compilerplugins/clang/store/cascadingcondop.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * Based on LLVM/Clang.
   6  *
   7  * This file is distributed under the University of Illinois Open Source
   8  * License. See LICENSE.TXT for details.
   9  *
  10  */
  11
  12 #include "cascadingcondop.hxx"
  13
  14 /*
  15 This is a compile check.
  16
  17 It checks for complex statements with conditional operators in conditional
  18 operators, which are error prone, e.g.
  19  Thing foo = IsBar() ? ( IsBaz() ? b1 : b2 ) : b3;
  20
  21 However, it finds 556 cases in sw/source alone, thus likely needs some more
  22 restricting, e.g. by checking for multiline conditional operator statements or
  23 a certain length in characters (but that needs the Context/SourceManager, which
  24 I haven't played with yet).
  25 */
  26
  27 // the value is rather arbitrary, but code above this number of stmts begins to
  28 // be smelly
  29 static const int stmtlimit = 50;
  30
  31 namespace loplugin
  32 {
  33
  34 struct WalkCounter
  35 {
  36     int  stmtcount;
  37     bool cascading;
  38 };
  39
  40 // Ctor, nothing special, pass the argument(s).
  41 CascadingCondOp::CascadingCondOp( const InstantiationData& data )
  42     : FilteringPlugin( data )
  43 {
  44 }
  45
  46 // Perform the actual action.
  47 void CascadingCondOp::run()
  48 {
  49     // Traverse the whole AST of the translation unit (i.e. examine the whole source file).
  50     // The Clang AST helper class will call VisitReturnStmt for every return statement.
  51     TraverseDecl( compiler.getASTContext().getTranslationUnitDecl());
  52 }
  53
  54 void CascadingCondOp::Walk( const Stmt* stmt, WalkCounter& c )
  55 {
  56     for(Stmt::const_child_iterator it = stmt->child_begin(); it != stmt->child_end(); ++it)
  57     {
  58         ++c.stmtcount;
  59         if ( dyn_cast< ConditionalOperator >( *it ))
  60             c.cascading = true;
  61         Walk(*it, c);
  62     }
  63 }
  64
  65 bool CascadingCondOp::VisitStmt( const Stmt* stmt )
  66 {
  67     if ( const ConditionalOperator* condop = dyn_cast< ConditionalOperator >( stmt ))
  68     {
  69         WalkCounter c = { 0, false };
  70         Walk(condop, c);
  71         if(c.cascading && c.stmtcount >= stmtlimit)
  72         {
  73             std::string msg("cascading conditional operator, complexity: ");
  74             msg.append(std::to_string(c.stmtcount));
  75             report( DiagnosticsEngine::Warning, msg, condop->getLocStart());
  76         }
  77     }
  78     return true;
  79 }
  80
  81 // Register the plugin action with the LO plugin handling.
  82 static Plugin::Registration< CascadingCondOp > X( "cascadingcondop" );
  83
  84 } // namespace loplugin
  85
  86 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */