syntaxtree.py 38.5 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
# syntaxtree.py - syntax tree classes for DHParser
#
# Copyright 2016  by Eckhart Arnold (arnold@badw.de)
#                 Bavarian Academy of Sciences an Humanities (badw.de)
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.  See the License for the specific language governing
# permissions and limitations under the License.
17 18 19


"""
20 21
Module ``syntaxtree`` defines the ``Node``-class for syntax trees as well
as an abstract base class for parser-objects. The latter is defined
eckhart's avatar
eckhart committed
22
here, because node-objects refer to parser-objects. All concrete
23 24 25
parser classes are defined in the ``parse`` module.
"""

26

Eckhart Arnold's avatar
Eckhart Arnold committed
27
import collections.abc
28
from collections import OrderedDict
29

30
from DHParser.error import Error, linebreaks, line_col
31
from DHParser.stringview import StringView
eckhart's avatar
eckhart committed
32
from DHParser.toolkit import re, typing
eckhart's avatar
eckhart committed
33
from typing import Callable, cast, Iterator, List, AbstractSet, Set, Union, Tuple, Optional
di68kap's avatar
di68kap committed
34

35

36 37
__all__ = ('ParserBase',
           'WHITESPACE_PTYPE',
di68kap's avatar
di68kap committed
38
           'PLAINTEXT_PTYPE',
39 40 41 42
           'TOKEN_PTYPE',
           'MockParser',
           'ZombieParser',
           'ZOMBIE_PARSER',
eckhart's avatar
eckhart committed
43
           'ZOMBIE_NODE',
44
           'Node',
di68kap's avatar
di68kap committed
45
           'RootNode',
46
           'parse_sxpr',
47 48 49
           'parse_xml',
           'flatten_sxpr',
           'flatten_xml')
Eckhart Arnold's avatar
Eckhart Arnold committed
50 51


52 53 54 55 56 57 58 59 60 61 62 63 64
#######################################################################
#
# parser base and mock parsers
#
#######################################################################


class ParserBase:
    """
    ParserBase is the base class for all real and mock parser classes.
    It is defined here, because Node objects require a parser object
    for instantiation.
    """
Eckhart Arnold's avatar
Eckhart Arnold committed
65 66
    __slots__ = '_name', '_ptype'

67
    def __init__(self, name=''):  # , pbases=frozenset()):
68
        self._name = name  # type: str
69 70 71
        self._ptype = ':' + self.__class__.__name__  # type: str

    def __repr__(self):
di68kap's avatar
di68kap committed
72
         return self.name + self.ptype
73 74 75 76

    def __str__(self):
        return self.name + (' = ' if self.name else '') + repr(self)

77 78 79
    def __call__(self, text: StringView) -> Tuple[Optional['Node'], StringView]:
        return None, text

80 81
    @property
    def name(self):
82 83
        """Returns the name of the parser or the empty string '' for unnamed
        parsers."""
84 85
        return self._name

86 87
    @property
    def ptype(self) -> str:
88 89
        """Returns the type of the parser. By default this is the parser's
        class name preceded by a colon, e.g. ':ZeroOrMore'."""
90 91 92 93
        return self._ptype

    @property
    def repr(self) -> str:
di68kap's avatar
di68kap committed
94
        """Returns the parser's name if it has a name and repr()"""
95 96
        return self.name if self.name else repr(self)

97
    def reset(self):
98
        """Resets any parser variables. (Should be overridden.)"""
99 100
        pass

eckhart's avatar
eckhart committed
101
    def grammar(self) -> Optional[object]:
102 103
        """Returns the Grammar object to which the parser belongs. If not
        yet connected to any Grammar object, None is returned."""
104 105 106
        return None

    def apply(self, func: Callable) -> bool:
eckhart's avatar
eckhart committed
107
        """Applies the function `func` to the parser. Returns False, if
108
        - for whatever reason - the functions has not been applied, True
eckhart's avatar
eckhart committed
109
        otherwise."""
110 111
        return False

