elm-review/tests/NoListLiteralsConcat.elm
2020-06-25 22:57:31 +02:00

118 lines
2.6 KiB
Elm

module NoListLiteralsConcat exposing (rule)
{-|
@docs rule
-}
import Elm.Syntax.Expression as Expression exposing (Expression)
import Elm.Syntax.Node as Node exposing (Node)
import Elm.Syntax.Range exposing (Range)
import Review.Rule as Rule exposing (Error, Rule)
import Review.Rule3 as Rule3
{-| Reports when an operation on lists could be simplified to a single literal list.
config =
[ NoListLiteralsConcat.rule
]
## Fail
_ =
[ 1, 2, 3 ] ++ [ 4, mysteryNumber, 6 ]
_ =
List.concat
[ [ 1, 2, 3 ]
, [ 4, mysteryNumber, 6 ]
]
_ =
List.concat
[ [ 1, 2, 3 ]
]
_ =
1 :: [ 2, 3 ]
_ =
[] ++ list
_ =
list ++ []
## Success
_ =
[ 1, 2, 3, 4, mysteryNumber, 6 ]
_ =
[ 1, 2, 3 ] ++ list ++ [ 4, mysteryNumber, 6 ]
_ =
List.concat
[ [ 1, 2, 3 ]
, list
, [ 4, mysteryNumber, 6 ]
]
-}
rule : Rule
rule =
Rule3.newModuleRuleSchema "NoListLiteralsConcat" ()
|> Rule3.withSimpleExpressionVisitor expressionVisitor
|> Rule3.fromModuleRuleSchema
error : Range -> Error {}
error range =
Rule.error
{ message = "Expression could be simplified to be a single List"
, details = [ "Try moving all the elements into a single list." ]
}
range
expressionVisitor : Node Expression -> List (Error {})
expressionVisitor node =
case Node.value node of
Expression.OperatorApplication "++" _ (Node.Node _ (Expression.ListExpr _)) (Node.Node _ (Expression.ListExpr _)) ->
[ error (Node.range node) ]
Expression.OperatorApplication "++" _ (Node.Node range (Expression.ListExpr [])) _ ->
[ error range ]
Expression.OperatorApplication "++" _ _ (Node.Node range (Expression.ListExpr [])) ->
[ error range ]
Expression.OperatorApplication "::" _ _ (Node.Node _ (Expression.ListExpr _)) ->
[ error (Node.range node) ]
Expression.Application [ Node.Node _ (Expression.FunctionOrValue [ "List" ] "concat"), Node.Node _ (Expression.ListExpr list) ] ->
if List.length list < 2 then
[ error (Node.range node) ]
else if List.all isListLiteral list then
[ error (Node.range node) ]
else
[]
_ ->
[]
isListLiteral : Node Expression -> Bool
isListLiteral node =
case Node.value node of
Expression.ListExpr _ ->
True
_ ->
False