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# -*- coding: utf-8 -*-
#
# Copyright (c) 2011-2013, Cédric Krier
# Copyright (c) 2011-2013, B2CK
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# * Neither the name of the <organization> nor the
# names of its contributors may be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
from sql import Expression, Flavor
__all__ = ['Case', 'Coalesce', 'NullIf', 'Greatest', 'Least']
class Conditional(Expression):
__slots__ = ()
_sql = ''
table = ''
name = ''
@staticmethod
def _format(value):
if isinstance(value, Expression):
return str(value)
else:
return Flavor().get().param
class Case(Conditional):
__slots__ = ('whens', 'else_')
def __init__(self, *whens, **kwargs):
self.whens = whens
self.else_ = kwargs.get('else_')
def __str__(self):
case = 'CASE '
for cond, result in self.whens:
case += 'WHEN %s THEN %s ' % (
self._format(cond), self._format(result))
if self.else_ is not None:
case += 'ELSE %s ' % self._format(self.else_)
case += 'END'
return case
@property
def params(self):
p = []
for cond, result in self.whens:
if isinstance(cond, Expression):
p.extend(cond.params)
else:
p.append(cond)
if isinstance(result, Expression):
p.extend(result.params)
else:
p.append(result)
if self.else_ is not None:
if isinstance(self.else_, Expression):
p.extend(self.else_.params)
else:
p.append(self.else_)
return tuple(p)
class Coalesce(Conditional):
__slots__ = ('values')
_conditional = 'COALESCE'
def __init__(self, *values):
self.values = values
def __str__(self):
return (self._conditional
+ '(' + ', '.join(map(self._format, self.values)) + ')')
@property
def params(self):
p = []
for value in self.values:
if isinstance(value, Expression):
p.extend(value.params)
else:
p.append(value)
return tuple(p)
class NullIf(Coalesce):
__slots__ = ()
_conditional = 'NULLIF'
class Greatest(Coalesce):
__slots__ = ()
_conditional = 'GREATEST'
class Least(Coalesce):
__slots__ = ()
_conditional = 'LEAST'
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