112 113

WHITESPACE_PTYPE = ':Whitespace'
di68kap's avatar
di68kap committed
114
PLAINTEXT_PTYPE = ':PlainText'
115
TOKEN_PTYPE = ':_Token'
116 117 118 119 120 121


class MockParser(ParserBase):
    """
    MockParser objects can be used to reconstruct syntax trees from a
    serialized form like S-expressions or XML. Mock objects can mimic
eckhart's avatar
eckhart committed
122
    different parser types by assigning them a `ptype` on initialization.
123 124 125 126 127

    Mock objects should not be used for anything other than
    syntax tree (re-)construction. In all other cases where a parser
    object substitute is needed, chose the singleton ZOMBIE_PARSER.
    """
Eckhart Arnold's avatar
Eckhart Arnold committed
128 129
    __slots__ = ()

130 131
    def __init__(self, name='', ptype=''):  # , pbases=frozenset()):
        assert not ptype or ptype[0] == ':'
132
        super().__init__(name)
133 134 135 136 137 138 139 140 141 142 143 144 145 146
        self._ptype = ptype or ':' + self.__class__.__name__


class ZombieParser(MockParser):
    """
    Serves as a substitute for a Parser instance.

    ``ZombieParser`` is the class of the singelton object
    ``ZOMBIE_PARSER``. The  ``ZOMBIE_PARSER`` has a name and can be
    called, but it never matches. It serves as a substitute where only
    these (or one of these properties) is needed, but no real Parser-
    object is instantiated.
    """
    alive = False
Eckhart Arnold's avatar
Eckhart Arnold committed
147
    __slots__ = ()
148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175

    def __init__(self):
        super(ZombieParser, self).__init__("__ZOMBIE__")
        assert not self.__class__.alive, "There can be only one!"
        assert self.__class__ == ZombieParser, "No derivatives, please!"
        self.__class__.alive = True

    def __copy__(self):
        return self

    def __deepcopy__(self, memo):
        return self

    def __call__(self, text):
        """Better call Saul ;-)"""
        return None, text


ZOMBIE_PARSER = ZombieParser()


#######################################################################
#
# syntaxtree nodes
#
#######################################################################


176
ChildrenType = Tuple['Node', ...]
Eckhart Arnold's avatar
Eckhart Arnold committed
177
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
eckhart's avatar
eckhart committed
178
StrictResultType = Union[ChildrenType, StringView, str]
179
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
180 181


Eckhart Arnold's avatar
Eckhart Arnold committed
182
def flatten_sxpr(sxpr: str) -> str:
183
    """Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
184 185 186
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
187
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
188 189
    '(a (b c))'
    """
190
    return re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
Eckhart Arnold's avatar
Eckhart Arnold committed
191 192


193
def flatten_xml(xml: str) -> str:
194
    """Returns an XML-tree as a one liner without unnecessary whitespace,
195 196
    i.e. only whitespace within leaf-nodes is preserved.
    """
197 198 199 200 201
    # works only with regex
    # return re.sub(r'\s+(?=<\w)', '', re.sub(r'(?<=</\w+>)\s+', '', xml))
    def tag_only(m):
        return m.groupdict()['closing_tag']
    return re.sub(r'\s+(?=<\w)', '', re.sub(r'(?P<closing_tag></\w+>)\s+', tag_only, xml))
202 203


Eckhart Arnold's avatar
Eckhart Arnold committed
204
class Node(collections.abc.Sized):
205 206 207
    """
    Represents a node in the concrete or abstract syntax tree.

208
    Attributes:
209 210
        tag_name (str):  The name of the node, which is either its
            parser's name or, if that is empty, the parser's class name
211

212 213 214
        result (str or tuple):  The result of the parser which
            generated this node, which can be either a string or a
            tuple of child nodes.
215

216 217
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
218

eckhart's avatar
eckhart committed
219 220 221 222
        content (str):  Yields the contents of the tree as string. The
            difference to ``str(node)`` is that ``node.content`` does
            not add the error messages to the returned string.

