syntaxtree.py 30.2 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
import copy
30

31
from DHParser.error import Error, linebreaks, line_col
32
from DHParser.stringview import StringView
eckhart's avatar
eckhart committed
33
from DHParser.toolkit import re, typing
eckhart's avatar
eckhart committed
34
from typing import Callable, cast, Iterator, List, AbstractSet, Set, Union, Tuple, Optional
di68kap's avatar
di68kap committed
35

36

37 38 39 40 41 42
__all__ = ('ParserBase',
           'WHITESPACE_PTYPE',
           'TOKEN_PTYPE',
           'MockParser',
           'ZombieParser',
           'ZOMBIE_PARSER',
eckhart's avatar
eckhart committed
43
           'ZOMBIE_NODE',
44
           'Node',
45
           'mock_syntax_tree',
46
           'flatten_sxpr')
Eckhart Arnold's avatar
Eckhart Arnold committed
47 48


49 50 51 52 53 54 55 56 57 58 59 60 61 62
#######################################################################
#
# 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.
    """
    def __init__(self, name=''):  # , pbases=frozenset()):
63
        self._name = name  # type: str
64 65 66
        self._ptype = ':' + self.__class__.__name__  # type: str

    def __repr__(self):
di68kap's avatar
di68kap committed
67
         return self.name + self.ptype
68 69 70 71

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

72 73 74
    def __call__(self, text: StringView) -> Tuple[Optional['Node'], StringView]:
        return None, text

75 76
    @property
    def name(self):
77 78
        """Returns the name of the parser or the empty string '' for unnamed
        parsers."""
79 80
        return self._name

81 82
    @property
    def ptype(self) -> str:
83 84
        """Returns the type of the parser. By default this is the parser's
        class name preceded by a colon, e.g. ':ZeroOrMore'."""
85 86 87 88
        return self._ptype

    @property
    def repr(self) -> str:
di68kap's avatar
di68kap committed
89
        """Returns the parser's name if it has a name and repr()"""
90 91
        return self.name if self.name else repr(self)

92
    def reset(self):
93
        """Resets any parser variables. (Should be overridden.)"""
94 95
        pass

eckhart's avatar
eckhart committed
96
    def grammar(self) -> Optional[object]:
97 98
        """Returns the Grammar object to which the parser belongs. If not
        yet connected to any Grammar object, None is returned."""
99 100 101
        return None

    def apply(self, func: Callable) -> bool:
eckhart's avatar
eckhart committed
102
        """Applies the function `func` to the parser. Returns False, if
103
        - for whatever reason - the functions has not been applied, True
eckhart's avatar
eckhart committed
104
        otherwise."""
105 106
        return False

107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123

WHITESPACE_PTYPE = ':Whitespace'
TOKEN_PTYPE = ':Token'


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
    different parser types by assigning them a ptype on initialization.

    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.
    """
    def __init__(self, name='', ptype=''):  # , pbases=frozenset()):
        assert not ptype or ptype[0] == ':'
124
        super().__init__(name)
125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166
        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

    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
#
#######################################################################


167
ChildrenType = Tuple['Node', ...]
Eckhart Arnold's avatar
Eckhart Arnold committed
168
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
eckhart's avatar
eckhart committed
169
StrictResultType = Union[ChildrenType, StringView, str]
170
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
171 172


Eckhart Arnold's avatar
Eckhart Arnold committed
173
def flatten_sxpr(sxpr: str) -> str:
174
    """Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
175 176 177
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
178
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
179 180
    '(a (b c))'
    """
181
    return re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
Eckhart Arnold's avatar
Eckhart Arnold committed
182 183


Eckhart Arnold's avatar
Eckhart Arnold committed
184
class Node(collections.abc.Sized):
185 186 187
    """
    Represents a node in the concrete or abstract syntax tree.

188
    Attributes:
189 190
        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
191

192 193 194
        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.
195

196 197
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
198

eckhart's avatar
eckhart committed
199 200 201 202
        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
203
        parser (Parser):  The parser which generated this node.
204 205
            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
206 207
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
208
            example by calling ``isinstance(node.parer, ...)``.
209

210 211
        errors (list):  A list of parser- or compiler-errors:
            tuple(position, string) attached to this node
212

213 214 215
        error_flag (int):  0 if no error occurred in either the node
            itself or any of its descendants. Otherwise contains the
            highest warning or error level or all errors that occurred.
216

217 218 219
        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
220
            the length before AST-transformation and will never change
221
            through AST-transformation. READ ONLY!
222

223 224
        pos (int):  the position of the node within the parsed text.

Eckhart Arnold's avatar
Eckhart Arnold committed
225
            The value of ``pos`` is -1 meaning invalid by default.
226
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
227
            nodes relative to this value.
228 229

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
230
            pos value of the root node should be set to 0 right
231 232
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
233
            Other than that, this value should be considered READ ONLY.
234 235
            At any rate, it should only be reassigned during the parsing
            stage and never during or after the AST-transformation.
236

237
        attributes (dict): An optional dictionary of XML-attributes. This
238 239 240
            dictionary is created lazily upon first usage. The attributes
            will only be shown in the XML-Representation, not in the
            S-Expression-output.
eckhart's avatar
eckhart committed
241 242 243


        _parent (Node): SLOT RESERVED FOR FUTURE USE!
244
    """
245

di68kap's avatar
di68kap committed
246
    __slots__ = ['_result', 'children', '_errors', '_len', '_pos', 'parser', 'error_flag',
247
                 '_xml_attr', '_content', '_parent']
248

249 250 251
    def __init__(self, parser, result: ResultType, leafhint: bool = False) -> None:
        """
        Initializes the ``Node``-object with the ``Parser``-Instance
252 253
        that generated the node and the parser's result.
        """
254 255
        self.error_flag = 0             # type: int
        self._errors = []               # type: List[Error]
eckhart's avatar
eckhart committed
256
        self._pos = -1                  # type: int
di68kap's avatar
di68kap committed
257 258
        # 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
259
        if leafhint:
eckhart's avatar
eckhart committed
260
            self._result = result       # type: StrictResultType
eckhart's avatar
eckhart committed
261
            self._content = None        # type: Optional[str]
262
            self.children = NoChildren  # type: ChildrenType
263
            self._len = -1              # type: int  # lazy evaluation
264 265
        else:
            self.result = result
266 267
        self.parser = parser or ZOMBIE_PARSER

Eckhart Arnold's avatar
Eckhart Arnold committed
268

269
    def __str__(self):
270
        s = "".join(str(child) for child in self.children) if self.children else self.content
271 272 273 274
        if self._errors:
            return ' <<< Error on "%s" | %s >>> ' % \
                   (s, '; '.join(e.message for e in self._errors))
        return s
275

Eckhart Arnold's avatar
Eckhart Arnold committed
276

277 278 279 280 281 282
    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)
283

Eckhart Arnold's avatar
Eckhart Arnold committed
284

285
    def __len__(self):
286
        if self._len < 0:
di68kap's avatar
di68kap committed
287
            self._len = sum(len(child) for child in self.children) \
288
                if self.children else len(self._result)
289 290 291 292 293 294 295 296
        return self._len


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


297
    def __eq__(self, other):
298 299 300 301
        """
        Equality of nodes: Two nodes are considered as equal, if their tag
        name is the same and if their results are equal.
        """
302
        return self.tag_name == other.tag_name and self.result == other.result
303

Eckhart Arnold's avatar
Eckhart Arnold committed
304

305
    def __hash__(self):
306
        return hash(self.tag_name)
307

Eckhart Arnold's avatar
Eckhart Arnold committed
308

309 310 311 312 313 314
    def __deepcopy__(self, memodict={}):
        result = copy.deepcopy(self.result)
        other = Node(self.parser, result)
        other._pos = self._pos
        return other

