syntaxtree.py 48.1 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
from typing import Callable, cast, Iterator, List, AbstractSet, Set, Union, Tuple, Optional, Dict
29

eckhart's avatar
eckhart committed
30
from DHParser.error import Error, ErrorCode, linebreaks, line_col
31
from DHParser.stringview import StringView
32
from DHParser.toolkit import get_config_value, re
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
           'serialize',
44
           'FrozenNode',
45
           'tree_sanity_check',
di68kap's avatar
di68kap committed
46
           'RootNode',
47
           'parse_sxpr',
48
           'parse_xml',
eckhart's avatar
eckhart committed
49
           'parse_tree',
50 51
           'flatten_sxpr',
           'flatten_xml')
Eckhart Arnold's avatar
Eckhart Arnold committed
52 53


54 55 56 57 58 59 60 61
#######################################################################
#
# parser base and mock parsers
#
#######################################################################


WHITESPACE_PTYPE = ':Whitespace'
62
TOKEN_PTYPE = ':Token'
63

64
ZOMBIE_TAG = "__ZOMBIE__"
65

66 67 68 69 70 71 72
#######################################################################
#
# syntaxtree nodes
#
#######################################################################


73
def flatten_sxpr(sxpr: str, threshold: int = -1) -> str:
74 75
    """
    Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
76 77
    whitespace.

78 79 80 81 82 83 84
    The ``threshold`` value is a maximum number of
    characters allowed in the flattened expression. If this number
    is exceeded the the unflattened S-expression is returned. A
    negative number means that the S-expression will always be
    flattened. Zero or (any postive integer <= 3) essentially means
    that the expression will not be flattened.

Eckhart Arnold's avatar
Eckhart Arnold committed
85
    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
86
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
87 88
    '(a (b c))'
    """
89

90 91 92 93
    flat = re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
    if threshold >= 0 and len(flat) > threshold:
        return sxpr.strip()
    return flat
Eckhart Arnold's avatar
Eckhart Arnold committed
94 95


96
def flatten_xml(xml: str) -> str:
97 98
    """
    Returns an XML-tree as a one liner without unnecessary whitespace,
99
    i.e. only whitespace within leaf-nodes is preserved.
100 101
    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`.
102
    """
103

104 105 106 107
    # 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']
108
    return re.sub(r'\s+(?=<[\w:])', '', re.sub(r'(?P<closing_tag></:?\w+>)\s+', tag_only, xml))
109 110


111 112 113 114 115
ChildrenType = Tuple['Node', ...]
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
StrictResultType = Union[ChildrenType, StringView, str]
ResultType = Union[ChildrenType, 'Node', StringView, str, None]

eckhart's avatar
eckhart committed
116
RX_AMP = re.compile(r'&(?!\w+;)')
117 118


Eckhart Arnold's avatar
Eckhart Arnold committed
119
class Node:  # (collections.abc.Sized): Base class omitted for cython-compatibility
120 121 122
    """
    Represents a node in the concrete or abstract syntax tree.

123 124
    TODO: Add some documentation and doc-tests here...

125
    Attributes:
126 127
        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
128

129 130 131
        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.
132

133 134
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
135

eckhart's avatar
eckhart committed
136 137 138 139
        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
140
        parser (Parser):  The parser which generated this node.
141 142
            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
143 144
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
145
            example by calling ``isinstance(node.parer, ...)``.
146

147 148 149
        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
150
            the length before AST-transformation and will never change
151
            through AST-transformation. READ ONLY!
152

153 154
        pos (int):  the position of the node within the parsed text.

Eckhart Arnold's avatar
Eckhart Arnold committed
155
            The value of ``pos`` is -1 meaning invalid by default.
156
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
157
            nodes relative to this value.
158 159

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
160
            pos value of the root node should be set to 0 right
161 162
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
163
            Other than that, this value should be considered READ ONLY.
164 165
            At any rate, it should only be reassigned during the parsing
            stage and never during or after the AST-transformation.
166

167 168
        attr (dict): An optional dictionary of XML-attr. This
            dictionary is created lazily upon first usage. The attr
169 170
            will only be shown in the XML-Representation, not in the
            S-Expression-output.
171
    """
172

173
    __slots__ = '_result', 'children', '_len', '_pos', 'tag_name', '_xml_attr'
174

