132 lines
4.8 KiB
C++
132 lines
4.8 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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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( const InstantiationData& data )
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: FilteringRewritePlugin( data )
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{
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}
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void PostfixIncrementFix::run()
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{
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TraverseDecl( compiler.getASTContext().getTranslationUnitDecl());
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}
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bool PostfixIncrementFix::VisitCXXOperatorCallExpr( const CXXOperatorCallExpr* op )
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{
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if( ignoreLocation( op ))
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return true;
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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 );
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// For primitive types it would be UnaryOperatorExpr, but probably no good reason to change those.
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return true;
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}
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void PostfixIncrementFix::fixPostfixOperator( const CXXOperatorCallExpr* op )
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{
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if( !canChangePostfixToPrefix( op, op ))
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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 Stmt* stmt , const CXXOperatorCallExpr* op )
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{
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const Stmt* parent = parentStmt( stmt );
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if( parent == NULL )
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return true;
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// check if foo++ can be safely replaced by ++foo
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switch( parent->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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return canChangePostfixToPrefix( parent, op );
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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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return canChangePostfixToPrefix( parent, op );
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case Stmt::ParenExprClass: // parentheses, go up
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return canChangePostfixToPrefix( parent, op );
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case Stmt::IfStmtClass:
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// cannot be changed in condition, can be changed in statements
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return cast< IfStmt >( parent )->getCond() != stmt;
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case Stmt::WhileStmtClass:
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return cast< WhileStmt >( parent )->getCond() != stmt;
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case Stmt::DoStmtClass:
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return cast< DoStmt >( parent )->getCond() != stmt;
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case Stmt::ForStmtClass:
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return cast< ForStmt >( parent )->getCond() != stmt;
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default:
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report( DiagnosticsEngine::Fatal, "cannot analyze operator++ (plugin needs fixing)",
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op->getLocStart()) << parent->getSourceRange();
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parent->dump();
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return false;
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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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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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