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Лабораторная работа №3. Зайцев Александр 381906-1 #30

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Лабораторная работа №3. Зайцев Александр 381906-1 #30

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13 changes: 12 additions & 1 deletion main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,13 +18,24 @@ using namespace clang::ast_matchers;
using namespace clang::tooling;

class CastCallBack : public MatchFinder::MatchCallback {
private: Rewriter &rewriter;
public:
CastCallBack(Rewriter& rewriter) {
CastCallBack(Rewriter& rewriter_):rewriter(rewriter_) {
// Your code goes here
};

void run(const MatchFinder::MatchResult &Result) override {
// Your code goes here
const auto *StyleCastExpr=Result.Nodes.getNodeAs<CStyleCastExpr>("cast");
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What if StyleCastExpr is a null pointer? How to protect the program from crashing in such cases?

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add this if(StyleCastExpr==nullptr) { return; }

auto leftParenLoc=StyleCastExpr->getLParenLoc();
auto rigthParenLoc=StyleCastExpr->getRParenLoc();
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Please describe the difference between the use of getRParenLoc() and getSubExprAsWritten()->getBeginLoc().

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getRParenLos() a special method of the CStyleCastExprclass, this method returns the position where the closing right bracket is located. An object of the CStyleCastExpr class is an indication of a node in the AST tree.
If call the getSubExprAsWritten() method, it will return the desired tree node, ignoring the auxiliary ImplicitCastExpr nodes.
getBeginLoc() is used here to get the start position of this variable. But need to separately call the method of removing the closing right bracket rewriter_.Remove Text(styleCastExpr->getRParenLoc(), 1); .
The main difference is that when using getRParenLoc(), the search for the desired position is carried out using a closing parenthesis, and when using getSubExprAsWritten(), it is carried out using a variable for which the CStyleCast transformation was called.

rewriter.RemoveText(leftParenLoc,1);
rewriter.RemoveText(rigthParenLoc,1);
auto &sourceManager=*Result.SourceManager;
auto endLine=Lexer::getLocForEndOfToken(StyleCastExpr->getEndLoc(),0,sourceManager,LangOptions());
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Please describe the reason of using theLexer::getLocForEndOfToken() function here.
What would be the difference if rewriter.InsertText(styleCastExpr->getEndLoc().getLocOffset(1), ")"); was used here?
What would be the difference if rewriter.InsertTextAfterToken(styleCastExpr->getEndLoc(), ")"); was used here?

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  1. get::LocForEndOfToken() . Computes the source location just past the end of the token at this source location.
  2. rewriter.InsertText(styleCastExpr->getEndLoc().getLocOffset(1),")"); give us position right after (cast) and getEndLoc().getLocOffset(1) shifts this position by one to the right. If the variable declared in main has a name of two or more symbol and use rewriter.InsertText(styleCastExpr->getEndLoc().getLocOffset(1),")"); . like main we will get m)ain .
    3)rewriter.InsertTextAfterToken(styleCastExpr->getEndLoc(),")"); . If use this we will get the same position and output but different way.

rewriter.InsertText(leftParenLoc,"static_cast<");
rewriter.InsertText(rigthParenLoc,">(");
rewriter.InsertText(endLine,")");
}
};

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