# Copyright 2024 Adobe. All rights reserved.
# This file is licensed to you under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License. You may obtain a copy
# of the License at http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software distributed under
# the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
# OF ANY KIND, either express or implied. See the License for the specific language
# governing permissions and limitations under the License.
defmodule Styler.Style.SingleNode do
@moduledoc """
Simple 1-1 rewrites all crammed into one module to make for more efficient traversals
Credo Rules addressed:
* Credo.Check.Consistency.ParameterPatternMatching
* Credo.Check.Readability.LargeNumbers
* Credo.Check.Readability.ParenthesesOnZeroArityDefs
* Credo.Check.Readability.PreferImplicitTry
* Credo.Check.Readability.StringSigils
* Credo.Check.Readability.WithSingleClause
* Credo.Check.Refactor.CaseTrivialMatches
* Credo.Check.Refactor.CondStatements
* Credo.Check.Refactor.RedundantWithClauseResult
* Credo.Check.Refactor.WithClauses
"""
@behaviour Styler.Style
@closing_delimiters [~s|"|, ")", "}", "|", "]", "'", ">", "/"]
# `|> Timex.now()` => `|> Timex.now()`
# skip over pipes into `Timex.now/1` so that we don't accidentally rewrite it as DateTime.utc_now/1
def run({{:|>, _, [_, {{:., _, [{:__aliases__, _, [:Timex]}, :now]}, _, []}]}, _} = zipper, ctx),
do: {:skip, zipper, ctx}
def run({node, meta}, ctx), do: {:cont, {style(node), meta}, ctx}
defp style({:assert, meta, [{:!=, _, [x, {:__block__, _, [nil]}]}]}), do: style({:assert, meta, [x]})
# refute nilly -> assert
defp style({:refute, meta, [{:is_nil, _, [x]}]}), do: style({:assert, meta, [x]})
defp style({:refute, meta, [{:==, _, [x, {:__block__, _, [nil]}]}]}), do: style({:assert, meta, [x]})
# boolean ops and assert hurt my brain.
# the lone exception is `==` (... for now) ((uh, and the exception to the exception is when it's `== nil`, above))
defp style({:refute, meta, [{:!=, m, xy}]}), do: style({:assert, meta, [{:==, m, xy}]})
defp style({:refute, meta, [{:!==, m, xy}]}), do: style({:assert, meta, [{:===, m, xy}]})
defp style({:refute, meta, [{:<, m, xy}]}), do: style({:assert, meta, [{:>=, m, xy}]})
defp style({:refute, meta, [{:<=, m, xy}]}), do: style({:assert, meta, [{:>, m, xy}]})
defp style({:refute, meta, [{:>, m, xy}]}), do: style({:assert, meta, [{:<=, m, xy}]})
defp style({:refute, meta, [{:>=, m, xy}]}), do: style({:assert, meta, [{:<, m, xy}]})
for {a, inverted} <- [{:assert, :refute}, {:refute, :assert}] do
# invert negations
defp style({unquote(a), meta, [{n, _, [x]}]}) when n in [:!, :not], do: style({unquote(inverted), meta, [x]})
# assert Enum.member? -> assert in
defp style({unquote(a), meta, [{{:., _, [{:__aliases__, _, [:Enum]}, :member?]}, _, [enum, elem]}]}),
do: {unquote(a), meta, [{:in, [line: meta[:line]], [elem, enum]}]}
# assert Enum.find -> assert Enum.any?
defp style({unquote(a), meta, [{{:., a, [{:__aliases__, b, [:Enum]}, :find]}, c, [enum, fun]}]}),
do: style({unquote(a), meta, [{{:., a, [{:__aliases__, b, [:Enum]}, :any?]}, c, [enum, fun]}]})
# Enum.any?(x, & &1 == y) => y in x
defp style({unquote(a) = a, m, [{{:., _, [{:__aliases__, _, [:Enum]}, :any?]}, _, [y, fun]}]} = node) do
case fun do
# & &1 == x
{:&, _, [{:==, _, [{:&, _, [1]}, x]}]} -> {a, m, [{:in, [line: m[:line]], [x, y]}]}
# & x == &1
{:&, _, [{:==, _, [x, {:&, _, [1]}]}]} -> {a, m, [{:in, [line: m[:line]], [x, y]}]}
# fn var -> var == x
{:fn, _, [{:->, _, [[{var, _, nil}], {:==, _, [{var, _, nil}, x]}]}]} -> {a, m, [{:in, [line: m[:line]], [x, y]}]}
# fn var -> x == var
{:fn, _, [{:->, _, [[{var, _, nil}], {:==, _, [x, {var, _, nil}]}]}]} -> {a, m, [{:in, [line: m[:line]], [x, y]}]}
_ -> node
end
end
end
# rewrite double-quote strings with >= 4 escaped double-quotes as sigils
defp style({:__block__, [{:delimiter, ~s|"|} | meta], [string]} = node) when is_binary(string) do
# running a regex against every double-quote delimited string literal in a codebase doesn't have too much impact
# on adobe's internal codebase, but perhaps other codebases have way more literals where this'd have an impact?
if string =~ ~r/".*".*".*"/ do
# choose whichever delimiter would require the least # of escapes,
# ties being broken by our stylish ordering of delimiters (reflected in the 1-8 values)
{closer, _} =
string
|> String.codepoints()
|> Stream.filter(&(&1 in @closing_delimiters))
|> Stream.concat(@closing_delimiters)
|> Enum.frequencies()
|> Enum.min_by(fn
{"\"", count} -> {count, 1}
{")", count} -> {count, 2}
{"}", count} -> {count, 3}
{"|", count} -> {count, 4}
{"]", count} -> {count, 5}
{"'", count} -> {count, 6}
{">", count} -> {count, 7}
{"/", count} -> {count, 8}
end)
delimiter =
case closer do
")" -> "("
"}" -> "{"
"]" -> "["
">" -> "<"
closer -> closer
end
{:sigil_s, [{:delimiter, delimiter} | meta], [{:<<>>, [line: meta[:line]], [string]}, []]}
else
node
end
end
# Add / Correct `_` location in large numbers. Formatter handles large number (>5 digits) rewrites,
# but doesn't rewrite typos like `100_000_0`, so it's worthwhile to have Styler do this
#
# `?-` isn't part of the number node - it's its parent - so all numbers are positive at this point
defp style({:__block__, meta, [number]}) when is_number(number) and number >= 10_000 do
# Checking here rather than in the anonymous function due to compiler bug https://github.com/elixir-lang/elixir/issues/10485
integer? = is_integer(number)
meta =
Keyword.update!(meta, :token, fn
"0x" <> _ = token ->
token
"0b" <> _ = token ->
token
"0o" <> _ = token ->
token
token when integer? ->
delimit(token)
# is float
token ->
[int_token, decimals] = String.split(token, ".")
"#{delimit(int_token)}.#{decimals}"
end)
{:__block__, meta, [number]}
end
## INEFFICIENT FUNCTION REWRITES
# Keep in mind when rewriting a `/n::pos_integer` arity function here that it should also be added
# to the pipes rewriting rules, where it will appear as `/n-1`
# Enum.into(enum, empty_map[, ...]) => Map.new(enum[, ...])
defp style({{:., _, [{:__aliases__, _, [:Enum]}, :into]} = into, m, [enum, collectable | rest]} = node) do
if replacement = replace_into(into, collectable, rest), do: {replacement, m, [enum | rest]}, else: node
