276953ef21
Change-Id: I0fa791733407199db5be2cc9606ac9be1da64188
166 lines
6.3 KiB
C++
166 lines
6.3 KiB
C++
/*
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* This file is part of the LibreOffice project.
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*
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* Based on LLVM/Clang.
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*
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* This file is distributed under the University of Illinois Open Source
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* License. See LICENSE.TXT for details.
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*
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*/
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#include "postfixincrementfix.hxx"
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/*
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This is a rewriter.
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Change all postfix ++ operators of non-trivial types to prefix if possible.
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*/
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namespace loplugin
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{
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PostfixIncrementFix::PostfixIncrementFix( ASTContext& context, Rewriter& rewriter )
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: RewritePlugin( context, rewriter )
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{
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}
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void PostfixIncrementFix::run()
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{
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TraverseDecl( context.getTranslationUnitDecl());
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}
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bool PostfixIncrementFix::VisitFunctionDecl( FunctionDecl* declaration )
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{
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if( ignoreLocation( declaration ))
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return true;
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if( !declaration->doesThisDeclarationHaveABody())
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return true;
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StmtParents parents;
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fixPostfixOperators( declaration->getBody(), parents );
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return true;
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}
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void PostfixIncrementFix::fixPostfixOperators( const Stmt* stmt, StmtParents& parents )
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{
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if( const CXXOperatorCallExpr* op = dyn_cast<CXXOperatorCallExpr>( stmt ))
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{ // postfix ++ has two arguments (the operand and the hidden extra int)
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if( op->getOperator() == OO_PlusPlus && op->getNumArgs() == 2 )
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fixPostfixOperator( op, parents );
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}
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// For primitive types it would be UnaryOperatorExpr, but probably no good reason to change those.
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parents.push_back( stmt );
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for( ConstStmtIterator it = stmt->child_begin();
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it != stmt->child_end();
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++it )
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{
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if( *it != NULL ) // some children can be apparently NULL
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fixPostfixOperators( *it, parents );
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}
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assert( parents.back() == stmt );
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parents.pop_back();
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}
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void PostfixIncrementFix::fixPostfixOperator( const CXXOperatorCallExpr* op, StmtParents& parents )
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{
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if( !canChangePostfixToPrefix( op, parents, parents.size() - 1 ))
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return;
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if( !shouldDoChange( op->getArg( 0 )))
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return;
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// Adding spaces around the moved ++ should not be necessary
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// (there might a problem with e.g. a+b++ -> a+++b (i.e. a++ +b),
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// but we don't change such expressions).
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if( insertText( op->getLocStart(), "++" )) // insert is intentionally first, in case it fails
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removeText( op->getCallee()->getSourceRange());
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}
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bool PostfixIncrementFix::canChangePostfixToPrefix( const CXXOperatorCallExpr* op, StmtParents& parents, int parent_pos )
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{
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// check if foo++ can be safely replaced by ++foo
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switch( parents[ parent_pos ]->getStmtClass())
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{
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case Stmt::CompoundStmtClass:
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return true;
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// these mean somebody is going to use it
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case Stmt::ImplicitCastExprClass:
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case Stmt::MaterializeTemporaryExprClass:
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case Stmt::BinaryOperatorClass:
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case Stmt::UnaryOperatorClass:
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case Stmt::CallExprClass:
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case Stmt::CXXOperatorCallExprClass:
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return false;
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case Stmt::CXXBindTemporaryExprClass:
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// tricky, it may just mean the temporary will be cleaned up
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// (by ExprWithCleanups), ignore and go up
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assert( parent_pos > 0 ); // should not happen
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return canChangePostfixToPrefix( op, parents, parent_pos - 1 );
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case Stmt::ExprWithCleanupsClass:
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// cleanup of a temporary, should be harmless (if the use
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// of the postfix ++ operator here relies on the fact that
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// the dtor for the object will be called, that's pretty insane
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// code). Ignore and go up.
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assert( parent_pos > 0 ); // should not happen
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return canChangePostfixToPrefix( op, parents, parent_pos - 1 );
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case Stmt::ParenExprClass: // parentheses, go up
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assert( parent_pos > 0 );
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return canChangePostfixToPrefix( op, parents, parent_pos - 1 );
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case Stmt::IfStmtClass:
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return canChangeInConditionStatement( op, cast< IfStmt >( parents[ parent_pos ] )->getCond(),
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parents, parent_pos );
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case Stmt::WhileStmtClass:
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return canChangeInConditionStatement( op, cast< WhileStmt >( parents[ parent_pos ] )->getCond(),
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parents, parent_pos );
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case Stmt::DoStmtClass:
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return canChangeInConditionStatement( op, cast< DoStmt >( parents[ parent_pos ] )->getCond(),
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parents, parent_pos );
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case Stmt::ForStmtClass:
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return canChangeInConditionStatement( op, dyn_cast< ForStmt >( parents[ parent_pos ] )->getCond(),
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parents, parent_pos );
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default:
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report( DiagnosticsEngine::Fatal, "cannot analyze operator++ (plugin needs fixing)",
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op->getLocStart()) << parents[ parent_pos ]->getSourceRange();
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// parents[ parent_pos ]->dump();
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// parents[ std::max( parent_pos - 3, 0 ) ]->dump();
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return false;
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}
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}
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bool PostfixIncrementFix::canChangeInConditionStatement( const CXXOperatorCallExpr* op, const Expr* condition,
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const StmtParents& parents, int parent_pos )
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{
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// cannot be changed in condition, can be changed in statements
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if( parent_pos == parents.size() - 1 )
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return op != condition;
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else
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{ // indirect child
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assert( parent_pos + 1 < parents.size());
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return parents[ parent_pos + 1 ] != condition;
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}
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}
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bool PostfixIncrementFix::shouldDoChange( const Expr* operand )
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{
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// TODO Changing 'a->b++' to '++a->b' is technically the same, but the latter probably looks confusing,
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// so either avoid that, or add parentheses. Avoid for now.
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const Expr* expr = const_cast< Expr* >( operand )->IgnoreImplicit(); // does not have const version
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switch( expr->getStmtClass())
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{
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case Stmt::ParenExprClass:
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return true; // there are already parentheses, ok to move the ++
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case Stmt::MemberExprClass:
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return false; // ++a->b , avoid
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case Stmt::DeclRefExprClass:
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return true;
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default:
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{
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report( DiagnosticsEngine::Fatal, "cannot analyze operator++ (plugin needs fixing)",
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expr->getLocStart()) << operand->getSourceRange();
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expr->dump();
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operand->dump();
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return false;
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}
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}
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}
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static Plugin::Registration< PostfixIncrementFix > X( "postfixincrementfix" );
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} // namespace
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