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


51 52 53 54 55 56 57 58 59 60 61 62 63
#######################################################################
#
# 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.
    """
64

65
    __slots__ = 'name', 'ptype'
Eckhart Arnold's avatar
Eckhart Arnold committed
66

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

    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 repr(self) -> str:
di68kap's avatar
di68kap committed
82
        """Returns the parser's name if it has a name and repr()"""
83 84
        return self.name if self.name else repr(self)

85
    def reset(self):
86
        """Resets any parser variables. (Should be overridden.)"""
87 88
        pass

eckhart's avatar
eckhart committed
89
    def grammar(self) -> Optional[object]:
90 91
        """Returns the Grammar object to which the parser belongs. If not
        yet connected to any Grammar object, None is returned."""
92 93 94
        return None

    def apply(self, func: Callable) -> bool:
eckhart's avatar
eckhart committed
95
        """Applies the function `func` to the parser. Returns False, if
96
        - for whatever reason - the functions has not been applied, True
eckhart's avatar
eckhart committed
97
        otherwise."""
98 99
        return False

100 101

WHITESPACE_PTYPE = ':Whitespace'
102
TOKEN_PTYPE = ':Token'
103 104 105 106 107 108


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
109
    different parser types by assigning them a `ptype` on initialization.
110 111 112 113 114

    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.
    """
115

Eckhart Arnold's avatar
Eckhart Arnold committed
116 117
    __slots__ = ()

118 119
    def __init__(self, name='', ptype=''):  # , pbases=frozenset()):
        assert not ptype or ptype[0] == ':'
120 121
        super().__init__()
        self.name = name
di68kap's avatar
di68kap committed
122 123
        if ptype:
            self.ptype = ptype  # or ':' + self.__class__.__name__
124 125 126 127 128 129 130 131 132 133 134 135


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.
    """
136

137
    alive = False
Eckhart Arnold's avatar
Eckhart Arnold committed
138
    __slots__ = ()
139 140

    def __init__(self):
141
        super(ZombieParser, self).__init__()
142 143
        assert not self.__class__.alive, "There can be only one!"
        assert self.__class__ == ZombieParser, "No derivatives, please!"
144
        self.name = "__ZOMBIE__"
145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167
        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
#
#######################################################################


168
ChildrenType = Tuple['Node', ...]
Eckhart Arnold's avatar
Eckhart Arnold committed
169
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
eckhart's avatar
eckhart committed
170
StrictResultType = Union[ChildrenType, StringView, str]
171
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
172 173


Eckhart Arnold's avatar
Eckhart Arnold committed
174
def flatten_sxpr(sxpr: str) -> str:
175 176
    """
    Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
177 178 179
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
180
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
181 182
    '(a (b c))'
    """
183

184
    return re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
Eckhart Arnold's avatar
Eckhart Arnold committed
185 186


187
def flatten_xml(xml: str) -> str:
188 189
    """
    Returns an XML-tree as a one liner without unnecessary whitespace,
190
    i.e. only whitespace within leaf-nodes is preserved.
191 192
    A more precise alternative to `flatten_xml` is to use Node.as_xml()
    ans passing a set containing the top level tag to parameter `inline_tags`.
193
    """
194

195 196 197 198
    # 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']
199
    return re.sub(r'\s+(?=<[\w:])', '', re.sub(r'(?P<closing_tag></:?\w+>)\s+', tag_only, xml))
200 201


Eckhart Arnold's avatar
Eckhart Arnold committed
202
class Node(collections.abc.Sized):
203 204 205
    """
    Represents a node in the concrete or abstract syntax tree.

206 207
    TODO: Add some documentation and doc-tests here...

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.

252 253
        attr (dict): An optional dictionary of XML-attr. This
            dictionary is created lazily upon first usage. The attr
254 255
            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
267
        # Assignment to self.result initializes the attr _result, children and _len
di68kap's avatar
di68kap committed
268
        # 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')
364 365


366 367 368 369 370 371 372 373 374 375 376 377 378 379
    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


380
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
381
    def tag_name(self) -> str:
382 383 384 385 386 387
        """
        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`.
        """
388
        return self.parser.name or self.parser.ptype
389

Eckhart Arnold's avatar
Eckhart Arnold committed
390

391
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
392
    def result(self) -> StrictResultType:
393 394 395 396 397
        """
        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.
        """
398 399
        return self._result

400

401
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
402
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
403
        # # made obsolete by static type checking with mypy
404 405 406
        # 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
407 408
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
409 410
        self._len = -1        # lazy evaluation
        self._content = None
411 412 413 414 415 416 417 418 419
        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
420
                self._result = result
421