Eckhart Arnold's avatar
Eckhart Arnold committed
315

316 317 318
    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
319
        an integer or the first child node with the given tag name. Examples::
320

321
            >>> tree = mock_syntax_tree('(a (b "X") (X (c "d")) (e (X "F")))')
322 323
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
324 325
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
326 327 328 329

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
330
        Returns:
331 332
            Node: All nodes which have a given tag name.
        """
333 334 335
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
336
            else:
337 338 339 340 341
                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!')
342 343 344 345


    def __contains__(self, tag_name: str) -> bool:
        """
346
        Returns true if a child with the given tag name exists.
347
        Args:
348 349
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
350 351 352 353
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
354 355 356 357 358
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
359
            return False
360
        raise ValueError('Leave node cannot contain other nodes')
361
        # generator = self.select_by_tag(tag_name, False)
362 363 364 365 366
        # try:
        #     generator.__next__()
        #     return True
        # except StopIteration:
        #     return False
367 368


369
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
370
    def tag_name(self) -> str:
371 372 373 374 375 376
        """
        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`.
        """
377
        return self.parser.name or self.parser.ptype
378

Eckhart Arnold's avatar
Eckhart Arnold committed
379

380
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
381
    def result(self) -> StrictResultType:
382 383 384 385 386
        """
        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.
        """
387 388
        return self._result

389

390
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
391
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
392
        # # made obsolete by static type checking with mypy
393 394 395
        # 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
396 397
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
398 399
        self._len = -1        # lazy evaluation
        self._content = None
400 401 402 403 404 405 406 407
        if isinstance(result, Node):
            self.children = (result,)
            self._result = self.children
            self.error_flag = result.error_flag
        else:
            if isinstance(result, tuple):
                self.children = result
                self._result = result or ''
408 409 410
                if result:
                    if self.error_flag == 0:
                        self.error_flag = max(child.error_flag for child in self.children)
411 412
            else:
                self.children = NoChildren
413
                self._result = result
414

415 416

    @property
eckhart's avatar
eckhart committed
417
    def content(self) -> str:
418
        """
419
        Returns content as string, omitting error messages.
420
        """
421 422 423 424
        if self._content is None:
            if self.children:
                self._content = "".join(child.content for child in self.children)
            else:
425
                # self._content = self._result
426 427 428
                self._content = str(self._result)
                self._result = self._content  # self._result might be more efficient as a string!?
        return self._content
429 430 431 432 433 434 435 436 437 438 439


    @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))


440
    @property
441
    def pos(self) -> int:
eckhart's avatar
eckhart committed
442 443
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
444
            raise AssertionError("Position value not initialized!")
445 446
        return self._pos

eckhart's avatar
eckhart committed
447

eckhart's avatar
eckhart committed
448
    def init_pos(self, pos: int, overwrite: bool = False) -> 'Node':
eckhart's avatar
eckhart committed
449 450 451 452 453 454 455 456 457
        """
        (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
458 459 460 461 462 463
        if overwrite or self._pos < 0:
            self._pos = pos
            for err in self._errors:
                err.pos = pos
        else:
            assert self._pos == pos, str("%i != %i" % (self._pos, pos))
464
        # recursively adjust pos-values of all children
eckhart's avatar
eckhart committed
465
        offset = self.pos
466
        for child in self.children:
eckhart's avatar
eckhart committed
467
            child.init_pos(offset, overwrite)
eckhart's avatar
eckhart committed
468 469 470
            offset = child.pos + len(child)
        return self

471 472

    @property
473
    def errors(self) -> List[Error]:
eckhart's avatar
eckhart committed
474
        """
475
        Returns the errors that occurred at this Node,
eckhart's avatar
eckhart committed
476 477
        not including any errors from child nodes.
        """
478 479
        return self._errors.copy()

480

eckhart's avatar
eckhart committed
481 482
    def add_error(self,
                  message: str,
483
                  code: int = Error.ERROR) -> 'Node':
eckhart's avatar
eckhart committed
484 485 486
        """
        Adds an error to this Node.
        Parameters:
eckhart's avatar
eckhart committed
487 488
            message(str): A string with the error message.abs
            code(int):    An error code to identify the kind of error
eckhart's avatar
eckhart committed
489
        """
490 491
        self._errors.append(Error(message, code))
        self.error_flag = max(self.error_flag, self._errors[-1].code)
Eckhart Arnold's avatar
Eckhart Arnold committed
492 493
        return self

494

495
    def collect_errors(self, clear_errors=False) -> List[Error]:
Eckhart Arnold's avatar
Eckhart Arnold committed
496
        """
497
        Recursively adds line- and column-numbers to all error objects.
Eckhart Arnold's avatar
Eckhart Arnold committed
498 499 500 501
        Returns all errors of this node or any child node in the form
        of a set of tuples (position, error_message), where position
        is always relative to this node.
        """
502
        errors = self.errors
503 504
        for err in errors:
            err.pos = self.pos
505 506
        if self.children:
            for child in self.children:
507
                errors.extend(child.collect_errors(clear_errors))
508 509 510
        if clear_errors:
            self._errors = []
            self.error_flag = 0
511
        else:
512 513 514 515 516 517 518
            if self._errors:
                self.error_flag = max(err.code for err in self.errors)
            if self.children:
                max_child_error = max(child.error_flag for child in self.children)
                self.error_flag = max(self.error_flag, max_child_error)
        return errors

519

520 521 522 523 524 525 526
    @property
    def attributes(self):
        """Returns a dictionary of XML-Attributes attached to the Node."""
        if not hasattr(self, '_xml_attr'):
            self._xml_attr = OrderedDict()
        return self._xml_attr

Eckhart Arnold's avatar
Eckhart Arnold committed
527

528
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i, density=0) -> str:
529 530 531 532 533 534 535 536
        """
        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.

537
        Args:
538
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
539
            open_fn:   (Node->str) A function that returns an opening
540
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
541
            close_fn:  (Node->str) A function that returns a closeF
542
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
543
            data_fn:   (str->str) A function that filters the data string
544 545 546 547 548 549
                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
550 551
        head = open_fn(self)
        tail = close_fn(self)
552 553

        if not self.result:
554
            return head.rstrip() + tail.lstrip()
555

eckhart's avatar
eckhart committed
556
        tail = tail.lstrip(None if density & 2 else '')
557 558 559

        if self.children:
            content = []
560
            for child in self.children:
eckhart's avatar
eckhart committed
561
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn, density).split('\n')
562
                content.append('\n'.join((tab + s) for s in subtree))
eckhart's avatar
eckhart committed
563
            return head + '\n'.join(content) + tail
564

565
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
566 567 568
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
            gap = ' ' if head.rstrip()[-1] != '>' else ''
eckhart's avatar
eckhart committed
569
            return head.rstrip() + gap + data_fn(self.result) + tail.lstrip()
570
        else:
eckhart's avatar
eckhart committed
571
            return head + '\n'.join([tab + data_fn(s) for s in res.split('\n')]) + tail
572

Eckhart Arnold's avatar
Eckhart Arnold committed
573

574
    def as_sxpr(self, src: str = None, compact: bool = False, showerrors: bool = True) -> str:
575 576 577
        """
        Returns content as S-expression, i.e. in lisp-like form.

578
        Args:
579 580 581
            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.
Eckhart Arnold's avatar
Eckhart Arnold committed
582
            compact:  If True a compact representation is returned where
583
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
584
                tree structure.
585 586
        """

eckhart's avatar
eckhart committed
587
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
588

589
        def opening(node) -> str:
eckhart's avatar
eckhart committed
590
            """Returns the opening string for the representation of `node`."""
591
            txt = [left_bracket,  node.tag_name]
592
            # s += " '(pos %i)" % node.pos
593 594
            if hasattr(node, '_xml_attr'):
                txt.extend(""" `(%s "%s")""" % (k, v) for k, v in node.attributes.items())
595
            if src:
596
                txt.append(" `(pos %i %i %i)" % (node.pos, *line_col(src, node.pos)))
di68kap's avatar
di68kap committed
597 598
            # if node.error_flag:   # just for debugging error collecting
            #     txt += " HAS ERRORS"
599
            if showerrors and node.errors:
600 601
                txt.append(" `(err %s)" % ' '.join(str(err) for err in node.errors))
            return "".join(txt) + '\n'
602

eckhart's avatar
eckhart committed
603 604 605
        def closing(node) -> str:
            """Returns the closing string for the representation of `node`."""
            return right_bracket
606

eckhart's avatar
eckhart committed
607 608 609 610 611
        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'\"')
612

eckhart's avatar
eckhart committed
613
        return self._tree_repr('    ', opening, closing, pretty, density=density)
Eckhart Arnold's avatar
Eckhart Arnold committed
614

eckhart's avatar
eckhart committed
615

616
    def as_xml(self, src: str = None, showerrors: bool = True) -> str:
617 618 619
        """
        Returns content as XML-tree.

620
        Args:
621 622 623 624 625
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
        """

626
        def opening(node) -> str:
eckhart's avatar
eckhart committed
627
            """Returns the opening string for the representation of `node`."""            
eckhart's avatar
eckhart committed
628
            txt = ['<', node.tag_name]
629 630
            has_reserved_attrs = hasattr(node, '_xml_attr') \
                and any (r in node.attributes for r in {'err', 'line', 'col'})
di68kap's avatar
di68kap committed
631
            if hasattr(node, '_xml_attr'):
632
                txt.extend(' %s="%s"' % (k, v) for k, v in node.attributes.items())
633
            if src and not has_reserved_attrs:
eckhart's avatar
eckhart committed
634
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
635
            if showerrors and node.errors and not has_reserved_attrs:
eckhart's avatar
eckhart committed
636 637 638
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
                                                 for err in node.errors))
            return "".join(txt + [">\n"])
639 640

        def closing(node):
eckhart's avatar
eckhart committed
641
            """Returns the closing string for the representation of `node`."""            
642
            return '\n</' + node.tag_name + '>'
643

644
        line_breaks = linebreaks(src) if src else []
645
        return self._tree_repr('    ', opening, closing, density=1)
646

Eckhart Arnold's avatar
Eckhart Arnold committed
647

648
    def select(self, match_function: Callable, include_root: bool=True) -> Iterator['Node']:
eckhart's avatar
eckhart committed
649
        """
650
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
651

652
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
653
        given `match_function` evaluates to True. The tree is
654 655 656
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
657

658 659 660
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
661 662
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
663
        Yields:
664
            Node: All nodes of the tree for which
665 666
            ``match_function(node)`` returns True
        """
667
        if include_root and match_function(self):
668 669 670
            yield self
        else:
            for child in self.children:
671
                for node in child.select(match_function, True):
eckhart's avatar
eckhart committed
672
                    yield node
673

Eckhart Arnold's avatar
Eckhart Arnold committed
674

eckhart's avatar
eckhart committed
675
    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
676
                      include_root: bool=True) -> Iterator['Node']:
677
        """
678 679 680 681
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
682 683

            >>> tree = mock_syntax_tree('(a (b "X") (X (c "d")) (e (X "F")))')
684
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
685
            ['(X (c "d"))', '(X "F")']
686
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
687
            ['(b "X")', '(X (c "d"))', '(X "F")']
688
            >>> any(tree.select_by_tag('a', False))
689
            False
690
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
691
            ['(a (b "X") (X (c "d")) (e (X "F")))']
692 693
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
694 695

        Args:
696 697 698 699
            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.
700 701 702
        Yields:
            Node: All nodes which have a given tag name.
        """
703
        if isinstance(tag_names, str):
eckhart's avatar
eckhart committed
704
            tag_names = frozenset({tag_names})
705
        return self.select(lambda node: node.tag_name in tag_names, include_root)
706 707


