libclang python如何获取具有默认值的函数的参数数量

Question

我正在使用带有 python 绑定的 libclang，并且我正在尝试获取 CallExpr 的参数数量，我发现如果成员函数具有默认值并且在缺少此参数的情况下被调用，则 libclang 返回参数的数量在函数声明中，而不是在调用表达式中。

例如：

class SomeClass
{
public:
    int sum(int x, int y)
    {
        return x + y;
    }

    int sum_def(int x, int y = 0)
    {
        return x + y;
    }
};

int main()
{
    SomeClass x;
    x.sum(10, 100);
    x.sum_def(20);
    return 0;
}

使用 liblcang 遍历 ast：

def traverse(node):
    if node.kind == clang.cindex.CursorKind.CALL_EXPR:
        print('%-35s %-20s %-10s [%-6s:%s - %-6s:%s] %s %s ' % (
        node.kind, node.spelling, node.type.spelling, node.extent.start.line, node.extent.start.column,
        node.extent.end.line, node.extent.end.column, node.location.file, node.mangled_name))
        print("%d  " % node.get_num_arguments())
        for arg in node.get_arguments():
            print("ARG=%s %s" % (arg.kind, arg.spelling))

    for child in node.get_children():
        traverse(child)

输出：

CursorKind.CALL_EXPR                sum                  int        [20    :5 - 20    :19] main.cpp
2  
ARG=CursorKind.INTEGER_LITERAL 
ARG=CursorKind.INTEGER_LITERAL 
CursorKind.CALL_EXPR                sum_def              int        [21    :5 - 21    :18] main.cpp  
2  
ARG=CursorKind.INTEGER_LITERAL 
ARG=CursorKind.UNEXPOSED_EXPR 

我希望在 sum_def 的 CALL_EXPR 中得到 1 作为参数的数量，有可能得到它，或者我应该自己解析代码，这是我真的不想做的事情。 谢谢。

Answer 1

我改变了一点遍历函数来打印更多细节

def traverse(node, level):
    print('%s %-35s %-20s %-10s [%-6s:%s - %-6s:%s] %s %s ' % (' ' * level,
    node.kind, node.spelling, node.type.spelling, node.extent.start.line, node.extent.start.column,
    node.extent.end.line, node.extent.end.column, node.location.file, node.mangled_name))
    if node.kind == clang.cindex.CursorKind.CALL_EXPR:
        for arg in node.get_arguments():
            print("ARG=%s %s" % (arg.kind, arg.spelling))

    for child in node.get_children():
        traverse(child, level+1)

