[PATCH] Added AlwaysBreakBeforeMultilineStrings option.

[Alexander Kornienko]

Hi djasper,

Always breaking before multiline strings can help format complex
expressions containing multiline strings more consistently, and avoid consuming
too much horizontal space.

http://llvm-reviews.chandlerc.com/D1097

Files:
  include/clang/Format/Format.h
  lib/Format/Format.cpp
  lib/Format/TokenAnnotator.cpp
  unittests/Format/FormatTest.cpp

Index: include/clang/Format/Format.h
===================================================================
--- include/clang/Format/Format.h
+++ include/clang/Format/Format.h
@@ -110,6 +110,9 @@
   /// declaration.
   bool AlwaysBreakTemplateDeclarations;
 
+  /// \brief If \c true, always break before multiline string literals.
+  bool AlwaysBreakBeforeMultilineStrings;
+
   /// \brief If true, \c IndentWidth consecutive spaces will be replaced with
   /// tab characters.
   bool UseTab;
@@ -144,6 +147,8 @@
                R.AllowShortIfStatementsOnASingleLine &&
            AlwaysBreakTemplateDeclarations ==
                R.AlwaysBreakTemplateDeclarations &&
+           AlwaysBreakBeforeMultilineStrings ==
+               R.AlwaysBreakBeforeMultilineStrings &&
            BinPackParameters == R.BinPackParameters &&
            BreakBeforeBraces == R.BreakBeforeBraces &&
            ColumnLimit == R.ColumnLimit &&
Index: lib/Format/Format.cpp
===================================================================
--- lib/Format/Format.cpp
+++ lib/Format/Format.cpp
@@ -87,6 +87,8 @@
                    Style.AllowShortLoopsOnASingleLine);
     IO.mapOptional("AlwaysBreakTemplateDeclarations",
                    Style.AlwaysBreakTemplateDeclarations);
+    IO.mapOptional("AlwaysBreakBeforeMultilineStrings",
+                   Style.AlwaysBreakBeforeMultilineStrings);
     IO.mapOptional("BinPackParameters", Style.BinPackParameters);
     IO.mapOptional("ColumnLimit", Style.ColumnLimit);
     IO.mapOptional("ConstructorInitializerAllOnOneLineOrOnePerLine",
@@ -127,6 +129,7 @@
   LLVMStyle.AllowShortIfStatementsOnASingleLine = false;
   LLVMStyle.AllowShortLoopsOnASingleLine = false;
   LLVMStyle.AlwaysBreakTemplateDeclarations = false;
+  LLVMStyle.AlwaysBreakBeforeMultilineStrings = false;
   LLVMStyle.BinPackParameters = true;
   LLVMStyle.ColumnLimit = 80;
   LLVMStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = false;
@@ -157,6 +160,7 @@
   GoogleStyle.AllowShortIfStatementsOnASingleLine = true;
   GoogleStyle.AllowShortLoopsOnASingleLine = true;
   GoogleStyle.AlwaysBreakTemplateDeclarations = true;
+  GoogleStyle.AlwaysBreakBeforeMultilineStrings = true;
   GoogleStyle.BinPackParameters = true;
   GoogleStyle.ColumnLimit = 80;
   GoogleStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = true;
Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -936,6 +936,13 @@
     } else if (Current->Previous->ClosesTemplateDeclaration &&
                Style.AlwaysBreakTemplateDeclarations) {
       Current->MustBreakBefore = true;
+    } else if (Style.AlwaysBreakBeforeMultilineStrings &&
+               Current->is(tok::string_literal) &&
+               Current->Previous->isNot(tok::lessless) &&
+               Current->Previous->Type != TT_InlineASMColon &&
+               Current->getNextNoneComment() &&
+               Current->getNextNoneComment()->is(tok::string_literal)) {
+      Current->MustBreakBefore = true;
     } else {
       Current->MustBreakBefore = false;
     }
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -2878,6 +2878,34 @@
                "  \"jkl\");");
 }
 
+TEST_F(FormatTest, AlwaysBreakBeforeMultilineStrings) {
+  FormatStyle NoBreak = getLLVMStyle();
+  NoBreak.AlwaysBreakBeforeMultilineStrings = false;
+  FormatStyle Break = getLLVMStyle();
+  Break.AlwaysBreakBeforeMultilineStrings = true;
+  EXPECT_EQ("aaaa = \"bbbb\"\n"
+            "       \"cccc\";",
+            format("aaaa=\"bbbb\" \"cccc\";", NoBreak));
+  EXPECT_EQ("aaaa =\n"
+            "    \"bbbb\"\n"
+            "    \"cccc\";",
+            format("aaaa=\"bbbb\" \"cccc\";", Break));
+  EXPECT_EQ("aaaa(\"bbbb\"\n"
+            "     \"cccc\");",
+            format("aaaa(\"bbbb\" \"cccc\");", NoBreak));
+  EXPECT_EQ("aaaa(\n"
+            "    \"bbbb\"\n"
+            "    \"cccc\");",
+            format("aaaa(\"bbbb\" \"cccc\");", Break));
+  EXPECT_EQ("aaaa(qqq, \"bbbb\"\n"
+            "          \"cccc\");",
+            format("aaaa(qqq, \"bbbb\" \"cccc\");", NoBreak));
+  EXPECT_EQ("aaaa(qqq,\n"
+            "     \"bbbb\"\n"
+            "     \"cccc\");",
+            format("aaaa(qqq, \"bbbb\" \"cccc\");", Break));
+}
+
 TEST_F(FormatTest, AlignsPipes) {
   verifyFormat(
       "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
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