Add python coverage 3.7 to depot tools.

third_party/coverage/parser.py

Index: third_party/coverage/parser.py
diff --git a/third_party/coverage/parser.py b/third_party/coverage/parser.py
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+"""Code parsing for Coverage."""
+
+import dis, re, sys, token, tokenize
+
+from coverage.backward import set, sorted, StringIO # pylint: disable=W0622
+from coverage.backward import open_source, range    # pylint: disable=W0622
+from coverage.backward import reversed              # pylint: disable=W0622
+from coverage.backward import bytes_to_ints
+from coverage.bytecode import ByteCodes, CodeObjects
+from coverage.misc import nice_pair, expensive, join_regex
+from coverage.misc import CoverageException, NoSource, NotPython
+
+
+class CodeParser(object):
+    """Parse code to find executable lines, excluded lines, etc."""
+
+    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, "CodeParser needs either text or filename"
+        self.filename = filename or "<code>"
+        self.text = text
+        if not self.text:
+            try:
+                sourcef = open_source(self.filename)
+                try:
+                    self.text = sourcef.read()
+                finally:
+                    sourcef.close()
+            except IOError:
+                _, err, _ = sys.exc_info()
+                raise NoSource(
+                    "No source for code: '%s': %s" % (self.filename, err)
+                    )
+
+        # Scrap the BOM if it exists.
+        if self.text and ord(self.text[0]) == 0xfeff:
+            self.text = self.text[1:]
+
+        self.exclude = exclude
+
+        self.show_tokens = False
+
+        # The text lines of the parsed code.
+        self.lines = self.text.split('\n')
+
+        # The line numbers of excluded lines of code.
+        self.excluded = set()
+
+        # The line numbers of docstring lines.
+        self.docstrings = set()
+
+        # The line numbers of class definitions.
+        self.classdefs = set()
+
+        # A dict mapping line numbers to (lo,hi) for multi-line statements.
+        self.multiline = {}
+
+        # The line numbers that start statements.
+        self.statement_starts = set()
+
+        # Lazily-created ByteParser
+        self._byte_parser = None
+
+    def _get_byte_parser(self):
+        """Create a ByteParser on demand."""
+        if not self._byte_parser:
+            self._byte_parser = \
+                            ByteParser(text=self.text, filename=self.filename)
+        return self._byte_parser
+    byte_parser = property(_get_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.
+
+        """
+        regex_c = re.compile(join_regex(regexes))
+        matches = set()
+        for i, ltext in enumerate(self.lines):
+            if regex_c.search(ltext):
+                matches.add(i+1)
+        return matches
+
+    def _raw_parse(self):
+        """Parse the source to find the interesting facts about its lines.
+
+        A handful of member fields are updated.
+
+        """
+        # Find lines which match an exclusion pattern.
+        if self.exclude:
+            self.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
+        prev_toktype = token.INDENT
+        first_line = None
+        empty = True
+
+        tokgen = tokenize.generate_tokens(StringIO(self.text).readline)
+        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 and 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.classdefs.add(slineno)
+            elif toktype == token.OP and ttext == ':':
+                if not excluding and elineno in self.excluded:
+                    # 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.
+                    exclude_indent = indent
+                    excluding = True
+            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.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.
+                    rng = (first_line, elineno)
+                    for l in range(first_line, elineno+1):
+                        self.multiline[l] = rng
+                first_line = None
+
+            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.excluded.add(elineno)
+
+            prev_toktype = toktype
+
+        # Find the starts of the executable statements.
+        if not empty:
+            self.statement_starts.update(self.byte_parser._find_statements())
+
+    def first_line(self, line):
+        """Return the first line number of the statement including `line`."""
+        rng = self.multiline.get(line)
+        if rng:
+            first_line = rng[0]
+        else:
+            first_line = line
+        return first_line
+
+    def first_lines(self, lines, ignore=None):
+        """Map the line numbers in `lines` to the correct first line of the
+        statement.
+
+        Skip any line mentioned in `ignore`.
+
+        Returns a sorted list of the first lines.
+
+        """
+        ignore = ignore or []
+        lset = set()
+        for l in lines:
+            if l in ignore:
+                continue
+            new_l = self.first_line(l)
+            if new_l not in ignore:
+                lset.add(new_l)
+        return sorted(lset)
+
+    def parse_source(self):
+        """Parse source text to find executable lines, excluded lines, etc.
