lineno = getattr(node, "lineno", None) if lineno is not None: linemark = " @ {0}".format(node.lineno) else: linemark = "" head = "{0}<{1}{2}".format(indent, node.__class__.__name__, linemark) named_fields = [ (name, value) for name, value in ast.iter_fields(node) if name not in SKIP_DUMP_FIELDS ] if not named_fields: print("{0}>".format(head)) elif len(named_fields) == 1 and is_simple_value(named_fields[0][1]): field_name, value = named_fields[0] print("{0} {1}: {2!r}>".format(head, field_name, value)) else: print(head) if 0: print("{0}# mro: {1}".format( indent, ", ".join(c.__name__ for c in node.__class__.__mro__[1:]), )) next_indent = indent + " " for field_name, value in named_fields: prefix = "{0}{1}:".format(next_indent, field_name) if is_simple_value(value): print("{0} {1!r}".format(prefix, value)) elif isinstance(value, list): print("{0} [".format(prefix)) for n in value: ast_dump(n, depth + 8) print("{0}]".format(next_indent)) else: print(prefix) ast_dump(value, depth + 8) print("{0}>".format(indent))