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# -*- coding: utf-8 -*-
# This file is part of beets.
# Copyright 2016, Adrian Sampson.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
"""Allows inline path template customization code in the config file.
"""
from __future__ import division, absolute_import, print_function
import traceback
import itertools
from beets.plugins import BeetsPlugin
from beets import config
FUNC_NAME = u'__INLINE_FUNC__'
class InlineError(Exception):
"""Raised when a runtime error occurs in an inline expression.
"""
def __init__(self, code, exc):
super(InlineError, self).__init__(
(u"error in inline path field code:\n"
u"%s\n%s: %s") % (code, type(exc).__name__, unicode(exc))
)
def _compile_func(body):
"""Given Python code for a function body, return a compiled
callable that invokes that code.
"""
body = u'def {0}():\n {1}'.format(
FUNC_NAME,
body.replace('\n', '\n ')
)
code = compile(body, 'inline', 'exec')
env = {}
eval(code, env)
return env[FUNC_NAME]
class InlinePlugin(BeetsPlugin):
def __init__(self):
super(InlinePlugin, self).__init__()
config.add({
'pathfields': {}, # Legacy name.
'item_fields': {},
'album_fields': {},
})
# Item fields.
for key, view in itertools.chain(config['item_fields'].items(),
config['pathfields'].items()):
self._log.debug(u'adding item field {0}', key)
func = self.compile_inline(view.get(unicode), False)
if func is not None:
self.template_fields[key] = func
# Album fields.
for key, view in config['album_fields'].items():
self._log.debug(u'adding album field {0}', key)
func = self.compile_inline(view.get(unicode), True)
if func is not None:
self.album_template_fields[key] = func
def compile_inline(self, python_code, album):
"""Given a Python expression or function body, compile it as a path
field function. The returned function takes a single argument, an
Item, and returns a Unicode string. If the expression cannot be
compiled, then an error is logged and this function returns None.
"""
# First, try compiling as a single function.
try:
code = compile(u'({0})'.format(python_code), 'inline', 'eval')
except SyntaxError:
# Fall back to a function body.
try:
func = _compile_func(python_code)
except SyntaxError:
self._log.error(u'syntax error in inline field definition:\n'
u'{0}', traceback.format_exc())
return
else:
is_expr = False
else:
is_expr = True
def _dict_for(obj):
out = dict(obj)
if album:
out['items'] = list(obj.items())
return out
if is_expr:
# For expressions, just evaluate and return the result.
def _expr_func(obj):
values = _dict_for(obj)
try:
return eval(code, values)
except Exception as exc:
raise InlineError(python_code, exc)
return _expr_func
else:
# For function bodies, invoke the function with values as global
# variables.
def _func_func(obj):
func.__globals__.update(_dict_for(obj))
try:
return func()
except Exception as exc:
raise InlineError(python_code, exc)
return _func_func
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