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#!/usr/bin/env python3
# --------------------( LICENSE )--------------------
# Copyright (c) 2014-2025 Beartype authors.
# See "LICENSE" for further details.
'''
Project-wide **Python expression indentation substrings** (i.e., string
constants intended to be embedded as syntactically valid indentation in
dynamically generated Python expressions).
This private submodule is *not* intended for importation by downstream callers.
'''
# ....................{ PRIVATE ~ subclasses }....................
class _IndentLevelToCode(dict):
'''
**Indentation cache** (i.e., dictionary mapping from 1-based indentation
levels to the corresponding indentation string constant).
See Also
--------
:data:`.INDENT_LEVEL_TO_CODE`
Singleton instance of this dictionary subclass.
'''
# ....................{ DUNDERS }....................
def __missing__(self, indent_level: int) -> str:
'''
Dunder method explicitly called by the superclass
:meth:`dict.__getitem__` method implicitly called on the first ``[``-
and ``]``-delimited attempt to access an indentation string constant
with the passed indentation level.
Parameters
----------
indent_level : int
1-based level of indentation to be created, cached, and returned.
Returns
-------
str
String constant indented to this level of indentation.
Raises
------
AssertionError
If either:
* ``indent_level`` is *not* an integer.
* ``indent_level`` is a **non-positive integer** (i.e., is less than
or equal to 0).
'''
assert isinstance(indent_level, int), (
f'{repr(indent_level)} not integer.')
assert indent_level > 0, f'{indent_level} <= 0.'
# print(f'Generating indentation level {indent_level}...')
# String constant indented to this level of indentation.
#
# Note that this could also be done recursively (e.g., as
# "self[indent_level - 1]"), but that doing so would be needlessly cute,
# overly slow, and dangerously fragile for *NO* good reason.
indent_code = ' ' * indent_level
# Cache this string constant.
self[indent_level] = indent_code
# Return this string constant.
return indent_code
# ....................{ MAPPINGS }....................
INDENT_LEVEL_TO_CODE = _IndentLevelToCode()
'''
**Indentation cache singleton** (i.e., global dictionary efficiently mapping
from 1-based indentation levels to the corresponding indentation string
constant).
Caveats
-------
**Indentation string constants should always be accessed via this cache rather
than manually generated.** This cache dynamically creates and efficiently caches
indentation string constants on the first access of those constants, obviating
the performance cost of string formatting required to create these constants.
Examples
--------
.. code-block:: pycon
>>> from beartype._data.code.datacodeindent import INDENT_LEVEL_TO_CODE
>>> INDENT_LEVEL_TO_CODE[1]
' '
>>> INDENT_LEVEL_TO_CODE[2]
' '
'''
# ....................{ STRINGS }....................
CODE_INDENT_1 = INDENT_LEVEL_TO_CODE[1]
'''
Code snippet expanding to a single level of indentation.
'''
CODE_INDENT_2 = INDENT_LEVEL_TO_CODE[2]
'''
Code snippet expanding to two levels of indentation.
'''
CODE_INDENT_3 = INDENT_LEVEL_TO_CODE[3]
'''
Code snippet expanding to three levels of indentation.
'''
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