422 423

    @property
eckhart's avatar
eckhart committed
424
    def content(self) -> str:
425
        """
di68kap's avatar
di68kap committed
426 427 428
        Returns content as string, omitting error messages. If the node has
        child-nodes, the string content of the child-nodes is recursively read
        and then concatenated.
429
        """
430 431 432 433
        if self._content is None:
            if self.children:
                self._content = "".join(child.content for child in self.children)
            else:
434
                # self._content = self._result
435 436 437
                self._content = str(self._result)
                self._result = self._content  # self._result might be more efficient as a string!?
        return self._content
438 439


di68kap's avatar
di68kap committed
440 441 442 443 444
    @content.setter
    def content(self, content: str):
        self.result = content


445 446 447 448 449 450 451 452 453
    @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))


454
    @property
455
    def pos(self) -> int:
eckhart's avatar
eckhart committed
456 457
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
458
            raise AssertionError("Position value not initialized!")
459 460
        return self._pos

eckhart's avatar
eckhart committed
461

eckhart's avatar
eckhart committed
462
    def init_pos(self, pos: int) -> 'Node':
eckhart's avatar
eckhart committed
463 464 465 466 467 468 469 470 471
        """
        (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
472 473
        assert self._pos < 0 or self.pos == pos, str("pos mismatch %i != %i" % (self._pos, pos))
        self._pos = pos
474
        # recursively adjust pos-values of all children
eckhart's avatar
eckhart committed
475
        offset = self.pos
476
        for child in self.children:
eckhart's avatar
eckhart committed
477
            child.init_pos(offset)
eckhart's avatar
eckhart committed
478 479 480
            offset = child.pos + len(child)
        return self

481

482
    @property
483
    def attr(self):
484
        """
485
        Returns a dictionary of XML-attr attached to the node.
486
        """
487 488 489 490
        if not hasattr(self, '_xml_attr'):
            self._xml_attr = OrderedDict()
        return self._xml_attr

Eckhart Arnold's avatar
Eckhart Arnold committed
491

492
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i,
493
                   density=0, inline=False, inline_fn=lambda node: False) -> str:
494 495 496 497 498 499 500 501
        """
        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.

502
        Args:
503
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
504
            open_fn:   (Node->str) A function that returns an opening
505
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
506
            close_fn:  (Node->str) A function that returns a closeF
507
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
508
            data_fn:   (str->str) A function that filters the data string
509 510 511 512 513 514
                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
515 516
        head = open_fn(self)
        tail = close_fn(self)
517 518

        if not self.result:
519
            return head.rstrip() + tail.lstrip()
520

eckhart's avatar
eckhart committed
521
        tail = tail.lstrip(None if density & 2 else '')
522

523
        inline = inline or inline_fn(self)
524 525 526 527 528
        if inline:
            head = head.rstrip()
            tail = tail.lstrip()
            usetab, sep = '', ''
        else:
eckhart's avatar
eckhart committed
529 530
            usetab = tab if head else ''    # no indentation if tag is already omitted
            sep = '\n'
531

532 533
        if self.children:
            content = []
534
            for child in self.children:
535
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn,
536
                                           density, inline, inline_fn)
eckhart's avatar
eckhart committed
537 538 539
                if subtree:
                    subtree = [subtree] if inline else subtree.split('\n')
                    content.append((sep + usetab).join(s for s in subtree))
540
            return head + usetab + (sep + usetab).join(content) + tail
541

542
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
eckhart's avatar
eckhart committed
543
        if not inline and not head:
eckhart's avatar
eckhart committed
544
            # strip whitespace for omitted non inline node, e.g. CharData in mixed elements
eckhart's avatar
eckhart committed
545
            res = res.strip()
546 547
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
548
            gap = ' ' if not inline and head and head.rstrip()[-1:] != '>' else ''
eckhart's avatar
eckhart committed
549
            return head.rstrip() + gap + data_fn(res) + tail.lstrip()
550
        else:
551
            return head + '\n'.join([usetab + data_fn(s) for s in res.split('\n')]) + tail
552

Eckhart Arnold's avatar
Eckhart Arnold committed
553

554 555 556
    def as_sxpr(self, src: str = None,
                showerrors: bool = True,
                indentation: int = 2,
557
                compact: bool = False) -> str:
558 559 560
        """
        Returns content as S-expression, i.e. in lisp-like form.

561
        Args:
562 563 564
            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.
565 566 567
            showerrors: If True, error messages will be shown.
            indentation: The number of whitespaces for indentation
            compact:  If True, a compact representation is returned where
568
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
569
                tree structure.
570 571
        """

eckhart's avatar
eckhart committed
572
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
eckhart's avatar
eckhart committed
573
        lbreaks = linebreaks(src) if src else []  # type: List[int]
574

575
        def opening(node) -> str:
eckhart's avatar
eckhart committed
576
            """Returns the opening string for the representation of `node`."""
577
            txt = [left_bracket,  node.tag_name]
578
            # s += " '(pos %i)" % node.add_pos
579
            if hasattr(node, '_xml_attr'):
580
                txt.extend(' `(%s "%s")' % (k, v) for k, v in node.attr.items())
581
            if src:
582 583
                line, col = line_col(lbreaks, node.pos)
                txt.append(" `(pos %i %i %i)" % (node.pos, line, col))
584
            if showerrors and node.errors:
585
                txt.append(" `(err `%s)" % ' '.join(str(err) for err in node.errors))
586
            return "".join(txt) + '\n'
587

eckhart's avatar
eckhart committed
588 589 590
        def closing(node) -> str:
            """Returns the closing string for the representation of `node`."""
            return right_bracket
591

eckhart's avatar
eckhart committed
592 593 594 595 596
        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'\"')
597

598
        return self._tree_repr(' ' * indentation, opening, closing, pretty, density=density)
Eckhart Arnold's avatar
Eckhart Arnold committed
599

eckhart's avatar
eckhart committed
600

601 602 603 604 605 606
    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:
607 608 609
        """
        Returns content as XML-tree.

610
        Args:
611 612 613
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
614 615
            showerrors: If True, error messages will be shown.
            indentation: The number of whitespaces for indentation
616 617 618
            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
619
                neither the opening tag nor its attr nor the closing tag. This
620 621 622
                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.
623 624
            empty_tags:  A set of tags which shall be rendered as empty elements, e.g.
                "<empty/>" instead of "<empty><empty>".
625 626
        """

627
        def opening(node) -> str:
628 629 630
            """Returns the opening string for the representation of `node`."""
            if node.tag_name in omit_tags:
                return ''
eckhart's avatar
eckhart committed
631
            txt = ['<', node.tag_name]
632
            has_reserved_attrs = hasattr(node, '_xml_attr') \
633
                and any (r in node.attr for r in {'err', 'line', 'col'})
di68kap's avatar
di68kap committed
634
            if hasattr(node, '_xml_attr'):
635
                txt.extend(' %s="%s"' % (k, v) for k, v in node.attr.items())
636
            if src and not has_reserved_attrs:
eckhart's avatar
eckhart committed
637
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
638
            if showerrors and node.errors and not has_reserved_attrs:
eckhart's avatar
eckhart committed
639 640
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
                                                 for err in node.errors))
641 642 643
            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
644
                ending = "/>\n" if not node.tag_name[0] == '?' else "?>\n"
645 646 647
            else:
                ending = ">\n"
            return "".join(txt + [ending])
648 649

        def closing(node):
650
            """Returns the closing string for the representation of `node`."""
651
            if node.tag_name in omit_tags or node.tag_name in empty_tags:
652
                return ''
653
            return ('\n</') + node.tag_name + '>'
654

655 656 657 658 659
        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.
            """
660
            return node.tag_name in inline_tags or (hasattr(node, '_xml_attr') \
661
                                                    and node.attr.get('xml:space', 'default') == 'preserve')
662

663
        line_breaks = linebreaks(src) if src else []
664 665
        return self._tree_repr(' ' * indentation, opening, closing,
                               density=1, inline_fn=inlining)
666

Eckhart Arnold's avatar
Eckhart Arnold committed
667

668
    def select(self, match_function: Callable, include_root: bool=False) -> Iterator['Node']:
eckhart's avatar
eckhart committed
669
        """
670
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
671

672
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
673
        given `match_function` evaluates to True. The tree is
674 675 676
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
677

678 679 680
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
681 682
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
683
        Yields:
684
            Node: All nodes of the tree for which
685 686
            ``match_function(node)`` returns True
        """
687
        if include_root and match_function(self):
688
            yield self
eckhart's avatar
eckhart committed
689 690 691
        for child in self.children:
            for node in child.select(match_function, True):
                yield node
692

Eckhart Arnold's avatar
Eckhart Arnold committed
693

eckhart's avatar
eckhart committed
694
    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
695
                      include_root: bool=False) -> Iterator['Node']:
696
        """
697 698 699 700
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
701

702
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
703
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
704
            ['(X (c "d"))', '(X "F")']
705
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
706
            ['(b "X")', '(X (c "d"))', '(X "F")']
707
            >>> any(tree.select_by_tag('a', False))
708
            False
709
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
710
            ['(a (b "X") (X (c "d")) (e (X "F")))']
711 712
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
713 714

        Args:
715 716 717 718
            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.
719 720 721
        Yields:
            Node: All nodes which have a given tag name.
        """
722
        if isinstance(tag_names, str):
eckhart's avatar
eckhart committed
723
            tag_names = frozenset({tag_names})
724
        return self.select(lambda node: node.tag_name in tag_names, include_root)
725 726


727 728 729 730 731 732 733 734 735 736 737 738 739 740 741
    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


742
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
743 744 745
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
746 747 748
        return sum(child.tree_size() for child in self.children) + 1


di68kap's avatar
di68kap committed
749
class RootNode(Node):
750
    """TODO: Add Documentation!!!
di68kap's avatar
di68kap committed
751

Eckhart Arnold's avatar
Eckhart Arnold committed
752
        all_errors (list):  A list of all errors that have occured so far during
753 754
                processing (i.e. parsing, AST-transformation, compiling)
                of this tree.
di68kap's avatar
di68kap committed
755

756 757
        error_flag (int):  the highest warning or error level of all errors
                that occurred.
di68kap's avatar
di68kap committed
758
    """
759

eckhart's avatar
eckhart committed
760
    def __init__(self, node: Optional[Node] = None) -> 'RootNode':
di68kap's avatar
di68kap committed
761
        super().__init__(ZOMBIE_PARSER, '')
762
        self.all_errors = []
di68kap's avatar
di68kap committed
763
        self.error_flag = 0
eckhart's avatar
eckhart committed
764 765
        if node is not None:
            self.swallow(node)
766 767 768 769
        # customization for XML-Representation
        self.inline_tags = set()
        self.omit_tags = set()
        self.empty_tags = set()
di68kap's avatar
di68kap committed
770

771
    def swallow(self, node: Node) -> 'RootNode':
772 773
        """
        Put `self` in the place of `node` by copying all its data.
774 775 776 777 778 779 780 781 782
        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
783 784 785 786 787
        self._result = node._result
        self.children = node.children
        self._len = node._len
        self._pos = node._pos
        self.parser = node.parser
788 789
        if hasattr(node, '_xml_attr'):
            self._xml_attr = node._xml_attr
di68kap's avatar
di68kap committed
790
        self._content = node._content
791
        return self
di68kap's avatar
di68kap committed
792

eckhart's avatar
eckhart committed
793
    def add_error(self, node: Node, error: Error) -> 'RootNode':
794 795 796
        """
        Adds an Error object to the tree, locating it at a specific node.
        """
di68kap's avatar
di68kap committed
797 798 799 800 801
        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
802
    def new_error(self,
803
                  node: Node,
di68kap's avatar
di68kap committed
804
                  message: str,
di68kap's avatar
di68kap committed
805
                  code: int = Error.ERROR) -> 'RootNode':
di68kap's avatar
di68kap committed
806
        """
eckhart's avatar
eckhart committed
807
        Adds an error to this tree, locating it at a specific node.
di68kap's avatar
di68kap committed
808 809 810 811 812
        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
813
        error = Error(message, node.pos, code)
eckhart's avatar
eckhart committed
814 815
        self.add_error(node, error)
        return self
di68kap's avatar
di68kap committed
816

eckhart's avatar
eckhart committed
817
    def collect_errors(self) -> List[Error]:
818 819
        """
        Returns the list of errors, ordered bv their position.
di68kap's avatar
di68kap committed
820
        """
821
        self.all_errors.sort(key=lambda e: e.pos)
Eckhart Arnold's avatar
Eckhart Arnold committed
822
        return self.all_errors
di68kap's avatar
di68kap committed
823

824
    def customized_XML(self):
825 826
        """
        Returns a customized XML representation of the tree.
827
        See the docstring of `Node.as_xml()` for an explanation of the
828 829
        customizations.
        """
830 831 832 833
        return self.as_xml(inline_tags = self.inline_tags,
                           omit_tags=self.omit_tags,
                           empty_tags=self.empty_tags)

di68kap's avatar
di68kap committed
834

eckhart's avatar
eckhart committed
835 836 837
ZOMBIE_NODE = Node(ZOMBIE_PARSER, '')


838
def parse_sxpr(sxpr: str) -> Node:
839
    """
840 841 842 843 844
    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.
845 846

    Example:
847
    >>> parse_sxpr("(a (b c))").as_sxpr()