1 //===--- Stencil.cpp - Stencil implementation -------------------*- 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 
9 #include "clang/Tooling/Transformer/Stencil.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/AST/ASTTypeTraits.h"
12 #include "clang/AST/Expr.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 #include "clang/ASTMatchers/ASTMatchers.h"
15 #include "clang/Basic/SourceLocation.h"
16 #include "clang/Lex/Lexer.h"
17 #include "clang/Tooling/Transformer/SourceCode.h"
18 #include "clang/Tooling/Transformer/SourceCodeBuilders.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/ADT/Twine.h"
21 #include "llvm/Support/Errc.h"
22 #include <atomic>
23 #include <memory>
24 #include <string>
25 
26 using namespace clang;
27 using namespace transformer;
28 
29 using ast_matchers::MatchFinder;
30 using llvm::errc;
31 using llvm::Error;
32 using llvm::Expected;
33 using llvm::StringError;
34 
35 static llvm::Expected<DynTypedNode>
36 getNode(const ast_matchers::BoundNodes &Nodes, StringRef Id) {
37   auto &NodesMap = Nodes.getMap();
38   auto It = NodesMap.find(Id);
39   if (It == NodesMap.end())
40     return llvm::make_error<llvm::StringError>(llvm::errc::invalid_argument,
41                                                "Id not bound: " + Id);
42   return It->second;
43 }
44 
45 namespace {
46 // An arbitrary fragment of code within a stencil.
47 struct RawTextData {
48   explicit RawTextData(std::string T) : Text(std::move(T)) {}
49   std::string Text;
50 };
51 
52 // A debugging operation to dump the AST for a particular (bound) AST node.
53 struct DebugPrintNodeData {
54   explicit DebugPrintNodeData(std::string S) : Id(std::move(S)) {}
55   std::string Id;
56 };
57 
58 // Operators that take a single node Id as an argument.
59 enum class UnaryNodeOperator {
60   Parens,
61   Deref,
62   MaybeDeref,
63   AddressOf,
64   MaybeAddressOf,
65 };
66 
67 // Generic container for stencil operations with a (single) node-id argument.
68 struct UnaryOperationData {
69   UnaryOperationData(UnaryNodeOperator Op, std::string Id)
70       : Op(Op), Id(std::move(Id)) {}
71   UnaryNodeOperator Op;
72   std::string Id;
73 };
74 
75 // The fragment of code corresponding to the selected range.
76 struct SelectorData {
77   explicit SelectorData(RangeSelector S) : Selector(std::move(S)) {}
78   RangeSelector Selector;
79 };
80 
81 // A stencil operation to build a member access `e.m` or `e->m`, as appropriate.
82 struct AccessData {
83   AccessData(StringRef BaseId, Stencil Member)
84       : BaseId(std::string(BaseId)), Member(std::move(Member)) {}
85   std::string BaseId;
86   Stencil Member;
87 };
88 
89 struct IfBoundData {
90   IfBoundData(StringRef Id, Stencil TrueStencil, Stencil FalseStencil)
91       : Id(std::string(Id)), TrueStencil(std::move(TrueStencil)),
92         FalseStencil(std::move(FalseStencil)) {}
93   std::string Id;
94   Stencil TrueStencil;
95   Stencil FalseStencil;
96 };
97 
98 struct SequenceData {
99   SequenceData(std::vector<Stencil> Stencils) : Stencils(std::move(Stencils)) {}
100   std::vector<Stencil> Stencils;
101 };
102 
103 std::string toStringData(const RawTextData &Data) {
104   std::string Result;
105   llvm::raw_string_ostream OS(Result);
106   OS << "\"";
107   OS.write_escaped(Data.Text);
108   OS << "\"";
109   OS.flush();
110   return Result;
111 }
112 
113 std::string toStringData(const DebugPrintNodeData &Data) {
114   return (llvm::Twine("dPrint(\"") + Data.Id + "\")").str();
115 }
116 
117 std::string toStringData(const UnaryOperationData &Data) {
118   StringRef OpName;
119   switch (Data.Op) {
120   case UnaryNodeOperator::Parens:
121     OpName = "expression";
122     break;
123   case UnaryNodeOperator::Deref:
124     OpName = "deref";
125     break;
126   case UnaryNodeOperator::MaybeDeref:
127     OpName = "maybeDeref";
128     break;
129   case UnaryNodeOperator::AddressOf:
130     OpName = "addressOf";
131     break;
132   case UnaryNodeOperator::MaybeAddressOf:
133     OpName = "maybeAddressOf";
134     break;
135   }
136   return (OpName + "(\"" + Data.Id + "\")").str();
137 }
138 
139 std::string toStringData(const SelectorData &) { return "selection(...)"; }
140 
141 std::string toStringData(const AccessData &Data) {
142   return (llvm::Twine("access(\"") + Data.BaseId + "\", " +
143           Data.Member->toString() + ")")
144       .str();
145 }
146 
147 std::string toStringData(const IfBoundData &Data) {
148   return (llvm::Twine("ifBound(\"") + Data.Id + "\", " +
149           Data.TrueStencil->toString() + ", " + Data.FalseStencil->toString() +
150           ")")
151       .str();
152 }
153 
154 std::string toStringData(const MatchConsumer<std::string> &) {
155   return "run(...)";
156 }
157 
158 std::string toStringData(const SequenceData &Data) {
159   llvm::SmallVector<std::string, 2> Parts;
160   Parts.reserve(Data.Stencils.size());
161   for (const auto &S : Data.Stencils)
162     Parts.push_back(S->toString());
163   return (llvm::Twine("seq(") + llvm::join(Parts, ", ") + ")").str();
164 }
165 
166 // The `evalData()` overloads evaluate the given stencil data to a string, given
167 // the match result, and append it to `Result`. We define an overload for each
168 // type of stencil data.
169 
170 Error evalData(const RawTextData &Data, const MatchFinder::MatchResult &,
171                std::string *Result) {
172   Result->append(Data.Text);
173   return Error::success();
174 }
175 
176 Error evalData(const DebugPrintNodeData &Data,
177                const MatchFinder::MatchResult &Match, std::string *Result) {
178   std::string Output;
179   llvm::raw_string_ostream Os(Output);
180   auto NodeOrErr = getNode(Match.Nodes, Data.Id);
181   if (auto Err = NodeOrErr.takeError())
182     return Err;
183   NodeOrErr->print(Os, PrintingPolicy(Match.Context->getLangOpts()));
184   *Result += Os.str();
185   return Error::success();
186 }
187 
188 Error evalData(const UnaryOperationData &Data,
189                const MatchFinder::MatchResult &Match, std::string *Result) {
190   const auto *E = Match.Nodes.getNodeAs<Expr>(Data.Id);
191   if (E == nullptr)
192     return llvm::make_error<StringError>(
193         errc::invalid_argument, "Id not bound or not Expr: " + Data.Id);
194   llvm::Optional<std::string> Source;
195   switch (Data.Op) {
196   case UnaryNodeOperator::Parens:
197     Source = tooling::buildParens(*E, *Match.Context);
198     break;
199   case UnaryNodeOperator::Deref:
200     Source = tooling::buildDereference(*E, *Match.Context);
201     break;
202   case UnaryNodeOperator::MaybeDeref:
203     if (!E->getType()->isAnyPointerType()) {
204       *Result += tooling::getText(*E, *Match.Context);
205       return Error::success();
206     }
207     Source = tooling::buildDereference(*E, *Match.Context);
208     break;
209   case UnaryNodeOperator::AddressOf:
210     Source = tooling::buildAddressOf(*E, *Match.Context);
211     break;
212   case UnaryNodeOperator::MaybeAddressOf:
213     if (E->getType()->isAnyPointerType()) {
214       *Result += tooling::getText(*E, *Match.Context);
215       return Error::success();
216     }
217     Source = tooling::buildAddressOf(*E, *Match.Context);
218     break;
219   }
220   if (!Source)
221     return llvm::make_error<StringError>(
222         errc::invalid_argument,
223         "Could not construct expression source from ID: " + Data.Id);
224   *Result += *Source;
225   return Error::success();
226 }
227 
228 Error evalData(const SelectorData &Data, const MatchFinder::MatchResult &Match,
229                std::string *Result) {
230   auto RawRange = Data.Selector(Match);
231   if (!RawRange)
232     return RawRange.takeError();
233   CharSourceRange Range = Lexer::makeFileCharRange(
234       *RawRange, *Match.SourceManager, Match.Context->getLangOpts());
235   if (auto Err = tooling::validateEditRange(Range, *Match.SourceManager))
236     return Err;
237   *Result += tooling::getText(Range, *Match.Context);
238   return Error::success();
239 }
240 
241 Error evalData(const AccessData &Data, const MatchFinder::MatchResult &Match,
242                std::string *Result) {
243   const auto *E = Match.Nodes.getNodeAs<Expr>(Data.BaseId);
244   if (E == nullptr)
245     return llvm::make_error<StringError>(errc::invalid_argument,
246                                          "Id not bound: " + Data.BaseId);
247   if (!E->isImplicitCXXThis()) {
248     if (llvm::Optional<std::string> S =
249             E->getType()->isAnyPointerType()
250                 ? tooling::buildArrow(*E, *Match.Context)
251                 : tooling::buildDot(*E, *Match.Context))
252       *Result += *S;
253     else
254       return llvm::make_error<StringError>(
255           errc::invalid_argument,
256           "Could not construct object text from ID: " + Data.BaseId);
257   }
258   return Data.Member->eval(Match, Result);
259 }
260 
