Metadata-Version: 2.4
Name: cs-lex
Version: 20261016
Summary: Lexical analysis functions, tokenisers, transcribers: an arbitrary assortment of lexical and tokenisation functions useful for writing recursive descent parsers, of which I have several. There are also some transcription functions for producing text from various objects, such as `hexify` and `unctrl`.
Keywords: python3
Author-email: Cameron Simpson <cs@cskk.id.au>
Description-Content-Type: text/markdown
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Topic :: Text Processing
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: Operating System :: OS Independent
Classifier: License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)
Requires-Dist: cs.dateutils>=20260912
Requires-Dist: cs.deco>=20261016
Requires-Dist: cs.gimmicks>=20260311
Requires-Dist: cs.obj>=20261016
Requires-Dist: cs.pfx>=20260912
Requires-Dist: cs.py.func>=20250914
Requires-Dist: cs.seq>=20260403
Requires-Dist: icontract
Requires-Dist: python-dateutil
Requires-Dist: typeguard
Project-URL: MonoRepo Commits, https://bitbucket.org/cameron_simpson/css/commits/branch/main
Project-URL: Monorepo Git Mirror, https://github.com/cameron-simpson/css
Project-URL: Monorepo Hg/Mercurial Mirror, https://hg.sr.ht/~cameron-simpson/css
Project-URL: Source, https://github.com/cameron-simpson/css/blob/main/lib/python/cs/lex.py

Lexical analysis functions, tokenisers, transcribers:
an arbitrary assortment of lexical and tokenisation functions useful
for writing recursive descent parsers, of which I have several.
There are also some transcription functions for producing text
from various objects, such as `hexify` and `unctrl`.

Generally the `get_*` functions accept a source string and an offset
(usually optional, default `0`) and return a token and the new offset,
raising `ValueError` on failed tokenisation.



Short summary:


* `as_lines`: Generator yielding complete lines from arbitrary pieces of text from the iterable of `str` `chunks`.


* `BaseToken`: A mixin for token dataclasses.


* `camelcase`: Convert a snake cased string `snakecased` into camel case.


* `common_prefix`: Return the common prefix of the strings `strs`.


* `common_suffix`: Return the common suffix of the strings `strs`.


* `CoreTokens`: A mixin for token dataclasses whose subclasses include `Identifier`, 'NumericValue` and `QuotedString`.


* `cropped`: If the length of `s` exceeds `max_length` (default `32`), replace enough of the tail with `ellipsis` and the last `roffset` (default `1`) characters of `s` to fit in `max_length` characters.


* `cropped_repr`: Compute a cropped `repr()` of `obj`.


* `cutprefix`: Remove `prefix` from the front of `s` if present. Return the suffix if `s.startswith(prefix)`, else `s`. As with `str.startswith`, `prefix` may be a `str` or a `tuple` of `str`. If a tuple, the first matching prefix from the tuple will be removed.


* `cutsuffix`: Remove `suffix` from the end of `s` if present. Return the prefix if `s.endswith(suffix)`, else `s`. As with `str.endswith`, `suffix` may be a `str` or a `tuple` of `str`. If a tuple, the first matching suffix from the tuple will be removed.


* `FFloat`: Formattable `float`.


* `FInt`: Formattable `int`.


* `FNumericMixin`: A `FormatableMixin` subclass.


* `format_as`: Format the string `format_s` using `Formatter.vformat`, return the formatted result. This is a wrapper for `str.format_map` which raises a more informative `FormatAsError` exception on failure.


* `format_attribute`: A decorator to mark a method as available as a format method. This sets `method.is_format_attribute=True`.


* `format_escape`: Escape `{}` characters in a string to protect them from `str.format`.


* `format_recover`: Decorator for `__format__` methods which replaces failed formats with `{self:format_spec}`.


* `FormatableFormatter`: A `string.Formatter` subclass interacting with objects which inherit from `FormatableMixin`.


* `FormatableMixin`: A subclass of `FormatableFormatter` which  provides 2 main features: - a `__format__` method which parses the `format_spec` string into multiple colon separated terms whose results chain - a `format_as` method which formats a format string using `str.format_map` with a suitable mapping derived from the instance via its `format_kwargs` method (whose default is to return the instance itself).


* `FormatAsError`: Subclass of `LookupError` for use by `format_as`.


* `FormatMapping`: A `Mapping` subclass based on an object and a mapping intended for use by the `FormatableMixin.format_as` method. The mapping maps field names to values, where the values may be callables accepting an object. Fetching a value from the mapping will call `value(obj)` if the value is callable. Some additonal extra field names are provided if not already present in the mapping: - `self`: the object.


* `FStr`: A `str` subclass with the `FormatableMixin` methods, particularly its `__format__` method which uses `str` method names as valid formats.


* `get_chars`: Scan the string `s` for characters in `gochars` starting at `offset`. Return `(match,new_offset)`.


* `get_decimal`: Scan the string `s` for decimal characters starting at `offset` (default `0`). Return `(dec_string,new_offset)`.


* `get_decimal_or_float_value`: Fetch a decimal or basic float (nnn.nnn) value from the str `s` at `offset` (default `0`). Return `(value,new_offset)`.


* `get_decimal_value`: Scan the string `s` for a decimal value starting at `offset` (default `0`). Return `(value,new_offset)`.


* `get_delimited`: Collect text from the string `s` from position `offset` up to the first occurence of delimiter `delim`; return the text excluding the delimiter and the offset after the delimiter.


* `get_dotted_identifier`: Scan the string `s` for a dotted identifier (by default an ASCII letter or underscore followed by letters, digits or underscores) with optional trailing dot and another dotted identifier, starting at `offset` (default `0`). Return `(match,new_offset)`.


* `get_envvar`: Parse a simple environment variable reference to $varname or $x where "x" is a special character.


* `get_hexadecimal`: Scan the string `s` for hexadecimal characters starting at `offset` (default `0`). Return `(hex_string,new_offset)`.


* `get_hexadecimal_value`: Scan the string `s` for a hexadecimal value starting at `offset` (default `0`). Return `(value,new_offset)`.


* `get_identifier`: Scan the string `s` for an identifier (by default an ASCII letter or underscore followed by letters, digits or underscores) starting at `offset` (default 0). Return `(match,new_offset)`.


* `get_ini_clause_entryname`: Parse a `[`*clausename*`]`*entryname* string from `s` at `offset` (default `0`). Return `(clausename,entryname,new_offset)`.


* `get_ini_clausename`: Parse a `[`*clausename*`]` string from `s` at `offset` (default `0`). Return `(clausename,new_offset)`.


* `get_nonwhite`: Scan the string `s` for characters not in `string.whitespace` starting at `offset` (default `0`). Return `(match,new_offset)`.