Eckhart Arnold's avatar
Eckhart Arnold committed
223
        parser (Parser):  The parser which generated this node.
224 225
            WARNING: In case you use mock syntax trees for testing or
            parser replacement during the AST-transformation: DO NOT
Eckhart Arnold's avatar
Eckhart Arnold committed
226 227
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
228
            example by calling ``isinstance(node.parer, ...)``.
229

230 231 232
        len (int):  The full length of the node's string result if the
            node is a leaf node or, otherwise, the concatenated string
            result's of its descendants. The figure always represents
233
            the length before AST-transformation and will never change
234
            through AST-transformation. READ ONLY!
235

236 237
        pos (int):  the position of the node within the parsed text.

Eckhart Arnold's avatar
Eckhart Arnold committed
238
            The value of ``pos`` is -1 meaning invalid by default.
239
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
240
            nodes relative to this value.
241 242

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
243
            pos value of the root node should be set to 0 right
244 245
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
246
            Other than that, this value should be considered READ ONLY.
247 248
            At any rate, it should only be reassigned during the parsing
            stage and never during or after the AST-transformation.
249

250 251
        errors (list):  A list of all errors that occured on this node.

252
        attributes (dict): An optional dictionary of XML-attributes. This
253 254 255
            dictionary is created lazily upon first usage. The attributes
            will only be shown in the XML-Representation, not in the
            S-Expression-output.
256
    """
257

Eckhart Arnold's avatar
Eckhart Arnold committed
258
    __slots__ = '_result', 'children', '_len', '_pos', 'parser', 'errors', '_xml_attr', '_content'
259

260 261 262
    def __init__(self, parser, result: ResultType, leafhint: bool = False) -> None:
        """
        Initializes the ``Node``-object with the ``Parser``-Instance
263 264
        that generated the node and the parser's result.
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
265
        self.errors = []                # type: List[Error]
eckhart's avatar
eckhart committed
266
        self._pos = -1                  # type: int
di68kap's avatar
di68kap committed
267 268
        # Assignment to self.result initializes the attributes _result, children and _len
        # The following if-clause is merely an optimization, i.e. a fast-path for leaf-Nodes
269
        if leafhint:
eckhart's avatar
eckhart committed
270
            self._result = result       # type: StrictResultType
eckhart's avatar
eckhart committed
271
            self._content = None        # type: Optional[str]
272
            self.children = NoChildren  # type: ChildrenType
273
            self._len = -1              # type: int  # lazy evaluation
274 275
        else:
            self.result = result
276 277
        self.parser = parser or ZOMBIE_PARSER

Eckhart Arnold's avatar
Eckhart Arnold committed
278

279
    def __str__(self):
280
        s = "".join(str(child) for child in self.children) if self.children else self.content
eckhart's avatar
eckhart committed
281
        if self.errors:
282
            return ' <<< Error on "%s" | %s >>> ' % \
eckhart's avatar
eckhart committed
283
                   (s, '; '.join(e.message for e in self.errors))
284
        return s
285

Eckhart Arnold's avatar
Eckhart Arnold committed
286

287 288 289 290 291 292
    def __repr__(self):
        mpargs = {'name': self.parser.name, 'ptype': self.parser.ptype}
        parg = "MockParser({name}, {ptype})".format(**mpargs)
        rarg = str(self) if not self.children else \
               "(" + ", ".join(repr(child) for child in self.children) + ")"
        return "Node(%s, %s)" % (parg, rarg)
293

Eckhart Arnold's avatar
Eckhart Arnold committed
294

295
    def __len__(self):
296
        if self._len < 0:
di68kap's avatar
di68kap committed
297
            self._len = sum(len(child) for child in self.children) \
298
                if self.children else len(self._result)
299 300 301 302 303 304 305 306
        return self._len


    def __bool__(self):
        # A node that is not None is always True, even if it's empty
        return True


307
    def __eq__(self, other):
308 309 310 311
        """
        Equality of nodes: Two nodes are considered as equal, if their tag
        name is the same and if their results are equal.
        """
312
        return self.tag_name == other.tag_name and self.result == other.result
313

Eckhart Arnold's avatar
Eckhart Arnold committed
314

315
    def __hash__(self):
316
        return hash(self.tag_name)
317

Eckhart Arnold's avatar
Eckhart Arnold committed
318

319 320 321
    def __getitem__(self, index_or_tagname: Union[int, str]) -> Union['Node', Iterator['Node']]:
        """
        Returns the child node with the given index if ``index_or_tagname`` is
322
        an integer or the first child node with the given tag name. Examples::
323

324
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
325 326
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
327 328
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
329 330 331 332

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
333
        Returns:
334 335
            Node: All nodes which have a given tag name.
        """
336 337 338
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
339
            else:
340 341 342 343 344
                for child in self.children:
                    if child.tag_name == index_or_tagname:
                        return child
                raise KeyError(index_or_tagname)
        raise ValueError('Leave nodes have no children that can be indexed!')
345 346 347 348


    def __contains__(self, tag_name: str) -> bool:
        """
349
        Returns true if a child with the given tag name exists.
350
        Args:
351 352
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
353 354 355 356
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
357 358 359 360 361
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
362
            return False
363
        raise ValueError('Leave node cannot contain other nodes')
364
        # generator = self.select_by_tag(tag_name, False)
365 366 367 368 369
        # try:
        #     generator.__next__()
        #     return True
        # except StopIteration:
        #     return False
370 371


372 373 374 375 376 377 378 379 380 381 382 383 384 385
    def get(self, index_or_tagname: Union[int, str],
            surrogate: Union['Node', Iterator['Node']]) -> Union['Node', Iterator['Node']]:
        """Returns the child node with the given index if ``index_or_tagname``
        is an integer or the first child node with the given tag name. If no
        child with the given index or tag_name exists, the ``surrogate`` is
        returned instead. This mimics the behaviour of Python's dictionary's
        get-method.
        """
        try:
            return self[index_or_tagname]
        except KeyError:
            return surrogate


386
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
387
    def tag_name(self) -> str:
388 389 390 391 392 393
        """
        Returns the tage name of Node, i.e. the name for XML or
        S-expression representation. By default the tag name is the
        name of the node's parser or, if the node's parser is unnamed, the
        node's parser's `ptype`.
        """
394
        return self.parser.name or self.parser.ptype
395

Eckhart Arnold's avatar
Eckhart Arnold committed
396

397
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
398
    def result(self) -> StrictResultType:
399 400 401 402 403
        """
        Returns the result from the parser that created the node.
        Error messages are not included in the result. Use `self.content()`
        if the result plus any error messages is needed.
        """
404 405
        return self._result

406

407
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
408
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
409
        # # made obsolete by static type checking with mypy
410 411 412
        # assert ((isinstance(result, tuple) and all(isinstance(child, Node) for child in result))
        #         or isinstance(result, Node)
        #         or isinstance(result, str)), str(result)
Eckhart Arnold's avatar
Eckhart Arnold committed
413 414
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
415 416
        self._len = -1        # lazy evaluation
        self._content = None
417 418 419 420 421 422 423 424 425
        if isinstance(result, Node):
            self.children = (result,)
            self._result = self.children
        else:
            if isinstance(result, tuple):
                self.children = result
                self._result = result or ''
            else:
                self.children = NoChildren
426
                self._result = result
427

428 429

    @property
eckhart's avatar
eckhart committed
430
    def content(self) -> str:
431
        """
432
        Returns content as string, omitting error messages.
433
        """
434 435 436 437
        if self._content is None:
            if self.children:
                self._content = "".join(child.content for child in self.children)
            else:
438
                # self._content = self._result
439 440 441
                self._content = str(self._result)
                self._result = self._content  # self._result might be more efficient as a string!?
        return self._content
442 443 444 445 446 447 448 449 450 451 452


    @property
    def structure(self) -> str:
        """
        Return structure (and content) as S-expression on a single line
        without any line breaks.
        """
        return flatten_sxpr(self.as_sxpr(showerrors=False))


453
    @property
454
    def pos(self) -> int:
eckhart's avatar
eckhart committed
455 456
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
457
            raise AssertionError("Position value not initialized!")
458 459
        return self._pos

eckhart's avatar
eckhart committed
460

eckhart's avatar
eckhart committed
461
    def init_pos(self, pos: int) -> 'Node':
eckhart's avatar
eckhart committed
462 463 464 465 466 467 468 469 470
        """
        (Re-)initialize position value. Usually, the parser guard
        (`parsers.add_parser_guard()`) takes care of assigning the
        position in the document to newly created nodes. However,
        where Nodes are created outside the reach of the parser
        guard, their document-position must be assigned manually.
        This function recursively reassigns the position values
        of the child nodes, too.
        """
eckhart's avatar
eckhart committed
471 472
        assert self._pos < 0 or self.pos == pos, str("pos mismatch %i != %i" % (self._pos, pos))
        self._pos = pos
473
        # recursively adjust pos-values of all children
eckhart's avatar
eckhart committed
474
        offset = self.pos
475
        for child in self.children:
eckhart's avatar
eckhart committed
476
            child.init_pos(offset)
eckhart's avatar
eckhart committed
477 478 479
            offset = child.pos + len(child)
        return self

480

481 482
    @property
    def attributes(self):
483 484 485
        """
        Returns a dictionary of XML-Attributes attached to the Node.
        """
486 487 488 489
        if not hasattr(self, '_xml_attr'):
            self._xml_attr = OrderedDict()
        return self._xml_attr

Eckhart Arnold's avatar
Eckhart Arnold committed
490

491
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i,
492
                   density=0, inline=False, inline_fn=lambda node: False) -> str:
493 494 495 496 497 498 499 500
        """
        Generates a tree representation of this node and its children
        in string from.

        The kind ot tree-representation that is determined by several
        function parameters. This could be an XML-representation or a
        lisp-like S-expression.

501
        Args:
502
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
503
            open_fn:   (Node->str) A function that returns an opening
504
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
505
            close_fn:  (Node->str) A function that returns a closeF
506
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
507
            data_fn:   (str->str) A function that filters the data string
508 509 510 511 512 513
                before printing, e.g. to add quotation marks

        Returns (str):
            A string that contains a (serialized) tree representation
            of the node and its children.
        """
eckhart's avatar
eckhart committed
514 515
        head = open_fn(self)
        tail = close_fn(self)
516 517

        if not self.result:
518
            return head.rstrip() + tail.lstrip()
519

eckhart's avatar
eckhart committed
520
        tail = tail.lstrip(None if density & 2 else '')
521

522
        inline = inline or inline_fn(self)
523 524 525 526 527
        if inline:
            head = head.rstrip()
            tail = tail.lstrip()
            usetab, sep = '', ''
        else:
eckhart's avatar
eckhart committed
528 529
            usetab = tab if head else ''    # no indentation if tag is already omitted
            sep = '\n'
530

531 532
        if self.children:
            content = []
533
            for child in self.children:
534
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn,
535
                                           density, inline, inline_fn)
eckhart's avatar
eckhart committed
536 537 538
                if subtree:
                    subtree = [subtree] if inline else subtree.split('\n')
                    content.append((sep + usetab).join(s for s in subtree))
539
            return head + usetab + (sep + usetab).join(content) + tail
540

541
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
eckhart's avatar
eckhart committed
542
        if not inline and not head:
eckhart's avatar
eckhart committed
543
            # strip whitespace for omitted non inline node, e.g. CharData in mixed elements
eckhart's avatar
eckhart committed
544
            res = res.strip()
545 546
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
547
            gap = ' ' if not inline and head and head.rstrip()[-1:] != '>' else ''
eckhart's avatar
eckhart committed
548
            return head.rstrip() + gap + data_fn(res) + tail.lstrip()
549
        else:
550
            return head + '\n'.join([usetab + data_fn(s) for s in res.split('\n')]) + tail
551

Eckhart Arnold's avatar
Eckhart Arnold committed
552

553 554 555
    def as_sxpr(self, src: str = None,
                showerrors: bool = True,
                indentation: int = 2,
556
                compact: bool = False) -> str:
557 558 559
        """
        Returns content as S-expression, i.e. in lisp-like form.

560
        Args:
561 562 563
            src:  The source text or `None`. In case the source text is
                given the position of the element in the text will be
                reported as line and column.
564 565 566
            showerrors: If True, error messages will be shown.
            indentation: The number of whitespaces for indentation
            compact:  If True, a compact representation is returned where
567
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
568
                tree structure.
569 570
        """

eckhart's avatar
eckhart committed
571
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
eckhart's avatar
eckhart committed
572
        lbreaks = linebreaks(src) if src else []  # type: List[int]
573

574
        def opening(node) -> str:
eckhart's avatar
eckhart committed
575
            """Returns the opening string for the representation of `node`."""
576
            txt = [left_bracket,  node.tag_name]
577
            # s += " '(pos %i)" % node.add_pos
578
            if hasattr(node, '_xml_attr'):
579
                txt.extend(' `(%s "%s")' % (k, v) for k, v in node.attributes.items())
580
            if src:
eckhart's avatar
eckhart committed
581
                txt.append(" `(pos %i %i %i)" % (node.pos, *line_col(lbreaks, node.pos)))
582
            if showerrors and node.errors:
583
                txt.append(" `(err `%s)" % ' '.join(str(err) for err in node.errors))
584
            return "".join(txt) + '\n'
585

eckhart's avatar
eckhart committed
586 587 588
        def closing(node) -> str:
            """Returns the closing string for the representation of `node`."""
            return right_bracket
589

eckhart's avatar
eckhart committed
590 591 592 593 594
        def pretty(strg):
            """Encloses `strg` with the right kind of quotation marks."""
            return '"%s"' % strg if strg.find('"') < 0 \
                else "'%s'" % strg if strg.find("'") < 0 \
                else '"%s"' % strg.replace('"', r'\"')
595

596
        return self._tree_repr(' ' * indentation, opening, closing, pretty, density=density)
Eckhart Arnold's avatar
Eckhart Arnold committed
597

eckhart's avatar
eckhart committed
598

599 600 601 602 603 604
    def as_xml(self, src: str = None,
               showerrors: bool = True,
               indentation: int = 2,
               inline_tags: Set[str]=set(),
               omit_tags: Set[str]=set(),
               empty_tags: Set[str]=set()) -> str:
605 606 607
        """
        Returns content as XML-tree.

608
        Args:
609 610 611
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
612 613
            showerrors: If True, error messages will be shown.
            indentation: The number of whitespaces for indentation
614 615 616 617 618 619 620
            inline_tags:  A set of tag names, the content of which will always be written
                on a single line, unless it contains explicit line feeds ('\n').
            omit_tags:  A set of tags from which only the content will be printed, but
                neither the opening tag nor its attributes nor the closing tag. This
                allows producing a mix of plain text and child tags in the output,
                which otherwise is not supported by the Node object, because it
                requires its content to be either a tuple of children or string content.
621 622
            empty_tags:  A set of tags which shall be rendered as empty elements, e.g.
                "<empty/>" instead of "<empty><empty>".
623 624
        """

625
        def opening(node) -> str:
626 627 628
            """Returns the opening string for the representation of `node`."""
            if node.tag_name in omit_tags:
                return ''
eckhart's avatar
eckhart committed
629
            txt = ['<', node.tag_name]
630 631
            has_reserved_attrs = hasattr(node, '_xml_attr') \
                and any (r in node.attributes for r in {'err', 'line', 'col'})
di68kap's avatar
di68kap committed
632
            if hasattr(node, '_xml_attr'):
633
                txt.extend(' %s="%s"' % (k, v) for k, v in node.attributes.items())
634
            if src and not has_reserved_attrs:
eckhart's avatar
eckhart committed
635
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
636
            if showerrors and node.errors and not has_reserved_attrs:
eckhart's avatar
eckhart committed
637 638
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
                                                 for err in node.errors))
639 640 641
            if node.tag_name in empty_tags:
                assert not node.result, ("Node %s with content %s is not an empty element!" %
                                         (node.tag_name, str(node)))
eckhart's avatar
eckhart committed
642
                ending = "/>\n" if not node.tag_name[0] == '?' else "?>\n"
643 644 645
            else:
                ending = ">\n"
            return "".join(txt + [ending])
646 647

        def closing(node):
648
            """Returns the closing string for the representation of `node`."""
649
            if node.tag_name in omit_tags or node.tag_name in empty_tags:
650
                return ''
651
            return ('\n</') + node.tag_name + '>'
652