261 Error evalData(const IfBoundData &Data, const MatchFinder::MatchResult &Match,
262                std::string *Result) {
263   auto &M = Match.Nodes.getMap();
264   return (M.find(Data.Id) != M.end() ? Data.TrueStencil : Data.FalseStencil)
265       ->eval(Match, Result);
266 }
267 
268 Error evalData(const MatchConsumer<std::string> &Fn,
269                const MatchFinder::MatchResult &Match, std::string *Result) {
270   Expected<std::string> Value = Fn(Match);
271   if (!Value)
272     return Value.takeError();
273   *Result += *Value;
274   return Error::success();
275 }
276 
277 Error evalData(const SequenceData &Data, const MatchFinder::MatchResult &Match,
278                std::string *Result) {
279   for (const auto &S : Data.Stencils)
280     if (auto Err = S->eval(Match, Result))
281       return Err;
282   return Error::success();
283 }
284 
285 template <typename T> class StencilImpl : public StencilInterface {
286   T Data;
287 
288 public:
289   template <typename... Ps>
290   explicit StencilImpl(Ps &&... Args) : Data(std::forward<Ps>(Args)...) {}
291 
292   Error eval(const MatchFinder::MatchResult &Match,
293              std::string *Result) const override {
294     return evalData(Data, Match, Result);
295   }
296 
297   std::string toString() const override { return toStringData(Data); }
298 };
299 } // namespace
300 
301 Stencil transformer::detail::makeStencil(StringRef Text) {
302   return std::make_shared<StencilImpl<RawTextData>>(std::string(Text));
303 }
304 
305 Stencil transformer::detail::makeStencil(RangeSelector Selector) {
306   return std::make_shared<StencilImpl<SelectorData>>(std::move(Selector));
307 }
308 
309 Stencil transformer::dPrint(StringRef Id) {
310   return std::make_shared<StencilImpl<DebugPrintNodeData>>(std::string(Id));
311 }
312 
313 Stencil transformer::expression(llvm::StringRef Id) {
314   return std::make_shared<StencilImpl<UnaryOperationData>>(
315       UnaryNodeOperator::Parens, std::string(Id));
316 }
317 
318 Stencil transformer::deref(llvm::StringRef ExprId) {
319   return std::make_shared<StencilImpl<UnaryOperationData>>(
320       UnaryNodeOperator::Deref, std::string(ExprId));
321 }
322 
323 Stencil transformer::maybeDeref(llvm::StringRef ExprId) {
324   return std::make_shared<StencilImpl<UnaryOperationData>>(
325       UnaryNodeOperator::MaybeDeref, std::string(ExprId));
326 }
327 
328 Stencil transformer::addressOf(llvm::StringRef ExprId) {
329   return std::make_shared<StencilImpl<UnaryOperationData>>(
330       UnaryNodeOperator::AddressOf, std::string(ExprId));
331 }
332 
333 Stencil transformer::maybeAddressOf(llvm::StringRef ExprId) {
334   return std::make_shared<StencilImpl<UnaryOperationData>>(
335       UnaryNodeOperator::MaybeAddressOf, std::string(ExprId));
336 }
337 
338 Stencil transformer::access(StringRef BaseId, Stencil Member) {
339   return std::make_shared<StencilImpl<AccessData>>(BaseId, std::move(Member));
340 }
341 
342 Stencil transformer::ifBound(StringRef Id, Stencil TrueStencil,
343                              Stencil FalseStencil) {
344   return std::make_shared<StencilImpl<IfBoundData>>(Id, std::move(TrueStencil),
345                                                     std::move(FalseStencil));
346 }
347 
348 Stencil transformer::run(MatchConsumer<std::string> Fn) {
349   return std::make_shared<StencilImpl<MatchConsumer<std::string>>>(
350       std::move(Fn));
351 }
352 
353 Stencil transformer::catVector(std::vector<Stencil> Parts) {
354   // Only one argument, so don't wrap in sequence.
355   if (Parts.size() == 1)
356     return std::move(Parts[0]);
357   return std::make_shared<StencilImpl<SequenceData>>(std::move(Parts));
358 }
359