* `get_other_chars`: Scan the string `s` for characters not in `stopchars` starting at `offset` (default `0`). Return `(match,new_offset)`.


* `get_prefix_n`: Strip a leading `prefix` and numeric value `n` from the string `s` starting at `offset` (default `0`). Return the matched prefix, the numeric value and the new offset. Returns `(None,None,offset)` on no match.


* `get_qstr`: Get quoted text with slosh escapes and optional environment substitution.


* `get_qstr_or_identifier`: Parse a double quoted string or an identifier.


* `get_sloshed_text`: Collect slosh escaped text from the string `s` from position `offset` (default `0`) and return the decoded unicode string and the offset of the completed parse.


* `get_suffix_part`: Strip a trailing "part N" suffix from the string `s`. Return the matched suffix and the number part number. Retrn `(None,None)` on no match.


* `get_tokens`: Parse the string `s` from position `offset` using the supplied tokeniser functions `getters`. Return the list of tokens matched and the final offset.


* `get_uc_identifier`: Scan the string `s` for an identifier as for `get_identifier`, but require the letters to be uppercase.


* `get_white`: Scan the string `s` for characters in `string.whitespace` starting at `offset` (default `0`). Return `(match,new_offset)`.


* `has_format_attributes`: OBSOLETE version of has_format_attributes, suggestion: @has_format_attributes is no longer needed.


* `hexify`: A flavour of `binascii.hexlify` returning a `str`.


* `html_escape`: Convert a string for safe transcription in HTML.


* `htmlify`: OBSOLETE version of html_escape.


* `htmlquote`: Quote a string for use in HTML.


* `Identifier`: A dotted identifier.


* `indent`: Return the `paragraph` indented by `line_indent` (default `"  "`).


* `is_dotted_identifier`: Test if the string `s` is an identifier from position `offset` onward.


* `is_identifier`: Test if the string `s` is an identifier from position `offset` (default `0`) onward.


* `is_uc_identifier`: Test if the string `s` is an uppercase identifier from position `offset` (default `0`) onward.


* `isUC_`: Check that a string matches the regular expression `^[A-Z][A-Z_0-9]*$`.


* `jsquote`: Quote a string for use in JavaScript.


* `lc_`: Return `value.lower()` with `'-'` translated into `'_'` and `' '` translated into `'-'`.


* `match_tokens`: Wrapper for `get_tokens` which catches `ValueError` exceptions and returns `(None,offset)`.


* `NumericValue`: An `int` or `float` literal.


* `parseUC_sAttr`: Take an attribute name `attr` and return `(key,is_plural)`.


* `phpquote`: Quote a string for use in PHP code.


* `printt`: OBSOLETE version of printt, suggestion: cs.printt.printt.


* `QuotedString`: A double quoted string.


* `r`: Like `typed_str` but using `repr` instead of `str`. This is available as both `typed_repr` and `r`.


* `s`: Return "type(obj).__name__:str(obj)" for some object `obj`. This is available as both `typed_str` and `s`.


* `single_space`: Return the string `s` stripped and with internal whitespace replaced by `sep` (default `" "`).


* `skipwhite`: Convenience routine for skipping past whitespace; returns the offset of the next nonwhitespace character.


* `slosh_mapper`: Return a string to replace backslash-`c`, or `None`.


* `slosh_quote`: Quote a string `raw_s` with quote character `q`.


* `snakecase`: Convert a camel cased string `camelcased` into snake case.


* `split_remote_path`: OBSOLETE version of split_remote_path, suggestion: cs.fs.RemotePath.from_str.


* `stripped_dedent`: Slightly smarter dedent which ignores a string's opening indent.


* `strlist`: Convert an iterable to strings and join with `sep` (default `', '`).


* `tabpadding`: Compute some spaces to use a tab padding at an offfset.


* `tabulate`: OBSOLETE version of tabulate, suggestion: cs.printt.tabulate.


* `texthexify`: Transcribe the bytes `bs` to text using compact text runs for some common text values.


* `titleify_lc`: Translate `'-'` into `' '` and `'_'` translated into `'-'`, then titlecase.


* `typed_repr`: Like `typed_str` but using `repr` instead of `str`. This is available as both `typed_repr` and `r`.


* `typed_str`: Return "type(obj).__name__:str(obj)" for some object `obj`. This is available as both `typed_str` and `s`.


* `unctrl`: Return the string `s` with `TAB`s expanded and control characters replaced with printable representations.


* `untexthexify`: Decode a textual representation of binary data into binary data.


* `without_prefix`: Remove `prefix` from `s` and return the suffix, or `None` if not present. As with `str.endswith`, `prefix` may be a `str` or a `tuple` of `str`. If a tuple, the first matching prefix from the tuple will be removed.


* `without_suffix`: Remove `suffix` from `s` and return the prefix, or `None` if not present. As with `str.endswith`, `suffix` may be a `str` or a `tuple` of `str`. If a tuple, the first matching suffix from the tuple will be removed.

# Functions

## as_lines(chunks, partials=None)

Generator yielding complete lines from arbitrary pieces of text from
the iterable of `str` `chunks`.

After completion, any remaining newline-free chunks remain
in the partials list; they will be unavailable to the caller
unless the list is presupplied.

## camelcase(snakecased: str, first_letter_only: bool = False) -> str

Convert a snake cased string `snakecased` into camel case.

Parameters:
* `snakecased`: the snake case string to convert
* `first_letter_only`: optional flag (default `False`);
  if true then just ensure that the first character of a word
  is uppercased, otherwise use `str.title`

Example:

    >>> camelcase('abc_def')
    'abcDef'
    >>> camelcase('ABc_def')
    'abcDef'
    >>> camelcase('abc_dEf')
    'abcDef'
    >>> camelcase('abc_dEf', first_letter_only=True)
    'abcDEf'

## common_prefix(*strs)

Return the common prefix of the strings `strs`.

Examples:

    >>> common_prefix('abc', 'def')
    ''
    >>> common_prefix('abc', 'abd')
    'ab'
    >>> common_prefix('abc', 'abcdef')
    'abc'
    >>> common_prefix('abc', 'abcdef', 'abz')
    'ab'
    >>> # contrast with cs.fileutils.common_path_prefix
    >>> common_prefix('abc/def', 'abc/def1', 'abc/def2')
    'abc/def'

## common_suffix(*strs)

Return the common suffix of the strings `strs`.

## cropped(s: str, max_length: int = 32, roffset: int = 1, ellipsis: str = '...')

If the length of `s` exceeds `max_length` (default `32`),
replace enough of the tail with `ellipsis`
and the last `roffset` (default `1`) characters of `s`
to fit in `max_length` characters.

## cropped_repr(obj, roffset=1, max_length=32, inner_max_length=None)

Compute a cropped `repr()` of `obj`.

