1 //===--- LexicallyOrderedRecursiveASTVisitor.h - ----------------*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines the LexicallyOrderedRecursiveASTVisitor interface, which
10 // recursively traverses the entire AST in a lexical order.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_AST_LEXICALLY_ORDERED_RECURSIVEASTVISITOR_H
15 #define LLVM_CLANG_AST_LEXICALLY_ORDERED_RECURSIVEASTVISITOR_H
17 #include "clang/AST/RecursiveASTVisitor.h"
18 #include "clang/Basic/LLVM.h"
19 #include "clang/Basic/SourceManager.h"
20 #include "llvm/Support/SaveAndRestore.h"
24 /// A RecursiveASTVisitor subclass that guarantees that AST traversal is
25 /// performed in a lexical order (i.e. the order in which declarations are
26 /// written in the source).
28 /// RecursiveASTVisitor doesn't guarantee lexical ordering because there are
29 /// some declarations, like Objective-C @implementation declarations
30 /// that might be represented in the AST differently to how they were written
32 /// In particular, Objective-C @implementation declarations may contain
33 /// non-Objective-C declarations, like functions:
35 /// @implementation MyClass
37 /// - (void) method { }
38 /// void normalFunction() { }
42 /// Clang's AST stores these declarations outside of the @implementation
43 /// declaration, so the example above would be represented using the following
45 /// |-ObjCImplementationDecl ... MyClass
46 /// | `-ObjCMethodDecl ... method
48 /// `-FunctionDecl ... normalFunction
51 /// This class ensures that these declarations are traversed before the
52 /// corresponding TraverseDecl for the @implementation returns. This ensures
53 /// that the lexical parent relationship between these declarations and the
54 /// @implementation is preserved while traversing the AST. Note that the
55 /// current implementation doesn't mix these declarations with the declarations
56 /// contained in the @implementation, so the traversal of all of the
57 /// declarations in the @implementation still doesn't follow the lexical order.
58 template <typename Derived>
59 class LexicallyOrderedRecursiveASTVisitor
60 : public RecursiveASTVisitor<Derived> {
61 using BaseType = RecursiveASTVisitor<Derived>;
64 LexicallyOrderedRecursiveASTVisitor(const SourceManager &SM) : SM(SM) {}
66 bool TraverseObjCImplementationDecl(ObjCImplementationDecl *D) {
67 // Objective-C @implementation declarations should not trigger early exit
68 // until the additional decls are traversed as their children are not
70 bool Result = BaseType::TraverseObjCImplementationDecl(D);
71 return TraverseAdditionalLexicallyNestedDeclarations() ? Result : false;
74 bool TraverseObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
75 bool Result = BaseType::TraverseObjCCategoryImplDecl(D);
76 return TraverseAdditionalLexicallyNestedDeclarations() ? Result : false;
79 bool TraverseDeclContextHelper(DeclContext *DC) {
83 for (auto I = DC->decls_begin(), E = DC->decls_end(); I != E;) {
85 if (BaseType::canIgnoreChildDeclWhileTraversingDeclContext(Child)) {
89 if (!isa<ObjCImplementationDecl>(Child) &&
90 !isa<ObjCCategoryImplDecl>(Child)) {
91 if (!BaseType::getDerived().TraverseDecl(Child))
96 // Gather declarations that follow the Objective-C implementation
97 // declarations but are lexically contained in the implementation.
98 LexicallyNestedDeclarations.clear();
99 for (++I; I != E; ++I) {
101 if (!SM.isBeforeInTranslationUnit(Sibling->getBeginLoc(),
104 if (!BaseType::canIgnoreChildDeclWhileTraversingDeclContext(Sibling))
105 LexicallyNestedDeclarations.push_back(Sibling);
107 if (!BaseType::getDerived().TraverseDecl(Child))
113 Stmt::child_range getStmtChildren(Stmt *S) { return S->children(); }
115 SmallVector<Stmt *, 8> getStmtChildren(CXXOperatorCallExpr *CE) {
116 SmallVector<Stmt *, 8> Children(CE->children());
118 // Switch the operator and the first operand for all infix and postfix
120 switch (CE->getOperator()) {
128 // These are postfix unless there is exactly one argument.
129 Swap = Children.size() != 2;
132 Swap = CE->isInfixBinaryOp();
135 if (Swap && Children.size() > 1)
136 std::swap(Children[0], Children[1]);
141 bool TraverseAdditionalLexicallyNestedDeclarations() {
142 // FIXME: Ideally the gathered declarations and the declarations in the
143 // @implementation should be mixed and sorted to get a true lexical order,
144 // but right now we only care about getting the correct lexical parent, so
145 // we can traverse the gathered nested declarations after the declarations
146 // in the decl context.
147 assert(!BaseType::getDerived().shouldTraversePostOrder() &&
148 "post-order traversal is not supported for lexically ordered "
149 "recursive ast visitor");
150 for (Decl *D : LexicallyNestedDeclarations) {
151 if (!BaseType::getDerived().TraverseDecl(D))
157 const SourceManager &SM;
158 llvm::SmallVector<Decl *, 8> LexicallyNestedDeclarations;
161 } // end namespace clang
163 #endif // LLVM_CLANG_AST_LEXICALLY_ORDERED_RECURSIVEASTVISITOR_H