Added AlwaysBreakBeforeMultilineStrings option.

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

Reviewers: djasper

Reviewed By: djasper

CC: cfe-commits, klimek

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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185622 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Format/TokenAnnotator.cpp b/lib/Format/TokenAnnotator.cpp
index 04f1c7f..806c805 100644
--- a/lib/Format/TokenAnnotator.cpp
+++ b/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;
     }