+
+        Return values are 1) a sorted list of executable line numbers, and
+        2) a sorted list of excluded line numbers.
+
+        Reported line numbers are normalized to the first line of multi-line
+        statements.
+
+        """
+        try:
+            self._raw_parse()
+        except (tokenize.TokenError, IndentationError):
+            _, tokerr, _ = sys.exc_info()
+            msg, lineno = tokerr.args
+            raise NotPython(
+                "Couldn't parse '%s' as Python source: '%s' at %s" %
+                    (self.filename, msg, lineno)
+                )
+
+        excluded_lines = self.first_lines(self.excluded)
+        ignore = excluded_lines + list(self.docstrings)
+        lines = self.first_lines(self.statement_starts, ignore)
+
+        return lines, excluded_lines
+
+    def arcs(self):
+        """Get information about the arcs available in the code.
+
+        Returns a sorted list of line number pairs.  Line numbers have been
+        normalized to the first line of multiline statements.
+
+        """
+        all_arcs = []
+        for l1, l2 in self.byte_parser._all_arcs():
+            fl1 = self.first_line(l1)
+            fl2 = self.first_line(l2)
+            if fl1 != fl2:
+                all_arcs.append((fl1, fl2))
+        return sorted(all_arcs)
+    arcs = expensive(arcs)
+
+    def exit_counts(self):
+        """Get a mapping from line numbers to count of exits from that line.
+
+        Excluded lines are excluded.
+
+        """
+        excluded_lines = self.first_lines(self.excluded)
+        exit_counts = {}
+        for l1, l2 in self.arcs():
+            if l1 < 0:
+                # Don't ever report -1 as a line number
+                continue
+            if l1 in excluded_lines:
+                # Don't report excluded lines as line numbers.
+                continue
+            if l2 in excluded_lines:
+                # Arcs to excluded lines shouldn't count.
+                continue
+            if l1 not in exit_counts:
+                exit_counts[l1] = 0
+            exit_counts[l1] += 1
+
+        # Class definitions have one extra exit, so remove one for each:
+        for l in self.classdefs:
+            # Ensure key is there: classdefs can include excluded lines.
+            if l in exit_counts:
+                exit_counts[l] -= 1
+
+        return exit_counts
+    exit_counts = expensive(exit_counts)
+
+
+## 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'
+    )
+
+# 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')
+
+# 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 const 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."""
+
+    def __init__(self, code=None, text=None, filename=None):
+        if code:
+            self.code = code
+            self.text = text
+        else:
+            if not text:
+                assert filename, "If no code or text, need a filename"
+                sourcef = open_source(filename)
+                try:
+                    text = sourcef.read()
+                finally:
+                    sourcef.close()
+            self.text = text
+
+            try:
+                # Python 2.3 and 2.4 don't like partial last lines, so be sure
+                # the text ends nicely for them.
+                self.code = compile(text + '\n', filename, "exec")
+            except SyntaxError:
+                _, synerr, _ = sys.exc_info()
+                raise NotPython(
+                    "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(code=c, text=self.text) 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):
+        """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
+
+        # 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()
+        for bc in ByteCodes(self.code.co_code):
+            if bc.jump_to >= 0:
+                jump_to.add(bc.jump_to)
+
+        chunk_lineno = 0
+
+        # Walk the byte codes building chunks.
+        for bc in ByteCodes(self.code.co_code):
+            # 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)
+                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.
+                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
+
+            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 # pylint: disable=W0631,C0301
+            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):
+        """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 chunks jumped into.
+        byte_chunks = dict([(c.byte, c) for c in chunks])
+
+        # There's always an entrance at the first chunk.
+        yield (-1, byte_chunks[0].line)
+
+        # Traverse from the first chunk in each line, and yield arcs where
+        # the trace function will be invoked.
+        for chunk in chunks:
+            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
+
+    `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.
+
+    """
+    def __init__(self, byte, line, first):
+        self.byte = byte
+        self.line = line
+        self.first = first
+        self.length = 0
+        self.exits = set()
+
+    def __repr__(self):
+        if self.first:
+            bang = "!"
+        else:
+            bang = ""
+        return "<%d+%d @%d%s %r>" % (
+            self.byte, self.length, self.line, bang, list(self.exits)
+            )