syntaxtree.py 41.6 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
178 179
        # assert tag_name is not None
        self.tag_name = tag_name        # type: str
180

eckhart's avatar
eckhart committed
181 182
    def __deepcopy__(self, memo):
        if self.children:
183
            duplicate = self.__class__(self.tag_name, copy.deepcopy(self.children), False)
eckhart's avatar
eckhart committed
184
        else:
185
            duplicate = self.__class__(self.tag_name, self.result, True)
eckhart's avatar
eckhart committed
186 187
        duplicate._pos = self._pos
        duplicate._len = self._len
eckhart's avatar
eckhart committed
188
        if self.attr_active():
di68kap's avatar
di68kap committed
189 190
            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
191
        return duplicate
Eckhart Arnold's avatar
Eckhart Arnold committed
192

193
    def __str__(self):
194 195
        if isinstance(self, RootNode):
            root = cast(RootNode, self)
196
            errors = root.errors_sorted
197 198 199 200 201 202
            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
203

204
    def __repr__(self):
205
        # mpargs = {'name': self.parser.name, 'ptype': self.parser.ptype}
206 207
        # name, ptype = (self._tag_name.split(':') + [''])[:2]
        # parg = "MockParser({name}, {ptype})".format(name=name, ptype=ptype)
208
        rarg = str(self) if not self.children else \
209
            "(" + ", ".join(child.__repr__() for child in self.children) + ")"
210
        return "Node(%s, %s)" % (self.tag_name, rarg)
211

Eckhart Arnold's avatar
Eckhart Arnold committed
212

213
    def __len__(self):
214
        if self._len < 0:
di68kap's avatar
di68kap committed
215
            self._len = sum(len(child) for child in self.children) \
216
                if self.children else len(self._result)
217 218 219 220 221 222 223 224
        return self._len


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


225
    def __eq__(self, other):
226 227
        """
        Equality of nodes: Two nodes are considered as equal, if their tag
228 229
        name is the same, if their results are equal and if their attributes
        and attribute values are the same.
230
        """
231 232
        return self.tag_name == other.tag_name and self.result == other.result \
            and self.compare_attr(other)
233

Eckhart Arnold's avatar
Eckhart Arnold committed
234

235
    def __hash__(self):
236
        return hash(self.tag_name)
237

Eckhart Arnold's avatar
Eckhart Arnold committed
238

239 240 241
    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
242
        an integer or the first child node with the given tag name. Examples::
243

244
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
245 246
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
247 248
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
249 250 251 252

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
253
        Returns:
254 255
            Node: All nodes which have a given tag name.
        """
256 257 258
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
259
            else:
260 261 262 263 264
                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!')
265 266 267 268


    def __contains__(self, tag_name: str) -> bool:
        """
269
        Returns true if a child with the given tag name exists.
270
        Args:
271 272
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
273 274 275 276
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
277 278 279 280 281
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
282
            return False
283
        raise ValueError('Leave node cannot contain other nodes')
284 285


286 287 288 289 290 291 292 293 294 295 296 297 298 299
    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


300
    def is_anonymous(self):
301
        return self.tag_name[0] == ':'
302

Eckhart Arnold's avatar
Eckhart Arnold committed
303

304
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
305
    def result(self) -> StrictResultType:
306 307 308 309 310
        """
        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.
        """
311 312
        return self._result

313

314
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
315
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
316
        # # made obsolete by static type checking with mypy
317 318 319
        # 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
320 321
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
322 323
        self._len = -1        # lazy evaluation
        self._content = None
324 325 326 327 328 329 330 331 332
        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
333
                self._result = result  # cast(StrictResultType, result)
334

335 336

    @property
eckhart's avatar
eckhart committed
337
    def content(self) -> str:
338
        """
339 340 341
        Returns content as string. If the node has child-nodes, the
        string content of the child-nodes is recursively read and then
        concatenated.
342
        """
343 344 345 346
        if self._content is None:
            if self.children:
                self._content = "".join(child.content for child in self.children)
            else:
347
                # self._content = self._result
348 349 350
                self._content = str(self._result)
                self._result = self._content  # self._result might be more efficient as a string!?
        return self._content
351 352 353 354 355
    #
    #
    # @content.setter
    # def content(self, content: str):
    #     self.result = content
di68kap's avatar
di68kap committed
356 357


358 359 360 361 362 363
    @property
    def structure(self) -> str:
        """
        Return structure (and content) as S-expression on a single line
        without any line breaks.
        """
364
        return flatten_sxpr(self.as_sxpr())
365 366


367
    @property
368
    def pos(self) -> int:
eckhart's avatar
eckhart committed
369 370
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
371
            raise AssertionError("Position value not initialized!")
372 373
        return self._pos

eckhart's avatar
eckhart committed
374

eckhart's avatar
eckhart committed
375
    def init_pos(self, pos: int) -> 'Node':
eckhart's avatar
eckhart committed
376 377 378 379 380 381 382 383 384
        """
        (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.
        """
385 386 387 388
        # 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's avatar
eckhart committed
389
        self._pos = pos
390
        # recursively adjust pos-values of all children
eckhart's avatar
eckhart committed
391
        offset = self.pos
392
        for child in self.children:
eckhart's avatar
eckhart committed
393
            child.init_pos(offset)
eckhart's avatar
eckhart committed
394 395 396
            offset = child.pos + len(child)
        return self

397

398 399 400 401 402 403 404 405 406 407 408 409 410
    @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
411 412 413 414 415 416 417 418 419 420 421 422 423
    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


424
    def compare_attr(self, other: 'Node') -> bool:
425
        """
426 427
        Returns True, if `self` and `other` have the same attributes with the
        same attribute values.
428
        """
429 430 431 432 433 434 435 436 437
        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
438

Eckhart Arnold's avatar
Eckhart Arnold committed
439

440
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i,
441
                   density=0, inline=False, inline_fn=lambda node: False) -> str:
442 443 444 445 446 447 448 449
        """
        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.

450
        Args:
451
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
452
            open_fn:   (Node->str) A function that returns an opening
453
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
454
            close_fn:  (Node->str) A function that returns a closeF
455
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
456
            data_fn:   (str->str) A function that filters the data string
457 458 459 460 461 462
                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
463 464
        head = open_fn(self)
        tail = close_fn(self)
465 466

        if not self.result:
467
            return head.rstrip() + tail.lstrip()
468

eckhart's avatar
eckhart committed
469
        tail = tail.lstrip(None if density & 2 else '')
470

471
        inline = inline or inline_fn(self)
472 473 474 475 476
        if inline:
            head = head.rstrip()
            tail = tail.lstrip()
            usetab, sep = '', ''
        else:
eckhart's avatar
eckhart committed
477 478
            usetab = tab if head else ''    # no indentation if tag is already omitted
            sep = '\n'
479

480 481
        if self.children:
            content = []
482
            for child in self.children:
483
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn,
484
                                           density, inline, inline_fn)
eckhart's avatar
eckhart committed
485
                if subtree:
eckhart's avatar
eckhart committed
486 487
                    st = [subtree] if inline else subtree.split('\n')
                    content.append((sep + usetab).join(s for s in st))
488
            return head + usetab + (sep + usetab).join(content) + tail
489

eckhart's avatar
eckhart committed
490
        res = self.content
eckhart's avatar
eckhart committed
491
        if not inline and not head:
eckhart's avatar
eckhart committed
492
            # strip whitespace for omitted non inline node, e.g. CharData in mixed elements
eckhart's avatar
eckhart committed
493
            res = res.strip()
494 495
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
496
            gap = ' ' if not inline and head and head.rstrip()[-1:] != '>' else ''
eckhart's avatar
eckhart committed
497
            return head.rstrip() + gap + data_fn(res) + tail.lstrip()
498
        else:
499
            return head + '\n'.join([usetab + data_fn(s) for s in res.split('\n')]) + tail
500

Eckhart Arnold's avatar
Eckhart Arnold committed
501

502 503
    def as_sxpr(self, src: str = None,
                indentation: int = 2,
504
                compact: bool = False) -> str:
505
        """
506 507
        Returns content as S-expression, i.e. in lisp-like form. If this
        method is callad on a RootNode-object,
508

509
        Args:
510 511 512
            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.
513 514
            indentation: The number of whitespaces for indentation
            compact:  If True, a compact representation is returned where
515
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
516
                tree structure.
517 518
        """

eckhart's avatar
eckhart committed
519
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
eckhart's avatar
eckhart committed
520
        lbreaks = linebreaks(src) if src else []  # type: List[int]
521
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[Node]
522

523
        def opening(node) -> str:
eckhart's avatar
eckhart committed
524
            """Returns the opening string for the representation of `node`."""
eckhart's avatar
eckhart committed
525
            txt = [left_bracket, node.tag_name]
526
            # s += " '(pos %i)" % node.add_pos
eckhart's avatar
eckhart committed
527
            if node.attr_active():
528
                txt.extend(' `(%s "%s")' % (k, v) for k, v in node.attr.items())
529
            if src:
530 531
                line, col = line_col(lbreaks, node.pos)
                txt.append(" `(pos %i %i %i)" % (node.pos, line, col))
532 533
            if root and id(node) in root.error_nodes:
                txt.append(" `(err `%s)" % ' '.join(str(err) for err in root.get_errors(node)))
534
            return "".join(txt) + '\n'
535

eckhart's avatar
eckhart committed
536 537 538
        def closing(node) -> str:
            """Returns the closing string for the representation of `node`."""
            return right_bracket
539

eckhart's avatar
eckhart committed
540 541 542 543 544
        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'\"')
545

