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add max_function_clause_length rule
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bormilan committed Oct 7, 2024
1 parent d1f2eaf commit ffb754f
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1 change: 1 addition & 0 deletions RULES.md
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Expand Up @@ -26,6 +26,7 @@ identified with `(since ...)` for convenience purposes.
- [Max Anonymous Function Arity](doc_rules/elvis_style/max_anonymous_function_arity.md)
- [Max Function Arity](doc_rules/elvis_style/max_function_arity.md)
- [Max Function Length](doc_rules/elvis_style/max_function_length.md)
- [Max Function Clause Length](doc_rules/elvis_style/max_function_clause_length.md)
- [Max Module Length](doc_rules/elvis_style/max_module_length.md)
- [Module Naming Convention](doc_rules/elvis_style/module_naming_convention.md)
- [Nesting Level](doc_rules/elvis_style/nesting_level.md)
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1 change: 1 addition & 0 deletions Untitled
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tyl
27 changes: 27 additions & 0 deletions doc_rules/elvis_style/max_function_clause_length.md
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# Max Function Clause Length

This specifies an upper bound on function clause **line** length. Lines that are comments and/or whitespace
can be either included or excluded from the line count.

> Works on `.beam` file? Not really! (it consumes results Ok, but these might be unexpected, since
the files are pre-processed)

## Options

- `max_length :: non_neg_integer()`.
- default: `30`.
- `count_comments :: boolean()`
- default: `false`
- `count_whitespace :: boolean()`
- default: `false`

## Example

```erlang
{elvis_style, max_function_clause_length}
%% or
{elvis_style, max_function_clause_length, #{ max_length => 30
, count_comments => false
, count_whitespace => false
}}
```
1 change: 1 addition & 0 deletions src/elvis_rulesets.erl
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Expand Up @@ -93,6 +93,7 @@ rules(erl_files_strict) ->
|| Rule
<- [always_shortcircuit,
consistent_generic_type,
max_function_clause_length,
max_function_length,
max_module_length,
no_call,
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87 changes: 85 additions & 2 deletions src/elvis_style.erl
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Expand Up @@ -7,8 +7,8 @@
invalid_dynamic_call/3, used_ignored_variable/3, no_behavior_info/3,
module_naming_convention/3, state_record_and_type/3, no_spec_with_records/3,
dont_repeat_yourself/3, max_module_length/3, max_anonymous_function_arity/3,
max_function_arity/3, max_function_length/3, no_call/3, no_debug_call/3,
no_common_caveats_call/3, no_nested_try_catch/3, no_successive_maps/3,
max_function_arity/3, max_function_length/3, max_function_clause_length/3, no_call/3,
no_debug_call/3, no_common_caveats_call/3, no_nested_try_catch/3, no_successive_maps/3,
atom_naming_convention/3, no_throw/3, no_dollar_space/3, no_author/3, no_import/3,
no_catch_expressions/3, no_single_clause_case/3, numeric_format/3, behaviour_spelling/3,
always_shortcircuit/3, consistent_generic_type/3, export_used_types/3,
Expand Down Expand Up @@ -96,6 +96,9 @@
-define(MAX_FUNCTION_LENGTH,
"The code for function ~p/~w has ~p lines which exceeds the "
"maximum of ~p.").
-define(MAX_FUNCTION_CLAUSE_LENGTH,
"The code for the ~ts clause of function ~p/~w has ~p lines which exceeds the "
"maximum of ~p.").
-define(NO_CALL_MSG, "The call to ~p:~p/~p on line ~p is in the no_call list.").
-define(NO_DEBUG_CALL_MSG, "Remove the debug call to ~p:~p/~p on line ~p.").
-define(NO_COMMON_CAVEATS_CALL_MSG,
Expand Down Expand Up @@ -190,6 +193,10 @@ default(max_function_length) ->
#{max_length => 30,
count_comments => false,
count_whitespace => false};
default(max_function_clause_length) ->
#{max_length => 30,
count_comments => false,
count_whitespace => false};
default(no_call) ->
#{no_call_functions => []};
default(no_debug_call) ->
Expand Down Expand Up @@ -891,6 +898,82 @@ max_function_arity(Config, Target, RuleConfig) ->
end,
Functions).

-spec max_function_clause_length(elvis_config:config(),
elvis_file:file(),
max_function_length_config()) ->
[elvis_result:item()].
max_function_clause_length(Config, Target, RuleConfig) ->
MaxLength = option(max_length, RuleConfig, max_function_length),
CountComments = option(count_comments, RuleConfig, max_function_length),
CountWhitespace = option(count_whitespace, RuleConfig, max_function_length),

Root = get_root(Config, Target, RuleConfig),
{Src, _} = elvis_file:src(Target),
Lines = elvis_utils:split_all_lines(Src, [trim]),

IsFunction = fun(Node) -> ktn_code:type(Node) == function end,
Functions0 = elvis_code:find(IsFunction, Root),

% clause
FilterClause =
fun(Line) ->
(CountComments orelse not line_is_comment(Line))
andalso (CountWhitespace orelse not line_is_whitespace(Line))
end,

PairClause =
fun(ClauseNode, {Result, PrevAccNum}) ->
{Min, Max} = node_line_limits(ClauseNode),
FunLines = lists:sublist(Lines, Min, Max - Min + 1),
FilteredLines = lists:filter(FilterClause, FunLines),
L = length(FilteredLines),
AccNum = PrevAccNum + 1,
ClauseNumber = parse_clause_num(AccNum),
{[{Min, ClauseNumber, L} | Result], AccNum}
end,