输出：

  CursorKind.CLASS_DECL               SomeClass            SomeClass  [2     :1 - 14    :2] main.cpp  
   CursorKind.CXX_ACCESS_SPEC_DECL                                     [4     :1 - 4     :8] main.cpp  
   CursorKind.CXX_METHOD               sum                  int (int, int) [5     :5 - 8     :6] main.cpp _ZN9SomeClass3sumEii 
    CursorKind.PARM_DECL                x                    int        [5     :13 - 5     :18] main.cpp _ZZN9SomeClass3sumEiiE1x 
    CursorKind.PARM_DECL                y                    int        [5     :20 - 5     :25] main.cpp _ZZN9SomeClass3sumEiiE1y 
    CursorKind.COMPOUND_STMT                                            [6     :5 - 8     :6] main.cpp  
     CursorKind.RETURN_STMT                                              [7     :9 - 7     :21] main.cpp  
      CursorKind.BINARY_OPERATOR                               int        [7     :16 - 7     :21] main.cpp  
       CursorKind.UNEXPOSED_EXPR           x                    int        [7     :16 - 7     :17] main.cpp  
        CursorKind.DECL_REF_EXPR            x                    int        [7     :16 - 7     :17] main.cpp  
       CursorKind.UNEXPOSED_EXPR           y                    int        [7     :20 - 7     :21] main.cpp  
        CursorKind.DECL_REF_EXPR            y                    int        [7     :20 - 7     :21] main.cpp  
   CursorKind.CXX_METHOD               sum_def              int (int, int) [10    :5 - 13    :6] main.cpp _ZN9SomeClass7sum_defEii 
    CursorKind.PARM_DECL                x                    int        [10    :17 - 10    :22] main.cpp _ZZN9SomeClass7sum_defEiiE1x 
    CursorKind.PARM_DECL                y                    int        [10    :24 - 10    :33] main.cpp _ZZN9SomeClass7sum_defEiiE1y 
     CursorKind.INTEGER_LITERAL                               int        [10    :32 - 10    :33] main.cpp  
    CursorKind.COMPOUND_STMT                                            [11    :5 - 13    :6] main.cpp  
     CursorKind.RETURN_STMT                                              [12    :9 - 12    :21] main.cpp  
      CursorKind.BINARY_OPERATOR                               int        [12    :16 - 12    :21] main.cpp  
       CursorKind.UNEXPOSED_EXPR           x                    int        [12    :16 - 12    :17] main.cpp  
        CursorKind.DECL_REF_EXPR            x                    int        [12    :16 - 12    :17] main.cpp  
       CursorKind.UNEXPOSED_EXPR           y                    int        [12    :20 - 12    :21] main.cpp  
        CursorKind.DECL_REF_EXPR            y                    int        [12    :20 - 12    :21] main.cpp  
  CursorKind.FUNCTION_DECL            main                 int ()     [17    :1 - 26    :2] main.cpp main 
   CursorKind.COMPOUND_STMT                                            [18    :1 - 26    :2] main.cpp  
    CursorKind.DECL_STMT                                                [19    :5 - 19    :22] main.cpp  
     CursorKind.VAR_DECL                 i                    int        [19    :5 - 19    :14] main.cpp _ZZ4mainE1i 
      CursorKind.INTEGER_LITERAL                               int        [19    :13 - 19    :14] main.cpp  
     CursorKind.VAR_DECL                 j                    int        [19    :16 - 19    :21] main.cpp _ZZ4mainE1j 
      CursorKind.INTEGER_LITERAL                               int        [19    :20 - 19    :21] main.cpp  
    CursorKind.DECL_STMT                                                [20    :5 - 20    :17] main.cpp  
     CursorKind.VAR_DECL                 x                    SomeClass  [20    :5 - 20    :16] main.cpp _ZZ4mainE1x 
      CursorKind.TYPE_REF                 class SomeClass      SomeClass  [20    :5 - 20    :14] main.cpp  
      CursorKind.CALL_EXPR                SomeClass            SomeClass  [20    :15 - 20    :16] main.cpp  
    CursorKind.CALL_EXPR                sum                  int        [21    :5 - 21    :19] main.cpp  
ARG=CursorKind.INTEGER_LITERAL 
ARG=CursorKind.INTEGER_LITERAL 
     CursorKind.MEMBER_REF_EXPR          sum                  <bound member function type> [21    :5 - 21    :10] main.cpp  
      CursorKind.DECL_REF_EXPR            x                    SomeClass  [21    :5 - 21    :6] main.cpp  
     CursorKind.INTEGER_LITERAL                               int        [21    :11 - 21    :13] main.cpp  
     CursorKind.INTEGER_LITERAL                               int        [21    :15 - 21    :18] main.cpp  
    CursorKind.CALL_EXPR                sum_def              int        [22    :5 - 22    :18] main.cpp  
ARG=CursorKind.INTEGER_LITERAL 
ARG=CursorKind.UNEXPOSED_EXPR 
     CursorKind.MEMBER_REF_EXPR          sum_def              <bound member function type> [22    :5 - 22    :14] main.cpp  
      CursorKind.DECL_REF_EXPR            x                    SomeClass  [22    :5 - 22    :6] main.cpp  
     CursorKind.INTEGER_LITERAL                               int        [22    :15 - 22    :17] main.cpp  
     CursorKind.UNEXPOSED_EXPR                                int        [0     :0 - 0     :0] None  
    CursorKind.CALL_EXPR                sum_def              int        [23    :5 - 23    :23] main.cpp  
ARG=CursorKind.INTEGER_LITERAL 
ARG=CursorKind.INTEGER_LITERAL 
     CursorKind.MEMBER_REF_EXPR          sum_def              <bound member function type> [23    :5 - 23    :14] main.cpp  
      CursorKind.DECL_REF_EXPR            x                    SomeClass  [23    :5 - 23    :6] main.cpp  
     CursorKind.INTEGER_LITERAL                               int        [23    :15 - 23    :17] main.cpp  
     CursorKind.INTEGER_LITERAL                               int        [23    :19 - 23    :22] main.cpp  
    CursorKind.CALL_EXPR                sum                  int        [24    :5 - 24    :16] main.cpp  
ARG=CursorKind.UNEXPOSED_EXPR i
ARG=CursorKind.UNEXPOSED_EXPR j
     CursorKind.MEMBER_REF_EXPR          sum                  <bound member function type> [24    :5 - 24    :10] main.cpp  
      CursorKind.DECL_REF_EXPR            x                    SomeClass  [24    :5 - 24    :6] main.cpp  
     CursorKind.UNEXPOSED_EXPR           i                    int        [24    :11 - 24    :12] main.cpp  
      CursorKind.DECL_REF_EXPR            i                    int        [24    :11 - 24    :12] main.cpp  
     CursorKind.UNEXPOSED_EXPR           j                    int        [24    :14 - 24    :15] main.cpp  
      CursorKind.DECL_REF_EXPR            j                    int        [24    :14 - 24    :15] main.cpp  
    CursorKind.RETURN_STMT                                              [25    :5 - 25    :13] main.cpp  
     CursorKind.INTEGER_LITERAL                               int        [25    :12 - 25    :13] main.cpp  

有了这个输出，以及我添加到源代码中的更多测试用例，我明白我应该将每个不是 UNEXPOSED_EXPR 的参数都算作参数，如果它是 UNEXPOSED_EXRP，我应该检查它是否有孩子。如果是，则表示我需要计算它。