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Add field access simplification for if/then/else #40

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merged 3 commits into from
Sep 5, 2022
Merged

Add field access simplification for if/then/else #40

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8710d48
Add field access simplification for if/then/else, let/in and case/of
miniBill Aug 19, 2022
6aa4cee
Remove redundant pattern
miniBill Aug 21, 2022
b35b5c7
Only apply simplification if all branches are records, or if it's a l…
miniBill Sep 5, 2022
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125 changes: 90 additions & 35 deletions src/Simplify.elm
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Original file line number Diff line number Diff line change
Expand Up @@ -1375,8 +1375,14 @@ expressionVisitorHelp node context =
Expression.RecordUpdateExpression (Node recordNameRange _) setters ->
onlyErrors (recordAccessChecks (Node.range node) (Just recordNameRange) (Node.value field) setters)

Expression.LetExpression { expression } ->
onlyErrors (recordAccessLetInChecks (Node.range node) field expression)
Expression.LetExpression _ ->
onlyErrors (distributeFieldAccess True "a let/in" record field)

Expression.IfBlock _ _ _ ->
onlyErrors (distributeFieldAccess False "an if/then/else" record field)

Expression.CaseExpression _ ->
onlyErrors (distributeFieldAccess False "a case/of" record field)

_ ->
onlyErrors []
Expand All @@ -1385,6 +1391,88 @@ expressionVisitorHelp node context =
onlyErrors []


distributeFieldAccess : Bool -> String -> Node Expression -> Node String -> List (Error {})
distributeFieldAccess isLet kind ((Node recordRange _) as record) (Node fieldRange fieldName) =
case recordLeavesRanges record of
{ records, withoutParens, withParens } ->
if not (List.isEmpty withParens && List.isEmpty withoutParens) && not isLet then
[]

else
[ let
removalRange : Range
removalRange =
{ start = recordRange.end, end = fieldRange.end }
in
Rule.errorWithFix
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside " ++ kind ++ " expression can be simplified to access the field inside it" ]
}
removalRange
(Fix.removeRange removalRange
:: List.map
(\leafRange -> Fix.insertAt leafRange.end ("." ++ fieldName))
(withoutParens ++ records)
++ List.concatMap
(\leafRange ->
[ Fix.insertAt leafRange.start "("
, Fix.insertAt leafRange.end (")." ++ fieldName)
]
)
withParens
)
]


combineRecordLeavesRanges :
{ records : List Range, withoutParens : List Range, withParens : List Range }
-> { records : List Range, withoutParens : List Range, withParens : List Range }
-> { records : List Range, withoutParens : List Range, withParens : List Range }
combineRecordLeavesRanges left right =
{ records = left.records ++ right.records
, withoutParens = left.withoutParens ++ right.withoutParens
, withParens = left.withParens ++ right.withParens
}


recordLeavesRanges :
Node Expression
-> { records : List Range, withoutParens : List Range, withParens : List Range }
recordLeavesRanges (Node range expr) =
case expr of
Expression.IfBlock _ thenNode elseNode ->
combineRecordLeavesRanges
(recordLeavesRanges thenNode)
(recordLeavesRanges elseNode)

Expression.LetExpression { expression } ->
recordLeavesRanges expression

Expression.ParenthesizedExpression child ->
recordLeavesRanges child

Expression.CaseExpression { cases } ->
List.foldl
(\( _, e ) -> combineRecordLeavesRanges (recordLeavesRanges e))
{ records = [], withParens = [], withoutParens = [] }
cases

Expression.RecordExpr _ ->
{ records = [ range ], withParens = [], withoutParens = [] }

Expression.RecordAccess _ _ ->
{ records = [], withParens = [], withoutParens = [ range ] }

Expression.RecordUpdateExpression _ _ ->
{ records = [ range ], withParens = [], withoutParens = [] }

Expression.FunctionOrValue _ _ ->
{ records = [], withParens = [], withoutParens = [ range ] }

_ ->
{ records = [], withParens = [ range ], withoutParens = [] }


recordAccessChecks : Range -> Maybe Range -> String -> List (Node RecordSetter) -> List (Error {})
recordAccessChecks nodeRange recordNameRange fieldName setters =
case
Expand Down Expand Up @@ -1465,39 +1553,6 @@ needsParens expr =
False


recordAccessLetInChecks : Range -> Node String -> Node Expression -> List (Error {})
recordAccessLetInChecks nodeRange (Node fieldRange fieldName) expr =
let
fieldRangeStart : Location
fieldRangeStart =
fieldRange.start

fieldRemovalFix : Fix
fieldRemovalFix =
Fix.removeRange
{ start = { row = fieldRangeStart.row, column = fieldRangeStart.column - 1 }
, end = fieldRange.end
}
in
[ Rule.errorWithFix
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside a let expression can be simplified to access the field inside it" ]
}
nodeRange
(if needsParens (Node.value expr) then
[ Fix.insertAt (Node.range expr).start "("
, Fix.insertAt (Node.range expr).end (")." ++ fieldName)
, fieldRemovalFix
]

else
[ Fix.insertAt (Node.range expr).end ("." ++ fieldName)
, fieldRemovalFix
]
)
]


type alias CheckInfo =
{ lookupTable : ModuleNameLookupTable
, inferredConstants : ( Infer.Inferred, List Infer.Inferred )
Expand Down
115 changes: 103 additions & 12 deletions tests/SimplifyTest.elm
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Original file line number Diff line number Diff line change
Expand Up @@ -10443,49 +10443,81 @@ a = d.c
, test "should simplify record accesses for let/in expressions" <|
\() ->
"""module A exposing (..)
a = (let b = c in { e = 3 }).e
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"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside a let/in expression can be simplified to access the field inside it" ]
, under = ".e"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (let b = c in { e = 3 }.e)
"""
]
, test "should simplify record accesses for let/in expressions, even if the leaf is not a record expression" <|
\() ->
"""module A exposing (..)
a = (let b = c in f x).e
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside a let expression can be simplified to access the field inside it" ]
, under = "(let b = c in f x).e"
, details = [ "Accessing the field outside a let/in expression can be simplified to access the field inside it" ]
, under = ".e"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (let b = c in (f x).e)
"""
]
, test "should simplify record accesses for let/in expressions, even if the leaf is not a record expression, without adding unnecessary parentheses" <|
\() ->
"""module A exposing (..)
a = (let b = c in x).e
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside a let/in expression can be simplified to access the field inside it" ]
, under = ".e"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (let b = c in x.e)
"""
]
, test "should simplify record accesses for let/in expressions in parentheses" <|
\() ->
"""module A exposing (..)
a = (((let b = c in f x))).e
a = (((let b = c in {e = 2}))).e
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside a let expression can be simplified to access the field inside it" ]
, under = "(((let b = c in f x))).e"
, details = [ "Accessing the field outside a let/in expression can be simplified to access the field inside it" ]
, under = ".e"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (((let b = c in (f x).e)))
a = (((let b = c in {e = 2}.e)))
"""
]
, test "should simplify nested record accesses for let/in expressions (inner)" <|
\() ->
"""module A exposing (..)
a = (let b = c in f x).e.f
a = (let b = c in { e = { f = 2 } }).e.f
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside a let expression can be simplified to access the field inside it" ]
, under = "(let b = c in f x).e"
, details = [ "Accessing the field outside a let/in expression can be simplified to access the field inside it" ]
, under = ".e"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (let b = c in (f x).e).f
a = (let b = c in { e = { f = 2 } }.e).f
"""
]
, test "should simplify nested record accesses for let/in expressions (outer)" <|
Expand All @@ -10497,11 +10529,70 @@ a = (let b = c in (f x).e).f
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside a let expression can be simplified to access the field inside it" ]
, under = "(let b = c in (f x).e).f"
, details = [ "Accessing the field outside a let/in expression can be simplified to access the field inside it" ]
, under = ".f"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (let b = c in (f x).e.f)
"""
]
, test "should simplify record accesses for if/then/else expressions" <|
\() ->
"""module A exposing (..)
a = (if x then { f = 3 } else { z | f = 3 }).f
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside an if/then/else expression can be simplified to access the field inside it" ]
, under = ".f"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (if x then { f = 3 }.f else { z | f = 3 }.f)
"""
]
, test "should not simplify record accesses if some branches are not records" <|
\() ->
"""module A exposing (..)
a = (if x then a else { f = 3 }).f
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectNoErrors
, test "should simplify record accesses for nested if/then/else expressions" <|
\() ->
"""module A exposing (..)
a = (if x then { f = 3 } else if y then { z | f = 4 } else { z | f = 3 }).f
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside an if/then/else expression can be simplified to access the field inside it" ]
, under = ".f"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (if x then { f = 3 }.f else if y then { z | f = 4 }.f else { z | f = 3 }.f)
"""
]
, test "should simplify record accesses for mixed if/then/else and case expressions" <|
\() ->
"""module A exposing (..)
a = (if x then { f = 3 } else if y then {f = 2} else
case b of Nothing -> { f = 4 }
Just _ -> { f = 5 }).f
"""
|> Review.Test.run (rule defaults)
|> Review.Test.expectErrors
[ Review.Test.error
{ message = "Field access can be simplified"
, details = [ "Accessing the field outside an if/then/else expression can be simplified to access the field inside it" ]
, under = ".f"
}
|> Review.Test.whenFixed """module A exposing (..)
a = (if x then { f = 3 }.f else if y then {f = 2}.f else
case b of Nothing -> { f = 4 }.f
Just _ -> { f = 5 }.f)
"""
]
]