Parameters:
* `obj`: the object to represent
* `max_length`: the maximum length of the representation, default `32`
* `inner_max_length`: the maximum length of the representations
  of members of `obj`, default `max_length//2`
* `roffset`: the number of trailing characters to preserve, default `1`

## cutprefix(s, prefix)

Remove `prefix` from the front of `s` if present.
Return the suffix if `s.startswith(prefix)`, else `s`.
As with `str.startswith`, `prefix` may be a `str` or a `tuple` of `str`.
If a tuple, the first matching prefix from the tuple will be removed.

Example:

    >>> abc_def = 'abc.def'
    >>> cutprefix(abc_def, 'abc.')
    'def'
    >>> cutprefix(abc_def, 'zzz.')
    'abc.def'
    >>> cutprefix(abc_def, '.zzz') is abc_def
    True
    >>> cutprefix('this_that', ('this', 'thusly'))
    '_that'
    >>> cutprefix('thusly_that', ('this', 'thusly'))
    '_that'

## cutsuffix(s, suffix)

Remove `suffix` from the end of `s` if present.
Return the prefix if `s.endswith(suffix)`, else `s`.
As with `str.endswith`, `suffix` may be a `str` or a `tuple` of `str`.
If a tuple, the first matching suffix from the tuple will be removed.

Example:

    >>> abc_def = 'abc.def'
    >>> cutsuffix(abc_def, '.def')
    'abc'
    >>> cutsuffix(abc_def, '.zzz')
    'abc.def'
    >>> cutsuffix(abc_def, '.zzz') is abc_def
    True
    >>> cutsuffix('this_that', ('that', 'tother'))
    'this_'
    >>> cutsuffix('this_tother', ('that', 'tother'))
    'this_'

## format_as(format_s: str, format_mapping, formatter=None, *, error_sep=None, missing: Optional[Callable[[Mapping, Any], Any]] = None, strict=False)

Format the string `format_s` using `Formatter.vformat`,
return the formatted result.
This is a wrapper for `str.format_map`
which raises a more informative `FormatAsError` exception on failure.

Parameters:
* `format_s`: the format string to use as the template
* `format_mapping`: the mapping of available replacement fields
* `formatter`: an optional `string.Formatter`-like instance
  with a `.vformat(format_string,args,kwargs)` method,
  usually a subclass of `string.Formatter`;
  if not specified then `FormatableFormatter` is used
* `error_sep`: optional separator for the multipart error message,
  default from `FormatAsError.DEFAULT_SEPARATOR`:
  `'; '`
* `missing`: an optional callable to turn a key missing from
  `format_mapping` into a value to interpolate

## format_attribute(method)

A decorator to mark a method as available as a format method.
This sets `method.is_format_attribute=True`.

For example,
the `FormatableMixin.json` method is defined like this:

    @format_attribute
    def json(self):
        return self.FORMAT_JSON_ENCODER.encode(self)

which allows a `FormatableMixin` subclass instance
to be used in a format string like this:

    {instance:json}

to insert a JSON transcription of the instance.

It is recommended that methods marked with `@format_attribute`
have no side effects and do not modify state,
as they are intended for use in ad hoc format strings
supplied by an end user.

## format_escape(s)

Escape `{}` characters in a string to protect them from `str.format`.

## format_recover(*da, **dkw)

Decorator for `__format__` methods which replaces failed formats
with `{self:format_spec}`.

## get_chars(s: str, offset: int, gochars: str) -> Tuple[str, int]

Scan the string `s` for characters in `gochars` starting at `offset`.
Return `(match,new_offset)`.

`gochars` may also be a callable, in which case a character
`ch` is accepted if `gochars(ch)` is true.

## get_decimal(s: str, offset: int = 0) -> Tuple[str, int]

Scan the string `s` for decimal characters starting at `offset` (default `0`).
Return `(dec_string,new_offset)`.

## get_decimal_or_float_value(s: str, offset: int = 0) -> Tuple[Union[int, float], int]

Fetch a decimal or basic float (nnn.nnn) value
from the str `s` at `offset` (default `0`).
Return `(value,new_offset)`.

## get_decimal_value(s: str, offset: int = 0) -> Tuple[int, int]

Scan the string `s` for a decimal value starting at `offset` (default `0`).
Return `(value,new_offset)`.

## get_delimited(s, offset, delim)

Collect text from the string `s` from position `offset` up
to the first occurence of delimiter `delim`; return the text
excluding the delimiter and the offset after the delimiter.

## get_dotted_identifier(s: str, offset: int = 0, **kw) -> Tuple[str, int]

Scan the string `s` for a dotted identifier (by default an
ASCII letter or underscore followed by letters, digits or
underscores) with optional trailing dot and another dotted
identifier, starting at `offset` (default `0`).
Return `(match,new_offset)`.

Note: the empty string and an unchanged offset will be returned if
there is no leading letter/underscore.

Keyword arguments are passed to `get_identifier`
(used for each component of the dotted identifier).

## get_envvar(s, offset=0, environ=None, default=None, specials=None)

Parse a simple environment variable reference to $varname or
$x where "x" is a special character.

Parameters:
* `s`: the string with the variable reference
* `offset`: the starting point for the reference
* `default`: default value for missing environment variables;
   if `None` (the default) a `ValueError` is raised
* `environ`: the environment mapping, default `os.environ`
* `specials`: the mapping of special single character variables

## get_hexadecimal(s: str, offset: int = 0) -> Tuple[str, int]

Scan the string `s` for hexadecimal characters starting at `offset` (default `0`).
Return `(hex_string,new_offset)`.

## get_hexadecimal_value(s: str, offset: int = 0) -> Tuple[int, int]

Scan the string `s` for a hexadecimal value starting at `offset` (default `0`).
Return `(value,new_offset)`.

## get_identifier(s: str, offset: int = 0, *, alpha: str = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', number: str = '0123456789', extras: str = '_') -> Tuple[str, int]

Scan the string `s` for an identifier (by default an ASCII
letter or underscore followed by letters, digits or underscores)
starting at `offset` (default 0).
Return `(match,new_offset)`.

*Note*: the empty string and an unchanged offset will be returned if
there is no leading letter/underscore.

Parameters:
* `s`: the string to scan
* `offset`: the starting offset, default `0`.
* `alpha`: the characters considered alphabetic,
  default `string.ascii_letters`.
* `number`: the characters considered numeric,
  default `string.digits`.
* `extras`: extra characters considered part of an identifier,
  default `'_'`.

## get_ini_clause_entryname(s: str, offset: int = 0) -> Tuple[str, str, int]

Parse a `[`*clausename*`]`*entryname* string
from `s` at `offset` (default `0`).
Return `(clausename,entryname,new_offset)`.

## get_ini_clausename(s: str, offset: int = 0) -> Tuple[str, int]

Parse a `[`*clausename*`]` string from `s` at `offset` (default `0`).
Return `(clausename,new_offset)`.

