Question

我有一段代码：

typedef struct S1{
 int a;
 int b; 
} S, *PS;

我可以通过clang-check获得以下AST：

| | -CXXRecordDecl 0x3dfde48 col：16隐式struct S1 | | -FieldDecl 0x3dfdef8 col：9 a＆＃39; int＆＃39; | -FieldDecl 0x3dfdf58 <line:4:5, col:9> col:9 b 'int' |-TypedefDecl 0x3dfe010 <line:1:1, line:5:3> col:3 S 'struct S1':'struct S1' | - ElaboratedType 0x3dfdfc0＆＃39; struct S1＆＃39;糖 | -RecordType 0x3dfddc0 'struct S1' | - CXXRecord 0x3dfdd28＆＃39; S1＆＃39; -TypedefDecl 0x3dfe0f0 <line:1:1, line:5:7> col:7 PS 'struct S1 *' - PointerType 0x3dfe0a0＆＃39; struct S1 *＆＃39; -ElaboratedType 0x3dfdfc0 'struct S1' sugar - RecordType 0x3dfddc0＆＃39; struct S1＆＃39; `-CXXRecord 0x3dfdd28＆＃39; S1＆＃39;

如果我使用typedefDecl（），我可以匹配S和PS，但是如何获得底层cxxRecordDecl（）？

Answer 1

一种方法是使用遍历匹配器限定typedefDecl。第一跳是typedef的类型，第二跳是该类型的声明。这将终止于您正在寻找的cxxRecordDecl。

typedefDecl(
  hasType(
    hasDeclaration(
      cxxRecordDecl().bind("the_struct")
))).bind("the_typedef")

这有效，但它至少有两个问题。首先，它还匹配您可能不希望匹配的内容，其次，它无法匹配代码中的指针typedef声明。要查看第一个问题，请在clang-query中运行该匹配器。将您的片段放入test_input_struct_type.cpp：

$ clang-query test_input_struct_type.cpp --
clang-query> let m1 typedefDecl( hasType( hasDeclaration(cxxRecordDecl().bind("the_struct"))))
clang-query> m m1

Match #1:


Match #2:

test_input_struct_type.cpp:1:1: note: "root" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~
test_input_struct_type.cpp:1:9: note: "the_struct" binds here
typedef struct S1{
        ^~~~~~~~~~
test_input_struct_type.cpp:1:1: note: "the_typedef" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~
2 matches.

比赛＃2看起来不错，但是比赛＃1是什么？我怀疑matcher正在点击一些typedef节点，这些节点似乎是由编译器在转换单元的AST开头插入的。

解决第一个问题的一种方法是增加一些特异性：

typedefDecl(
  hasType(
    elaboratedType(
      namesType(
        recordType(
          hasDeclaration(
            cxxRecordDecl().bind("the_struct")
))))).bind("the_typedef")

回到clang-query：

clang-query> let m2  typedefDecl(hasType(elaboratedType( namesType( recordType( hasDeclaration(cxxRecordDecl().bind("the_struct")))) ))).bind("the_typedef")
clang-query> m m2

Match #1:

test_input_struct_type.cpp:1:1: note: "root" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~
test_input_struct_type.cpp:1:9: note: "the_struct" binds here
typedef struct S1{
        ^~~~~~~~~~
test_input_struct_type.cpp:1:1: note: "the_typedef" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~
1 match.

第二个问题 - 找到指针typedef怎么样？这需要稍微不同的匹配器：

typedefDecl(
  hasType(
    pointerType(
      pointee(
        hasDeclaration(
          cxxRecordDecl().bind("pointee_struct")
))))).bind("the_typedef")

然后可以使用anyOf组合两个匹配器。回到clang-query：

clang-query> let m2a hasType(elaboratedType( namesType( recordType( hasDeclaration(cxxRecordDecl().bind("the_struct"))))))
clang-query> let m3a hasType(pointerType( pointee( hasDeclaration(cxxRecordDecl().bind("pointee_struct")))))
clang-query> let m4 typedefDecl( anyOf(m2a,m3a)).bind("the_typedef")
clang-query> m m4

Match #1:

test_input_struct_type.cpp:1:1: note: "root" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~
test_input_struct_type.cpp:1:9: note: "the_struct" binds here
typedef struct S1{
        ^~~~~~~~~~
test_input_struct_type.cpp:1:1: note: "the_typedef" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~

Match #2:

test_input_struct_type.cpp:1:9: note: "pointee_struct" binds here
typedef struct S1{
        ^~~~~~~~~~
test_input_struct_type.cpp:1:1: note: "root" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~
test_input_struct_type.cpp:1:1: note: "the_typedef" binds here
typedef struct S1{
^~~~~~~~~~~~~~~~~~
2 matches.

如何从typedefDecl获取cxxRecordDecl

1 个答案: