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1 from types import UnicodeType |
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2 |
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3 def gqn(val): |
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4 """ |
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5 The geographic quote name function; used for quoting tables and |
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6 geometries (they use single rather than the double quotes of the |
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7 backend quotename function). |
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8 """ |
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9 if isinstance(val, basestring): |
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10 if isinstance(val, UnicodeType): val = val.encode('ascii') |
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11 return "'%s'" % val |
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12 else: |
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13 return str(val) |
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14 |
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15 class SpatialOperation(object): |
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16 """ |
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17 Base class for generating spatial SQL. |
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18 """ |
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19 def __init__(self, function='', operator='', result='', beg_subst='', end_subst=''): |
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20 self.function = function |
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21 self.operator = operator |
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22 self.result = result |
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23 self.beg_subst = beg_subst |
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24 try: |
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25 # Try and put the operator and result into to the |
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26 # end substitution. |
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27 self.end_subst = end_subst % (operator, result) |
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28 except TypeError: |
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29 self.end_subst = end_subst |
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30 |
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31 @property |
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32 def sql_subst(self): |
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33 return ''.join([self.beg_subst, self.end_subst]) |
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34 |
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35 def as_sql(self, geo_col): |
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36 return self.sql_subst % self.params(geo_col) |
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37 |
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38 def params(self, geo_col): |
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39 return (geo_col, self.operator) |
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40 |
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41 class SpatialFunction(SpatialOperation): |
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42 """ |
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43 Base class for generating spatial SQL related to a function. |
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44 """ |
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45 def __init__(self, func, beg_subst='%s(%s, %%s', end_subst=')', result='', operator=''): |
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46 # Getting the function prefix. |
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47 kwargs = {'function' : func, 'operator' : operator, 'result' : result, |
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48 'beg_subst' : beg_subst, 'end_subst' : end_subst,} |
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49 super(SpatialFunction, self).__init__(**kwargs) |
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50 |
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51 def params(self, geo_col): |
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52 return (self.function, geo_col) |