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aaronmk
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# SQL code generation
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import sql
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class Code:
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def to_str(self, db): raise NotImplemented()
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2216
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aaronmk
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class Literal(Code):
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2211
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aaronmk
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def __init__(self, value): self.value = value
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2213
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aaronmk
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def to_str(self, db): return db.esc_value(self.value)
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2211
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aaronmk
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2216
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aaronmk
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def is_null(value): return isinstance(value, Literal) and value.value == None
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2211
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aaronmk
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class Table(Code):
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def __init__(self, name, schema=None):
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'''
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@param schema str|None (for no schema)
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'''
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self.name = name
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self.schema = schema
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def to_str(self, db): return sql.qual_name(db, self.schema, self.name)
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class Col(Code):
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def __init__(self, name, table=None):
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'''
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@param table Table|None (for no table)
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'''
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assert table == None or isinstance(table, Table)
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self.name = name
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self.table = table
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def to_str(self, db):
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str_ = ''
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if self.table != None: str_ += self.table.to_str(db)+'.'
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str_ += sql.esc_name(db, self.name)
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return str_
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2214
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aaronmk
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class ValueCond:
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2213
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aaronmk
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def __init__(self, value):
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if not isinstance(value, Literal): value = Literal(value)
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self.value = value
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2214
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aaronmk
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2216
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aaronmk
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def to_str(self, db, left_value):
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2214
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aaronmk
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'''
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2216
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aaronmk
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@param left_value The Code object that the condition is being applied on
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2214
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aaronmk
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'''
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raise NotImplemented()
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2211
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aaronmk
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class CompareCond(ValueCond):
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def __init__(self, value, operator='='):
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ValueCond.__init__(self, value)
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self.operator = operator
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2216
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aaronmk
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def to_str(self, db, left_value):
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if not isinstance(left_value, Code): left_value = Col(left_value)
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operator = self.operator
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if is_null(self.value): operator = 'IS'
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return left_value.to_str(db)+' '+operator+' '+self.value.to_str(db)
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def as_ValueCond(value):
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if not isinstance(value, ValueCond): return CompareCond(value)
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else: return value
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