r236851 - clang-format: Several improvements around formatting braced lists.

Daniel Jasper djasper at google.com
Fri May 8 08:18:05 PDT 2015


On Fri, May 8, 2015 at 5:16 PM, Tobias Grosser <tobias at grosser.es> wrote:

> On 05/08/2015 03:51 PM, Daniel Jasper wrote:
>
>> Author: djasper
>> Date: Fri May  8 08:51:14 2015
>> New Revision: 236851
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=236851&view=rev
>> Log:
>> clang-format: Several improvements around formatting braced lists.
>>
>> In particular:
>> * If the difference between the longest and shortest element, we copped
>>    out of column format completely. Now, we instead allow to arrange
>>    these in a single column, essentially enforcing a one-per-line format.
>> * Allow column layout even if there are braced lists. Especially, if
>>    there are many short lists, this can be beneficial. The bad case,
>>    where there is a long nested init list is usually caught as we now
>>    limit the length difference of the longest and shortest element.
>>
>
> Hi Daniel,
>
> this change caused the following formatting change in Polly:
>
> -  Value *Args[] = {SubFn, SubFnParam, NumberOfThreads, LB, UB, Stride};
> +  Value *Args[] = {SubFn,
> +                   SubFnParam,
> +                   NumberOfThreads,
> +                   LB,
> +                   UB,
> +                   Stride};
>
> I will change this in Polly. It might be useful to add some test case
> that shows that in certain cases we want to format a list in column layout
> even though it fits a single line.


Do we? Do you actually think the new format is better?


> Best,
> Tobias
>
>
>  Modified:
>>      cfe/trunk/lib/Format/FormatToken.cpp
>>      cfe/trunk/unittests/Format/FormatTest.cpp
>>
>> Modified: cfe/trunk/lib/Format/FormatToken.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/FormatToken.cpp?rev=236851&r1=236850&r2=236851&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Format/FormatToken.cpp (original)
>> +++ cfe/trunk/lib/Format/FormatToken.cpp Fri May  8 08:51:14 2015
>> @@ -199,13 +199,14 @@ void CommaSeparatedList::precomputeForma
>>     // create a column layout. If it has a nested list, column layout
>> ensures one
>>     // list element per line. If the difference between the shortest and
>> longest
>>     // element is too large, column layout would create too much
>> whitespace.
>> -  if (HasNestedBracedList || Commas.size() < 5 || Token->NestingLevel !=
>> 0 ||
>> -      MaxItemLength - MinItemLength > 10)
>> +  if (Commas.size() < 5 || Token->NestingLevel != 0)
>>       return;
>>
>>     // We can never place more than ColumnLimit / 3 items in a row
>> (because of the
>>     // spaces and the comma).
>> -  for (unsigned Columns = 1; Columns <= Style.ColumnLimit / 3;
>> ++Columns) {
>> +  unsigned MaxColumns =
>> +      MaxItemLength - MinItemLength > 10 ? 1 : Style.ColumnLimit / 3;
>> +  for (unsigned Columns = 1; Columns <= MaxColumns; ++Columns) {
>>       ColumnFormat Format;
>>       Format.Columns = Columns;
>>       Format.ColumnSizes.resize(Columns);
>>
>> Modified: cfe/trunk/unittests/Format/FormatTest.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/Format/FormatTest.cpp?rev=236851&r1=236850&r2=236851&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/unittests/Format/FormatTest.cpp (original)
>> +++ cfe/trunk/unittests/Format/FormatTest.cpp Fri May  8 08:51:14 2015
>> @@ -6223,9 +6223,18 @@ TEST_F(FormatTest, LayoutCxx11BraceIniti
>>         ExtraSpaces);
>>     verifyFormat(
>>         "std::vector<MyValues> aaaaaaaaaaaaaaaaaaa{\n"
>> -      "    aaaaaaa, aaaaaaaaaa, aaaaa, aaaaaaaaaaaaaaa, aaa, aaaaaaaaaa,
>> a,\n"
>> -      "    aaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaa,\n"
>> -      "    aaaaaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaaaaa, aaaaaaa, a};");
>> +      "    aaaaaaa,\n"
>> +      "    aaaaaaaaaa,\n"
>> +      "    aaaaa,\n"
>> +      "    aaaaaaaaaaaaaaa,\n"
>> +      "    aaa,\n"
>> +      "    aaaaaaaaaa,\n"
>> +      "    a,\n"
>> +      "    aaaaaaaaaaaaaaaaaaaaa,\n"
>> +      "    aaaaaaaaaaaa,\n"
>> +      "    aaaaaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaaaaa,\n"
>> +      "    aaaaaaa,\n"
>> +      "    a};");
>>     verifyFormat("vector<int> foo = { ::SomeGlobalFunction() };",
>> ExtraSpaces);
>>   }
>>
>> @@ -6263,6 +6272,19 @@ TEST_F(FormatTest, FormatsBracedListsInC
>>     verifyFormat("vector<int> aaaaaaaaaaaaaaaaaaaaaa = {\n"
>>                  "    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};",
>>                  getLLVMStyleWithColumns(43));
>> +  verifyFormat(
>> +      "static unsigned SomeValues[10][3] = {\n"
>> +      "    {1, 4, 0},  {4, 9, 0},  {4, 5, 9},  {8, 5, 4}, {1, 8, 4},\n"
>> +      "    {10, 1, 6}, {11, 0, 9}, {2, 11, 9}, {5, 2, 9}, {11, 2, 7}};");
>> +  verifyFormat("static auto fields = new vector<string>{\n"
>> +               "    \"aaaaaaaaaaaaa\",\n"
>> +               "    \"aaaaaaaaaaaaa\",\n"
>> +               "    \"aaaaaaaaaaaa\",\n"
>> +               "    \"aaaaaaaaaaaaaa\",\n"
>> +               "    \"aaaaaaaaaaaaaaaaaaaaaaaaa\",\n"
>> +               "    \"aaaaaaaaaaaa\",\n"
>> +               "    \"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\",\n"
>> +               "};");
>>
>>     // Trailing commas.
>>     verifyFormat("vector<int> x = {\n"
>> @@ -6277,15 +6299,15 @@ TEST_F(FormatTest, FormatsBracedListsInC
>>                  "                 1, 1, 1, 1,\n"
>>                  "                 /**/ /**/};",
>>                  getLLVMStyleWithColumns(39));
>> +
>> +  // With nested lists, we should either format one item per line or all
>> nested
>> +  // lists one on line.
>> +  // FIXME: For some nested lists, we can do better.
>>     verifyFormat("return {{aaaaaaaaaaaaaaaaaaaaa},\n"
>>                  "        {aaaaaaaaaaaaaaaaaaa},\n"
>>                  "        {aaaaaaaaaaaaaaaaaaaaa},\n"
>>                  "        {aaaaaaaaaaaaaaaaa}};",
>>                  getLLVMStyleWithColumns(60));
>> -
>> -  // With nested lists, we should either format one item per line or all
>> nested
>> -  // lists one one line.
>> -  // FIXME: For some nested lists, we can do better.
>>     verifyFormat(
>>         "SomeStruct my_struct_array = {\n"
>>         "    {aaaaaa, aaaaaaaa, aaaaaaaaaa, aaaaaaaaa, aaaaaaaaa,
>> aaaaaaaaaa,\n"
>>
>>
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>>
>>
>
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