50 lines
1.4 KiB
OCaml
50 lines
1.4 KiB
OCaml
type logical_plan =
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| Project of logical_plan option * string list
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| Scan of string (* Table name *)
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| Filter of logical_plan
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| Join of logical_plan * Ast.join_type * logical_plan
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| Group of logical_plan * string list
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let rec ast_to_logical ast =
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match ast with
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| Ast.Select(cols, table_exp) -> Project((table_expression_to_logical table_exp), (columns_to_logical cols))
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| _ -> failwith "Query not supported yet"
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and table_expression_to_logical table_exp =
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match table_exp with
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| Ast.TableExpression(tables, None, None) -> tables_to_logical tables
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| _ -> failwith "Table expression not supported yet"
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and columns_to_logical columns =
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let rec aux cols acc =
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match cols with
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| [] -> acc
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| Ast.Column(col,_)::l ->
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let s = expression_to_logical col in
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aux l (s::acc)
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| _ -> failwith "Not supported"
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in
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aux columns []
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and expression_to_logical exp =
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match exp with
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| Ast.Ref(s) -> s
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| Ast.StringLiteral(s) -> s
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| _ -> failwith "Expression not supported yet"
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and tables_to_logical tables =
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let aux t =
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match t with
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| [] -> None
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| [Ast.Table(table_name)] -> Some(Scan(table_name))
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| _ -> failwith "tables not supported"
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in
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match tables with
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| None -> None
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| Some(t) -> aux t
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let pp_logical_plan plan =
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match plan with
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| Project(_, name) -> (String.concat ";" name)
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| _ -> "Not supported"
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