## get_nonwhite(s: str, offset: int = 0) -> Tuple[str, int]

Scan the string `s` for characters not in `string.whitespace`
starting at `offset` (default `0`).
Return `(match,new_offset)`.

## get_other_chars(s: str, offset: int = 0, stopchars: Optional[str] = None) -> Tuple[str, int]

Scan the string `s` for characters not in `stopchars` starting
at `offset` (default `0`).
Return `(match,new_offset)`.

## get_prefix_n(s: str, prefix: str, n: Optional[int] = None, *, offset: int = 0) -> Tuple[Optional[str], Optional[int], int]

Strip a leading `prefix` and numeric value `n` from the string `s`
starting at `offset` (default `0`).
Return the matched prefix, the numeric value and the new offset.
Returns `(None,None,offset)` on no match.

Parameters:
* `s`: the string to parse
* `prefix`: the prefix string which must appear at `offset`
  or an object with a `match(str,offset)` method
  such as an `re.Pattern` regexp instance
* `n`: optional integer value;
  if omitted any value will be accepted, otherwise the numeric
  part must match `n`

If `prefix` is a `str`, the "matched prefix" return value is `prefix`.
Otherwise the "matched prefix" return value is the result of
the `prefix.match(s,offset)` call. The result must also support
a `.end()` method returning the offset in `s` beyond the match,
used to locate the following numeric portion.

Examples:

   >>> import re
   >>> get_prefix_n('s03e01--', 's')
   ('s', 3, 3)
   >>> get_prefix_n('s03e01--', 's', 3)
   ('s', 3, 3)
   >>> get_prefix_n('s03e01--', 's', 4)
   (None, None, 0)
   >>> get_prefix_n('s03e01--', re.compile('[es]',re.I))
   (<re.Match object; span=(0, 1), match='s'>, 3, 3)
   >>> get_prefix_n('s03e01--', re.compile('[es]',re.I), offset=3)
   (<re.Match object; span=(3, 4), match='e'>, 1, 6)

## get_qstr(s, offset=0, q='"', environ=None, default=None, env_specials=None)

Get quoted text with slosh escapes and optional environment substitution.

Parameters:
* `s`: the string containg the quoted text.
* `offset`: the starting point, default `0`.
* `q`: the quote character, default `'"'`. If `q` is `None`,
  do not expect the string to be delimited by quote marks.
* `environ`: if not `None`, also parse and expand `$`*envvar* references.
* `default`: passed to `get_envvar`

## get_qstr_or_identifier(s, offset)

Parse a double quoted string or an identifier.

## get_sloshed_text(s, delim, offset=0, slosh='\\', mapper=<function slosh_mapper at 0x10b3447c0>, specials=None)

Collect slosh escaped text from the string `s` from position
`offset` (default `0`) and return the decoded unicode string and
the offset of the completed parse.

Parameters:
* `delim`: end of string delimiter, such as a single or double quote.
* `offset`: starting offset within `s`, default `0`.
* `slosh`: escape character, default a slosh ('\').
* `mapper`: a mapping function which accepts a single character
  and returns a replacement string or `None`; this is used the
  replace things such as '\t' or '\n'. The default is the
  `slosh_mapper` function, whose default mapping is `SLOSH_CHARMAP`.
* `specials`: a mapping of other special character sequences and parse
  functions for gathering them up. When one of the special
  character sequences is found in the string, the parse
  function is called to parse at that point.
  The parse functions accept
  `s` and the offset of the special character. They return
  the decoded string and the offset past the parse.

The escape character `slosh` introduces an encoding of some
replacement text whose value depends on the following character.
If the following character is:
* the escape character `slosh`, insert the escape character.
* the string delimiter `delim`, insert the delimiter.
* the character 'x', insert the character with code from the following
  2 hexadecimal digits.
* the character 'u', insert the character with code from the following
  4 hexadecimal digits.
* the character 'U', insert the character with code from the following
  8 hexadecimal digits.
* a character from the keys of `mapper`

## get_suffix_part(s: str, *, keywords: Iterable[str] = ('part',), numeral_map: Optional[Mapping[str, int]] = None) -> Union[Tuple[str, int], Tuple[NoneType, NoneType]]

Strip a trailing "part N" suffix from the string `s`.
Return the matched suffix and the number part number.
Retrn `(None,None)` on no match.

Parameters:
* `s`: the string
* `keywords`: an iterable of `str` to match, or a single `str`;
  default `'part'`
* `numeral_map`: an optional mapping of numeral names to numeric values;
  default `NUMERAL_NAMES['en']`, the English numerals

Exanmple:

    >>> get_suffix_part('s09e10 - A New World: Part One')
    (': Part One', 1)

## get_tokens(s, offset, getters)

Parse the string `s` from position `offset` using the supplied
tokeniser functions `getters`.
Return the list of tokens matched and the final offset.

Parameters:
* `s`: the string to parse.
* `offset`: the starting position for the parse.
* `getters`: an iterable of tokeniser specifications.

Each tokeniser specification `getter` is either:
* a callable expecting `(s,offset)` and returning `(token,new_offset)`
* a literal string, to be matched exactly
* a `tuple` or `list` with values `(func,args,kwargs)`;
  call `func(s,offset,*args,**kwargs)`
* an object with a `.match` method such as a regex;
  call `getter.match(s,offset)` and return a match object with
  a `.end()` method returning the offset of the end of the match

## get_uc_identifier(s: str, offset: int = 0, number: str = '0123456789', extras: str = '_') -> Tuple[str, int]

Scan the string `s` for an identifier as for `get_identifier`,
but require the letters to be uppercase.

## get_white(s: str, offset: int = 0) -> Tuple[str, int]

Scan the string `s` for characters in `string.whitespace`
starting at `offset` (default `0`).
Return `(match,new_offset)`.

## has_format_attributes(*da, **dkw)

OBSOLETE version of has_format_attributes, suggestion: @has_format_attributes is no longer needed

A obsolete class decorator formerly used to walk the class for `@formatmethod`
methods. This is now done by `FormatableMixin.__init_subclass__`.

## hexify(bs: bytes) -> str

A flavour of `binascii.hexlify` returning a `str`.

## html_escape(s: str, nbsp: bool = False) -> str

Convert a string for safe transcription in HTML.

Parameters:
* `s`: the string
* `nbsp`: replaces spaces with `"&nbsp;"` to prevent word folding,
  default `False`.

## htmlify(s: str, nbsp: bool = False) -> str

OBSOLETE version of html_escape

Convert a string for safe transcription in HTML.

Parameters:
* `s`: the string
* `nbsp`: replaces spaces with `"&nbsp;"` to prevent word folding,
  default `False`.

## htmlquote(s: str) -> str

Quote a string for use in HTML.

