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121 lines
3.5 KiB
Elm
121 lines
3.5 KiB
Elm
module NoNegationInIfCondition 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.Fix as Fix
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import Review.Rule as Rule exposing (Rule)
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{-| Reports when negations are used in
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config =
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[ NoNegationInIfCondition.rule
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]
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## Fail
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a =
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if not condition then
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1
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else
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2
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## Success
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a =
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if condition then
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1
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else
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2
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## When (not) to enable this rule
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This rule is not meant to be published. It is primarily meant to be a test rule for `withSourceCodeExtractor` and
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an example for its usage.
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I don't think it's a good rule to enforce, and I personally like to put the "happy" path/branch first,
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instead of the non-negated one. As such, I have left this rule incomplete meaning there are more cases that should be
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handled for this rule to do what it is meant to do.
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-}
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rule : Rule
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rule =
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Rule.newModuleRuleSchemaUsingContextCreator "NoNegationInIfCondition" initialContext
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|> Rule.withExpressionEnterVisitor expressionVisitor
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|> Rule.providesFixesForModuleRule
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|> Rule.fromModuleRuleSchema
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type alias Context =
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{ extractSourceCode : Range -> String
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}
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initialContext : Rule.ContextCreator () Context
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initialContext =
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Rule.initContextCreator
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(\extractSourceCode () -> { extractSourceCode = extractSourceCode })
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|> Rule.withSourceCodeExtractor
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expressionVisitor : Node Expression -> Context -> ( List (Rule.Error {}), Context )
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expressionVisitor node context =
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case Node.value node of
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Expression.IfBlock condition thenBranch elseBranch ->
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case Node.value condition of
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Expression.Application ((Node notRange (Expression.FunctionOrValue [] "not")) :: _) ->
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if isIfExpr elseBranch then
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( [], context )
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else
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let
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elseKeywordString : String
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elseKeywordString =
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context.extractSourceCode { start = (Node.range thenBranch).end, end = (Node.range elseBranch).start }
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in
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( [ Rule.errorWithFix
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{ message = "Don't use if expressions with negated conditions"
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, details = [ "We at fruits.com think that if expressions are more readable when the condition is not negated." ]
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}
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notRange
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[ Fix.removeRange notRange
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, Fix.removeRange { start = (Node.range thenBranch).start, end = (Node.range elseBranch).start }
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, Fix.insertAt
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(Node.range elseBranch).end
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(elseKeywordString ++ context.extractSourceCode (Node.range thenBranch))
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]
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]
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, context
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)
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_ ->
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( [], context )
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_ ->
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( [], context )
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isIfExpr : Node Expression -> Bool
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isIfExpr node =
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case Node.value node of
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Expression.ParenthesizedExpression expr ->
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isIfExpr expr
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Expression.IfBlock _ _ _ ->
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True
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_ ->
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False
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