In January 2021 we will introduce a 10 GB quota for project repositories. Higher limits for individual projects will be available on request. Please see https://doku.lrz.de/display/PUBLIC/GitLab for more information.

syntaxtree.py 41.9 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
from collections import OrderedDict
eckhart's avatar
eckhart committed
27
import copy
28

eckhart's avatar
eckhart committed
29
from DHParser.error import Error, ErrorCode, linebreaks, line_col
30
from DHParser.stringview import StringView
di68kap's avatar
di68kap committed
31 32
from DHParser.toolkit import re
from typing import Callable, cast, Iterator, List, AbstractSet, Set, Union, Tuple, Optional
di68kap's avatar
di68kap committed
33

34

di68kap's avatar
di68kap committed
35
__all__ = ('WHITESPACE_PTYPE',
36
           'TOKEN_PTYPE',
37 38
           'ZOMBIE_TAG',
           'PLACEHOLDER',
eckhart's avatar
eckhart committed
39 40 41
           'ResultType',
           'StrictResultType',
           'ChildrenType',
42
           'Node',
43
           'FrozenNode',
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
#######################################################################
#
# parser base and mock parsers
#
#######################################################################


WHITESPACE_PTYPE = ':Whitespace'
59
TOKEN_PTYPE = ':Token'
60

61
ZOMBIE_TAG = "__ZOMBIE__"
62

63 64 65 66 67 68 69
#######################################################################
#
# syntaxtree nodes
#
#######################################################################


70
ChildrenType = Tuple['Node', ...]
Eckhart Arnold's avatar
Eckhart Arnold committed
71
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
eckhart's avatar
eckhart committed
72
StrictResultType = Union[ChildrenType, StringView, str]
73
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
74 75


Eckhart Arnold's avatar
Eckhart Arnold committed
76
def flatten_sxpr(sxpr: str) -> str:
77 78
    """
    Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
79 80 81
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
82
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
83 84
    '(a (b c))'
    """
85

86
    return re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
Eckhart Arnold's avatar
Eckhart Arnold committed
87 88


89
def flatten_xml(xml: str) -> str:
90 91
    """
    Returns an XML-tree as a one liner without unnecessary whitespace,
92
    i.e. only whitespace within leaf-nodes is preserved.
93 94
    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`.
95
    """
96

97 98 99 100
    # 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']
101
    return re.sub(r'\s+(?=<[\w:])', '', re.sub(r'(?P<closing_tag></:?\w+>)\s+', tag_only, xml))
102 103


eckhart's avatar
eckhart committed
104
RX_AMP = re.compile(r'&(?!\w+;)')
105 106


Eckhart Arnold's avatar
Eckhart Arnold committed
107
class Node:  # (collections.abc.Sized): Base class omitted for cython-compatibility
108 109 110
    """
    Represents a node in the concrete or abstract syntax tree.

111 112
    TODO: Add some documentation and doc-tests here...

113
    Attributes:
114 115
        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
116

117 118 119
        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.
120

121 122
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
123

eckhart's avatar
eckhart committed
124 125 126 127
        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
128
        parser (Parser):  The parser which generated this node.
129 130
            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
131 132
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
133
            example by calling ``isinstance(node.parer, ...)``.
134

135 136 137
        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
138
            the length before AST-transformation and will never change
139
            through AST-transformation. READ ONLY!
140

141 142
        pos (int):  the position of the node within the parsed text.

Eckhart Arnold's avatar
Eckhart Arnold committed
143
            The value of ``pos`` is -1 meaning invalid by default.
144
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
145
            nodes relative to this value.
146 147

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
148
            pos value of the root node should be set to 0 right
149 150
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
151
            Other than that, this value should be considered READ ONLY.
152 153
            At any rate, it should only be reassigned during the parsing
            stage and never during or after the AST-transformation.
154

155 156
        attr (dict): An optional dictionary of XML-attr. This
            dictionary is created lazily upon first usage. The attr
157 158
            will only be shown in the XML-Representation, not in the
            S-Expression-output.
159
    """
160

161
    __slots__ = '_result', 'children', '_len', '_pos', 'tag_name', '_xml_attr', '_content'
162

163
    def __init__(self, tag_name: str, result: ResultType, leafhint: bool = False) -> None:
164 165
        """
        Initializes the ``Node``-object with the ``Parser``-Instance
166 167
        that generated the node and the parser's result.
        """
eckhart's avatar
eckhart committed
168
        self._pos = -1                  # type: int
169
        # Assignment to self.result initializes the attr _result, children and _len
di68kap's avatar
di68kap committed
170
        # The following if-clause is merely an optimization, i.e. a fast-path for leaf-Nodes
171
        if leafhint:
eckhart's avatar
eckhart committed
172
            self._result = result       # type: StrictResultType  # cast(StrictResultType, result)
eckhart's avatar
eckhart committed
173
            self._content = None        # type: Optional[str]
174
            self.children = NoChildren  # type: ChildrenType
175
            self._len = -1              # type: int  # lazy evaluation
176 177
        else:
            self.result = result
178
        self.tag_name = tag_name        # type: str
179

eckhart's avatar
eckhart committed
180 181
    def __deepcopy__(self, memo):
        if self.children:
182
            duplicate = self.__class__(self.tag_name, copy.deepcopy(self.children), False)
eckhart's avatar
eckhart committed
183
        else:
184
            duplicate = self.__class__(self.tag_name, self.result, True)
eckhart's avatar
eckhart committed
185 186
        duplicate._pos = self._pos
        duplicate._len = self._len
eckhart's avatar
eckhart committed
187
        if self.attr_active():
di68kap's avatar
di68kap committed
188 189
            duplicate.attr.update(copy.deepcopy(self._xml_attr))
            # duplicate._xml_attr = copy.deepcopy(self._xml_attr)  # this is not cython compatible
eckhart's avatar
eckhart committed
190
        return duplicate
Eckhart Arnold's avatar
Eckhart Arnold committed
191

192
    def __str__(self):
193 194
        if isinstance(self, RootNode):
            root = cast(RootNode, self)
195
            errors = root.errors_sorted
196 197 198 199 200 201
            if errors:
                e_pos = errors[0].pos
                return self.content[:e_pos] + \
                   ' <<< Error on "%s" | %s >>> ' % \
                   (self.content[e_pos - self.pos:], '; '.join(e.message for e in errors))
        return self.content
Eckhart Arnold's avatar
Eckhart Arnold committed
202

203
    def __repr__(self):
204
        # mpargs = {'name': self.parser.name, 'ptype': self.parser.ptype}
205 206
        # name, ptype = (self._tag_name.split(':') + [''])[:2]
        # parg = "MockParser({name}, {ptype})".format(name=name, ptype=ptype)
207
        rarg = str(self) if not self.children else \
208
            "(" + ", ".join(child.__repr__() for child in self.children) + ")"
209
        return "Node(%s, %s)" % (self.tag_name, rarg)
210

Eckhart Arnold's avatar
Eckhart Arnold committed
211

212
    def __len__(self):
213
        if self._len < 0:
di68kap's avatar
di68kap committed
214
            self._len = sum(len(child) for child in self.children) \
215
                if self.children else len(self._result)
216 217 218 219 220 221 222 223
        return self._len


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


224
    def __eq__(self, other):
225 226
        """
        Equality of nodes: Two nodes are considered as equal, if their tag
227 228
        name is the same, if their results are equal and if their attributes
        and attribute values are the same.
229
        """
230 231
        return self.tag_name == other.tag_name and self.result == other.result \
            and self.compare_attr(other)
232

Eckhart Arnold's avatar
Eckhart Arnold committed
233

234
    def __hash__(self):
235
        return hash(self.tag_name)
236

Eckhart Arnold's avatar
Eckhart Arnold committed
237

238 239 240
    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
241
        an integer or the first child node with the given tag name. Examples::
242

243
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
244 245
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
246 247
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
248 249 250 251

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
252
        Returns:
253 254
            Node: All nodes which have a given tag name.
        """
255 256 257
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
258
            else:
259 260 261 262 263
                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!')
264 265 266 267


    def __contains__(self, tag_name: str) -> bool:
        """
268
        Returns true if a child with the given tag name exists.
269
        Args:
270 271
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
272 273 274 275
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
276 277 278 279 280
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
281
            return False
282
        raise ValueError('Leave node cannot contain other nodes')
283 284


285 286 287 288 289 290 291 292 293 294 295 296 297 298
    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


299
    def is_anonymous(self):
Eckhart Arnold's avatar
Eckhart Arnold committed
300
        return not self.tag_name or self.tag_name[0] == ':'
301

Eckhart Arnold's avatar
Eckhart Arnold committed
302

303
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
304
    def result(self) -> StrictResultType:
305 306 307 308 309
        """
        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.
        """
310 311
        return self._result

312

313
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
314
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
315
        # # made obsolete by static type checking with mypy
316 317 318
        # 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
319 320
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
321 322
        self._len = -1        # lazy evaluation
        self._content = None
323 324 325 326 327 328 329 330 331
        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
eckhart's avatar
eckhart committed
332
                self._result = result  # cast(StrictResultType, result)
333

334 335

    @property
eckhart's avatar
eckhart committed
336
    def content(self) -> str:
337
        """
338 339 340
        Returns content as string. If the node has child-nodes, the
        string content of the child-nodes is recursively read and then
        concatenated.
341
        """
342 343 344 345
        if self._content is None:
            if self.children:
                self._content = "".join(child.content for child in self.children)
            else:
346
                # self._content = self._result
347 348 349
                self._content = str(self._result)
                self._result = self._content  # self._result might be more efficient as a string!?
        return self._content
350 351 352 353 354
    #
    #
    # @content.setter
    # def content(self, content: str):
    #     self.result = content
di68kap's avatar
di68kap committed
355 356


357 358 359 360 361 362
    @property
    def structure(self) -> str:
        """
        Return structure (and content) as S-expression on a single line
        without any line breaks.
        """
363
        return flatten_sxpr(self.as_sxpr())
364 365


366
    @property
367
    def pos(self) -> int:
eckhart's avatar
eckhart committed
368 369
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
Eckhart Arnold's avatar
Eckhart Arnold committed
370
            raise AssertionError("Position value not initialized! Use Node.with_pos()")
371 372
        return self._pos

eckhart's avatar
eckhart committed
373

Eckhart Arnold's avatar
Eckhart Arnold committed
374
    def with_pos(self, pos: int) -> 'Node':
eckhart's avatar
eckhart committed
375
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
376
        Initialize position value. Usually, the parser guard
eckhart's avatar
eckhart committed
377 378
        (`parsers.add_parser_guard()`) takes care of assigning the
        position in the document to newly created nodes. However,
Eckhart Arnold's avatar
Eckhart Arnold committed
379
        when Nodes are created outside the reach of the parser
eckhart's avatar
eckhart committed
380
        guard, their document-position must be assigned manually.
Eckhart Arnold's avatar
Eckhart Arnold committed
381 382
        Position values of the child nodes are assigned recursively, too.
        Returns the node itself for convenience.
eckhart's avatar
eckhart committed
383
        """
384 385 386 387
        # condition self.pos == pos cannot be assumed when tokens or whitespace
        # are dropped early!
        # assert self._pos < 0 or self.pos == pos, ("pos mismatch %i != %i at Node: %s"
        #                                           % (self._pos, pos, repr(self)))
Eckhart Arnold's avatar
Eckhart Arnold committed
388 389 390 391 392 393 394 395 396 397
        if pos != self._pos >= 0:
            raise AssertionError("Position value cannot be reassigned to a different value!")
        if self._pos < 0:
            self._pos = pos
            # recursively adjust pos-values of all children
            offset = self.pos
            for child in self.children:
                if child._pos < 0:
                    child.with_pos(offset)
                offset = child.pos + len(child)
eckhart's avatar
eckhart committed
398 399
        return self

400

401 402 403 404 405 406 407 408 409 410 411 412 413
    @property
    def attr(self):
        """
        Returns a dictionary of XML-attr attached to the node.
        """
        try:
            if self._xml_attr is None:          # cython compatibility
                self._xml_attr = OrderedDict()
        except AttributeError:
            self._xml_attr = OrderedDict()
        return self._xml_attr


eckhart's avatar
eckhart committed
414 415 416 417 418 419 420 421 422 423 424 425 426
    def attr_active(self) -> bool:
        """
        Returns True, if XML-Attributes of this node have ever been set
        or queried, even if unsuccessfully.
        """
        try:
            if self._xml_attr is not None:
                return True
        except AttributeError:
            pass
        return False


427
    def compare_attr(self, other: 'Node') -> bool:
428
        """
429 430
        Returns True, if `self` and `other` have the same attributes with the
        same attribute values.
431
        """
432 433 434 435 436 437 438 439 440
        if self.attr_active():
            if other.attr_active():
                return self.attr == other.attr
            return len(self.attr) == 0
            # self has empty dictionary and other has no attributes
        elif other.attr_active():
            return len(other.attr) == 0
            # other has empty attribute dictionary and self as no attributes
        return True  # neither self nor other have any attributes
441

Eckhart Arnold's avatar
Eckhart Arnold committed
442

443
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i,
444
                   density=0, inline=False, inline_fn=lambda node: False) -> str:
445 446 447 448 449 450 451 452
        """
        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.

453
        Args:
454
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
455
            open_fn:   (Node->str) A function that returns an opening
456
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
457
            close_fn:  (Node->str) A function that returns a closeF
458
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
459
            data_fn:   (str->str) A function that filters the data string
460 461 462 463 464 465
                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
466 467
        head = open_fn(self)
        tail = close_fn(self)
468 469

        if not self.result:
470
            return head.rstrip() + tail.lstrip()
471

eckhart's avatar
eckhart committed
472
        tail = tail.lstrip(None if density & 2 else '')
473

474
        inline = inline or inline_fn(self)
475 476 477 478 479
        if inline:
            head = head.rstrip()
            tail = tail.lstrip()
            usetab, sep = '', ''
        else:
eckhart's avatar
eckhart committed
480 481
            usetab = tab if head else ''    # no indentation if tag is already omitted
            sep = '\n'
482

483 484
        if self.children:
            content = []
485
            for child in self.children:
486
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn,
487
                                           density, inline, inline_fn)
eckhart's avatar
eckhart committed
488
                if subtree:
eckhart's avatar
eckhart committed
489 490
                    st = [subtree] if inline else subtree.split('\n')
                    content.append((sep + usetab).join(s for s in st))
491
            return head + usetab + (sep + usetab).join(content) + tail
492

eckhart's avatar
eckhart committed
493
        res = self.content
eckhart's avatar
eckhart committed
494
        if not inline and not head:
eckhart's avatar
eckhart committed
495
            # strip whitespace for omitted non inline node, e.g. CharData in mixed elements
eckhart's avatar
eckhart committed
496
            res = res.strip()
497 498
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
499
            gap = ' ' if not inline and head and head.rstrip()[-1:] != '>' else ''
eckhart's avatar
eckhart committed
500
            return head.rstrip() + gap + data_fn(res) + tail.lstrip()
501
        else:
502
            return head + '\n'.join([usetab + data_fn(s) for s in res.split('\n')]) + tail
503

