1 //===--- CodeCompletionStrings.cpp -------------------------------*- C++-*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "CodeCompletionStrings.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/DeclObjC.h"
13 #include "clang/AST/RawCommentList.h"
14 #include "clang/Basic/SourceManager.h"
15 #include <utility>
16 
17 namespace clang {
18 namespace clangd {
19 
20 namespace {
21 
22 bool isInformativeQualifierChunk(CodeCompletionString::Chunk const &Chunk) {
23   return Chunk.Kind == CodeCompletionString::CK_Informative &&
24          StringRef(Chunk.Text).endswith("::");
25 }
26 
27 void appendEscapeSnippet(const llvm::StringRef Text, std::string *Out) {
28   for (const auto Character : Text) {
29     if (Character == '$' || Character == '}' || Character == '\\')
30       Out->push_back('\\');
31     Out->push_back(Character);
32   }
33 }
34 
35 bool looksLikeDocComment(llvm::StringRef CommentText) {
36   // We don't report comments that only contain "special" chars.
37   // This avoids reporting various delimiters, like:
38   //   =================
39   //   -----------------
40   //   *****************
41   return CommentText.find_first_not_of("/*-= \t\r\n") != llvm::StringRef::npos;
42 }
43 
44 } // namespace
45 
46 std::string getDocComment(const ASTContext &Ctx,
47                           const CodeCompletionResult &Result,
48                           bool CommentsFromHeaders) {
49   // FIXME: clang's completion also returns documentation for RK_Pattern if they
50   // contain a pattern for ObjC properties. Unfortunately, there is no API to
51   // get this declaration, so we don't show documentation in that case.
52   if (Result.Kind != CodeCompletionResult::RK_Declaration)
53     return "";
54   return Result.getDeclaration() ? getDeclComment(Ctx, *Result.getDeclaration())
55                                  : "";
56 }
57 
58 std::string getDeclComment(const ASTContext &Ctx, const NamedDecl &Decl) {
59   if (llvm::isa<NamespaceDecl>(Decl)) {
60     // Namespaces often have too many redecls for any particular redecl comment
61     // to be useful. Moreover, we often confuse file headers or generated
62     // comments with namespace comments. Therefore we choose to just ignore
63     // the comments for namespaces.
64     return "";
65   }
66   const RawComment *RC = getCompletionComment(Ctx, &Decl);
67   if (!RC)
68     return "";
69   // Sanity check that the comment does not come from the PCH. We choose to not
70   // write them into PCH, because they are racy and slow to load.
71   assert(!Ctx.getSourceManager().isLoadedSourceLocation(RC->getBeginLoc()));
72   std::string Doc = RC->getFormattedText(Ctx.getSourceManager(), Ctx.getDiagnostics());
73   return looksLikeDocComment(Doc) ? Doc : "";
74 }
75 
76 void getSignature(const CodeCompletionString &CCS, std::string *Signature,
77                   std::string *Snippet, std::string *RequiredQualifiers) {
78   unsigned ArgCount = 0;
79   for (const auto &Chunk : CCS) {
80     // Informative qualifier chunks only clutter completion results, skip
81     // them.
82     if (isInformativeQualifierChunk(Chunk))
83       continue;
84 
85     switch (Chunk.Kind) {
86     case CodeCompletionString::CK_TypedText:
87       // The typed-text chunk is the actual name. We don't record this chunk.
88       // In general our string looks like <qualifiers><name><signature>.
89       // So once we see the name, any text we recorded so far should be
90       // reclassified as qualifiers.
91       if (RequiredQualifiers)
92         *RequiredQualifiers = std::move(*Signature);
93       Signature->clear();
94       Snippet->clear();
95       break;
96     case CodeCompletionString::CK_Text:
97       *Signature += Chunk.Text;
98       *Snippet += Chunk.Text;
99       break;
100     case CodeCompletionString::CK_Optional:
101       break;
102     case CodeCompletionString::CK_Placeholder:
103       *Signature += Chunk.Text;
104       ++ArgCount;
105       *Snippet += "${" + std::to_string(ArgCount) + ':';
106       appendEscapeSnippet(Chunk.Text, Snippet);
107       *Snippet += '}';
108       break;
109     case CodeCompletionString::CK_Informative:
110       // For example, the word "const" for a const method, or the name of
111       // the base class for methods that are part of the base class.
112       *Signature += Chunk.Text;
113       // Don't put the informative chunks in the snippet.
114       break;
115     case CodeCompletionString::CK_ResultType:
116       // This is not part of the signature.
117       break;
118     case CodeCompletionString::CK_CurrentParameter:
119       // This should never be present while collecting completion items,
120       // only while collecting overload candidates.
121       llvm_unreachable("Unexpected CK_CurrentParameter while collecting "
122                        "CompletionItems");
123       break;
124     case CodeCompletionString::CK_LeftParen:
125     case CodeCompletionString::CK_RightParen:
126     case CodeCompletionString::CK_LeftBracket:
127     case CodeCompletionString::CK_RightBracket:
128     case CodeCompletionString::CK_LeftBrace:
129     case CodeCompletionString::CK_RightBrace:
130     case CodeCompletionString::CK_LeftAngle:
131     case CodeCompletionString::CK_RightAngle:
132     case CodeCompletionString::CK_Comma:
133     case CodeCompletionString::CK_Colon:
134     case CodeCompletionString::CK_SemiColon:
135     case CodeCompletionString::CK_Equal:
136     case CodeCompletionString::CK_HorizontalSpace:
137       *Signature += Chunk.Text;
138       *Snippet += Chunk.Text;
139       break;
140     case CodeCompletionString::CK_VerticalSpace:
141       *Snippet += Chunk.Text;
142       // Don't even add a space to the signature.
143       break;
144     }
145   }
146 }
147 
148 std::string formatDocumentation(const CodeCompletionString &CCS,
149                                 llvm::StringRef DocComment) {
150   // Things like __attribute__((nonnull(1,3))) and [[noreturn]]. Present this
151   // information in the documentation field.
152   std::string Result;
153   const unsigned AnnotationCount = CCS.getAnnotationCount();
154   if (AnnotationCount > 0) {
155     Result += "Annotation";
156     if (AnnotationCount == 1) {
157       Result += ": ";
158     } else /* AnnotationCount > 1 */ {
159       Result += "s: ";
160     }
161     for (unsigned I = 0; I < AnnotationCount; ++I) {
162       Result += CCS.getAnnotation(I);
163       Result.push_back(I == AnnotationCount - 1 ? '\n' : ' ');
164     }
165   }
166   // Add brief documentation (if there is any).
167   if (!DocComment.empty()) {
168     if (!Result.empty()) {
169       // This means we previously added annotations. Add an extra newline
170       // character to make the annotations stand out.
171       Result.push_back('\n');
172     }
173     Result += DocComment;
174   }
175   return Result;
176 }
177 
178 std::string getReturnType(const CodeCompletionString &CCS) {
179   for (const auto &Chunk : CCS)
180     if (Chunk.Kind == CodeCompletionString::CK_ResultType)
181       return Chunk.Text;
182   return "";
183 }
184 
185 } // namespace clangd
186 } // namespace clang
187