path: root/Cython/Compiler/Scanning.py

# cython: infer_types=True, language_level=3, auto_pickle=False
#
#   Cython Scanner
#

from __future__ import absolute_import

import cython
cython.declare(make_lexicon=object, lexicon=object,
               print_function=object, error=object, warning=object,
               os=object, platform=object)

import os
import platform
from unicodedata import normalize
from contextlib import contextmanager

from .. import Utils
from ..Plex.Scanners import Scanner
from ..Plex.Errors import UnrecognizedInput
from .Errors import error, warning, hold_errors, release_errors, CompileError
from .Lexicon import any_string_prefix, make_lexicon, IDENT
from .Future import print_function

debug_scanner = 0
trace_scanner = 0
scanner_debug_flags = 0
scanner_dump_file = None

lexicon = None


def get_lexicon():
    global lexicon
    if not lexicon:
        lexicon = make_lexicon()
    return lexicon


#------------------------------------------------------------------

py_reserved_words = [
    "global", "nonlocal", "def", "class", "print", "del", "pass", "break",
    "continue", "return", "raise", "import", "exec", "try",
    "except", "finally", "while", "if", "elif", "else", "for",
    "in", "assert", "and", "or", "not", "is", "lambda",
    "from", "yield", "with",
]

pyx_reserved_words = py_reserved_words + [
    "include", "ctypedef", "cdef", "cpdef",
    "cimport", "DEF", "IF", "ELIF", "ELSE"
]


#------------------------------------------------------------------

class CompileTimeScope(object):

    def __init__(self, outer=None):
        self.entries = {}
        self.outer = outer

    def declare(self, name, value):
        self.entries[name] = value

    def update(self, other):
        self.entries.update(other)

    def lookup_here(self, name):
        return self.entries[name]

    def __contains__(self, name):
        return name in self.entries

    def lookup(self, name):
        try:
            return self.lookup_here(name)
        except KeyError:
            outer = self.outer
            if outer:
                return outer.lookup(name)
            else:
                raise


def initial_compile_time_env():
    benv = CompileTimeScope()
    names = ('UNAME_SYSNAME', 'UNAME_NODENAME', 'UNAME_RELEASE', 'UNAME_VERSION', 'UNAME_MACHINE')
    for name, value in zip(names, platform.uname()):
        benv.declare(name, value)
    try:
        import __builtin__ as builtins
    except ImportError:
        import builtins

    names = (
        'False', 'True',
        'abs', 'all', 'any', 'ascii', 'bin', 'bool', 'bytearray', 'bytes',
        'chr', 'cmp', 'complex', 'dict', 'divmod', 'enumerate', 'filter',
        'float', 'format', 'frozenset', 'hash', 'hex', 'int', 'len',
        'list', 'map', 'max', 'min', 'oct', 'ord', 'pow', 'range',
        'repr', 'reversed', 'round', 'set', 'slice', 'sorted', 'str',
        'sum', 'tuple', 'zip',
        ### defined below in a platform independent way
        # 'long', 'unicode', 'reduce', 'xrange'
    )

    for name in names:
        try:
            benv.declare(name, getattr(builtins, name))
        except AttributeError:
            # ignore, likely Py3
            pass

    # Py2/3 adaptations
    from functools import reduce
    benv.declare('reduce', reduce)
    benv.declare('unicode', getattr(builtins, 'unicode', getattr(builtins, 'str')))
    benv.declare('long', getattr(builtins, 'long', getattr(builtins, 'int')))
    benv.declare('xrange', getattr(builtins, 'xrange', getattr(builtins, 'range')))

    denv = CompileTimeScope(benv)
    return denv


#------------------------------------------------------------------

class SourceDescriptor(object):
    """
    A SourceDescriptor should be considered immutable.
    """
    filename = None

    _file_type = 'pyx'

    _escaped_description = None
    _cmp_name = ''
    def __str__(self):
        assert False  # To catch all places where a descriptor is used directly as a filename

    def set_file_type_from_name(self, filename):
        name, ext = os.path.splitext(filename)
        self._file_type = ext in ('.pyx', '.pxd', '.py') and ext[1:] or 'pyx'

    def is_cython_file(self):
        return self._file_type in ('pyx', 'pxd')

    def is_python_file(self):
        return self._file_type == 'py'

    def get_escaped_description(self):
        if self._escaped_description is None:
            esc_desc = \
                self.get_description().encode('ASCII', 'replace').decode("ASCII")
            # Use forward slashes on Windows since these paths
            # will be used in the #line directives in the C/C++ files.
            self._escaped_description = esc_desc.replace('\\', '/')
        return self._escaped_description

    def __gt__(self, other):
        # this is only used to provide some sort of order
        try:
            return self._cmp_name > other._cmp_name
        except AttributeError:
            return False

    def __lt__(self, other):
        # this is only used to provide some sort of order
        try:
            return self._cmp_name < other._cmp_name
        except AttributeError:
            return False

    def __le__(self, other):
        # this is only used to provide some sort of order
        try:
            return self._cmp_name <= other._cmp_name
        except AttributeError:
            return False

    def __copy__(self):
        return self  # immutable, no need to copy

    def __deepcopy__(self, memo):
        return self  # immutable, no need to copy


class FileSourceDescriptor(SourceDescriptor):
    """
    Represents a code source. A code source is a more generic abstraction
    for a "filename" (as sometimes the code doesn't come from a file).
    Instances of code sources are passed to Scanner.__init__ as the
    optional name argument and will be passed back when asking for
    the position()-tuple.
    """
    def __init__(self, filename, path_description=None):
        filename = Utils.decode_filename(filename)
        self.path_description = path_description or filename
        self.filename = filename
        # Prefer relative paths to current directory (which is most likely the project root) over absolute paths.
        workdir = os.path.abspath('.') + os.sep
        self.file_path = filename[len(workdir):] if filename.startswith(workdir) else filename
        self.set_file_type_from_name(filename)
        self._cmp_name = filename
        self._lines = {}

    def get_lines(self, encoding=None, error_handling=None):
        # we cache the lines only the second time this is called, in
        # order to save memory when they are only used once
        key = (encoding, error_handling)
        try:
            lines = self._lines[key]
            if lines is not None:
                return lines
        except KeyError:
            pass

        with Utils.open_source_file(self.filename, encoding=encoding, error_handling=error_handling) as f:
            lines = list(f)

        if key in self._lines:
            self._lines[key] = lines
        else:
            # do not cache the first access, but remember that we
            # already read it once
            self._lines[key] = None
        return lines

    def get_description(self):
        try:
            return os.path.relpath(self.path_description)
        except ValueError:
            # path not under current directory => use complete file path
            return self.path_description

    def get_error_description(self):
        path = self.filename
        cwd = Utils.decode_filename(os.getcwd() + os.path.sep)
        if path.startswith(cwd):
            return path[len(cwd):]
        return path

    def get_filenametable_entry(self):
        return self.file_path

    def __eq__(self, other):
        return isinstance(other, FileSourceDescriptor) and self.filename == other.filename

    def __hash__(self):
        return hash(self.filename)

    def __repr__(self):
        return "<FileSourceDescriptor:%s>" % self.filename


class StringSourceDescriptor(SourceDescriptor):
    """
    Instances of this class can be used instead of a filenames if the
    code originates from a string object.
    """
    def __init__(self, name, code):
        self.name = name
        #self.set_file_type_from_name(name)
        self.codelines = [x + "\n" for x in code.split("\n")]
        self._cmp_name = name

    def get_lines(self, encoding=None, error_handling=None):
        if not encoding:
            return self.codelines
        else:
            return [line.encode(encoding, error_handling).decode(encoding)
                    for line in self.codelines]

    def get_description(self):
        return self.name

    get_error_description = get_description

    def get_filenametable_entry(self):
        return "<stringsource>"

    def __hash__(self):
        return id(self)
        # Do not hash on the name, an identical string source should be the
        # same object (name is often defaulted in other places)
        # return hash(self.name)

    def __eq__(self, other):
        return isinstance(other, StringSourceDescriptor) and self.name == other.name

    def __repr__(self):
        return "<StringSourceDescriptor:%s>" % self.name


#------------------------------------------------------------------

class PyrexScanner(Scanner):
    #  context            Context  Compilation context
    #  included_files     [string] Files included with 'include' statement
    #  compile_time_env   dict     Environment for conditional compilation
    #  compile_time_eval  boolean  In a true conditional compilation context
    #  compile_time_expr  boolean  In a compile-time expression context
    #  put_back_on_failure  list or None  If set, this records states so the tentatively_scan
    #                                       contextmanager can restore it

    def __init__(self, file, filename, parent_scanner=None,
                 scope=None, context=None, source_encoding=None, parse_comments=True, initial_pos=None):
        Scanner.__init__(self, get_lexicon(), file, filename, initial_pos)

        if filename.is_python_file():
            self.in_python_file = True
            self.keywords = set(py_reserved_words)
        else:
            self.in_python_file = False
            self.keywords = set(pyx_reserved_words)

        self.async_enabled = 0

        if parent_scanner:
            self.context = parent_scanner.context
            self.included_files = parent_scanner.included_files
            self.compile_time_env = parent_scanner.compile_time_env
            self.compile_time_eval = parent_scanner.compile_time_eval
            self.compile_time_expr = parent_scanner.compile_time_expr

            if parent_scanner.async_enabled:
                self.enter_async()
        else:
            self.context = context
            self.included_files = scope.included_files
            self.compile_time_env = initial_compile_time_env()
            self.compile_time_eval = 1
            self.compile_time_expr = 0
            if getattr(context.options, 'compile_time_env', None):
                self.compile_time_env.update(context.options.compile_time_env)
        self.parse_comments = parse_comments
        self.source_encoding = source_encoding
        self.trace = trace_scanner
        self.indentation_stack = [0]
        self.indentation_char = None
        self.bracket_nesting_level = 0

        self.put_back_on_failure = None

        self.begin('INDENT')
        self.sy = ''
        self.next()

    def normalize_ident(self, text):
        try:
            text.encode('ascii')  # really just name.isascii but supports Python 2 and 3
        except UnicodeEncodeError:
            text = normalize('NFKC', text)
        self.produce(IDENT, text)

    def commentline(self, text):
        if self.parse_comments:
            self.produce('commentline', text)

    def strip_underscores(self, text, symbol):
        self.produce(symbol, text.replace('_', ''))

    def current_level(self):
        return self.indentation_stack[-1]

    def open_bracket_action(self, text):
        self.bracket_nesting_level += 1
        return text

    def close_bracket_action(self, text):
        self.bracket_nesting_level -= 1
        return text

    def newline_action(self, text):
        if self.bracket_nesting_level == 0:
            self.begin('INDENT')
            self.produce('NEWLINE', '')

    string_states = {
        "'":   'SQ_STRING',
        '"':   'DQ_STRING',
        "'''": 'TSQ_STRING',
        '"""': 'TDQ_STRING'
    }

    def begin_string_action(self, text):
        while text[:1] in any_string_prefix:
            text = text[1:]
        self.begin(self.string_states[text])
        self.produce('BEGIN_STRING')

    def end_string_action(self, text):
        self.begin('')
        self.produce('END_STRING')

    def unclosed_string_action(self, text):
        self.end_string_action(text)
        self.error_at_scanpos("Unclosed string literal")

    def indentation_action(self, text):
        self.begin('')
        # Indentation within brackets should be ignored.
        #if self.bracket_nesting_level > 0:
        #    return
        # Check that tabs and spaces are being used consistently.
        if text:
            c = text[0]
            #print "Scanner.indentation_action: indent with", repr(c) ###
            if self.indentation_char is None:
                self.indentation_char = c
                #print "Scanner.indentation_action: setting indent_char to", repr(c)
            else:
                if self.indentation_char != c:
                    self.error_at_scanpos("Mixed use of tabs and spaces")
            if text.replace(c, "") != "":
                self.error_at_scanpos("Mixed use of tabs and spaces")
        # Figure out how many indents/dedents to do
        current_level = self.current_level()
        new_level = len(text)
        #print "Changing indent level from", current_level, "to", new_level ###
        if new_level == current_level:
            return
        elif new_level > current_level:
            #print "...pushing level", new_level ###
            self.indentation_stack.append(new_level)
            self.produce('INDENT', '')
        else:
            while new_level < self.current_level():
                #print "...popping level", self.indentation_stack[-1] ###
                self.indentation_stack.pop()
                self.produce('DEDENT', '')
            #print "...current level now", self.current_level() ###
            if new_level != self.current_level():
                self.error_at_scanpos("Inconsistent indentation")

    def eof_action(self, text):
        while len(self.indentation_stack) > 1:
            self.produce('DEDENT', '')
            self.indentation_stack.pop()
        self.produce('EOF', '')

    def next(self):
        try:
            sy, systring = self.read()
        except UnrecognizedInput:
            self.error_at_scanpos("Unrecognized character")
            return  # just a marker, error() always raises
        if sy == IDENT:
            if systring in self.keywords:
                if systring == u'print' and print_function in self.context.future_directives:
                    self.keywords.discard('print')
                elif systring == u'exec' and self.context.language_level >= 3:
                    self.keywords.discard('exec')
                else:
                    sy = systring
            systring = self.context.intern_ustring(systring)
        if self.put_back_on_failure is not None:
            self.put_back_on_failure.append((sy, systring, self.position()))
        self.sy = sy
        self.systring = systring
        if False:  # debug_scanner:
            _, line, col = self.position()
            if not self.systring or self.sy == self.systring:
                t = self.sy
            else:
                t = "%s %s" % (self.sy, self.systring)
            print("--- %3d %2d %s" % (line, col, t))

    def peek(self):
        saved = self.sy, self.systring
        saved_pos = self.position()
        self.next()
        next = self.sy, self.systring
        self.unread(self.sy, self.systring, self.position())
        self.sy, self.systring = saved
        self.last_token_position_tuple = saved_pos
        return next

    def put_back(self, sy, systring, pos):
        self.unread(self.sy, self.systring, self.last_token_position_tuple)
        self.sy = sy
        self.systring = systring
        self.last_token_position_tuple = pos


    def error(self, message, pos=None, fatal=True):
        if pos is None:
            pos = self.position()
        if self.sy == 'INDENT':
            error(pos, "Possible inconsistent indentation")
        err = error(pos, message)
        if fatal: raise err

    def error_at_scanpos(self, message):
        # Like error(fatal=True), but gets the current scanning position rather than
        # the position of the last token read.
        pos = self.get_current_scan_pos()
        self.error(message, pos, True)

    def expect(self, what, message=None):
        if self.sy == what:
            self.next()
        else:
            self.expected(what, message)

    def expect_keyword(self, what, message=None):
        if self.sy == IDENT and self.systring == what:
            self.next()
        else:
            self.expected(what, message)

    def expected(self, what, message=None):
        if message:
            self.error(message)
        else:
            if self.sy == IDENT:
                found = self.systring
            else:
                found = self.sy
            self.error("Expected '%s', found '%s'" % (what, found))

    def expect_indent(self):
        self.expect('INDENT', "Expected an increase in indentation level")

    def expect_dedent(self):
        self.expect('DEDENT', "Expected a decrease in indentation level")

    def expect_newline(self, message="Expected a newline", ignore_semicolon=False):
        # Expect either a newline or end of file
        useless_trailing_semicolon = None
        if ignore_semicolon and self.sy == ';':
            useless_trailing_semicolon = self.position()
            self.next()
        if self.sy != 'EOF':
            self.expect('NEWLINE', message)
        if useless_trailing_semicolon is not None:
            warning(useless_trailing_semicolon, "useless trailing semicolon")

    def enter_async(self):
        self.async_enabled += 1
        if self.async_enabled == 1:
            self.keywords.add('async')
            self.keywords.add('await')

    def exit_async(self):
        assert self.async_enabled > 0
        self.async_enabled -= 1
        if not self.async_enabled:
            self.keywords.discard('await')
            self.keywords.discard('async')
            if self.sy in ('async', 'await'):
                self.sy, self.systring = IDENT, self.context.intern_ustring(self.sy)

@contextmanager
@cython.locals(scanner=Scanner)
def tentatively_scan(scanner):
    errors = hold_errors()
    try:
        put_back_on_failure = scanner.put_back_on_failure
        scanner.put_back_on_failure = []
        initial_state = (scanner.sy, scanner.systring, scanner.position())
        try:
            yield errors
        except CompileError as e:
            pass
        finally:
            if errors:
                if scanner.put_back_on_failure:
                    for put_back in reversed(scanner.put_back_on_failure[:-1]):
                        scanner.put_back(*put_back)
                    # we need to restore the initial state too
                    scanner.put_back(*initial_state)
            elif put_back_on_failure is not None:
                # the outer "tentatively_scan" block that we're in might still
                # want to undo this block
                put_back_on_failure.extend(scanner.put_back_on_failure)
            scanner.put_back_on_failure = put_back_on_failure
    finally:
        release_errors(ignore=True)