| //===- examples/Tooling/RemoveCStrCalls.cpp - Redundant c_str call removal ===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements a tool that prints replacements that remove redundant |
| // calls of c_str() on strings. |
| // |
| // Usage: |
| // remove-cstr-calls <cmake-output-dir> <file1> <file2> ... |
| // |
| // Where <cmake-output-dir> is a CMake build directory in which a file named |
| // compile_commands.json exists (enable -DCMAKE_EXPORT_COMPILE_COMMANDS in |
| // CMake to get this output). |
| // |
| // <file1> ... specify the paths of files in the CMake source tree. This path |
| // is looked up in the compile command database. If the path of a file is |
| // absolute, it needs to point into CMake's source tree. If the path is |
| // relative, the current working directory needs to be in the CMake source |
| // tree and the file must be in a subdirectory of the current working |
| // directory. "./" prefixes in the relative files will be automatically |
| // removed, but the rest of a relative path must be a suffix of a path in |
| // the compile command line database. |
| // |
| // For example, to use remove-cstr-calls on all files in a subtree of the |
| // source tree, use: |
| // |
| // /path/in/subtree $ find . -name '*.cpp'| |
| // xargs remove-cstr-calls /path/to/build |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/ASTMatchers/ASTMatchers.h" |
| #include "clang/ASTMatchers/ASTMatchFinder.h" |
| #include "clang/Basic/SourceManager.h" |
| #include "clang/Frontend/FrontendActions.h" |
| #include "clang/Lex/Lexer.h" |
| #include "clang/Tooling/CompilationDatabase.h" |
| #include "clang/Tooling/Refactoring.h" |
| #include "clang/Tooling/Tooling.h" |
| #include "llvm/ADT/Twine.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/MemoryBuffer.h" |
| #include "llvm/Support/Path.h" |
| #include "llvm/Support/Signals.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <system_error> |
| |
| using namespace clang; |
| using namespace clang::ast_matchers; |
| using namespace llvm; |
| using clang::tooling::newFrontendActionFactory; |
| using clang::tooling::Replacement; |
| using clang::tooling::CompilationDatabase; |
| |
| // FIXME: Pull out helper methods in here into more fitting places. |
| |
| // Returns the text that makes up 'node' in the source. |
| // Returns an empty string if the text cannot be found. |
| template <typename T> |
| static std::string getText(const SourceManager &SourceManager, const T &Node) { |
| SourceLocation StartSpellingLocation = |
| SourceManager.getSpellingLoc(Node.getLocStart()); |
| SourceLocation EndSpellingLocation = |
| SourceManager.getSpellingLoc(Node.getLocEnd()); |
| if (!StartSpellingLocation.isValid() || !EndSpellingLocation.isValid()) { |
| return std::string(); |
| } |
| bool Invalid = true; |
| const char *Text = |
| SourceManager.getCharacterData(StartSpellingLocation, &Invalid); |
| if (Invalid) { |
| return std::string(); |
| } |
| std::pair<FileID, unsigned> Start = |
| SourceManager.getDecomposedLoc(StartSpellingLocation); |
| std::pair<FileID, unsigned> End = |
| SourceManager.getDecomposedLoc(Lexer::getLocForEndOfToken( |
| EndSpellingLocation, 0, SourceManager, LangOptions())); |
| if (Start.first != End.first) { |
| // Start and end are in different files. |
| return std::string(); |
| } |
| if (End.second < Start.second) { |
| // Shuffling text with macros may cause this. |
| return std::string(); |
| } |
| return std::string(Text, End.second - Start.second); |
| } |
| |
| // Return true if expr needs to be put in parens when it is an argument of a |
| // prefix unary operator, e.g. when it is a binary or ternary operator |
| // syntactically. |
| static bool needParensAfterUnaryOperator(const Expr &ExprNode) { |
| if (dyn_cast<clang::BinaryOperator>(&ExprNode) || |
| dyn_cast<clang::ConditionalOperator>(&ExprNode)) { |
| return true; |
| } |
| if (const CXXOperatorCallExpr *op = |
| dyn_cast<CXXOperatorCallExpr>(&ExprNode)) { |
| return op->getNumArgs() == 2 && |
| op->getOperator() != OO_PlusPlus && |
| op->getOperator() != OO_MinusMinus && |
| op->getOperator() != OO_Call && |
| op->getOperator() != OO_Subscript; |
| } |
| return false; |
| } |
| |
| // Format a pointer to an expression: prefix with '*' but simplify |
| // when it already begins with '&'. Return empty string on failure. |
| static std::string formatDereference(const SourceManager &SourceManager, |
| const Expr &ExprNode) { |
| if (const clang::UnaryOperator *Op = |
| dyn_cast<clang::UnaryOperator>(&ExprNode)) { |
| if (Op->getOpcode() == UO_AddrOf) { |
| // Strip leading '&'. |
| return getText(SourceManager, *Op->getSubExpr()->IgnoreParens()); |
| } |
| } |
| const std::string Text = getText(SourceManager, ExprNode); |
| if (Text.empty()) return std::string(); |
| // Add leading '*'. |
| if (needParensAfterUnaryOperator(ExprNode)) { |
| return std::string("*(") + Text + ")"; |
| } |
| return std::string("*") + Text; |
| } |
| |
| namespace { |
| class FixCStrCall : public ast_matchers::MatchFinder::MatchCallback { |
| public: |
| FixCStrCall(tooling::Replacements *Replace) |
| : Replace(Replace) {} |
| |
| virtual void run(const ast_matchers::MatchFinder::MatchResult &Result) { |
| const CallExpr *Call = |
| Result.Nodes.getStmtAs<CallExpr>("call"); |
| const Expr *Arg = |
| Result.Nodes.getStmtAs<Expr>("arg"); |
| const bool Arrow = |
| Result.Nodes.getStmtAs<MemberExpr>("member")->isArrow(); |
| // Replace the "call" node with the "arg" node, prefixed with '*' |
| // if the call was using '->' rather than '.'. |
| const std::string ArgText = Arrow ? |
| formatDereference(*Result.SourceManager, *Arg) : |
| getText(*Result.SourceManager, *Arg); |
| if (ArgText.empty()) return; |
| |
| Replace->insert(Replacement(*Result.SourceManager, Call, ArgText)); |
| } |
| |
| private: |
| tooling::Replacements *Replace; |
| }; |
| } // end namespace |
| |
| const char *StringConstructor = |
| "::std::basic_string<char, std::char_traits<char>, std::allocator<char> >" |
| "::basic_string"; |
| |
| const char *StringCStrMethod = |
| "::std::basic_string<char, std::char_traits<char>, std::allocator<char> >" |
| "::c_str"; |
| |
| cl::opt<std::string> BuildPath( |
| cl::Positional, |
| cl::desc("<build-path>")); |
| |
| cl::list<std::string> SourcePaths( |
| cl::Positional, |
| cl::desc("<source0> [... <sourceN>]"), |
| cl::OneOrMore); |
| |
| int main(int argc, const char **argv) { |
| llvm::sys::PrintStackTraceOnErrorSignal(); |
| std::unique_ptr<CompilationDatabase> Compilations( |
| tooling::FixedCompilationDatabase::loadFromCommandLine(argc, argv)); |
| cl::ParseCommandLineOptions(argc, argv); |
| if (!Compilations) { |
| std::string ErrorMessage; |
| Compilations.reset( |
| CompilationDatabase::loadFromDirectory(BuildPath, ErrorMessage)); |
| if (!Compilations) |
| llvm::report_fatal_error(ErrorMessage); |
| } |
| tooling::RefactoringTool Tool(*Compilations, SourcePaths); |
| ast_matchers::MatchFinder Finder; |
| FixCStrCall Callback(&Tool.getReplacements()); |
| Finder.addMatcher( |
| constructExpr( |
| hasDeclaration(methodDecl(hasName(StringConstructor))), |
| argumentCountIs(2), |
| // The first argument must have the form x.c_str() or p->c_str() |
| // where the method is string::c_str(). We can use the copy |
| // constructor of string instead (or the compiler might share |
| // the string object). |
| hasArgument( |
| 0, |
| id("call", memberCallExpr( |
| callee(id("member", memberExpr())), |
| callee(methodDecl(hasName(StringCStrMethod))), |
| on(id("arg", expr()))))), |
| // The second argument is the alloc object which must not be |
| // present explicitly. |
| hasArgument( |
| 1, |
| defaultArgExpr())), |
| &Callback); |
| Finder.addMatcher( |
| constructExpr( |
| // Implicit constructors of these classes are overloaded |
| // wrt. string types and they internally make a StringRef |
| // referring to the argument. Passing a string directly to |
| // them is preferred to passing a char pointer. |
| hasDeclaration(methodDecl(anyOf( |
| hasName("::llvm::StringRef::StringRef"), |
| hasName("::llvm::Twine::Twine")))), |
| argumentCountIs(1), |
| // The only argument must have the form x.c_str() or p->c_str() |
| // where the method is string::c_str(). StringRef also has |
| // a constructor from string which is more efficient (avoids |
| // strlen), so we can construct StringRef from the string |
| // directly. |
| hasArgument( |
| 0, |
| id("call", memberCallExpr( |
| callee(id("member", memberExpr())), |
| callee(methodDecl(hasName(StringCStrMethod))), |
| on(id("arg", expr())))))), |
| &Callback); |
| return Tool.runAndSave(newFrontendActionFactory(&Finder).get()); |
| } |