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89 lines
2.8 KiB
89 lines
2.8 KiB
class ColRef:
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def __init__(self, _ty, cobj, table:'TableInfo', name, id, compound = False):
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self.type = _ty
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self.cobj = cobj
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self.table = table
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self.name = name
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self.alias = set()
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self.id = id # position in table
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self.compound = compound # compound field (list as a field)
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# e.g. order by, group by, filter by expressions
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self.__arr__ = (_ty, cobj, table, name, id)
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def __getitem__(self, key):
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if type(key) is str:
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return getattr(self, key)
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else:
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return self.__arr__[key]
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def __setitem__(self, key, value):
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self.__arr__[key] = value
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class TableInfo:
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def __init__(self, table_name, cols, cxt:'Context'):
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# statics
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self.table_name = table_name
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self.alias = set([table_name])
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self.columns_byname = dict() # column_name, type
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self.columns = []
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self.cxt = cxt
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# keep track of temp vars
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self.rec = None
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self.add_cols(cols)
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# runtime
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self.order = [] # assumptions
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cxt.tables_byname[self.table_name] = self # construct reverse map
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def add_cols(self, cols, new = True):
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for i, c in enumerate(cols):
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self.add_col(c, new, i)
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def add_col(self, c, new = True, i = 0):
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_ty = c['type']
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if new:
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_ty = _ty if type(c) is ColRef else list(_ty.keys())[0]
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col_object = ColRef(_ty, c, self, c['name'], len(self.columns))
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else:
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col_object = c
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c.table = self
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self.columns_byname[c['name']] = col_object
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self.columns.append(col_object)
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def add_alias(self, alias):
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if alias in self.cxt.tables_byname.keys():
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print("Error: table alias already exists")
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return
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self.cxt.tables_byname[alias] = self
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self.alias.add(alias)
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def parse_col_names(self, colExpr) -> ColRef:
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parsedColExpr = colExpr.split('.')
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if len(parsedColExpr) <= 1:
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return self.columns_byname[colExpr]
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else:
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datasource = self.cxt.tables_byname[parsedColExpr[0]]
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if datasource is None:
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raise ValueError(f'Table name/alias not defined{parsedColExpr[0]}')
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else:
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return datasource.parse_col_names(parsedColExpr[1])
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class Context:
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def __init__(self):
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self.sql = ''
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self.tables_byname = dict()
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self.col_byname = dict()
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self.tables = []
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self.cols = []
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self.datasource = None
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self.udf_map = dict()
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def emit(self, sql:str):
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self.sql += sql + ' '
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def add_table(self, table_name, cols):
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tbl = TableInfo(table_name, cols, self)
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self.tables.append(tbl)
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return tbl
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