end
# lhs |> Enum.into(%{}, ...) => lhs |> Map.new(...)
defp style({:|>, meta, [lhs, {{:., _, [{_, _, [:Enum]}, :into]} = into, m, [collectable | rest]}]} = node) do
if replacement = replace_into(into, collectable, rest), do: {:|>, meta, [lhs, {replacement, m, rest}]}, else: node
end
for m <- [:Map, :Keyword] do
# lhs |> Map.merge(%{key: value}) => lhs |> Map.put(key, value)
defp style({:|>, pm, [lhs, {{:., dm, [{_, _, [unquote(m)]} = module, :merge]}, m, [{:%{}, _, [{key, value}]}]}]}),
do: {:|>, pm, [lhs, {{:., dm, [module, :put]}, m, [key, value]}]}
# lhs |> Map.merge(key: value) => lhs |> Map.put(:key, value)
defp style({:|>, pm, [lhs, {{:., dm, [{_, _, [unquote(m)]} = module, :merge]}, m, [[{key, value}]]}]}),
do: {:|>, pm, [lhs, {{:., dm, [module, :put]}, m, [key, value]}]}
# Map.merge(foo, %{one_key: :bar}) => Map.put(foo, :one_key, :bar)
defp style({{:., dm, [{_, _, [unquote(m)]} = module, :merge]}, m, [lhs, {:%{}, _, [{key, value}]}]}),
do: {{:., dm, [module, :put]}, m, [lhs, key, value]}
# Map.merge(foo, one_key: :bar) => Map.put(foo, :one_key, :bar)
defp style({{:., dm, [{_, _, [unquote(m)]} = module, :merge]}, m, [lhs, [{key, value}]]}),
do: {{:., dm, [module, :put]}, m, [lhs, key, value]}
# (lhs |>) Map.drop([key]) => Map.delete(key)
defp style({{:., dm, [{_, _, [unquote(m)]} = module, :drop]}, m, [{:__block__, _, [[{op, _, _} = key]]}]})
when op != :|,
do: {{:., dm, [module, :delete]}, m, [key]}
# Map.drop(foo, [one_key]) => Map.delete(foo, one_key)
defp style({{:., dm, [{_, _, [unquote(m)]} = module, :drop]}, m, [lhs, {:__block__, _, [[{op, _, _} = key]]}]})
when op != :|,
do: {{:., dm, [module, :delete]}, m, [lhs, key]}
end
# Timex.now() => DateTime.utc_now()
defp style({{:., dm, [{:__aliases__, am, [:Timex]}, :now]}, funm, []}),
do: {{:., dm, [{:__aliases__, am, [:DateTime]}, :utc_now]}, funm, []}
# {DateTime,NaiveDateTime,Time,Date}.compare(a, b) == :lt => {DateTime,NaiveDateTime,Time,Date}.before?(a, b)
# {DateTime,NaiveDateTime,Time,Date}.compare(a, b) == :gt => {DateTime,NaiveDateTime,Time,Date}.after?(a, b)
defp style({:==, _, [{{:., dm, [{:__aliases__, am, [mod]}, :compare]}, funm, args}, {:__block__, _, [result]}]})
when mod in ~w[DateTime NaiveDateTime Time Date]a and result in [:lt, :gt] do
fun = if result == :lt, do: :before?, else: :after?
{{:., dm, [{:__aliases__, am, [mod]}, fun]}, funm, args}
end
# Remove parens from 0 arity funs (Credo.Check.Readability.ParenthesesOnZeroArityDefs)
defp style({def, dm, [{fun, funm, []} | rest]}) when def in ~w(def defp)a and is_atom(fun),
do: style({def, dm, [{fun, Keyword.delete(funm, :closing), nil} | rest]})
# `Credo.Check.Readability.PreferImplicitTry`
defp style({def, dm, [head, [{_, {:try, _, [try_children]}}]]}) when def in ~w(def defp)a,
do: style({def, dm, [head, try_children]})
defp style({def, dm, [{fun, funm, params} | rest]}) when def in ~w(def defp)a,
do: {def, dm, [{fun, funm, put_matches_on_right(params)} | rest]}
# `Enum.reverse(foo) ++ bar` => `Enum.reverse(foo, bar)`
defp style({:++, _, [{{:., _, [{_, _, [:Enum]}, :reverse]} = reverse, r_meta, [lhs]}, rhs]}),
do: {reverse, r_meta, [lhs, rhs]}
# ARROW REWRITES
# `with`, `for` left arrow - if only we could write something this trivial for `->`!
defp style({:<-, cm, [lhs, rhs]}), do: {:<-, cm, [put_matches_on_right(lhs), rhs]}
