Question

我有以下使用clang-c API的代码。

#include <iostream>
#include <string>
#include <clang-c/Index.h>

CXChildVisitResult printVisitor(CXCursor cursor, CXCursor parent, CXClientData client_data) 
{       
    CXCursor cursor1 = clang_getCursorReferenced(cursor);

    CXType type = clang_getCursorType(cursor1);
    CXCursorKind kind = clang_getCursorKind(cursor1);
    CXString str = clang_getTypeSpelling(type);
    CXString str1 = clang_getCursorSpelling(cursor1);
    std::string cstr = clang_getCString(str);
    std::string cstr1 = clang_getCString(str1);

    if(type.kind != 0 && kind == CXCursorKind::CXCursor_FunctionDecl)
    {
        std::cout << "Declaration!\n" << "type is: " << cstr << std::endl;
        std::cout << "name is: " << cstr1 << std::endl;
    }

    return CXChildVisit_Recurse;
}

int main (int argc, char** argv)
{
 CXIndex index = clang_createIndex (
         false, // excludeDeclarationFromPCH
         true   // displayDiagnostics
 );
 CXTranslationUnit unit = clang_parseTranslationUnit (
         index,                           // CIdx
         "main1.cpp",                      // source_filename
         argv + 1 ,                        // command_line_args
         argc - 1 ,                        // num_command_line_args
         0,                                // unsave_files
         0,                                // num_unsaved_files
         CXTranslationUnit_None           // options
 );
 if (unit != 0 )
         std::cout << "Translation unit successfully created" << std::endl;
 else
         std::cout << "Translation unit was not created" << std::endl;

 CXCursor rootCursor = clang_getTranslationUnitCursor(unit);

    clang_visitChildren(rootCursor, printVisitor, NULL);


 clang_disposeTranslationUnit(unit);
 clang_disposeIndex(index);
}

此代码解析以下内容。

double getSum(double a, float b)
{
    return a + b;
}

int main(void)
{
    int a = 5;
    float b = 6;
    double c = a + b;
    return getSum(c, b);
}

程序运行时，我会看到以下内容。

    Translation unit successfully created
    Declaration!
    type is: double (double, float)
    name is: getSum
    Declaration!
    type is: int ()
    name is: main
    Declaration!
    type is: double (double, float)
    name is: getSum
    Declaration!
    type is: double (double, float)
    name is: getSum
    Declaration!
    type is: double (double, float)
    name is: getSum
    Declaration!
    type is: double (double, float)
    name is: getSum

为什么我在{1}}中获得了如此多的声明，在代码中我有一个声明？

Answer 1

使用clang_getCursorReferenced时，您会获得当前位置引用的CXCursor。例如，函数声明引用自身，并由相应的函数调用引用。在您的示例中，您将因此获得对函数声明（函数声明本身或函数调用）的每个引用的正匹配。

现在另一件事是每个CXCursor代表AST的一部分，无论是叶子还是带有子部分的更复杂的部分。例如，在遍历AST时，您将依次找到以下游标：

return getSum (c, b)
getSum (c, b)
getSum

所有这些游标都引用了getSum函数声明，我的猜测是这些游标会触发对getSum的多次引用。

您可以通过调用clang_getCursorExtent

来检查源代码的哪个部分对应当前光标

Answer 2

我从未使用过clang，但基于the documentation of CXCursor，只要光标在某个地方某处，CXCursorKind似乎总是Declaration （main我可能会得到特殊待遇）。这可以解释为什么您有多个Sum声明的报告。

我的猜想基于CXCursorKind的定义，找到here：

enum CXCursorKind {
  /* Declarations */
  /**
   * \brief A declaration whose specific kind is not exposed via this
   * interface.
   *
   * Unexposed declarations have the same operations as any other kind
   * of declaration; one can extract their location information,
   * spelling, find their definitions, etc. However, the specific kind
   * of the declaration is not reported.
   */
...
}

libclang返回有关函数声明的太多信息

2 个答案: