| from types import UnicodeType |
| |
| def gqn(val): |
| """ |
| The geographic quote name function; used for quoting tables and |
| geometries (they use single rather than the double quotes of the |
| backend quotename function). |
| """ |
| if isinstance(val, basestring): |
| if isinstance(val, UnicodeType): val = val.encode('ascii') |
| return "'%s'" % val |
| else: |
| return str(val) |
| |
| class SpatialOperation(object): |
| """ |
| Base class for generating spatial SQL. |
| """ |
| def __init__(self, function='', operator='', result='', beg_subst='', end_subst=''): |
| self.function = function |
| self.operator = operator |
| self.result = result |
| self.beg_subst = beg_subst |
| try: |
| # Try and put the operator and result into to the |
| # end substitution. |
| self.end_subst = end_subst % (operator, result) |
| except TypeError: |
| self.end_subst = end_subst |
| |
| @property |
| def sql_subst(self): |
| return ''.join([self.beg_subst, self.end_subst]) |
| |
| def as_sql(self, geo_col): |
| return self.sql_subst % self.params(geo_col) |
| |
| def params(self, geo_col): |
| return (geo_col, self.operator) |
| |
| class SpatialFunction(SpatialOperation): |
| """ |
| Base class for generating spatial SQL related to a function. |
| """ |
| def __init__(self, func, beg_subst='%s(%s, %%s', end_subst=')', result='', operator=''): |
| # Getting the function prefix. |
| kwargs = {'function' : func, 'operator' : operator, 'result' : result, |
| 'beg_subst' : beg_subst, 'end_subst' : end_subst,} |
| super(SpatialFunction, self).__init__(**kwargs) |
| |
| def params(self, geo_col): |
| return (self.function, geo_col) |