Eckhart Arnold's avatar
Eckhart Arnold committed
504

505 506
    def as_sxpr(self, src: str = None,
                indentation: int = 2,
507
                compact: bool = False) -> str:
508
        """
509 510
        Returns content as S-expression, i.e. in lisp-like form. If this
        method is callad on a RootNode-object,
511

512
        Args:
513 514 515
            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.
516 517
            indentation: The number of whitespaces for indentation
            compact:  If True, a compact representation is returned where
518
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
519
                tree structure.
520 521
        """

eckhart's avatar
eckhart committed
522
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
eckhart's avatar
eckhart committed
523
        lbreaks = linebreaks(src) if src else []  # type: List[int]
524
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[Node]
525

526
        def opening(node) -> str:
eckhart's avatar
eckhart committed
527
            """Returns the opening string for the representation of `node`."""
eckhart's avatar
eckhart committed
528
            txt = [left_bracket, node.tag_name]
529
            # s += " '(pos %i)" % node.add_pos
eckhart's avatar
eckhart committed
530
            if node.attr_active():
531
                txt.extend(' `(%s "%s")' % (k, v) for k, v in node.attr.items())
532
            if src:
533 534
                line, col = line_col(lbreaks, node.pos)
                txt.append(" `(pos %i %i %i)" % (node.pos, line, col))
535 536
            if root and id(node) in root.error_nodes:
                txt.append(" `(err `%s)" % ' '.join(str(err) for err in root.get_errors(node)))
537
            return "".join(txt) + '\n'
538

eckhart's avatar
eckhart committed
539 540 541
        def closing(node) -> str:
            """Returns the closing string for the representation of `node`."""
            return right_bracket
542

eckhart's avatar
eckhart committed
543 544 545 546 547
        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'\"')
548

549
        return self._tree_repr(' ' * indentation, opening, closing, pretty, density=density)
Eckhart Arnold's avatar
Eckhart Arnold committed
550

eckhart's avatar
eckhart committed
551

552 553
    def as_xml(self, src: str = None,
               indentation: int = 2,
eckhart's avatar
eckhart committed
554 555 556
               inline_tags: Set[str] = set(),
               omit_tags: Set[str] = set(),
               empty_tags: Set[str] = set()) -> str:
557 558 559
        """
        Returns content as XML-tree.

560
        Args:
561 562 563
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
564
            indentation: The number of whitespaces for indentation
565 566 567
            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
568
                neither the opening tag nor its attr nor the closing tag. This
569 570 571
                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.
572 573
            empty_tags:  A set of tags which shall be rendered as empty elements, e.g.
                "<empty/>" instead of "<empty><empty>".
574
        """
575
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[Node]
576

577
        def opening(node) -> str:
578 579 580
            """Returns the opening string for the representation of `node`."""
            if node.tag_name in omit_tags:
                return ''
eckhart's avatar
eckhart committed
581
            txt = ['<', node.tag_name]
eckhart's avatar
eckhart committed
582
            has_reserved_attrs = node.attr_active() \
eckhart's avatar
eckhart committed
583
                and any(r in node.attr for r in {'err', 'line', 'col'})
eckhart's avatar
eckhart committed
584
            if node.attr_active():
585
                txt.extend(' %s="%s"' % (k, v) for k, v in node.attr.items())
586
            if src and not has_reserved_attrs:
eckhart's avatar
eckhart committed
587
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
588
            if root and id(node) in root.error_nodes and not has_reserved_attrs:
eckhart's avatar
eckhart committed
589
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
590
                                                 for err in root.get_error(node)))
591 592 593
            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
594
                ending = "/>\n" if not node.tag_name[0] == '?' else "?>\n"
595 596 597
            else:
                ending = ">\n"
            return "".join(txt + [ending])
598 599

        def closing(node):
600
            """Returns the closing string for the representation of `node`."""
601
            if node.tag_name in omit_tags or node.tag_name in empty_tags:
602
                return ''
603
            return ('\n</') + node.tag_name + '>'
604

