[英]Retrieve template parameters from CXXConstructExpr in Clang AST
Say I have a variable declaration like this: 说我有一个这样的变量声明:
std::vector<MyType> myVector(1);
This is represented as a CXXConstructExpr
in the Clang AST. 在Clang AST中将其表示为CXXConstructExpr
。 I have a matcher that finds this CXXConstructExpr
, but I'd like to extract the decl for MyType
from it. 我有一个匹配器,可以找到此CXXConstructExpr
,但我想从中提取MyType
的decl。
I've tried all sorts of things, but nothing seems to work: 我已经尝试过各种方法,但是似乎没有任何效果:
const CXXConstructExpr* construct = Result.Nodes.getNodeAs<CXXConstructExpr>("expr");
construct->getConstructor()->getTemplateSpecializationArgs() // Always nullptr
construct->getConstructor()->getParent() // Seems to lose the template parameters
construct->getConstructor()->getDescribedTemplate() // Always nullptr
Here's a matcher: 这是一个匹配器:
varDecl(
has(
cxxConstructExpr()
)
,hasType(
classTemplateSpecializationDecl().bind(sp_dcl_bd_name_)
)
).bind(var_bd_name_);
It starts with the VarDecl and traverses to the type, which is a ClassTemplateSpecializationDecl
buried in vector's ClassTemplateDecl
. 它开始与VarDecl和横梁的类型,这是一个ClassTemplateSpecializationDecl
埋在载体的ClassTemplateDecl
。 In the callback, one can work from the ClassTemplateSpecializationDecl
to the template argument list, and operate on the individual template arguments: 在回调中,可以从ClassTemplateSpecializationDecl
到模板参数列表,然后对各个模板参数进行操作:
using CTSD = ClassTemplateSpecializationDecl;
CTSD * spec_decl =
const_cast<CTSD *>(result.Nodes.getNodeAs<CTSD>(sp_dcl_bd_name_));
VarDecl * var_decl =
const_cast<VarDecl *>(result.Nodes.getNodeAs<VarDecl>(var_bd_name_));
if(spec_decl && var_decl) {
// get the template args
TemplateArgumentList const &tal(spec_decl->getTemplateArgs());
for(unsigned i = 0; i < tal.size(); ++i){
TemplateArgument const &ta(tal[i]);
// is this arg a type arg? If so, get that type
TemplateArgument::ArgKind k(ta.getKind());
std::string argName = "";
if(k==TemplateArgument::ArgKind::Type){
QualType t = ta.getAsType();
argName = t.getAsString();
}
// Could do similar actions for integral args, etc...
std::cout << "For variable declared at "
<< corct::sourceRangeAsString(var_decl->getSourceRange(),&sm) << ":"
<< spec_decl->getNameAsString()
<< ": template arg " << (i+1) << ": " << argName << std::endl;
} // for template args
} // if
For this code: 对于此代码:
struct B{int b_;};
std::vector<B> vb(1);
this produces: 这将产生:
For variable declared at <line:14:1, col:20>:vector: template arg 1: struct B
For variable declared at <col:1, col:20>:vector: template arg 2: class std::__1::allocator<struct B>
The full example is in the Code Analysis and Refactoring with Clang Tools examples repo at github: https://github.com/lanl/CoARCT (see apps/TemplateType.cc) 完整的示例在github上的代码分析和使用Clang工具重构示例存储库中: https : //github.com/lanl/CoARCT (请参阅apps / TemplateType.cc)
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