175
    def __init__(self, tag_name: str, result: ResultType, leafhint: bool = False) -> None:
176 177
        """
        Initializes the ``Node``-object with the ``Parser``-Instance
178 179
        that generated the node and the parser's result.
        """
eckhart's avatar
eckhart committed
180
        self._pos = -1                  # type: int
181
        # Assignment to self.result initializes the attr _result, children and _len
di68kap's avatar
di68kap committed
182
        # The following if-clause is merely an optimization, i.e. a fast-path for leaf-Nodes
183
        if leafhint:
eckhart's avatar
eckhart committed
184
            self._result = result       # type: StrictResultType  # cast(StrictResultType, result)
185
            # self._content = None        # type: Optional[str]
186
            self.children = NoChildren  # type: ChildrenType
187
            self._len = -1              # type: int  # lazy evaluation
188 189
        else:
            self.result = result
190
        self.tag_name = tag_name        # type: str
191

eckhart's avatar
eckhart committed
192 193
    def __deepcopy__(self, memo):
        if self.children:
194
            duplicate = self.__class__(self.tag_name, copy.deepcopy(self.children), False)
eckhart's avatar
eckhart committed
195
        else:
196
            duplicate = self.__class__(self.tag_name, self.result, True)
eckhart's avatar
eckhart committed
197 198
        duplicate._pos = self._pos
        duplicate._len = self._len
eckhart's avatar
eckhart committed
199
        if self.attr_active():
di68kap's avatar
di68kap committed
200 201
            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
202
        return duplicate
Eckhart Arnold's avatar
Eckhart Arnold committed
203

204
    def __str__(self):
205 206
        if isinstance(self, RootNode):
            root = cast(RootNode, self)
207
            errors = root.errors_sorted
208 209
            if errors:
                e_pos = errors[0].pos
Eckhart Arnold's avatar
Eckhart Arnold committed
210 211
                content = self.content
                return content[:e_pos] + \
212
                   ' <<< Error on "%s" | %s >>> ' % \
Eckhart Arnold's avatar
Eckhart Arnold committed
213
                   (content[e_pos - self.pos:], '; '.join(e.message for e in errors))
214
        return self.content
Eckhart Arnold's avatar
Eckhart Arnold committed
215

216
    def __repr__(self):
217
        # mpargs = {'name': self.parser.name, 'ptype': self.parser.ptype}
218 219
        # name, ptype = (self._tag_name.split(':') + [''])[:2]
        # parg = "MockParser({name}, {ptype})".format(name=name, ptype=ptype)
220
        rarg = str(self) if not self.children else \
221
            "(" + ", ".join(child.__repr__() for child in self.children) + ")"
222
        return "Node(%s, %s)" % (self.tag_name, rarg)
223

Eckhart Arnold's avatar
Eckhart Arnold committed
224

225
    def __len__(self):
226
        if self._len < 0:
di68kap's avatar
di68kap committed
227
            self._len = sum(len(child) for child in self.children) \
228
                if self.children else len(self._result)
229 230 231 232 233 234 235 236
        return self._len


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


237 238 239 240 241 242 243 244 245
    # can lead to obscure mistakes, where default object comparison behaviour is expected
    # def __eq__(self, other):
    #     """
    #     Equality of nodes: Two nodes are considered as equal, if their tag
    #     name is the same, if their results are equal and if their attributes
    #     and attribute values are the same.
    #     """
    #     return self.tag_name == other.tag_name and self.result == other.result \
    #         and self.compare_attr(other)
246

Eckhart Arnold's avatar
Eckhart Arnold committed
247

248
    def __hash__(self):
249
        return hash(self.tag_name)
250

Eckhart Arnold's avatar
Eckhart Arnold committed
251

252 253 254
    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
255
        an integer or the first child node with the given tag name. Examples::
256

257
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
258 259
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
260 261
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
262 263 264 265

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
266
        Returns:
267 268
            Node: All nodes which have a given tag name.
        """
269 270 271
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
272
            else:
273 274 275 276 277
                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!')
278 279 280 281


    def __contains__(self, tag_name: str) -> bool:
        """
282
        Returns true if a child with the given tag name exists.
283
        Args:
284 285
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
286 287 288 289
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
290 291 292 293 294
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
295
            return False
296
        raise ValueError('Leave node cannot contain other nodes')
297 298


299
    def equals(self, other: 'Node') -> bool:
300
        """
301 302 303 304 305 306
        Equality of value: Two nodes are considered as having the same value,
        if their tag name is the same, if their results are equal and
        if their attributes and attribute values are the same.

