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aaronmk
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# SQL code generation
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import sql
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aaronmk
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import strings
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aaronmk
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import util
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aaronmk
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aaronmk
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##### SQL code objects
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aaronmk
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class Code:
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def to_str(self, db): raise NotImplemented()
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def __str__(self): return str(self.__dict__)
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aaronmk
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aaronmk
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class Literal(Code):
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def __init__(self, value): self.value = value
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def to_str(self, db): return db.esc_value(self.value)
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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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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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def as_Table(table):
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if table == None or isinstance(table, Table): return table
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elif isinstance(table, tuple):
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schema, table = table
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return Table(table, schema)
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else: return Table(table)
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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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class NamedCode(Code):
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def __init__(self, name, code):
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if not isinstance(code, Code): code = Literal(code)
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self.name = name
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self.code = code
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def to_str(self, db):
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return self.code.to_str(db)+' AS '+sql.esc_name(db, self.name)
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class ValueCond:
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def __init__(self, value):
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if not isinstance(value, Code): value = Literal(value)
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self.value = value
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def to_str(self, db, left_value):
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'''
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@param left_value The Code object that the condition is being applied on
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'''
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raise NotImplemented()
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def __str__(self): return str(self.__dict__)
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class CompareCond(ValueCond):
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def __init__(self, value, operator='='):
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aaronmk
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'''
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@param operator By default, compares NULL values literally. Use '~=' or
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'~!=' to pass NULLs through.
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'''
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ValueCond.__init__(self, value)
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self.operator = operator
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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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right_value = self.value
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left = left_value.to_str(db)
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right = right_value.to_str(db)
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# Parse operator
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operator = self.operator
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passthru_null_ref = [False]
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operator = strings.remove_prefix('~', operator, passthru_null_ref)
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neg_ref = [False]
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operator = strings.remove_prefix('!', operator, neg_ref)
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equals = operator.endswith('=')
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if equals and is_null(self.value): operator = 'IS'
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# Create str
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str_ = left+' '+operator+' '+right
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if equals and not passthru_null_ref[0] and isinstance(right_value, Col):
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str_ += ' OR ('+left+' IS NULL AND '+right+' IS NULL)'
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if neg_ref[0]: str_ = 'NOT ('+str_+')'
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return str_
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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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aaronmk
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##### Old-style format support
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def unescape_table(table):
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'''Currently only works with PostgreSQL.'''
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if table == None: return table
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assert table.count('.') <= 1
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parts = tuple((v.replace('"', '') for v in table.split('"."', 2)))
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if len(parts) == 1: parts, = parts
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return parts
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aaronmk
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def col2sql_gen(col, default_table=None, table_is_esc=False):
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'''Converts old-style (tuple-based) columns to sql_gen-compatible columns.
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@param table_is_esc If False, assumes any table name is not escaped or that
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re-escaping it will produce the same value.
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'''
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if isinstance(col, Col): return col # already in sql_gen form
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table = default_table
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if isinstance(col, tuple): table, col = col
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if table_is_esc: table = unescape_table(table)
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return Col(col, as_Table(table))
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def value2sql_gen(value, default_table=None, table_is_esc=False,
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assume_col=False):
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'''Converts old-style (tuple-based) values to sql_gen-compatible values.
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@param table_is_esc If False, assumes any table name is not escaped or that
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re-escaping it will produce the same value.
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'''
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if isinstance(value, Code): return value # already in sql_gen form
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is_tuple = isinstance(value, tuple)
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if is_tuple and len(value) == 1: return Literal(value[0])
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if is_tuple or (assume_col and util.is_str(value)):
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return col2sql_gen(value, default_table, table_is_esc)
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else: return Literal(value)
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def cond2sql_gen(value, default_table=None, table_is_esc=False):
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'''Converts old-style (tuple-based) conditions to sql_gen-compatible values.
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@param table_is_esc If False, assumes any table name is not escaped or that
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re-escaping it will produce the same value.
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'''
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if isinstance(value, ValueCond): return value # already in sql_gen form
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return as_ValueCond(value2sql_gen(value, default_table, table_is_esc))
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