1 //===--- SourceExtraction.cpp - Clang refactoring library -----------------===//
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/Refactoring/Extract/SourceExtraction.h"
10 #include "clang/AST/Stmt.h"
11 #include "clang/AST/StmtCXX.h"
12 #include "clang/AST/StmtObjC.h"
13 #include "clang/Basic/SourceManager.h"
14 #include "clang/Lex/Lexer.h"
15 
16 using namespace clang;
17 
18 namespace {
19 
20 /// Returns true if the token at the given location is a semicolon.
21 bool isSemicolonAtLocation(SourceLocation TokenLoc, const SourceManager &SM,
22                            const LangOptions &LangOpts) {
23   return Lexer::getSourceText(
24              CharSourceRange::getTokenRange(TokenLoc, TokenLoc), SM,
25              LangOpts) == ";";
26 }
27 
28 /// Returns true if there should be a semicolon after the given statement.
29 bool isSemicolonRequiredAfter(const Stmt *S) {
30   if (isa<CompoundStmt>(S))
31     return false;
32   if (const auto *If = dyn_cast<IfStmt>(S))
33     return isSemicolonRequiredAfter(If->getElse() ? If->getElse()
34                                                   : If->getThen());
35   if (const auto *While = dyn_cast<WhileStmt>(S))
36     return isSemicolonRequiredAfter(While->getBody());
37   if (const auto *For = dyn_cast<ForStmt>(S))
38     return isSemicolonRequiredAfter(For->getBody());
39   if (const auto *CXXFor = dyn_cast<CXXForRangeStmt>(S))
40     return isSemicolonRequiredAfter(CXXFor->getBody());
41   if (const auto *ObjCFor = dyn_cast<ObjCForCollectionStmt>(S))
42     return isSemicolonRequiredAfter(ObjCFor->getBody());
43   if(const auto *Switch = dyn_cast<SwitchStmt>(S))
44     return isSemicolonRequiredAfter(Switch->getBody());
45   if(const auto *Case = dyn_cast<SwitchCase>(S))
46     return isSemicolonRequiredAfter(Case->getSubStmt());
47   switch (S->getStmtClass()) {
48   case Stmt::DeclStmtClass:
49   case Stmt::CXXTryStmtClass:
50   case Stmt::ObjCAtSynchronizedStmtClass:
51   case Stmt::ObjCAutoreleasePoolStmtClass:
52   case Stmt::ObjCAtTryStmtClass:
53     return false;
54   default:
55     return true;
56   }
57 }
58 
59 /// Returns true if the two source locations are on the same line.
60 bool areOnSameLine(SourceLocation Loc1, SourceLocation Loc2,
61                    const SourceManager &SM) {
62   return !Loc1.isMacroID() && !Loc2.isMacroID() &&
63          SM.getSpellingLineNumber(Loc1) == SM.getSpellingLineNumber(Loc2);
64 }
65 
66 } // end anonymous namespace
67 
68 namespace clang {
69 namespace tooling {
70 
71 ExtractionSemicolonPolicy
72 ExtractionSemicolonPolicy::compute(const Stmt *S, SourceRange &ExtractedRange,
73                                    const SourceManager &SM,
74                                    const LangOptions &LangOpts) {
75   auto neededInExtractedFunction = []() {
76     return ExtractionSemicolonPolicy(true, false);
77   };
78   auto neededInOriginalFunction = []() {
79     return ExtractionSemicolonPolicy(false, true);
80   };
81 
82   /// The extracted expression should be terminated with a ';'. The call to
83   /// the extracted function will replace this expression, so it won't need
84   /// a terminating ';'.
85   if (isa<Expr>(S))
86     return neededInExtractedFunction();
87 
88   /// Some statements don't need to be terminated with ';'. The call to the
89   /// extracted function will be a standalone statement, so it should be
90   /// terminated with a ';'.
91   bool NeedsSemi = isSemicolonRequiredAfter(S);
92   if (!NeedsSemi)
93     return neededInOriginalFunction();
94 
95   /// Some statements might end at ';'. The extraction will move that ';', so
96   /// the call to the extracted function should be terminated with a ';'.
97   SourceLocation End = ExtractedRange.getEnd();
98   if (isSemicolonAtLocation(End, SM, LangOpts))
99     return neededInOriginalFunction();
100 
101   /// Other statements should generally have a trailing ';'. We can try to find
102   /// it and move it together it with the extracted code.
103   Optional<Token> NextToken = Lexer::findNextToken(End, SM, LangOpts);
104   if (NextToken && NextToken->is(tok::semi) &&
105       areOnSameLine(NextToken->getLocation(), End, SM)) {
106     ExtractedRange.setEnd(NextToken->getLocation());
107     return neededInOriginalFunction();
108   }
109 
110   /// Otherwise insert semicolons in both places.
111   return ExtractionSemicolonPolicy(true, true);
112 }
113 
114 } // end namespace tooling
115 } // end namespace clang
116