        Returns True, if the tree originating in node `self` is equal by
        value to the tree originating in node `other`.
307 308 309 310 311 312 313 314 315 316
        """
        if self.tag_name == other.tag_name and self.compare_attr(other):
            if self.children:
                return (len(self.children) == len(other.children)
                        and all(a.equals(b) for a, b in zip(self.children, other.children)))
            else:
                return self.result == other.result
        return False


317 318 319 320 321 322 323 324 325 326 327 328 329 330
    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


331
    def is_anonymous(self) -> bool:
Eckhart Arnold's avatar
Eckhart Arnold committed
332
        return not self.tag_name or self.tag_name[0] == ':'
333

Eckhart Arnold's avatar
Eckhart Arnold committed
334

335
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
336
    def result(self) -> StrictResultType:
337 338 339 340 341
        """
        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.
        """
342 343
        return self._result

344

345
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
346
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
347
        # # made obsolete by static type checking with mypy
Eckhart Arnold's avatar
Eckhart Arnold committed
348 349 350 351
        assert ((isinstance(result, tuple) and all(isinstance(child, Node) for child in result))
                or isinstance(result, Node)
                or isinstance(result, str)
                or isinstance(result, StringView)), "%s (%s)" % (str(result), str(type(result)))
Eckhart Arnold's avatar
Eckhart Arnold committed
352 353
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
354
        self._len = -1        # lazy evaluation
355
        # self._content = None
356 357 358 359 360 361 362 363 364
        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
365
                self._result = result  # cast(StrictResultType, result)
366

367

368 369 370 371 372 373 374 375 376 377 378 379
    def _content(self) -> List[str]:
        """
        Returns string content as list of string fragments
        that are gathered from all child nodes in order.
        """
        if self.children:
            fragments = []
            for child in self.children:
                fragments.extend(child._content())
            return fragments
        self._result = str(self._result)
        return [self._result]
380

381

382
    @property
eckhart's avatar
eckhart committed
383
    def content(self) -> str:
384
        """
385 386 387
        Returns content as string. If the node has child-nodes, the
        string content of the child-nodes is recursively read and then
        concatenated.
388
        """
389 390 391 392 393 394 395 396
        if self.children:
            fragments = []
            for child in self.children:
                fragments.extend(child._content())
            return ''.join(fragments)
        self._result = str(self._result)
        return self._result
        # unoptimized
Eckhart Arnold's avatar
Eckhart Arnold committed
397 398
        # return "".join(child.content for child in self.children) if self.children \
        #     else str(self._result)
di68kap's avatar
di68kap committed
399 400


401 402 403 404 405 406
    @property
    def structure(self) -> str:
        """
        Return structure (and content) as S-expression on a single line
        without any line breaks.
        """
407
        return flatten_sxpr(self.as_sxpr())
408 409


410
    @property
411
    def pos(self) -> int:
eckhart's avatar
eckhart committed
412 413
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
Eckhart Arnold's avatar
Eckhart Arnold committed
414
            raise AssertionError("Position value not initialized! Use Node.with_pos()")
415 416
        return self._pos

eckhart's avatar
eckhart committed
417

Eckhart Arnold's avatar
Eckhart Arnold committed
418
    def with_pos(self, pos: int) -> 'Node':
eckhart's avatar
eckhart committed
419
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
420
        Initialize position value. Usually, the parser guard
eckhart's avatar
eckhart committed
421 422
        (`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
423
        when Nodes are created outside the reach of the parser
eckhart's avatar
eckhart committed
424
        guard, their document-position must be assigned manually.
Eckhart Arnold's avatar
Eckhart Arnold committed
425 426
        Position values of the child nodes are assigned recursively, too.
        Returns the node itself for convenience.
eckhart's avatar
eckhart committed
427
        """
428 429 430 431
        # 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
432 433 434 435 436 437 438 439 440 441
        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
442 443
        return self

444

445 446 447 448 449 450 451 452 453 454 455 456 457
    @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
458 459 460 461 462 463 464 465 466 467 468 469 470
    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


471
    def compare_attr(self, other: 'Node') -> bool:
472
        """
473 474
        Returns True, if `self` and `other` have the same attributes with the
        same attribute values.
475
        """
476 477 478 479 480 481 482 483 484
        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
485

Eckhart Arnold's avatar
Eckhart Arnold committed
486

487
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i,
488
                   density=0, inline=False, inline_fn=lambda node: False) -> str:
489 490 491 492 493 494 495 496
        """
        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.

497
        Args:
498
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
499
            open_fn:   (Node->str) A function that returns an opening
500
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
501
            close_fn:  (Node->str) A function that returns a closeF
502
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
503
            data_fn:   (str->str) A function that filters the data string
504 505 506 507 508 509
                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
510 511
        head = open_fn(self)
        tail = close_fn(self)
512 513

        if not self.result:
514
            return head.rstrip() + tail.lstrip()
515

eckhart's avatar
eckhart committed
516
        tail = tail.lstrip(None if density & 2 else '')
517

518
        inline = inline or inline_fn(self)
519 520 521 522 523
        if inline:
            head = head.rstrip()
            tail = tail.lstrip()
            usetab, sep = '', ''
        else:
eckhart's avatar
eckhart committed
524 525
            usetab = tab if head else ''    # no indentation if tag is already omitted
            sep = '\n'
526

527 528
        if self.children:
            content = []
529
            for child in self.children:
530
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn,
531
                                           density, inline, inline_fn)
eckhart's avatar
eckhart committed
532
                if subtree:
eckhart's avatar
eckhart committed
533 534
                    st = [subtree] if inline else subtree.split('\n')
                    content.append((sep + usetab).join(s for s in st))
535
            return head + usetab + (sep + usetab).join(content) + tail
536

eckhart's avatar
eckhart committed
537
        res = self.content
eckhart's avatar
eckhart committed
538
        if not inline and not head:
eckhart's avatar
eckhart committed
539
            # strip whitespace for omitted non inline node, e.g. CharData in mixed elements
eckhart's avatar
eckhart committed
540
            res = res.strip()
541 542
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
543
            gap = ' ' if not inline and head and head.rstrip()[-1:] != '>' else ''
eckhart's avatar
eckhart committed
544
            return head.rstrip() + gap + data_fn(res) + tail.lstrip()
545
        else:
546
            return head + '\n'.join([usetab + data_fn(s) for s in res.split('\n')]) + tail
547

Eckhart Arnold's avatar
Eckhart Arnold committed
548

549 550
    def as_sxpr(self, src: str = None,
                indentation: int = 2,
551 552
                compact: bool = False,
                flatten_threshold: int = 0) -> str:
553
        """
554 555
        Returns content as S-expression, i.e. in lisp-like form. If this
        method is callad on a RootNode-object,
556

557
        Args:
558 559 560
            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.
561 562
            indentation: The number of whitespaces for indentation
            compact:  If True, a compact representation is returned where
563
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
564
                tree structure.
565 566 567
            flatten_threshold:  Return the S-expression in flattened form if
                the flattened expression does not exceed the threshold length.
                A negative number means that it will always be flattened.
568 569
        """

eckhart's avatar
eckhart committed
570
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
eckhart's avatar
eckhart committed
571
        lbreaks = linebreaks(src) if src else []  # type: List[int]
572
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[RootNode]
573

574
        def opening(node: Node) -> str:
eckhart's avatar
eckhart committed
575
            """Returns the opening string for the representation of `node`."""
eckhart's avatar
eckhart committed
576
            txt = [left_bracket, node.tag_name]
577
            # s += " '(pos %i)" % node.add_pos
578
            # txt.append(str(id(node)))  # for debugging
eckhart's avatar
eckhart committed
579
            if node.attr_active():
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))
584 585
            if root and id(node) in root.error_nodes:
                txt.append(" `(err `%s)" % ' '.join(str(err) for err in root.get_errors(node)))
586
            return "".join(txt) + '\n'
587

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

592
        def pretty(strg: str) -> str:
eckhart's avatar
eckhart committed
593 594 595 596
            """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