605 606 607 608 609 610 611
        def sanitizer(content: str) -> str:
            """Substitute "&", "<", ">" in XML-content by the respective entities."""
            content = RX_AMP.sub('&amp;', content)
            content = content.replace('<', '&lt;').replace('>', '&gt;')
            return content


612 613 614 615 616
        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.
            """
eckhart's avatar
eckhart committed
617
            return node.tag_name in inline_tags \
eckhart's avatar
eckhart committed
618
                or (node.attr_active()
eckhart's avatar
eckhart committed
619
                    and node.attr.get('xml:space', 'default') == 'preserve')
620

621
        line_breaks = linebreaks(src) if src else []
622
        return self._tree_repr(' ' * indentation, opening, closing, sanitizer,
623
                               density=1, inline_fn=inlining)
624

Eckhart Arnold's avatar
Eckhart Arnold committed
625

eckhart's avatar
eckhart committed
626
    def select(self, match_function: Callable, include_root: bool = False, reverse: bool = False) \
627
            -> Iterator['Node']:
eckhart's avatar
eckhart committed
628
        """
629
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
630

631
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
632
        given `match_function` evaluates to True. The tree is
633 634 635
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
636

637 638 639
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
640 641
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
642 643
            reverse (bool): If True, the tree will be walked in reverse
                order, i.e. last children first.
644
        Yields:
645
            Node: All nodes of the tree for which
646 647
            ``match_function(node)`` returns True
        """
648
        if include_root and match_function(self):
649
            yield self
650 651 652
        child_iterator = reversed(self.children) if reverse else self.children
        for child in child_iterator:
            for node in child.select(match_function, True, reverse):
eckhart's avatar
eckhart committed
653
                yield node
654

Eckhart Arnold's avatar
Eckhart Arnold committed
655

eckhart's avatar
eckhart committed
656
    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
eckhart's avatar
eckhart committed
657
                      include_root: bool = False) -> Iterator['Node']:
658
        """
659 660 661 662
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
663

664
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
665
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
666
            ['(X (c "d"))', '(X "F")']
667
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
668
            ['(b "X")', '(X (c "d"))', '(X "F")']
669
            >>> any(tree.select_by_tag('a', False))
670
            False
671
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
672
            ['(a (b "X") (X (c "d")) (e (X "F")))']
673 674
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
675 676

        Args:
677 678 679 680
            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.
681 682 683
        Yields:
            Node: All nodes which have a given tag name.
        """
684
        if isinstance(tag_names, str):
eckhart's avatar
eckhart committed
685
            tag_names = frozenset({tag_names})
686
        return self.select(lambda node: node.tag_name in tag_names, include_root)
687 688


689 690 691 692
    def pick(self, tag_names: Union[str, Set[str]]) -> Optional['Node']:
        """
        Picks the first descendant with one of the given tag_names.

693
        This function is mostly just syntactic sugar for
694 695 696 697 698 699 700 701 702 703
        ``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


704
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
705 706 707
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
708 709 710
        return sum(child.tree_size() for child in self.children) + 1


711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728
class FrozenNode(Node):

    def __init__(self, tag_name: str, result: ResultType) -> None:
        if isinstance(result, str) or isinstance(result, StringView):
            result = str(result)
        else:
            raise TypeError('FrozenNode only accepts string as results. '
                            '(Only leaf-nodes can be frozen nodes.)')
        super(FrozenNode, self).__init__(tag_name, result, True)

    @property
    def result(self) -> StrictResultType:
        return self._result

    @result.setter
    def result(self, result: ResultType):
        raise TypeError('FrozenNode does not allow re-assignment of results.')

eckhart's avatar
eckhart committed
729 730 731 732
    @property
    def attr(self):
        raise AssertionError("Attributes cannot be accessed on a frozen node")

733 734 735 736 737 738 739 740
    # @property
    # def errors(self) -> List[Error]:
    #     return ()
    #
    # @errors.setter
    # def errors(self, errors: List[Error]):
    #     if errors:
    #         raise AssertionError('Cannot assign error list to frozen node')
eckhart's avatar
eckhart committed
741

Eckhart Arnold's avatar
Eckhart Arnold committed
742
    def with_pos(self, pos: int) -> 'Node':
743 744 745 746
        pass


PLACEHOLDER = Node('__PLACEHOLDER__', '')
di68kap's avatar
di68kap committed
747 748


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

752
        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):
761
        super().__init__('__not_yet_ready__', '')
762
        self.errors = []           # type: List[Error]
763 764
        self.error_nodes = dict()      # type: Dict[int, List[Error]]  # id(node) -> error list
        self.error_positions = dict()  # type: Dict[int, Set[int]]  # pos -> set of id(node)
di68kap's avatar
di68kap committed
765
        self.error_flag = 0
eckhart's avatar
eckhart committed
766 767
        if node is not None:
            self.swallow(node)
768
        # customization for XML-Representation
eckhart's avatar
eckhart committed
769 770 771
        self.inline_tags = set()  # type: Set[str]
        self.omit_tags = set()  # type: Set[str]
        self.empty_tags = set()  # type: Set[str]
di68kap's avatar
di68kap committed
772

773 774 775 776 777 778 779 780 781 782
    def __deepcopy__(self, memodict={}):
        duplicate = self.__class__(None)
        if self.children:
            duplicate.children = copy.deepcopy(self.children)
            duplicate._result = duplicate.children
        else:
            duplicate.children = NoChildren
            duplicate._result = self._result
        duplicate._pos = self._pos
        duplicate._len = self._len
eckhart's avatar
eckhart committed
783
        if self.attr_active():
di68kap's avatar
di68kap committed
784
            duplicate.attr.update(copy.deepcopy(self._xml_attr))
785
            # duplicate._xml_attr = copy.deepcopy(self._xml_attr)  # this is blocked by cython
786
        duplicate.errors = copy.copy(self.errors)
787 788
        duplicate.error_nodes = copy.copy(self.error_nodes)
        duplicate.error_positions = copy.deepcopy(self.error_positions)
789 790 791 792
        duplicate.error_flag = self.error_flag
        duplicate.inline_tags = self.inline_tags
        duplicate.omit_tags = self.omit_tags
        duplicate.empty_tags = self.empty_tags
793
        duplicate.tag_name = self.tag_name
794 795 796
        return duplicate


797
    def swallow(self, node: Node) -> 'RootNode':
798 799
        """
        Put `self` in the place of `node` by copying all its data.
800 801 802 803 804 805 806 807 808
        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
809 810 811 812
        self._result = node._result
        self.children = node.children
        self._len = node._len
        self._pos = node._pos
813
        self.tag_name = node.tag_name
eckhart's avatar
eckhart committed
814
        if node.attr_active():
815
            self._xml_attr = node._xml_attr
di68kap's avatar
di68kap committed
816
        self._content = node._content
817 818
        if id(node) in self.error_nodes:
            self.error_nodes[id(self)] = self.error_nodes[id(node)]
819
        return self
di68kap's avatar
di68kap committed
820

eckhart's avatar
eckhart committed
821
    def add_error(self, node: Node, error: Error) -> 'RootNode':
822 823 824
        """
        Adds an Error object to the tree, locating it at a specific node.
        """
eckhart's avatar
eckhart committed
825
        assert not isinstance(node, FrozenNode)
826
        assert node.pos == error.pos
827
        self.errors.append(error)
di68kap's avatar
di68kap committed
828
        self.error_flag = max(self.error_flag, error.code)
829 830
        self.error_nodes.setdefault(id(node), []).append(error)
        self.error_positions.setdefault(node.pos, set()).add(id(node))
di68kap's avatar
di68kap committed
831 832
        return self

eckhart's avatar
eckhart committed
833
    def new_error(self,
di68kap's avatar