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126 lines
2.7 KiB
Elm
126 lines
2.7 KiB
Elm
module NoListLiteralsConcat exposing (rule)
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{-|
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@docs rule
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-}
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import Elm.Syntax.Expression as Expression exposing (Expression)
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import Elm.Syntax.Node as Node exposing (Node)
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import Elm.Syntax.Range exposing (Range)
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import Review.Rule as Rule exposing (Error, Rule)
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{-| Reports when an operation on lists could be simplified to a single literal list.
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config =
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[ NoListLiteralsConcat.rule
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]
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## Fail
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_ =
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[ 1, 2, 3 ] ++ [ 4, mysteryNumber, 6 ]
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_ =
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List.concat
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[ [ 1, 2, 3 ]
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, [ 4, mysteryNumber, 6 ]
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]
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_ =
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List.concat
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[ [ 1, 2, 3 ]
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]
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_ =
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1 :: [ 2, 3 ]
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_ =
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[] ++ list
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_ =
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list ++ []
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## Success
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_ =
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[ 1, 2, 3, 4, mysteryNumber, 6 ]
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_ =
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[ 1, 2, 3 ] ++ list ++ [ 4, mysteryNumber, 6 ]
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_ =
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List.concat
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[ [ 1, 2, 3 ]
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, list
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, [ 4, mysteryNumber, 6 ]
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]
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## Try it out
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You can try this rule out by running the following command:
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```bash
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elm-review --template jfmengels/elm-review-simplification/example --rules NoListLiteralsConcat
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```
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-}
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rule : Rule
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rule =
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Rule.newModuleRuleSchema "NoListLiteralsConcat" ()
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|> Rule.withSimpleExpressionVisitor expressionVisitor
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|> Rule.fromModuleRuleSchema
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error : Range -> Error {}
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error range =
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Rule.error
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{ message = "Expression could be simplified to be a single List"
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, details = [ "Try moving all the elements into a single list." ]
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}
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range
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expressionVisitor : Node Expression -> List (Error {})
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expressionVisitor node =
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case Node.value node of
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Expression.OperatorApplication "++" _ (Node.Node _ (Expression.ListExpr _)) (Node.Node _ (Expression.ListExpr _)) ->
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[ error (Node.range node) ]
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Expression.OperatorApplication "++" _ (Node.Node range (Expression.ListExpr [])) _ ->
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[ error range ]
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Expression.OperatorApplication "++" _ _ (Node.Node range (Expression.ListExpr [])) ->
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[ error range ]
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Expression.OperatorApplication "::" _ _ (Node.Node _ (Expression.ListExpr _)) ->
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[ error (Node.range node) ]
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Expression.Application [ Node.Node _ (Expression.FunctionOrValue [ "List" ] "concat"), Node.Node _ (Expression.ListExpr list) ] ->
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if List.length list < 2 then
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[ error (Node.range node) ]
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else if List.all isListLiteral list then
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[ error (Node.range node) ]
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else
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[]
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_ ->
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[]
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isListLiteral : Node Expression -> Bool
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isListLiteral node =
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case Node.value node of
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Expression.ListExpr _ ->
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True
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_ ->
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False
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