1 //===- Mutations.cpp ------------------------------------------*- C++ -*-=====//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8 #include "clang/Tooling/Syntax/Mutations.h"
9 #include "clang/Basic/LLVM.h"
10 #include "clang/Basic/SourceLocation.h"
11 #include "clang/Lex/Token.h"
12 #include "clang/Tooling/Core/Replacement.h"
13 #include "clang/Tooling/Syntax/BuildTree.h"
14 #include "clang/Tooling/Syntax/Nodes.h"
15 #include "clang/Tooling/Syntax/Tokens.h"
16 #include "clang/Tooling/Syntax/Tree.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/Support/Casting.h"
20 #include <cassert>
21 #include <string>
22
23 using namespace clang;
24
25 // This class has access to the internals of tree nodes. Its sole purpose is to
26 // define helpers that allow implementing the high-level mutation operations.
27 class syntax::MutationsImpl {
28 public:
29 /// Add a new node with a specified role.
addAfter(syntax::Node * Anchor,syntax::Node * New,NodeRole Role)30 static void addAfter(syntax::Node *Anchor, syntax::Node *New, NodeRole Role) {
31 assert(Anchor != nullptr);
32 assert(Anchor->Parent != nullptr);
33 assert(New->Parent == nullptr);
34 assert(New->NextSibling == nullptr);
35 assert(New->PreviousSibling == nullptr);
36 assert(New->isDetached());
37 assert(Role != NodeRole::Detached);
38
39 New->setRole(Role);
40 auto *P = Anchor->getParent();
41 P->replaceChildRangeLowLevel(Anchor->getNextSibling(),
42 Anchor->getNextSibling(), New);
43
44 P->assertInvariants();
45 }
46
47 /// Replace the node, keeping the role.
replace(syntax::Node * Old,syntax::Node * New)48 static void replace(syntax::Node *Old, syntax::Node *New) {
49 assert(Old != nullptr);
50 assert(Old->Parent != nullptr);
51 assert(Old->canModify());
52 assert(New->Parent == nullptr);
53 assert(New->NextSibling == nullptr);
54 assert(New->PreviousSibling == nullptr);
55 assert(New->isDetached());
56
57 New->Role = Old->Role;
58 auto *P = Old->getParent();
59 P->replaceChildRangeLowLevel(Old, Old->getNextSibling(), New);
60
61 P->assertInvariants();
62 }
63
64 /// Completely remove the node from its parent.
remove(syntax::Node * N)65 static void remove(syntax::Node *N) {
66 assert(N != nullptr);
67 assert(N->Parent != nullptr);
68 assert(N->canModify());
69
70 auto *P = N->getParent();
71 P->replaceChildRangeLowLevel(N, N->getNextSibling(),
72 /*New=*/nullptr);
73
74 P->assertInvariants();
75 N->assertInvariants();
76 }
77 };
78
removeStatement(syntax::Arena & A,TokenBufferTokenManager & TBTM,syntax::Statement * S)79 void syntax::removeStatement(syntax::Arena &A, TokenBufferTokenManager &TBTM,
80 syntax::Statement *S) {
81 assert(S);
82 assert(S->canModify());
83
84 if (isa<CompoundStatement>(S->getParent())) {
85 // A child of CompoundStatement can just be safely removed.
86 MutationsImpl::remove(S);
87 return;
88 }
89 // For the rest, we have to replace with an empty statement.
90 if (isa<EmptyStatement>(S))
91 return; // already an empty statement, nothing to do.
92
93 MutationsImpl::replace(S, createEmptyStatement(A, TBTM));
94 }
95