# there's complexity to `:->` due to `cond` also utilizing the symbol but with different semantics.
# thus, we have to have a clause for each place that `:->` can show up
# `with` elses
defp style({{:__block__, _, [:else]} = else_, arrows}), do: {else_, rewrite_arrows(arrows)}
defp style({:case, cm, [head, [{do_, arrows}]]}), do: {:case, cm, [head, [{do_, rewrite_arrows(arrows)}]]}
defp style({:fn, m, arrows}), do: {:fn, m, rewrite_arrows(arrows)}
defp style({:to_timeout, m, [[_ | _] = args]}), do: {:to_timeout, m, [Enum.map(args, &style_to_timeout_arg/1)]}
defp style(node), do: node
# 1. convert plurals to singulars (`minutes` -> `minute`)
# 2. upgrade values, eg `minute: 5 * 60` -> `hour: 5` and `minute: 60` -> `hour: 1`
defp style_to_timeout_arg({{:__block__, m, [unit]}, value}) do
{unit, step, next_unit} =
case unit do
:day -> {:day, 7, :week}
:days -> {:day, 7, :week}
:hour -> {:hour, 24, :day}
:hours -> {:hour, 24, :day}
:millisecond -> {:millisecond, 1000, :second}
:milliseconds -> {:millisecond, 1000, :second}
:minute -> {:minute, 60, :hour}
:minutes -> {:minute, 60, :hour}
:second -> {:second, 60, :minute}
:seconds -> {:second, 60, :minute}
:week -> {:week, :"$no_next_step", nil}
:weeks -> {:week, :"$no_next_step", nil}
unit -> {unit, :"$no_next_step", nil}
end
{unit, value} =
case value do
# minute: 60 -> hours: 1
{:__block__, tm, [^step]} ->
{next_unit, {:__block__, [token: "1", line: tm[:line]], [1]}}
# minute: 60 * rhs -> hours: rhs
{:*, _, [{_, _, [^step]}, rhs]} ->
{{_, _, [next_unit]}, value} = style_to_timeout_arg({{:__block__, m, [next_unit]}, rhs})
{next_unit, value}
# minute: lhs * 60 -> hours: lhs
{:*, _, [lhs, {_, _, [^step]}]} ->
{{_, _, [next_unit]}, value} = style_to_timeout_arg({{:__block__, m, [next_unit]}, lhs})
{next_unit, value}
value ->
{unit, value}
end
{{:__block__, m, [unit]}, value}
end
defp style_to_timeout_arg(other), do: other
defp replace_into({:., dm, [{_, am, _} = enum, _]}, collectable, rest) do
case collectable do
{{:., _, [{_, _, [mod]}, :new]}, _, []} when mod in ~w(Map Keyword MapSet)a ->
{:., dm, [{:__aliases__, am, [mod]}, :new]}
{:%{}, _, []} ->
{:., dm, [{:__aliases__, am, [:Map]}, :new]}
{:__block__, _, [[]]} ->
if Enum.empty?(rest), do: {:., dm, [enum, :to_list]}, else: {:., dm, [enum, :map]}
_ ->
nil
end
end
defp rewrite_arrows(arrows) when is_list(arrows),
do: Enum.map(arrows, fn {:->, m, [lhs, rhs]} -> {:->, m, [put_matches_on_right(lhs), rhs]} end)
defp rewrite_arrows(macros_or_something_crazy_oh_no_abooort), do: macros_or_something_crazy_oh_no_abooort
defp put_matches_on_right(ast) do
Macro.prewalk(ast, fn
# `_ = var ->` => `var ->`
{:=, _, [{:_, _, nil}, var]} -> var
# `var = _ ->` => `var ->`
{:=, _, [var, {:_, _, nil}]} -> var
# `var = *match*` -> `*match -> var`
{:=, m, [{_, _, nil} = var, match]} -> {:=, m, [match, var]}
node -> node
end)
end
defp delimit(token), do: token |> String.to_charlist() |> remove_underscores([]) |> add_underscores([])
defp remove_underscores([?_ | rest], acc), do: remove_underscores(rest, acc)
defp remove_underscores([digit | rest], acc), do: remove_underscores(rest, [digit | acc])
defp remove_underscores([], reversed_list), do: reversed_list
defp add_underscores([a, b, c, d | rest], acc), do: add_underscores([d | rest], [?_, c, b, a | acc])
defp add_underscores(reversed_list, acc), do: reversed_list |> Enum.reverse(acc) |> to_string()
end