598 599
        sxpr = self._tree_repr(' ' * indentation, opening, closing, pretty, density=density)
        return flatten_sxpr(sxpr, flatten_threshold)
Eckhart Arnold's avatar
Eckhart Arnold committed
600

eckhart's avatar
eckhart committed
601

602 603
    def as_xml(self, src: str = None,
               indentation: int = 2,
eckhart's avatar
eckhart committed
604 605 606
               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
            indentation: The number of whitespaces for indentation
615 616 617
            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
618
                neither the opening tag nor its attr nor the closing tag. This
619 620 621
                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.
622 623
            empty_tags:  A set of tags which shall be rendered as empty elements, e.g.
                "<empty/>" instead of "<empty><empty>".
624
        """
625
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[RootNode]
626

627
        def opening(node: 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]
eckhart's avatar
eckhart committed
632
            has_reserved_attrs = node.attr_active() \
eckhart's avatar
eckhart committed
633
                and any(r in node.attr for r in {'err', 'line', 'col'})
eckhart's avatar
eckhart committed
634
            if node.attr_active():
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 root and id(node) in root.error_nodes and not has_reserved_attrs:
eckhart's avatar
eckhart committed
639
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
eckhart's avatar
eckhart committed
640
                                                 for err in root.get_errors(node)))
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: 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

655 656 657 658 659 660
        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

661
        def inlining(node: Node):
662 663 664 665
            """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
666
            return node.tag_name in inline_tags \
eckhart's avatar
eckhart committed
667
                or (node.attr_active()
eckhart's avatar
eckhart committed
668
                    and node.attr.get('xml:space', 'default') == 'preserve')
669

670
        line_breaks = linebreaks(src) if src else []
671
        return self._tree_repr(' ' * indentation, opening, closing, sanitizer,
672
                               density=1, inline_fn=inlining)
673

Eckhart Arnold's avatar
Eckhart Arnold committed
674

eckhart's avatar
eckhart committed
675
    def select(self, match_function: Callable, include_root: bool = False, reverse: bool = False) \
676
            -> Iterator['Node']:
eckhart's avatar
eckhart committed
677
        """
678
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
679

680
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
681
        given `match_function` evaluates to True. The tree is
682 683 684
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
685

686 687 688
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
689 690
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
691 692
            reverse (bool): If True, the tree will be walked in reverse
                order, i.e. last children first.
693
        Yields:
694
            Node: All nodes of the tree for which
695 696
            ``match_function(node)`` returns True
        """
697
        if include_root and match_function(self):
698
            yield self
699 700
        child_iterator = reversed(self.children) if reverse else self.children
        for child in child_iterator:
701 702 703 704 705 706
            if match_function(child):
                yield child
            yield from child.select(match_function, False, reverse)
        # The above variant is slightly faster
        # for child in child_iterator:
        #     yield from child.select(match_function, True, reverse)
707

Eckhart Arnold's avatar
Eckhart Arnold committed
708

eckhart's avatar
eckhart committed
709
    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
eckhart's avatar
eckhart committed
710
                      include_root: bool = False) -> Iterator['Node']:
711
        """
712 713 714 715
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
716

717
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
718
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
719
            ['(X (c "d"))', '(X "F")']
720
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
721
            ['(b "X")', '(X (c "d"))', '(X "F")']
722
            >>> any(tree.select_by_tag('a', False))
723
            False
724
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
725
            ['(a (b "X") (X (c "d")) (e (X "F")))']
726 727
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
728 729

        Args:
730 731 732 733
            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.
734 735 736
        Yields:
            Node: All nodes which have a given tag name.
        """
737
        if isinstance(tag_names, str):
eckhart's avatar
eckhart committed
738
            tag_names = frozenset({tag_names})
739
        return self.select(lambda node: node.tag_name in tag_names, include_root)
740 741


742 743 744 745
    def pick(self, tag_names: Union[str, Set[str]]) -> Optional['Node']:
        """
        Picks the first descendant with one of the given tag_names.

