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 struct WalkCounter
  34 {
  35     int stmtcount;
  36     bool cascading;
  37 };
  38
  39 // Ctor, nothing special, pass the argument(s).
  40 CascadingCondOp::CascadingCondOp(const InstantiationData& data)
  41     : FilteringPlugin(data)
  42 {
  43 }
  44
  45 // Perform the actual action.
  46 void CascadingCondOp::run()
  47 {
  48     // Traverse the whole AST of the translation unit (i.e. examine the whole source file).
  49     // The Clang AST helper class will call VisitReturnStmt for every return statement.
  50     TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  51 }
  52
  53 void CascadingCondOp::Walk(const Stmt* stmt, WalkCounter& c)
  54 {
  55     for (Stmt::const_child_iterator it = stmt->child_begin(); it != stmt->child_end(); ++it)
  56     {
  57         ++c.stmtcount;
  58         if (dyn_cast<ConditionalOperator>(*it))
  59             c.cascading = true;
  60         Walk(*it, c);
  61     }
  62 }
  63
  64 bool CascadingCondOp::VisitStmt(const Stmt* stmt)
  65 {
  66     if (const ConditionalOperator* condop = dyn_cast<ConditionalOperator>(stmt))
  67     {
  68         WalkCounter c = { 0, false };
  69         Walk(condop, c);
  70         if (c.cascading && c.stmtcount >= stmtlimit)
  71         {
  72             std::string msg("cascading conditional operator, complexity: ");
  73             msg.append(std::to_string(c.stmtcount));
  74             report(DiagnosticsEngine::Warning, msg, condop->getLocStart());
  75         }
  76     }
  77     return true;
  78 }
  79
  80 // Register the plugin action with the LO plugin handling.
  81 static Plugin::Registration<CascadingCondOp> X("cascadingcondop");
  82
  83 } // namespace loplugin
  84
  85 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */