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"""
Data structures for the CSS abstract syntax tree.
"""
from webencodings import ascii_lower
from .serializer import _serialize_to, serialize_identifier, serialize_name
class Node:
"""Every node type inherits from this class,
which is never instantiated directly.
.. attribute:: type
Each child class has a :attr:`type` class attribute
with a unique string value.
This allows checking for the node type with code like:
.. code-block:: python
if node.type == 'whitespace':
instead of the more verbose:
.. code-block:: python
from tinycss2.ast import WhitespaceToken
if isinstance(node, WhitespaceToken):
Every node also has these attributes and methods,
which are not repeated for brevity:
.. attribute:: source_line
The line number of the start of the node in the CSS source.
Starts at 1.
.. attribute:: source_column
The column number within :attr:`source_line` of the start of the node
in the CSS source.
Starts at 1.
.. automethod:: serialize
"""
__slots__ = ['source_line', 'source_column']
def __init__(self, source_line, source_column):
self.source_line = source_line
self.source_column = source_column
def __repr__(self):
return self.repr_format.format(self=self)
def serialize(self):
"""Serialize this node to CSS syntax and return a Unicode string."""
chunks = []
self._serialize_to(chunks.append)
return ''.join(chunks)
def _serialize_to(self, write):
"""Serialize this node to CSS syntax, writing chunks as Unicode string
by calling the provided :obj:`write` callback.
"""
raise NotImplementedError # pragma: no cover
class ParseError(Node):
"""A syntax error of some sort. May occur anywhere in the tree.
Syntax errors are not fatal in the parser
to allow for different error handling behaviors.
For example, an error in a Selector list makes the whole rule invalid,
but an error in a Media Query list only replaces one comma-separated query
with ``not all``.
.. autoattribute:: type
.. attribute:: kind
Machine-readable string indicating the type of error.
Example: ``'bad-url'``.
.. attribute:: message
Human-readable explanation of the error, as a string.
Could be translated, expanded to include details, etc.
"""
__slots__ = ['kind', 'message']
type = 'error'
repr_format = '<{self.__class__.__name__} {self.kind}>'
def __init__(self, line, column, kind, message):
Node.__init__(self, line, column)
self.kind = kind
self.message = message
def _serialize_to(self, write):
if self.kind == 'bad-string':
write('"[bad string]\n')
elif self.kind == 'bad-url':
write('url([bad url])')
elif self.kind in ')]}':
write(self.kind)
elif self.kind in ('eof-in-string', 'eof-in-url'):
pass
else: # pragma: no cover
raise TypeError('Can not serialize %r' % self)
class Comment(Node):
"""A CSS comment.
Comments can be ignored by passing ``skip_comments=True``
to functions such as :func:`~tinycss2.parse_component_value_list`.
.. autoattribute:: type
.. attribute:: value
The content of the comment, between ``/*`` and ``*/``, as a string.
"""
__slots__ = ['value']
type = 'comment'
repr_format = '<{self.__class__.__name__} {self.value}>'
def __init__(self, line, column, value):
Node.__init__(self, line, column)
self.value = value
def _serialize_to(self, write):
write('/*')
write(self.value)
write('*/')
class WhitespaceToken(Node):
"""A :diagram:`whitespace-token`.
.. autoattribute:: type
.. attribute:: value
The whitespace sequence, as a string, as in the original CSS source.
"""
__slots__ = ['value']
type = 'whitespace'
repr_format = '<{self.__class__.__name__}>'
def __init__(self, line, column, value):
Node.__init__(self, line, column)
self.value = value
def _serialize_to(self, write):
write(self.value)
class LiteralToken(Node):
r"""Token that represents one or more characters as in the CSS source.
.. autoattribute:: type
.. attribute:: value
A string of one to four characters.
Instances compare equal to their :attr:`value`,
so that these are equivalent:
.. code-block:: python
if node == ';':
if node.type == 'literal' and node.value == ';':
This regroups what `the specification`_ defines as separate token types:
.. _the specification: https://drafts.csswg.org/css-syntax-3/
* *<colon-token>* ``:``
* *<semicolon-token>* ``;``
* *<comma-token>* ``,``
* *<cdc-token>* ``-->``
* *<cdo-token>* ``<!--``
* *<include-match-token>* ``~=``
* *<dash-match-token>* ``|=``
* *<prefix-match-token>* ``^=``
* *<suffix-match-token>* ``$=``
* *<substring-match-token>* ``*=``
* *<column-token>* ``||``
* *<delim-token>* (a single ASCII character not part of any another token)
"""
__slots__ = ['value']
type = 'literal'
repr_format = '<{self.__class__.__name__} {self.value}>'
def __init__(self, line, column, value):
Node.__init__(self, line, column)
self.value = value
def __eq__(self, other):
return self.value == other or self is other
def __ne__(self, other):
return not self == other
def _serialize_to(self, write):
write(self.value)
class IdentToken(Node):
"""An :diagram:`ident-token`.
.. autoattribute:: type
.. attribute:: value
The unescaped value, as a Unicode string.
.. attribute:: lower_value
Same as :attr:`value` but normalized to *ASCII lower case*,
see :func:`~webencodings.ascii_lower`.
This is the value to use when comparing to a CSS keyword.
"""
__slots__ = ['value', 'lower_value']
type = 'ident'
repr_format = '<{self.__class__.__name__} {self.value}>'
def __init__(self, line, column, value):
Node.__init__(self, line, column)
self.value = value
try:
self.lower_value = ascii_lower(value)
except UnicodeEncodeError:
self.lower_value = value
def _serialize_to(self, write):
write(serialize_identifier(self.value))
class AtKeywordToken(Node):
"""An :diagram:`at-keyword-token`.
.. code-block:: text
'@' <value>
.. autoattribute:: type
.. attribute:: value
The unescaped value, as a Unicode string, without the preceding ``@``.
.. attribute:: lower_value
Same as :attr:`value` but normalized to *ASCII lower case*,
see :func:`~webencodings.ascii_lower`.
This is the value to use when comparing to a CSS at-keyword.
.. code-block:: python
if node.type == 'at-keyword' and node.lower_value == 'import':
"""
__slots__ = ['value', 'lower_value']
type = 'at-keyword'
repr_format = '<{self.__class__.__name__} @{self.value}>'
def __init__(self, line, column, value):
Node.__init__(self, line, column)
self.value = value
try:
self.lower_value = ascii_lower(value)
except UnicodeEncodeError:
self.lower_value = value
def _serialize_to(self, write):
write('@')
write(serialize_identifier(self.value))
class HashToken(Node):
r"""A :diagram:`hash-token`.
.. code-block:: text
'#' <value>
.. autoattribute:: type
.. attribute:: value
The unescaped value, as a Unicode string, without the preceding ``#``.
.. attribute:: is_identifier
A boolean, true if the CSS source for this token
was ``#`` followed by a valid identifier.
(Only such hash tokens are valid ID selectors.)
"""
__slots__ = ['value', 'is_identifier']
type = 'hash'
repr_format = '<{self.__class__.__name__} #{self.value}>'
def __init__(self, line, column, value, is_identifier):
Node.__init__(self, line, column)
self.value = value
self.is_identifier = is_identifier
def _serialize_to(self, write):
write('#')
if self.is_identifier:
write(serialize_identifier(self.value))
else:
write(serialize_name(self.value))
class StringToken(Node):
"""A :diagram:`string-token`.
.. code-block:: text
'"' <value> '"'
.. autoattribute:: type
.. attribute:: value
The unescaped value, as a Unicode string, without the quotes.
"""
__slots__ = ['value', 'representation']
type = 'string'
repr_format = '<{self.__class__.__name__} {self.representation}>'
def __init__(self, line, column, value, representation):
Node.__init__(self, line, column)
self.value = value
self.representation = representation
def _serialize_to(self, write):
write(self.representation)
class URLToken(Node):
"""An :diagram:`url-token`.