## indent(paragraph: str, line_indent: str = '  ') -> str

Return the `paragraph` indented by `line_indent` (default `"  "`).

## isUC_(s)

Check that a string matches the regular expression `^[A-Z][A-Z_0-9]*$`.

## is_dotted_identifier(s: str, offset: int = 0, **kw) -> bool

Test if the string `s` is an identifier from position `offset` onward.

## is_identifier(s: str, offset: int = 0, **kw) -> bool

Test if the string `s` is an identifier
from position `offset` (default `0`) onward.

## is_uc_identifier(s: str, offset: int = 0, **kw) -> bool

Test if the string `s` is an uppercase identifier
from position `offset` (default `0`) onward.

## jsquote(s: str) -> str

Quote a string for use in JavaScript.

## lc_(value: str) -> str

Return `value.lower()`
with `'-'` translated into `'_'` and `' '` translated into `'-'`.

I use this to construct lowercase filenames containing a
readable transcription of a title string.

See also `titleify_lc()`, an imperfect reversal of this.

## match_tokens(s, offset, getters)

Wrapper for `get_tokens` which catches `ValueError` exceptions
and returns `(None,offset)`.

## parseUC_sAttr(attr)

Take an attribute name `attr` and return `(key,is_plural)`.

Examples:
* `'FOO'` returns `('FOO',False)`.
* `'FOOs'` or `'FOOes'` returns `('FOO',True)`.
Otherwise return `(None,False)`.

## phpquote(s: str) -> str

Quote a string for use in PHP code.

## printt(*a, **kw)

OBSOLETE version of printt, suggestion: cs.printt.printt

Compatibility shim for `cs.printt.printt()`, which was formerly here.

## r(obj: Any, max_length: Optional[int] = None, *, use_cls: bool = False) -> str

Like `typed_str` but using `repr` instead of `str`.
This is available as both `typed_repr` and `r`.

## s(obj: Any, *, use_cls: bool = False, use_repr: bool = False, max_length: Optional[int] = 32) -> str

Return "type(obj).__name__:str(obj)" for some object `obj`.
This is available as both `typed_str` and `s`.

Parameters:
* `use_cls`: default `False`;
  if true, use `str(type(obj))` instead of `type(obj).__name__`
* `use_repr`: default `False`;
  if true, use `repr(obj)` instead of `str(obj)`

I use this a lot when debugging. Example:

    from cs.lex import typed_str as s
    ......
    X("foo = %s", s(foo))

## single_space(s: str, *, sep=' ') -> str

Return the string `s` stripped and with internal whitespace replaced by `sep` (default `" "`).

## skipwhite(s: str, offset: int = 0) -> int

Convenience routine for skipping past whitespace;
returns the offset of the next nonwhitespace character.

## slosh_mapper(c, charmap=None)

Return a string to replace backslash-`c`, or `None`.

## slosh_quote(raw_s: str, q: str)

Quote a string `raw_s` with quote character `q`.

## snakecase(camelcased: str) -> str

Convert a camel cased string `camelcased` into snake case.

Parameters:
* `cameelcased`: the cameel case string to convert
* `first_letter_only`: optional flag (default `False`);
  if true then just ensure that the first character of a word
  is uppercased, otherwise use `str.title`

Example:

    >>> snakecase('abcDef')
    'abc_def'
    >>> snakecase('abcDEf')
    'abc_def'
    >>> snakecase('AbcDef')
    'abc_def'

## split_remote_path(remotepath: str) -> Tuple[Optional[str], str]

OBSOLETE version of split_remote_path, suggestion: cs.fs.RemotePath.from_str

Split a path with an optional leading `[user@]rhost:` prefix
into the prefix and the remaining path.
`None` is returned for the prefix is there is none.
This is useful for things like `rsync` targets etc.

OBSOLETE, use `cs.fs.RemotePath.from_str` instead.

## stripped_dedent(s: str, post_indent: str = '', sub_indent: str = '') -> str

Slightly smarter dedent which ignores a string's opening indent.

Algorithm:
strip the supplied string `s`, pull off the leading line,
dedent the rest, put back the leading line.

This is a lot like the `inspect.cleandoc()` function.

This supports my preferred docstring layout, where the opening
line of text is on the same line as the opening quote.

The optional `post_indent` parameter may be used to indent
the dedented text before return.

The optional `sub_indent` parameter may be used to indent
the second and following lines if the dedented text before return.

Examples:

    >>> def func(s):
    ...   """ Slightly smarter dedent which ignores a string's opening indent.
    ...       Strip the supplied string `s`. Pull off the leading line.
    ...       Dedent the rest. Put back the leading line.
    ...   """
    ...   pass
    ...
    >>> from cs.lex import stripped_dedent
    >>> print(stripped_dedent(func.__doc__))
    Slightly smarter dedent which ignores a string's opening indent.
    Strip the supplied string `s`. Pull off the leading line.
    Dedent the rest. Put back the leading line.
    >>> print(stripped_dedent(func.__doc__, sub_indent='  '))
    Slightly smarter dedent which ignores a string's opening indent.
      Strip the supplied string `s`. Pull off the leading line.
      Dedent the rest. Put back the leading line.
    >>> print(stripped_dedent(func.__doc__, post_indent='  '))
      Slightly smarter dedent which ignores a string's opening indent.
      Strip the supplied string `s`. Pull off the leading line.
      Dedent the rest. Put back the leading line.
    >>> print(stripped_dedent(func.__doc__, post_indent='  ', sub_indent='| '))
      Slightly smarter dedent which ignores a string's opening indent.
      | Strip the supplied string `s`. Pull off the leading line.
      | Dedent the rest. Put back the leading line.

## strlist(ary: Iterable, sep: str = ', ') -> str

Convert an iterable to strings and join with `sep` (default `', '`).

## tabpadding(padlen: int, tabsize: int = 8, offset: int = 0) -> str

Compute some spaces to use a tab padding at an offfset.

## tabulate(*a, **kw)

OBSOLETE version of tabulate, suggestion: cs.printt.tabulate

Compatibility shim for `cs.printt.tabulate()`, which was formerly here.

## texthexify(bs: bytes, shiftin: str = '[', shiftout: str = ']', whitelist: Union[str, bytes, NoneType] = None) -> str

Transcribe the bytes `bs` to text using compact text runs for
some common text values.

This can be reversed with the `untexthexify` function.

This is an ad doc format devised to be compact but also to
expose "text" embedded within to the eye. The original use
case was transcribing a binary directory entry format, where
the filename parts would be somewhat visible in the transcription.

The output is a string of hexadecimal digits for the encoded
bytes except for runs of values from the whitelist, which are
enclosed in the shiftin and shiftout markers and transcribed
as is. The default whitelist is values of the ASCII letters,
the decimal digits and the punctuation characters '_-+.,'.
The default shiftin and shiftout markers are '[' and ']'.

String objects converted with either `hexify` and `texthexify`
output strings may be freely concatenated and decoded with
`untexthexify`.

Example:

    >>> texthexify(b'&^%&^%abcdefghi)(*)(*')
    '265e25265e25[abcdefghi]29282a29282a'

Parameters:
* `bs`: the bytes to transcribe
* `shiftin`: Optional. The marker string used to indicate a shift to
  direct textual transcription of the bytes, default: `'['`.
* `shiftout`: Optional. The marker string used to indicate a
  shift from text mode back into hexadecimal transcription,
  default `']'`.
* `whitelist`: an optional bytes or string object indicating byte
  values which may be represented directly in text;
  the default value is the ASCII letters, the decimal digits
  and the punctuation characters `'_-+.,'`.

## titleify_lc(value_lc: str) -> str

Translate `'-'` into `' '` and `'_'` translated into `'-'`,
then titlecase.

See also `lc_()`, which this reverses imperfectly.

## typed_repr(obj: Any, max_length: Optional[int] = None, *, use_cls: bool = False) -> str

Like `typed_str` but using `repr` instead of `str`.
This is available as both `typed_repr` and `r`.

## typed_str(obj: Any, *, use_cls: bool = False, use_repr: bool = False, max_length: Optional[int] = 32) -> str

Return "type(obj).__name__:str(obj)" for some object `obj`.
This is available as both `typed_str` and `s`.

Parameters:
* `use_cls`: default `False`;
  if true, use `str(type(obj))` instead of `type(obj).__name__`
* `use_repr`: default `False`;
  if true, use `repr(obj)` instead of `str(obj)`

I use this a lot when debugging. Example:

    from cs.lex import typed_str as s
    ......
    X("foo = %s", s(foo))

## unctrl(s: str, tabsize: int = 8) -> str

Return the string `s` with `TAB`s expanded and control characters
replaced with printable representations.

## untexthexify(s: str, shiftin: str = '[', shiftout: str = ']') -> bytes

Decode a textual representation of binary data into binary data.

This is the reverse of the `texthexify` function.

Outside of the `shiftin`/`shiftout` markers the binary data
are represented as hexadecimal. Within the markers the bytes
have the values of the ordinals of the characters.

Example:

    >>> untexthexify('265e25265e25[abcdefghi]29282a29282a')
    b'&^%&^%abcdefghi)(*)(*'

Parameters:
* `s`: the string containing the text representation.
* `shiftin`: Optional. The marker string commencing a sequence
  of direct text transcription, default `'['`.
* `shiftout`: Optional. The marker string ending a sequence
  of direct text transcription, default `']'`.

## without_prefix(s, prefix)

Remove `prefix` from `s` and return the suffix, or `None` if not present.
As with `str.endswith`, `prefix` may be a `str` or a `tuple` of `str`.
If a tuple, the first matching prefix from the tuple will be removed.

Example:

    >>> if attr := without_prefix("obj.attrname", "obj."):
    ...     print("attribute is", attr)
    ...
    attribute is attrname
    >>> if attr := without_prefix("notobj.attrname", "obj."):
    ...     print("processing", attr, "now")
    ... else:
    ...     print("expected leading 'obj.'")
    ...
    expected leading 'obj.'
    >>>

## without_suffix(s, suffix)

Remove `suffix` from `s` and return the prefix, or `None` if not present.
As with `str.endswith`, `suffix` may be a `str` or a `tuple` of `str`.
If a tuple, the first matching suffix from the tuple will be removed.

Example:

    >>> if typename := without_suffix("ComicPageConnection", "Connection"):
    ...     print("typename is", typename)
    ...
    typename is ComicPage
    >>> edgetypename = "ComicCoverObject"
    >>> if edgetype := without_suffix(edgetypename, "Edge"):
    ...     print("processing edge for type", edgetype)
    ... else:
    ...     print("unexpected edge type name", edgetypename)
    ...
    unexpected edge type name ComicCoverObject
    >>>

# Classes

## class BaseToken(cs.deco.Promotable)

A mixin for token dataclasses.

Presently I use this in `cs.app.tagger.rules` and `cs.app.pilfer.parse`.

### `BaseToken.EXTRAS`

    ()

### `BaseToken.__hash__`

    None

### `BaseToken.__post_init__(self)`

An omitted `offset,end_offset` means the token is the whole `source_text`.

### `BaseToken.from_str(text: str) -> 'BaseToken'`

Parse `test` as a token of type `cls`, return the token.
Raises `SyntaxError` on a parse failure.
This is a wrapper for the `parse` class method.

### `BaseToken.matched_text`

    <property object at 0x10b2e70b0>

### `BaseToken.parse(text: str, offset: int = 0, *, skip=False) -> Tuple[ForwardRef('BaseToken'), int]`

Parse a token from `test` at `offset` (default `0`).
Return a `BaseToken` subclass instance.
Raise `SyntaxError` if no subclass parses it.
Raise `EOFError` if at the end of the `text`,
checked after any whitespace if `skip` is true.
The returned token's `.end_offset` is the next parse point.

This base class method attempts the `.parse` method of all
the public subclasses.

Parameters:
* `text`: the text being parsed
* `offset`: the offset within the `text` of the the parse cursor
* `skip`: if true (default `False`), skip any leading
  whitespace before matching

### `BaseToken.scan(text: str, offset: int = 0, *, skip=True) -> Iterable[ForwardRef('BaseToken')]`

Scan `text`, parsing tokens using `BaseToken.parse` and yielding them.
Parameters are as for `BaseToken.parse` except as follows:
- encountering end of text end the iteration instead of raising `EOFError`
- `skip` defaults to `True` to allow whitespace between tokens

### `BaseToken.token_classes()`

Return the `baseToken` subclasses to consider when parsing a token stream.

## class CoreTokens(BaseToken)

A mixin for token dataclasses whose subclasses include `Identifier`,
'NumericValue` and `QuotedString`.

## class FFloat(FNumericMixin, builtins.float)

Formattable `float`.

### `FFloat.format_attributes`

    {   'json': <function FormatableMixin.json at 0x10b347a60>,
        'localtime': <function FNumericMixin.localtime at 0x10b3474c0>,
        'utctime': <function FNumericMixin.utctime at 0x10b347380>}

## class FInt(FNumericMixin, builtins.int)

Formattable `int`.

### `FInt.format_attributes`

    {   'json': <function FormatableMixin.json at 0x10b347a60>,
        'localtime': <function FNumericMixin.localtime at 0x10b3474c0>,
        'utctime': <function FNumericMixin.utctime at 0x10b347380>}

## class FNumericMixin(FormatableMixin)

A `FormatableMixin` subclass.

### `FNumericMixin.format_attributes`

    {   'json': <function FormatableMixin.json at 0x10b347a60>,
        'localtime': <function FNumericMixin.localtime at 0x10b3474c0>,
        'utctime': <function FNumericMixin.utctime at 0x10b347380>}

### `FNumericMixin.localtime(self)`

Treat this as a UNIX timestamp and return a localtime `datetime`.

### `FNumericMixin.utctime(self)`

Treat this as a UNIX timestamp and return a UTC `datetime`.

## class FStr(FormatableMixin, builtins.str)

A `str` subclass with the `FormatableMixin` methods,
particularly its `__format__` method
which uses `str` method names as valid formats.

It also has a bunch of utility methods which are available
as `:`*method* in format strings.

### `FStr.basename(self)`

Treat as a filesystem path and return the basename.

### `FStr.dirname(self)`

Treat as a filesystem path and return the dirname.

### `FStr.f(self)`

Parse `self` as a `float`.

### `FStr.format_attributes`

    {   'basename': <function FStr.basename at 0x10b345ee0>,
        'capitalize': <method 'capitalize' of 'str' objects>,
        'casefold': <method 'casefold' of 'str' objects>,
        'center': <method 'center' of 'str' objects>,
        'count': <method 'count' of 'str' objects>,
        'dirname': <function FStr.dirname at 0x10b346160>,
        'encode': <method 'encode' of 'str' objects>,
        'endswith': <method 'endswith' of 'str' objects>,
        'expandtabs': <method 'expandtabs' of 'str' objects>,
        'f': <function FStr.f at 0x10b3463e0>,
        'find': <method 'find' of 'str' objects>,
        'format': <method 'format' of 'str' objects>,
        'format_map': <method 'format_map' of 'str' objects>,
        'i': <function FStr.i at 0x10b346700>,
        'index': <method 'index' of 'str' objects>,
        'isalnum': <method 'isalnum' of 'str' objects>,
        'isalpha': <method 'isalpha' of 'str' objects>,
        'isascii': <method 'isascii' of 'str' objects>,
        'isdecimal': <method 'isdecimal' of 'str' objects>,
        'isdigit': <method 'isdigit' of 'str' objects>,
        'isidentifier': <method 'isidentifier' of 'str' objects>,
        'islower': <method 'islower' of 'str' objects>,
        'isnumeric': <method 'isnumeric' of 'str' objects>,
        'isprintable': <method 'isprintable' of 'str' objects>,
        'isspace': <method 'isspace' of 'str' objects>,
        'istitle': <method 'istitle' of 'str' objects>,
        'isupper': <method 'isupper' of 'str' objects>,
        'join': <method 'join' of 'str' objects>,
        'json': <function FormatableMixin.json at 0x10b347a60>,
        'lc_': <function FStr.lc_ at 0x10b346980>,
        'ljust': <method 'ljust' of 'str' objects>,
        'lower': <method 'lower' of 'str' objects>,
        'lstrip': <method 'lstrip' of 'str' objects>,
        'maketrans': <built-in method maketrans of type object at 0x10a183c10>,
        'partition': <method 'partition' of 'str' objects>,
        'path': <function FStr.path at 0x10b346c00>,
        'posix_path': <function FStr.posix_path at 0x10b346fc0>,
        'removeprefix': <method 'removeprefix' of 'str' objects>,
        'removesuffix': <method 'removesuffix' of 'str' objects>,
        'replace': <method 'replace' of 'str' objects>,
        'rfind': <method 'rfind' of 'str' objects>,
        'rindex': <method 'rindex' of 'str' objects>,
        'rjust': <method 'rjust' of 'str' objects>,
        'rpartition': <method 'rpartition' of 'str' objects>,
        'rsplit': <method 'rsplit' of 'str' objects>,
        'rstrip': <method 'rstrip' of 'str' objects>,
        'split': <method 'split' of 'str' objects>,
        'splitlines': <method 'splitlines' of 'str' objects>,
        'startswith': <method 'startswith' of 'str' objects>,
        'strip': <method 'strip' of 'str' objects>,
        'swapcase': <method 'swapcase' of 'str' objects>,
        'title': <method 'title' of 'str' objects>,
        'translate': <method 'translate' of 'str' objects>,
        'upper': <method 'upper' of 'str' objects>,
        'windows_path': <function FStr.windows_path at 0x10b345da0>,
        'zfill': <method 'zfill' of 'str' objects>}

### `FStr.i(self, base=10)`

Parse `self` as an `int`.

### `FStr.lc_(self)`

Lowercase using `lc_()`.

### `FStr.path(self)`

Convert to a native filesystem `pathlib.Path`.

### `FStr.posix_path(self)`

Convert to a Posix filesystem `pathlib.Path`.

### `FStr.windows_path(self)`

Convert to a Windows filesystem `pathlib.Path`.

## class FormatAsError(builtins.LookupError)

Subclass of `LookupError` for use by `format_as`.

### `FormatAsError.DEFAULT_SEPARATOR`

    '; '

## class FormatMapping(collections.abc.Mapping)

A `Mapping` subclass based on an object and a mapping
intended for use by the `FormatableMixin.format_as` method.
The mapping maps field names to values, where the values may be
callables accepting an object.
Fetching a value from the mapping will call `value(obj)` if
the value is callable.
Some additonal extra field names are provided if not already
present in the mapping:
- `self`: the object

### `FormatMapping.__getitem__(self, field_name: str)`

Fetch the value for `field_name`.
If the value is callable, call `value(self.obj)` to get the value.

### `FormatMapping.items(self)`

Proxy `.items` via `self.mapping`.

### `FormatMapping.keys(self)`

Proxy `.keys` via `self.mapping`.

## class FormatableFormatter(string.Formatter)

A `string.Formatter` subclass interacting with objects
which inherit from `FormatableMixin`.

### `FormatableFormatter.FORMAT_RE_ARG_NAME_s`

    '([a-z_][a-z_0-9]*|\\d+(\\.\\d+)?[a-z]+)'

### `FormatableFormatter.FORMAT_RE_ATTRIBUTE_NAME_s`

    '\\.[a-z_][a-z_0-9]*'

### `FormatableFormatter.FORMAT_RE_ELEMENT_INDEX_s`

    '[^]]*'

### `FormatableFormatter.FORMAT_RE_FIELD`

    re.compile('{(?P<arg_name>([a-z_][a-z_0-9]*|\\d+(\\.\\d+)?[a-z]+)(\\.[a-z_][a-z_0-9]*|\\[[^]]*\\])*)?(!(?P<conversion>[^:}]*))?(:(?P<format_spec>[^}]*))?}', re.IGNORECASE)

### `FormatableFormatter.FORMAT_RE_FIELD_EXPR`

    re.compile('([a-z_][a-z_0-9]*|\\d+(\\.\\d+)?[a-z]+)(\\.[a-z_][a-z_0-9]*|\\[[^]]*\\])*', re.IGNORECASE)

### `FormatableFormatter.FORMAT_RE_FIELD_EXPR_s`

    '([a-z_][a-z_0-9]*|\\d+(\\.\\d+)?[a-z]+)(\\.[a-z_][a-z_0-9]*|\\[[^]]*\\])*'

### `FormatableFormatter.FORMAT_RE_IDENTIFIER_s`

    '[a-z_][a-z_0-9]*'

### `FormatableFormatter.FORMAT_RE_LITERAL_TEXT`

    re.compile('([^{]+|{{)*')

### `FormatableFormatter.format_field(value, format_spec: str)`

Format a value using `format_field`, returning an `FStr`
(a `str` subclass with additional `format_spec` features).