% fun
PairFun =
fun(FunctionNode) ->
Name = ktn_code:attr(name, FunctionNode),
Arity = ktn_code:attr(arity, FunctionNode),

IsClause = fun(Node) -> ktn_code:type(Node) == clause end,
Clauses = elvis_code:find(IsClause, FunctionNode),

{ClauseLenInfos, _} = lists:foldl(PairClause, {[], 0}, Clauses),

[{Name, Arity, Min, StringClauseNumber, L}
|| {Min, StringClauseNumber, L} <- ClauseLenInfos]
end,

ClauseLenInfos =
lists:reverse(
lists:append(
lists:map(PairFun, Functions0))),

MaxLengthPred = fun({_, _, _, _, L}) -> L > MaxLength end,
ClauseLenMaxPairs = lists:filter(MaxLengthPred, ClauseLenInfos),

ResultFun =
fun({Name, Arity, StartPos, ClauseNumber, L}) ->
Info = [ClauseNumber, Name, Arity, L, MaxLength],
Msg = ?MAX_FUNCTION_CLAUSE_LENGTH,
elvis_result:new(item, Msg, Info, StartPos)
end,
lists:map(ResultFun, ClauseLenMaxPairs).

parse_clause_num(Num) when Num rem 100 >= 11, Num rem 100 =< 13 ->
integer_to_list(Num) ++ "th";
parse_clause_num(Num) when Num rem 10 == 1 ->
integer_to_list(Num) ++ "st";
parse_clause_num(Num) when Num rem 10 == 2 ->
integer_to_list(Num) ++ "nd";
parse_clause_num(Num) when Num rem 10 == 3 ->
integer_to_list(Num) ++ "rd";
parse_clause_num(Num) ->
integer_to_list(Num) ++ "th".

-spec max_function_length(elvis_config:config(),
elvis_file:file(),
max_function_length_config()) ->
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90 changes: 90 additions & 0 deletions test/examples/fail_max_function_clause_length.erl
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-module(fail_max_function_clause_length).

-export([f5/1, f6/1, f7/1]).

f5(a) -> %% 1
%% 2
%% 3

ok; %% 5

f5(b) -> %% 1
%% 2
%% 3
%% 4

%% 6
%% 7

%% 9



ok; %% 13

f5(c) -> %% 1
%% 2
%% 3
%% 4

%% 6
%% 7
%% 8
%% 9

%% 11
%% 12

%% 14
ok. %% 15

f6(d) -> %% 1
%% 2
%% 3
%% 4

%% 6
%% 7
%% 8
%% 9

%% 11
%% 12

%% 14
ok; %% 15

f6(e) -> %% 1
ok;
f6(f) -> %% 1
ok.

f7(a) -> 1;
f7(b) -> 2;
f7(c) -> 3;
f7(d) -> 4;
f7(e) -> 5;
f7(f) -> 6;
f7(aa) -> 7;
f7(bb) ->
8;
f7(cc) -> 9;
f7(dd) ->
10;
f7(ee) -> 11;
f7(ff) -> 12;
f7(aaa) -> 13;
f7(bbb) -> 14;
f7(ccc) -> 15;
f7(ddd) -> 16;
f7(eee) -> 17;
f7(fff) -> 18;
f7(aaaa) -> 19;
f7(bbbb) ->
20;
f7(cccc) -> 21;
f7(dddd) -> 22;
f7(eeee) -> 23;
f7(ffff) ->
24;
f7(aaaaa) -> 25.
50 changes: 50 additions & 0 deletions test/examples/function_clause_numbers.erl
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-module(function_clause_numbers).

-export([clause/1]).

clause(1) ->
"ok";
clause(2) -> "ok";
clause(3) -> "ok";
clause(4) -> "ok";
clause(5) ->
"ok";
clause(6) ->
"ok";
clause(7) ->
"ok";
clause(8) -> "ok";
clause(9) -> "ok";
clause(10) -> "ok";
clause(11) ->
"ok";
clause(12) -> "ok";
clause(13) ->
"ok";
clause(14) -> "ok";
clause(15) -> "ok";
clause(16) -> "ok";
clause(17) -> "ok";
clause(18) -> "ok";
clause(19) ->
"ok";
clause(20) ->
"ok";
clause(21) ->
"ok";
clause(22) -> "ok";
clause(23) -> "ok";
clause(24) -> "ok";
clause(25) -> "ok";
clause(26) -> "ok";
clause(27) -> "ok";
clause(28) -> "ok";
clause(29) ->
"ok";
clause(30) ->
"ok";
clause(31) ->
"ok";
clause(32) -> "ok";
clause(33) ->
"ok".
52 changes: 52 additions & 0 deletions test/examples/pass_max_function_clause_length.erl
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-module(pass_max_function_clause_length).

-export([f5/1]).
f5(a) -> %% 1
%% 2
%% 3

ok; %% 5

f5(b) -> %% 1
%% 2
%% 3
%% 4

%% 6
%% 7

%% 9
ok; %% 10

f5(c) -> %% 1
%% 2
%% 3
%% 4

%% 6
%% 7
%% 8
%% 9
ok; %% 10

f5(d) -> %% 1
%% 2
%% 3
%% 4

%% 6
%% 7
%% 8
%% 9
ok; %% 10

f5(e) -> %% 1
%% 2
%% 3
%% 4

%% 6
%% 7
%% 8
%% 9
ok. %% 10
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