.. code-block:: text
'url(' <value> ')'
.. autoattribute:: type
.. attribute:: value
The unescaped URL, as a Unicode string, without the ``url(`` and ``)``
markers.
"""
__slots__ = ['value', 'representation']
type = 'url'
repr_format = '<{self.__class__.__name__} {self.representation}>'
def __init__(self, line, column, value, representation):
Node.__init__(self, line, column)
self.value = value
self.representation = representation
def _serialize_to(self, write):
write(self.representation)
class UnicodeRangeToken(Node):
"""A `unicode-range token <https://www.w3.org/TR/css-syntax-3/#urange>`_.
.. autoattribute:: type
.. attribute:: start
The start of the range, as an integer between 0 and 1114111.
.. attribute:: end
The end of the range, as an integer between 0 and 1114111.
Same as :attr:`start` if the source only specified one value.
"""
__slots__ = ['start', 'end']
type = 'unicode-range'
repr_format = '<{self.__class__.__name__} {self.start} {self.end}>'
def __init__(self, line, column, start, end):
Node.__init__(self, line, column)
self.start = start
self.end = end
def _serialize_to(self, write):
if self.end == self.start:
write('U+%X' % self.start)
else:
write('U+%X-%X' % (self.start, self.end))
class NumberToken(Node):
"""A :diagram:`number-token`.
.. autoattribute:: type
.. attribute:: value
The numeric value as a :class:`float`.
.. attribute:: int_value
The numeric value as an :class:`int`
if :attr:`is_integer` is true, :obj:`None` otherwise.
.. attribute:: is_integer
Whether the token was syntactically an integer, as a boolean.
.. attribute:: representation
The CSS representation of the value, as a Unicode string.
"""
__slots__ = ['value', 'int_value', 'is_integer', 'representation']
type = 'number'
repr_format = '<{self.__class__.__name__} {self.representation}>'
def __init__(self, line, column, value, int_value, representation):
Node.__init__(self, line, column)
self.value = value
self.int_value = int_value
self.is_integer = int_value is not None
self.representation = representation
def _serialize_to(self, write):
write(self.representation)
class PercentageToken(Node):
"""A :diagram:`percentage-token`.
.. code-block:: text
<representation> '%'
.. autoattribute:: type
.. attribute:: value
The value numeric as a :class:`float`.
.. attribute:: int_value
The numeric value as an :class:`int`
if the token was syntactically an integer,
or :obj:`None`.
.. attribute:: is_integer
Whether the token’s value was syntactically an integer, as a boolean.
.. attribute:: representation
The CSS representation of the value without the unit,
as a Unicode string.
"""
__slots__ = ['value', 'int_value', 'is_integer', 'representation']
type = 'percentage'
repr_format = '<{self.__class__.__name__} {self.representation}%>'
def __init__(self, line, column, value, int_value, representation):
Node.__init__(self, line, column)
self.value = value
self.int_value = int_value
self.is_integer = int_value is not None
self.representation = representation
def _serialize_to(self, write):
write(self.representation)
write('%')
class DimensionToken(Node):
"""A :diagram:`dimension-token`.
.. code-block:: text
<representation> <unit>
.. autoattribute:: type
.. attribute:: value
The value numeric as a :class:`float`.
.. attribute:: int_value
The numeric value as an :class:`int`
if the token was syntactically an integer,
or :obj:`None`.
.. attribute:: is_integer
Whether the token’s value was syntactically an integer, as a boolean.
.. attribute:: representation
The CSS representation of the value without the unit,
as a Unicode string.
.. attribute:: unit
The unescaped unit, as a Unicode string.
.. attribute:: lower_unit
Same as :attr:`unit` but normalized to *ASCII lower case*,
see :func:`~webencodings.ascii_lower`.
This is the value to use when comparing to a CSS unit.
.. code-block:: python
if node.type == 'dimension' and node.lower_unit == 'px':
"""
__slots__ = ['value', 'int_value', 'is_integer', 'representation',
'unit', 'lower_unit']
type = 'dimension'
repr_format = ('<{self.__class__.__name__} '
'{self.representation}{self.unit}>')
def __init__(self, line, column, value, int_value, representation, unit):
Node.__init__(self, line, column)
self.value = value
self.int_value = int_value
self.is_integer = int_value is not None
self.representation = representation
self.unit = unit
self.lower_unit = ascii_lower(unit)
def _serialize_to(self, write):
write(self.representation)
# Disambiguate with scientific notation
unit = self.unit
if unit in ('e', 'E') or unit.startswith(('e-', 'E-')):
write('\\65 ')
write(serialize_name(unit[1:]))
else:
write(serialize_identifier(unit))
class ParenthesesBlock(Node):
"""A :diagram:`()-block`.
.. code-block:: text
'(' <content> ')'
.. autoattribute:: type
.. attribute:: content
The content of the block, as list of :term:`component values`.
The ``(`` and ``)`` markers themselves are not represented in the list.
"""
__slots__ = ['content']
type = '() block'
repr_format = '<{self.__class__.__name__} ( … )>'
def __init__(self, line, column, content):
Node.__init__(self, line, column)
self.content = content
def _serialize_to(self, write):
write('(')
_serialize_to(self.content, write)
write(')')
class SquareBracketsBlock(Node):
"""A :diagram:`[]-block`.
.. code-block:: text
'[' <content> ']'
.. autoattribute:: type
.. attribute:: content
The content of the block, as list of :term:`component values`.
The ``[`` and ``]`` markers themselves are not represented in the list.
"""
__slots__ = ['content']
type = '[] block'
repr_format = '<{self.__class__.__name__} [ … ]>'
def __init__(self, line, column, content):
Node.__init__(self, line, column)
self.content = content
def _serialize_to(self, write):
write('[')
_serialize_to(self.content, write)
write(']')
class CurlyBracketsBlock(Node):
"""A :diagram:`{}-block`.
.. code-block:: text
'{' <content> '}'
.. autoattribute:: type
.. attribute:: content
The content of the block, as list of :term:`component values`.
The ``[`` and ``]`` markers themselves are not represented in the list.
"""
__slots__ = ['content']
type = '{} block'
repr_format = '<{self.__class__.__name__} {{ … }}>'
def __init__(self, line, column, content):
Node.__init__(self, line, column)
self.content = content
def _serialize_to(self, write):
write('{')
_serialize_to(self.content, write)
write('}')
class FunctionBlock(Node):
"""A :diagram:`function-block`.
.. code-block:: text
<name> '(' <arguments> ')'
.. autoattribute:: type
.. attribute:: name
The unescaped name of the function, as a Unicode string.
.. attribute:: lower_name
Same as :attr:`name` but normalized to *ASCII lower case*,
see :func:`~webencodings.ascii_lower`.
This is the value to use when comparing to a CSS function name.
.. attribute:: arguments
The arguments of the function, as list of :term:`component values`.
The ``(`` and ``)`` markers themselves are not represented in the list.
Commas are not special, but represented as :obj:`LiteralToken` objects
in the list.
"""
__slots__ = ['name', 'lower_name', 'arguments']
type = 'function'
repr_format = '<{self.__class__.__name__} {self.name}( … )>'
def __init__(self, line, column, name, arguments):
Node.__init__(self, line, column)
self.name = name
self.lower_name = ascii_lower(name)
self.arguments = arguments
def _serialize_to(self, write):
write(serialize_identifier(self.name))
write('(')
_serialize_to(self.arguments, write)
function = self
while isinstance(function, FunctionBlock) and function.arguments:
eof_in_string = (
isinstance(function.arguments[-1], ParseError) and
function.arguments[-1].kind == 'eof-in-string')
if eof_in_string:
return
function = function.arguments[-1]
write(')')
class Declaration(Node):
"""A (property or descriptor) :diagram:`declaration`.
.. code-block:: text
<name> ':' <value>
<name> ':' <value> '!important'
.. autoattribute:: type
.. attribute:: name
The unescaped name, as a Unicode string.
.. attribute:: lower_name
Same as :attr:`name` but normalized to *ASCII lower case*,
see :func:`~webencodings.ascii_lower`.
This is the value to use when comparing to
a CSS property or descriptor name.
.. code-block:: python
if node.type == 'declaration' and node.lower_name == 'color':
.. attribute:: value
The declaration value as a list of :term:`component values`:
anything between ``:`` and
the end of the declaration, or ``!important``.
.. attribute:: important
A boolean, true if the declaration had an ``!important`` marker.
It is up to the consumer to reject declarations that do not accept
this flag, such as non-property descriptor declarations.
"""
__slots__ = ['name', 'lower_name', 'value', 'important']
type = 'declaration'
repr_format = '<{self.__class__.__name__} {self.name}: …>'
def __init__(self, line, column, name, lower_name, value, important):
Node.__init__(self, line, column)
self.name = name
self.lower_name = lower_name
self.value = value
self.important = important
def _serialize_to(self, write):
write(serialize_identifier(self.name))
write(':')
_serialize_to(self.value, write)
if self.important:
write('!important')
class QualifiedRule(Node):
"""A :diagram:`qualified rule`.
.. code-block:: text
<prelude> '{' <content> '}'
The interpretation of qualified rules depend on their context.
At the top-level of a stylesheet
or in a conditional rule such as ``@media``,
they are **style rules** where the :attr:`prelude` is Selectors list
and the :attr:`content` is a list of property declarations.
.. autoattribute:: type
.. attribute:: prelude
The rule’s prelude, the part before the {} block,
as a list of :term:`component values`.
.. attribute:: content
The rule’s content, the part inside the {} block,
as a list of :term:`component values`.
"""
__slots__ = ['prelude', 'content']
type = 'qualified-rule'
repr_format = ('<{self.__class__.__name__} '
'… {{ … }}>')
def __init__(self, line, column, prelude, content):
Node.__init__(self, line, column)
self.prelude = prelude
self.content = content
def _serialize_to(self, write):
_serialize_to(self.prelude, write)
write('{')
_serialize_to(self.content, write)
write('}')
class AtRule(Node):
"""An :diagram:`at-rule`.
.. code-block:: text
@<at_keyword> <prelude> '{' <content> '}'
@<at_keyword> <prelude> ';'
The interpretation of at-rules depend on their at-keyword
as well as their context.
Most types of at-rules (ie. at-keyword values)
are only allowed in some context,
and must either end with a {} block or a semicolon.
.. autoattribute:: type
.. attribute:: at_keyword
The unescaped value of the rule’s at-keyword,
without the ``@`` symbol, as a Unicode string.
.. attribute:: lower_at_keyword
Same as :attr:`at_keyword` but normalized to *ASCII lower case*,
see :func:`~webencodings.ascii_lower`.
This is the value to use when comparing to a CSS at-keyword.
.. code-block:: python
if node.type == 'at-rule' and node.lower_at_keyword == 'import':
.. attribute:: prelude
The rule’s prelude, the part before the {} block or semicolon,
as a list of :term:`component values`.
.. attribute:: content
The rule’s content, if any.
The block’s content as a list of :term:`component values`
for at-rules with a {} block,
or :obj:`None` for at-rules ending with a semicolon.
"""
__slots__ = ['at_keyword', 'lower_at_keyword', 'prelude', 'content']
type = 'at-rule'
repr_format = ('<{self.__class__.__name__} '
'@{self.at_keyword} … {{ … }}>')
def __init__(self, line, column,
at_keyword, lower_at_keyword, prelude, content):
Node.__init__(self, line, column)
self.at_keyword = at_keyword
self.lower_at_keyword = lower_at_keyword
self.prelude = prelude
self.content = content
def _serialize_to(self, write):
write('@')
write(serialize_identifier(self.at_keyword))
_serialize_to(self.prelude, write)
if self.content is None:
write(';')
else:
write('{')
_serialize_to(self.content, write)
write('}')
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