708 709 710 711 712 713 714 715 716 717 718 719 720 721 722
    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


723
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
724 725 726
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
727 728 729
        return sum(child.tree_size() for child in self.children) + 1


eckhart's avatar
eckhart committed
730 731 732
ZOMBIE_NODE = Node(ZOMBIE_PARSER, '')


733
def mock_syntax_tree(sxpr: str) -> Node:
734
    """
di68kap's avatar
di68kap committed
735 736
    Generates a tree of nodes from an S-expression. The main purpose of this is
    to generate test data.
737 738 739 740 741 742 743

    Example:
    >>> mock_syntax_tree("(a (b c))").as_sxpr()
    '(a\\n    (b\\n        "c"\\n    )\\n)'
    """

    def next_block(s):
eckhart's avatar
eckhart committed
744 745 746
        """Generator that yields all characters until the next closing bracket
        that does not match an opening bracket matched earlier within the same
        package."""
747
        s = s.strip()
748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766
        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)
767

768
    sxpr = StringView(sxpr).strip()
eckhart's avatar
eckhart committed
769 770
    if sxpr[0] != '(':
        raise ValueError('"(" expected, not ' + sxpr[:10])
771 772
    # assert sxpr[0] == '(', sxpr
    sxpr = sxpr[1:].strip()
eckhart's avatar
eckhart committed
773
    match = re.match(r'[\w:]+', sxpr)
774 775 776
    if match is None:
        raise AssertionError('Malformed S-expression Node-tagname or identifier expected, '
                             'not "%s"' % sxpr[:40].replace('\n', ''))
eckhart's avatar
eckhart committed
777 778
    name, class_name = (sxpr[:match.end()].split(':') + [''])[:2]
    sxpr = sxpr[match.end():].strip()
779 780
    pos = 0
    attributes = OrderedDict()
781 782
    if sxpr[0] == '(':
        result = tuple(mock_syntax_tree(block) for block in next_block(sxpr))
783 784 785
        for node in result:
            node._pos = pos
            pos += len(node)
786 787
    else:
        lines = []
788
        while sxpr and sxpr[0] != ')':
789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805
            # parse attributes
            while sxpr[:2] == "`(":
                i = sxpr.find('"')
                k = sxpr.find(')')
                if sxpr[2:5] == "pos" and (i < 0 or k < i):
                    pos = int(sxpr[5:k].strip().split(' ')[0])
                elif sxpr[2:5] == "err":
                    m = sxpr.find('(', 5)
                    while m >= 0 and m < k:
                        m = sxpr.find('(', k)
                        k = max(k, sxpr.find(')', max(m, 0)))
                else:
                    attr = sxpr[2:i].strip()
                    value = sxpr[i:k].strip()[1:-1]
                    attributes[attr] = value
                sxpr = sxpr[k+1:].strip()
            # parse content
eckhart's avatar
eckhart committed
806 807 808 809 810 811
            for qtmark in ['"""', "'''", '"', "'"]:
                match = re.match(qtmark + r'.*?' + qtmark, sxpr, re.DOTALL)
                if match:
                    i = len(qtmark)
                    lines.append(sxpr[i:match.end() - i])
                    sxpr = sxpr[match.end():].strip()
812 813
                    break
            else:
eckhart's avatar
eckhart committed
814 815 816
                match = re.match(r'(?:(?!\)).)*', sxpr, re.DOTALL)
                lines.append(sxpr[:match.end()])
                sxpr = sxpr[match.end():]
817
        result = "\n".join(lines)
818
    node = Node(MockParser(name, ':' + class_name), result)
819 820 821
    if attributes:
        node.attributes.update(attributes)
    node._pos = pos
822
    return node
823

824 825 826 827
# if __name__ == "__main__":
#     st = mock_syntax_tree("(alpha (beta (gamma i\nj\nk) (delta y)) (epsilon z))")
#     print(st.as_sxpr())
#     print(st.as_xml())