653 654 655 656 657
        def inlining(node):
            """Returns True, if `node`'s tag name is contained in `inline_tags`,
            thereby signalling that the children of this node shall not be
            printed on several lines to avoid unwanted gaps in the output.
            """
658 659
            return node.tag_name in inline_tags or (hasattr(node, '_xml_attr') \
                and node.attributes.get('xml:space', 'default') == 'preserve')
660

661
        line_breaks = linebreaks(src) if src else []
662 663
        return self._tree_repr(' ' * indentation, opening, closing,
                               density=1, inline_fn=inlining)
664

Eckhart Arnold's avatar
Eckhart Arnold committed
665

666
    def select(self, match_function: Callable, include_root: bool=False) -> Iterator['Node']:
eckhart's avatar
eckhart committed
667
        """
668
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
669

670
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
671
        given `match_function` evaluates to True. The tree is
672 673 674
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
675

676 677 678
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
679 680
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
681
        Yields:
682
            Node: All nodes of the tree for which
683 684
            ``match_function(node)`` returns True
        """
685
        if include_root and match_function(self):
686
            yield self
eckhart's avatar
eckhart committed
687 688 689
        for child in self.children:
            for node in child.select(match_function, True):
                yield node
690

Eckhart Arnold's avatar
Eckhart Arnold committed
691

eckhart's avatar
eckhart committed
692
    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
693
                      include_root: bool=False) -> Iterator['Node']:
694
        """
695 696 697 698
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
699

700
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
701
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
702
            ['(X (c "d"))', '(X "F")']
703
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
704
            ['(b "X")', '(X (c "d"))', '(X "F")']
705
            >>> any(tree.select_by_tag('a', False))
706
            False
707
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
708
            ['(a (b "X") (X (c "d")) (e (X "F")))']
709 710
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
711 712

        Args:
713 714 715 716
            tag_name(set): A tag name or set of tag names that is being
                searched for
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
717 718 719
        Yields:
            Node: All nodes which have a given tag name.
        """
720
        if isinstance(tag_names, str):
eckhart's avatar
eckhart committed
721
            tag_names = frozenset({tag_names})
722
        return self.select(lambda node: node.tag_name in tag_names, include_root)
723 724


725 726 727 728 729 730 731 732 733 734 735 736 737 738 739
    def pick(self, tag_names: Union[str, Set[str]]) -> Optional['Node']:
        """
        Picks the first descendant with one of the given tag_names.

        This function is just syntactic sugar for
        ``next(node.select_by_tag(tag_names, False))``. However, rather than
        raising a StopIterationError if no descendant with the given tag-name
        exists, it returns None.
        """
        try:
            return next(self.select_by_tag(tag_names, False))
        except StopIteration:
            return None


740
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
741 742 743
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
744 745 746
        return sum(child.tree_size() for child in self.children) + 1


di68kap's avatar
di68kap committed
747
class RootNode(Node):
748
    """TODO: Add Documentation!!!
di68kap's avatar
di68kap committed
749

Eckhart Arnold's avatar
Eckhart Arnold committed
750
        all_errors (list):  A list of all errors that have occured so far during
751 752
                processing (i.e. parsing, AST-transformation, compiling)
                of this tree.
di68kap's avatar
di68kap committed
753

754 755
        error_flag (int):  the highest warning or error level of all errors
                that occurred.
di68kap's avatar
di68kap committed
756
    """
eckhart's avatar
eckhart committed
757
    def __init__(self, node: Optional[Node] = None) -> 'RootNode':
di68kap's avatar
di68kap committed
758
        super().__init__(ZOMBIE_PARSER, '')
759
        self.all_errors = []
di68kap's avatar
di68kap committed
760
        self.error_flag = 0
eckhart's avatar
eckhart committed
761 762
        if node is not None:
            self.swallow(node)
763 764 765 766
        # customization for XML-Representation
        self.inline_tags = set()
        self.omit_tags = set()
        self.empty_tags = set()
di68kap's avatar
di68kap committed
767

768
    def swallow(self, node: Node) -> 'RootNode':
769 770 771 772 773 774 775 776 777 778
        """Put `self` in the place of `node` by copying all its data.
        Returns self.

        This is done by the parse.Grammar object after
        parsing has finished, so that the Grammar object always
        returns a syntax tree rooted in a RootNode object.

        It is possible to add errors to a RootNode object, before it
        has actually swallowed the root of the syntax tree.
        """
di68kap's avatar
di68kap committed
779 780 781 782 783
        self._result = node._result
        self.children = node.children
        self._len = node._len
        self._pos = node._pos
        self.parser = node.parser
784 785
        if hasattr(node, '_xml_attr'):
            self._xml_attr = node._xml_attr
di68kap's avatar
di68kap committed
786
        self._content = node._content
787
        return self
di68kap's avatar
di68kap committed
788

eckhart's avatar
eckhart committed
789 790
    def add_error(self, node: Node, error: Error) -> 'RootNode':
        """Adds an Error object to the tree, locating it at a specific node."""
di68kap's avatar
di68kap committed
791 792 793 794 795
        self.all_errors.append(error)
        self.error_flag = max(self.error_flag, error.code)
        node.errors.append(error)
        return self

eckhart's avatar
eckhart committed
796
    def new_error(self,
797
                  node: Node,
di68kap's avatar
di68kap committed
798
                  message: str,
di68kap's avatar
di68kap committed
799
                  code: int = Error.ERROR) -> 'RootNode':
di68kap's avatar
di68kap committed
800
        """
eckhart's avatar
eckhart committed
801
        Adds an error to this tree, locating it at a specific node.
di68kap's avatar
di68kap committed
802 803 804 805 806
        Parameters:
            pos(int):     The position of the error in the source text
            message(str): A string with the error message.abs
            code(int):    An error code to identify the kind of error
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
807
        error = Error(message, node.pos, code)
eckhart's avatar
eckhart committed
808 809
        self.add_error(node, error)
        return self
di68kap's avatar
di68kap committed
810

eckhart's avatar
eckhart committed
811
    def collect_errors(self) -> List[Error]:
di68kap's avatar
di68kap committed
812 813
        """Returns the list of errors, ordered bv their position.
        """
814
        self.all_errors.sort(key=lambda e: e.pos)
Eckhart Arnold's avatar
Eckhart Arnold committed
815
        return self.all_errors
di68kap's avatar
di68kap committed
816

817 818 819 820 821 822 823 824
    def customized_XML(self):
        """Returns a customized XML representation of the tree.
        See the docstring of `Node.as_xml()` for an explanation of the
        customizations."""
        return self.as_xml(inline_tags = self.inline_tags,
                           omit_tags=self.omit_tags,
                           empty_tags=self.empty_tags)

di68kap's avatar
di68kap committed
825

eckhart's avatar
eckhart committed
826 827 828
ZOMBIE_NODE = Node(ZOMBIE_PARSER, '')


829
def parse_sxpr(sxpr: str) -> Node:
830
    """
831 832 833 834 835
    Generates a tree of nodes from an S-expression.

    This can - among other things - be used for deserialization of trees that
    have been serialized with `Node.as_sxpr()` or as a convenient way to
    generate test data.
836 837

    Example:
838
    >>> parse_sxpr("(a (b c))").as_sxpr()
839
    '(a\\n  (b\\n    "c"\\n  )\\n)'
840
    """
841 842
    sxpr = StringView(sxpr).strip()
    mock_parsers = dict()
843

844
    def next_block(s: StringView):
eckhart's avatar
eckhart committed
845 846 847
        """Generator that yields all characters until the next closing bracket
        that does not match an opening bracket matched earlier within the same
        package."""
848
        s = s.strip()
849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867
        try:
            while s[0] != ')':
                if s[0] != '(':
                    raise ValueError('"(" expected, not ' + s[:10])
                # assert s[0] == '(', s
                level = 1
                k = 1
                while level > 0:
                    if s[k] == '(':
                        level += 1
                    elif s[k] == ')':
                        level -= 1
                    k += 1
                yield s[:k]
                s = s[k:].strip()
        except IndexError:
            errmsg = ('Malformed S-expression. Unprocessed part: "%s"' % s) if s \
                else 'Malformed S-expression. Closing bracket(s) ")" missing.'
            raise AssertionError(errmsg)
868

869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904