clang-format: Add basic support for try and catch statements

[sdt]

Summary

This patch adds parsing of try and catch statements to LibFormat, respecting the break before brace style as appropriate.

[djasper]

First of all, thank you for working on this!

There is already another patch out there that is doing the same thing: http://llvm-reviews.chandlerc.com/D2555. Not quite sure how to move forward. I'll ping that patch once more and pick it up if nothing happens. Generally:

• I think it doesn't really make sense to parse try and cat independently. Especially, many coding styles require the "}" on the same line as the following "catch".
• We have a unit testing infrastructure in cfe/unittests/Format/FormatTest.cpp, which we prefer over the file-check-based tests for various reasons.

[sdt]

Hah, I'm not surprised someone's already taken a stab at this. OK, I'll look at that patch; perhaps I can finish that one up.

Thanks for pointing me to the correct place to do testing (I was a bit surprised by the sparseness of the FileCheck tests :)).

[djasper]

I think this is now obsolete. I submitted a version of the other patch as r208302.

lib/Format/UnwrappedLineParser.h

private:
   void parseStructuralElement();
   bool tryToParseBracedList();
   bool parseBracedList(bool ContinueOnSemicolons = false);
   void parseParens();
   void parseSquare();
   void parseIfThenElse();
   void parseForOrWhileLoop();
   void parseDoWhile();
+  void parseTry();
+  void parseCatch();
   void parseLabel();
   void parseCaseLabel();
   void parseSwitch();
   void parseNamespace();
   void parseAccessSpecifier();
   void parseEnum();
   void parseRecord();
   void parseObjCProtocolList();

lib/Format/UnwrappedLineParser.cpp

case tok::kw_switch:
     return;
   case tok::kw_default:
     nextToken();
     parseLabel();
     return;
   case tok::kw_case:
     parseCaseLabel();
     return;
+  case tok::kw_try:
+    parseTry();
+    return;
+  case tok::kw_catch:
+    parseCatch();
+    return;
   case tok::kw_extern:
     nextToken();
     if (FormatTok->Tok.is(tok::string_literal)) {
       nextToken();
       if (FormatTok->Tok.is(tok::l_brace)) {
         parseBlock(/*MustBeDeclaration=*/true, /*AddLevel=*/false);
         addUnwrappedLine();
         return;
if (!FormatTok->Tok.is(tok::kw_while)) {
     addUnwrappedLine();
     return;
   }
 
   nextToken();
   parseStructuralElement();
 }
 
+void UnwrappedLineParser::parseTry() {
+  assert(FormatTok->Tok.is(tok::kw_try) && "'try' expected");
+  nextToken();
+
+  if (FormatTok->Tok.is(tok::l_brace)) {
+    CompoundStatementIndenter Indenter(this, Style, Line->Level);
+    parseBlock(/*MustBeDeclaration=*/false);
+
+    if (Style.BreakBeforeBraces == FormatStyle::BS_GNU)
+      addUnwrappedLine();
+  } else {
+    // FIXME: Add error handling.
+    addUnwrappedLine();
+    return;
+  }
+}
+
+void UnwrappedLineParser::parseCatch() {
+  assert(FormatTok->Tok.is(tok::kw_catch) && "'catch' expected");
+  nextToken();
+
+  if (FormatTok->Tok.is(tok::l_paren)) {
+    parseParens();
+  }
+
+  if (FormatTok->Tok.is(tok::l_brace)) {
+    CompoundStatementIndenter Indenter(this, Style, Line->Level);
+    parseBlock(/*MustBeDeclaration=*/false);
+
+    if (FormatTok->Tok.is(tok::kw_catch)) {
+      if (Style.BreakBeforeBraces == FormatStyle::BS_GNU)
+        addUnwrappedLine();
+    } else {
+      addUnwrappedLine();
+    }
+  } else {
+    // FIXME: Add error handling.
+    addUnwrappedLine();
+    return;
+  }
+}
+
 void UnwrappedLineParser::parseLabel() {
   nextToken();
   unsigned OldLineLevel = Line->Level;
   if (Line->Level > 1 || (!Line->InPPDirective && Line->Level > 0))
     --Line->Level;
   if (CommentsBeforeNextToken.empty() && FormatTok->Tok.is(tok::l_brace)) {
     CompoundStatementIndenter Indenter(this, Style, Line->Level);
     parseBlock(/*MustBeDeclaration=*/false);

test/Format/try-catch.cpp

+// RUN: grep -Ev "// *[A-Z0-9-]+:" %s > %t.cpp
+// RUN: clang-format -style="{BasedOnStyle: Google, BreakBeforeBraces: Stroustrup}" %t.cpp | FileCheck %s -strict-whitespace -check-prefix=CHECK1
+// RUN: clang-format -style="{BasedOnStyle: Google, BreakBeforeBraces: GNU}" %t.cpp | FileCheck %s -strict-whitespace -check-prefix=CHECK2
+// CHECK1:      {{^\ \ try\ \{}}
+// CHECK1-NEXT: {{^\ \ \ \ g\(\);}}
+// CHECK1-NEXT: {{^\ \ \} catch \(int\) \{}}
+// CHECK1-NEXT: {{^\ \ \ \ g\(\);}}
+// CHECK1-NEXT: {{^\ \ \} catch \(\.\.\.\) \{}}
+// CHECK1-NEXT: {{^\ \ \ \ g\(\);}}
+// CHECK1-NEXT: {{^\ \ [}]}}
+// CHECK2:      {{^\ \ try}}
+// CHECK2-NEXT: {{^\ \ \ \ {}}
+// CHECK2-NEXT: {{^\ \ \ \ \ \ g\(\);}}
+// CHECK2-NEXT: {{^\ \ \ \ [}]}}
+// CHECK2-NEXT: {{^\ \ catch \(int\)}}
+// CHECK2-NEXT: {{^\ \ \ \ {}}
+// CHECK2-NEXT: {{^\ \ \ \ \ \ g\(\);}}
+// CHECK2-NEXT: {{^\ \ \ \ [}]}}
+// CHECK2-NEXT: {{^\ \ catch \(\.\.\.\)}}
+// CHECK2-NEXT: {{^\ \ \ \ {}}
+// CHECK2-NEXT: {{^\ \ \ \ \ \ g\(\);}}
+// CHECK2-NEXT: {{^\ \ \ \ [}]}}
+
+void g();
+
+void f() { try { g(); } catch (int) { g(); } catch (...) { g(); } }