746
        This function is mostly just syntactic sugar for
747 748 749 750 751 752 753 754 755 756
        ``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


757
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
758 759 760
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
761 762 763
        return sum(child.tree_size() for child in self.children) + 1


764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781
def serialize(node: Node, how: str='default') -> str:
    """
    Serializes the tree starting with `node` either as S-expression, XML
    or in compact form. Possible values for `how` are 'S-expression',
    'XML', 'compact' accordingly, or 'AST', 'CST', 'default' in which case
    the value of respective configuration variable determines the
    serialization format. (See module `configuration.py`.)
    """
    switch = how.lower()

    if switch == 'ast':
        switch = get_config_value('ast_serialization').lower()
    elif switch == 'cst':
        switch = get_config_value('cst_serialization').lower()
    elif switch == 'default':
        switch = get_config_value('default_serialization').lower()

    if switch == 's-expression':
782
        return node.as_sxpr(flatten_threshold=get_config_value('flatten_sxpr_threshold'))
783 784 785 786 787 788 789 790
    elif switch == 'xml':
        return node.as_xml()
    elif switch == 'compact':
        return node.as_sxpr(compact=True)
    else:
        raise ValueError('Unknown serialization %s, %s' % (how, switch))


791
class FrozenNode(Node):
792 793 794 795 796 797 798 799 800 801
    """
    FrozenNode is an immutable kind of Node, i.e. it must not be changed
    after initialization. The purpose is mainly to allow certain kinds of
    optimization, like not having to instantiate empty nodes (because they
    are always the same and will be dropped while parsing, anyway).

    Frozen nodes must be used only temporarily during parsing or
    tree-transformation and should not occur in the product of the
    transformation any more. This can be verified with `tree_sanity_check()`.
    """
802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818

    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
819 820 821 822
    @property
    def attr(self):
        raise AssertionError("Attributes cannot be accessed on a frozen node")

Eckhart Arnold's avatar
Eckhart Arnold committed
823
    def with_pos(self, pos: int) -> 'Node':
824 825 826
        pass


827
PLACEHOLDER = FrozenNode('__PLACEHOLDER__', '')
di68kap's avatar
di68kap committed
828 829


830
def tree_sanity_check(tree: Node) -> bool:
831 832 833 834 835 836 837 838 839
    """
    Sanity check for syntax trees: One and the same node must never appear
    twice in the syntax tree. Frozen Nodes (EMTPY_NODE, PLACEHOLDER)
    should only exist temporarily and must have been dropped or eliminated
    before any kind of tree generation (i.e. parsing) or transformation
    is finished.
    :param tree: the root of the tree to be checked
    :return: True, if the tree is `sane`, False otherwise.
    """
840
    node_set = set()  # type: Set[Node]
841
    for node in tree.select(lambda nd: True, include_root=True):
842
        if node in node_set or isinstance(Node, FrozenNode):
843 844 845 846 847
            return False
        node_set.add(node)
    return True


di68kap's avatar
di68kap committed
848
class RootNode(Node):
849 850 851 852 853 854 855 856 857 858 859 860
    """The root node for the syntax tree is a special kind of node that keeps
    and manages global properties of the tree as a whole. These are first and
    foremost the list off errors that occurred during tree generation
    (i.e. parsing) or any transformation of the tree. Other properties concern
    the customization of the XML-serialization.

    The root node can be instantiated before the tree is fully parsed. This is
    necessary, because the root node is needed for managing error messages
    during the parsing process, already. In order to connect the root node to
    the tree, when parsing is finished, the swallow()-method must be called.

        errors (list):  A list of all errors that have occurred so far during
861 862
                processing (i.e. parsing, AST-transformation, compiling)
                of this tree.
di68kap's avatar
di68kap committed
863

864 865 866 867 868 869
        error_nodes (dict): A mapping of node-ids to a list of errors that
                occurred on the node with the respective id.

        error_positions (dict): A mapping of locations to a set of ids of
                nodes that contain an error at that particular location

870 871
        error_flag (int):  the highest warning or error level of all errors
                that occurred.
872 873 874 875 876 877

        inline_tags (set of strings): see `Node.as_xml()` for an explanation.

        omit_tags (set of strings): see `Node.as_xml()` for an explanation.

        empty_tags (set oif strings): see `Node.as_xml()` for an explanation.
di68kap's avatar
di68kap committed
878
    """
879

eckhart's avatar
eckhart committed
880
    def __init__(self, node: Optional[Node] = None):