We actually recognise colon separated chains of formats
and apply each format to the previously converted value.
The final result is promoted to an `FStr` before return.

### `FormatableFormatter.get_arg_name(field_name)`

The default initial arg_name is an identifier.

Returns `(prefix,offset)`, and `('',0)` if there is no arg_name.

### `FormatableFormatter.get_field(self, field_name, args, kwargs)`

Get the object referenced by the field text `field_name`.
Raises `KeyError` for an unknown `field_name`.

### `FormatableFormatter.get_format_subspecs(format_spec)`

Parse a `format_spec` as a sequence of colon separated components,
return a list of the components.

### `FormatableFormatter.get_subfield(value, subfield_text: str)`

Resolve `value` against `subfield_text`,
the remaining field text after the term which resolved to `value`.

For example, a format `{name.blah[0]}`
has the field text `name.blah[0]`.
A `get_field` implementation might initially
resolve `name` to some value,
leaving `.blah[0]` as the `subfield_text`.
This method supports taking that value
and resolving it against the remaining text `.blah[0]`.

For generality, if `subfield_text` is the empty string
`value` is returned unchanged.

### `FormatableFormatter.get_value(self, arg_name, args, kwargs)`

Get the object with index `arg_name`.

This default implementation returns `(kwargs[arg_name],arg_name)`.

## class FormatableMixin(FormatableFormatter)

A subclass of `FormatableFormatter` which  provides 2 main features:
- a `__format__` method which parses the `format_spec` string
  into multiple colon separated terms whose results chain
- a `format_as` method which formats a format string using `str.format_map`
  with a suitable mapping derived from the instance
  via its `format_kwargs` method
  (whose default is to return the instance itself)

The `format_as` method is like an inside out `str.format` or
`object.__format__` method.

The `str.format` method is designed for formatting a string
from a variety of other objects supplied in the keyword arguments.

The `object.__format__` method is for filling out a single `str.format`
replacement field from a single object.

By contrast, `format_as` is designed to fill out an entire format
string from the current object.

For example, the `cs.tagset.TagSet` class subclasses
`FormatableMixin` to provide a `format_as` method whose
replacement fields are derived from the tags in the tag set.

Subclasses wanting to provide additional `format_spec` terms
should:
- override `FormatableFormatter.format_field1` to implement
  terms with no colons, letting `format_field` do the split into terms
- override `FormatableFormatter.get_format_subspecs` to implement
  the parse of `format_spec` into a sequence of terms.
  This might recognise a special additional syntax
  and quietly fall back to `super().get_format_subspecs`
  if that is not present.

### `FormatableMixin.FORMAT_JSON_ENCODER`

    <json.encoder.JSONEncoder object at 0x10ad26210>

### `FormatableMixin.__format__(self, format_spec)`

Format `self` according to `format_spec`.

This implementation calls `self.format_field`.
As such, a `format_spec` is considered
a sequence of colon separated terms.

Classes wanting to implement additional format string syntaxes
should either:
- override `FormatableFormatter.format_field1` to implement
  terms with no colons, letting `format_field1` do the split into terms
- override `FormatableFormatter.get_format_subspecs` to implement
  the term parse.

The default implementation of `__format1__` just calls `super().__format__`.
Implementations providing specialised formats
should implement them in `__format1__`
with fallback to `super().__format1__`.

### `FormatableMixin.__init_subclass__(**kw)`

Prefill the `cls.format_attributes` mapping from the
superclass and any format attributes of `cls`.

### `FormatableMixin.convert_field(self, value, conversion)`

The default converter for fields calls `Formatter.convert_field`.

This is a tiny shim to transmute the `''` conversion to `None`
which is what `Formatter.convert_field` expects.

### `FormatableMixin.convert_via_method_or_attr(self, format_spec) -> Tuple[Any, int]`

Apply a method or attribute name based conversion to `self`
where `format_spec` starts with a method or attribute name.
Return `(converted,offset)`
being the converted value and the offset after the method name.

Note that if there is not a leading identifier on `format_spec`
then this method returns `(self,0)`.

The converted value is obtained from `getattr(self,name)`;
if this raises an `AttributeError` a second attempt is made with
`getattr(FStr(self),attr)` if `self` is not already an `FStr`
(this provides the common utility methods on other types).

If the value is callable but does not have a true
`.is_format_attribute` a `TypeError` is raised, otherwise
the value is called to complete the conversion.
(The `.is_format_attribute` is usually set by decorating a
method with the `@format_attribute` decorator.)

The motivating example was a `PurePosixPath`,
which does not JSON transcribe;
this tweak supports both
`posixpath:basename` via the pathlib stuff
and `posixpath:json` via `FStr`
even though a `PurePosixPath` does not subclass `FStr`.

### `FormatableMixin.format_as(self, format_s: str, *, error_sep: Optional[str] = None, missing: Optional[Callable[[Mapping, Any], Any]] = None, strict=True, **format_kwargs_kw)`

Return the string `format_s` formatted using the mapping
returned by `self.format_kwargs(**format_kwargs_kw)`.

If a class using the mixin has no `format_kwargs()` method
to provide a mapping for `str.format_map`
then the instance itself is used as the mapping.

### `FormatableMixin.json(self)`

The value transcribed as compact JSON.

## class Identifier(CoreTokens)

A dotted identifier.

### `Identifier.__hash__`

    None

### `Identifier.parse(text: str, offset: int = 0, *, skip=False) -> Tuple[str, cs.lex.CoreTokens, int]`

Parse a dotted identifier from `test`.

## class NumericValue(_LiteralValue)

An `int` or `float` literal.

### `NumericValue.__hash__`

    None

### `NumericValue.parse(text: str, offset: int = 0, *, skip=False) -> 'NumericValue'`

Parse a Python style `int` or `float`.

## class QuotedString(_LiteralValue)

A double quoted string.

### `QuotedString.__hash__`

    None

### `QuotedString.parse(text: str, offset: int = 0, *, skip=False) -> 'QuotedString'`

Parse a double quoted string from `text`.

### `QuotedString.quote`

    '"'