546
        return self._tree_repr(' ' * indentation, opening, closing, pretty, density=density)
Eckhart Arnold's avatar
Eckhart Arnold committed
547

eckhart's avatar
eckhart committed
548

549 550
    def as_xml(self, src: str = None,
               indentation: int = 2,
eckhart's avatar
eckhart committed
551 552 553
               inline_tags: Set[str] = set(),
               omit_tags: Set[str] = set(),
               empty_tags: Set[str] = set()) -> str:
554 555 556
        """
        Returns content as XML-tree.

557
        Args:
558 559 560
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
561
            indentation: The number of whitespaces for indentation
562 563 564
            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
565
                neither the opening tag nor its attr nor the closing tag. This
566 567 568
                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.
569 570
            empty_tags:  A set of tags which shall be rendered as empty elements, e.g.
                "<empty/>" instead of "<empty><empty>".
571
        """
572
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[Node]
573

574
        def opening(node) -> str:
575 576 577
            """Returns the opening string for the representation of `node`."""
            if node.tag_name in omit_tags:
                return ''
eckhart's avatar
eckhart committed
578
            txt = ['<', node.tag_name]
eckhart's avatar
eckhart committed
579
            has_reserved_attrs = node.attr_active() \
eckhart's avatar
eckhart committed
580
                and any(r in node.attr for r in {'err', 'line', 'col'})
eckhart's avatar
eckhart committed
581
            if node.attr_active():
582
                txt.extend(' %s="%s"' % (k, v) for k, v in node.attr.items())
583
            if src and not has_reserved_attrs:
eckhart's avatar
eckhart committed
584
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
585
            if root and id(node) in root.error_nodes and not has_reserved_attrs:
eckhart's avatar
eckhart committed
586
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
587
                                                 for err in root.get_error(node)))
588 589 590
            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
591
                ending = "/>\n" if not node.tag_name[0] == '?' else "?>\n"
592 593 594
            else:
                ending = ">\n"
            return "".join(txt + [ending])
595 596

        def closing(node):
597
            """Returns the closing string for the representation of `node`."""
598
            if node.tag_name in omit_tags or node.tag_name in empty_tags:
599
                return ''
600
            return ('\n</') + node.tag_name + '>'
601

602 603 604 605 606 607 608
        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


609 610 611 612 613
        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
614
            return node.tag_name in inline_tags \
eckhart's avatar
eckhart committed
615
                or (node.attr_active()
eckhart's avatar
eckhart committed
616
                    and node.attr.get('xml:space', 'default') == 'preserve')
617

618
        line_breaks = linebreaks(src) if src else []
619
        return self._tree_repr(' ' * indentation, opening, closing, sanitizer,
620
                               density=1, inline_fn=inlining)
621

Eckhart Arnold's avatar
Eckhart Arnold committed
622

eckhart's avatar
eckhart committed
623
    def select(self, match_function: Callable, include_root: bool = False, reverse: bool = False) \
624
            -> Iterator['Node']:
eckhart's avatar
eckhart committed
625
        """
626
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
627

628
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
629
        given `match_function` evaluates to True. The tree is
630 631 632
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
633

634 635 636
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
637 638
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
639 640
            reverse (bool): If True, the tree will be walked in reverse
                order, i.e. last children first.
641
        Yields:
642
            Node: All nodes of the tree for which
643 644
            ``match_function(node)`` returns True
        """
645
        if include_root and match_function(self):
646
            yield self
647 648 649
        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
650
                yield node
651

Eckhart Arnold's avatar
Eckhart Arnold committed
652

eckhart's avatar
eckhart committed
653
    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
eckhart's avatar
eckhart committed
654
                      include_root: bool = False) -> Iterator['Node']:
655
        """
656 657 658 659
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
660

661
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
662
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
663
            ['(X (c "d"))', '(X "F")']
664
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
665
            ['(b "X")', '(X (c "d"))', '(X "F")']
666
            >>> any(tree.select_by_tag('a', False))
667
            False
668
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
669
            ['(a (b "X") (X (c "d")) (e (X "F")))']
670 671
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
672 673

        Args:
674 675 676 677
            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.
678 679 680
        Yields:
            Node: All nodes which have a given tag name.
        """
681
        if isinstance(tag_names, str):
eckhart's avatar
eckhart committed
682
            tag_names = frozenset({tag_names})
683
        return self.select(lambda node: node.tag_name in tag_names, include_root)
684 685


686 687 688 689
    def pick(self, tag_names: Union[str, Set[str]]) -> Optional['Node']:
        """
        Picks the first descendant with one of the given tag_names.

690
        This function is mostly just syntactic sugar for
691 692 693 694 695 696 697 698 699 700
        ``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


701
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
702 703 704
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
705 706 707
        return sum(child.tree_size() for child in self.children) + 1


708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725
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
726 727 728 729
    @property
    def attr(self):
        raise AssertionError("Attributes cannot be accessed on a frozen node")

730 731 732 733 734 735 736 737
    # @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
738

739 740 741 742 743
    def init_pos(self, pos: int) -> 'Node':
        pass


PLACEHOLDER = Node('__PLACEHOLDER__', '')
di68kap's avatar
di68kap committed
744 745


di68kap's avatar
di68kap committed
746
class RootNode(Node):
747
    """TODO: Add Documentation!!!
di68kap's avatar
di68kap committed
748

749
        errors (list):  A list of all errors that have occured so far during
750 751
                processing (i.e. parsing, AST-transformation, compiling)
                of this tree.
di68kap's avatar
di68kap committed
752

753 754
        error_flag (int):  the highest warning or error level of all errors
                that occurred.
di68kap's avatar
di68kap committed
755
    """
756

eckhart's avatar
eckhart committed
757
    def __init__(self, node: Optional[Node] = None):
758
        super().__init__('__not_yet_ready__', '')
759
        self.errors = []           # type: List[Error]
760 761
        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
762
        self.error_flag = 0
eckhart's avatar
eckhart committed
763 764
        if node is not None:
            self.swallow(node)
765
        # customization for XML-Representation
eckhart's avatar
eckhart committed
766 767 768
        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
769

770 771 772 773 774 775 776 777 778 779
    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
780
        if self.attr_active():
di68kap's avatar
di68kap committed
781
            duplicate.attr.update(copy.deepcopy(self._xml_attr))
782
            # duplicate._xml_attr = copy.deepcopy(self._xml_attr)  # this is blocked by cython
783
        duplicate.errors = copy.copy(self.errors)
784 785
        duplicate.error_nodes = copy.copy(self.error_nodes)
        duplicate.error_positions = copy.deepcopy(self.error_positions)
786 787 788 789
        duplicate.error_flag = self.error_flag
        duplicate.inline_tags = self.inline_tags
        duplicate.omit_tags = self.omit_tags
        duplicate.empty_tags = self.empty_tags
790
        duplicate.tag_name = self.tag_name
791 792 793
        return duplicate


794
    def swallow(self, node: Node) -> 'RootNode':
795 796
        """
        Put `self` in the place of `node` by copying all its data.
797 798 799 800 801 802 803 804 805
        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
806 807 808 809
        self._result = node._result
        self.children = node.children
        self._len = node._len
        self._pos = node._pos
810
        self.tag_name = node.tag_name
eckhart's avatar
eckhart committed
811
        if node.attr_active():
812
            self._xml_attr = node._xml_attr
di68kap's avatar
di68kap committed
813
        self._content = node._content
814 815
        if id(node) in self.error_nodes:
            self.error_nodes[id(self)] = self.error_nodes[id(node)]
816
        return self
di68kap's avatar
di68kap committed
817

eckhart's avatar
eckhart committed
818
    def add_error(self, node: Node, error: Error) -> 'RootNode':
819 820 821
        """
        Adds an Error object to the tree, locating it at a specific node.
        """
eckhart's avatar
eckhart committed
822
        assert not isinstance(node, FrozenNode)
823
        assert node.pos == error.pos
824
        self.errors.append(error)
di68kap's avatar
di68kap committed
825
        self.error_flag = max(self.error_flag, error.code)
826 827
        self.error_nodes.setdefault(id(node), []).append(error)
        self.error_positions.setdefault(node.pos, set()).add(id(node))
di68kap's avatar
di68kap committed
828 829
        return self

eckhart's avatar
eckhart committed
830
    def new_error(self,
831
                  node: Node,
di68kap's avatar
di68kap committed
832
                  message: str,
eckhart's avatar
eckhart committed
833
                  code: ErrorCode = Error.ERROR) -> 'RootNode':
di68kap's avatar
di68kap committed
834
        """