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"""
A collection of utility routines and classes used by the spatial
backends.
"""
class SpatialOperation(object):
"""
Base class for generating spatial SQL.
"""
sql_template = '%(geo_col)s %(operator)s %(geometry)s'
def __init__(self, function='', operator='', result='', **kwargs):
self.function = function
self.operator = operator
self.result = result
self.extra = kwargs
def as_sql(self, geo_col, geometry='%s'):
return self.sql_template % self.params(geo_col, geometry), []
def params(self, geo_col, geometry):
params = {'function': self.function,
'geo_col': geo_col,
'geometry': geometry,
'operator': self.operator,
'result': self.result,
}
params.update(self.extra)
return params
class SpatialFunction(SpatialOperation):
"""
Base class for generating spatial SQL related to a function.
"""
sql_template = '%(function)s(%(geo_col)s, %(geometry)s)'
def __init__(self, func, result='', operator='', **kwargs):
# Getting the function prefix.
default = {'function': func,
'operator': operator,
'result': result
}
kwargs.update(default)
super(SpatialFunction, self).__init__(**kwargs)
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