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1 //===- InheritViz.cpp - Graphviz visualization for inheritance --*- 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 //  This file implements CXXRecordDecl::viewInheritance, which
11 //  generates a GraphViz DOT file that depicts the class inheritance
12 //  diagram and then calls Graphviz/dot+gv on it.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/TypeOrdering.h"
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/GraphWriter.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include <map>
24 #include <set>
25 using namespace clang;
26 
27 namespace {
28 /// InheritanceHierarchyWriter - Helper class that writes out a
29 /// GraphViz file that diagrams the inheritance hierarchy starting at
30 /// a given C++ class type. Note that we do not use LLVM's
31 /// GraphWriter, because the interface does not permit us to properly
32 /// differentiate between uses of types as virtual bases
33 /// vs. non-virtual bases.
34 class InheritanceHierarchyWriter {
35   ASTContext& Context;
36   raw_ostream &Out;
37   std::map<QualType, int, QualTypeOrdering> DirectBaseCount;
38   std::set<QualType, QualTypeOrdering> KnownVirtualBases;
39 
40 public:
InheritanceHierarchyWriter(ASTContext & Context,raw_ostream & Out)41   InheritanceHierarchyWriter(ASTContext& Context, raw_ostream& Out)
42     : Context(Context), Out(Out) { }
43 
WriteGraph(QualType Type)44   void WriteGraph(QualType Type) {
45     Out << "digraph \"" << llvm::DOT::EscapeString(Type.getAsString())
46         << "\" {\n";
47     WriteNode(Type, false);
48     Out << "}\n";
49   }
50 
51 protected:
52   /// WriteNode - Write out the description of node in the inheritance
53   /// diagram, which may be a base class or it may be the root node.
54   void WriteNode(QualType Type, bool FromVirtual);
55 
56   /// WriteNodeReference - Write out a reference to the given node,
57   /// using a unique identifier for each direct base and for the
58   /// (only) virtual base.
59   raw_ostream& WriteNodeReference(QualType Type, bool FromVirtual);
60 };
61 } // namespace
62 
WriteNode(QualType Type,bool FromVirtual)63 void InheritanceHierarchyWriter::WriteNode(QualType Type, bool FromVirtual) {
64   QualType CanonType = Context.getCanonicalType(Type);
65 
66   if (FromVirtual) {
67     if (KnownVirtualBases.find(CanonType) != KnownVirtualBases.end())
68       return;
69 
70     // We haven't seen this virtual base before, so display it and
71     // its bases.
72     KnownVirtualBases.insert(CanonType);
73   }
74 
75   // Declare the node itself.
76   Out << "  ";
77   WriteNodeReference(Type, FromVirtual);
78 
79   // Give the node a label based on the name of the class.
80   std::string TypeName = Type.getAsString();
81   Out << " [ shape=\"box\", label=\"" << llvm::DOT::EscapeString(TypeName);
82 
83   // If the name of the class was a typedef or something different
84   // from the "real" class name, show the real class name in
85   // parentheses so we don't confuse ourselves.
86   if (TypeName != CanonType.getAsString()) {
87     Out << "\\n(" << CanonType.getAsString() << ")";
88   }
89 
90   // Finished describing the node.
91   Out << " \"];\n";
92 
93   // Display the base classes.
94   const CXXRecordDecl *Decl
95     = static_cast<const CXXRecordDecl *>(Type->getAs<RecordType>()->getDecl());
96   for (const auto &Base : Decl->bases()) {
97     QualType CanonBaseType = Context.getCanonicalType(Base.getType());
98 
99     // If this is not virtual inheritance, bump the direct base
100     // count for the type.
101     if (!Base.isVirtual())
102       ++DirectBaseCount[CanonBaseType];
103 
104     // Write out the node (if we need to).
105     WriteNode(Base.getType(), Base.isVirtual());
106 
107     // Write out the edge.
108     Out << "  ";
109     WriteNodeReference(Type, FromVirtual);
110     Out << " -> ";
111     WriteNodeReference(Base.getType(), Base.isVirtual());
112 
113     // Write out edge attributes to show the kind of inheritance.
114     if (Base.isVirtual()) {
115       Out << " [ style=\"dashed\" ]";
116     }
117     Out << ";";
118   }
119 }
120 
121 /// WriteNodeReference - Write out a reference to the given node,
122 /// using a unique identifier for each direct base and for the
123 /// (only) virtual base.
124 raw_ostream&
WriteNodeReference(QualType Type,bool FromVirtual)125 InheritanceHierarchyWriter::WriteNodeReference(QualType Type,
126                                                bool FromVirtual) {
127   QualType CanonType = Context.getCanonicalType(Type);
128 
129   Out << "Class_" << CanonType.getAsOpaquePtr();
130   if (!FromVirtual)
131     Out << "_" << DirectBaseCount[CanonType];
132   return Out;
133 }
134 
135 /// viewInheritance - Display the inheritance hierarchy of this C++
136 /// class using GraphViz.
viewInheritance(ASTContext & Context) const137 void CXXRecordDecl::viewInheritance(ASTContext& Context) const {
138   QualType Self = Context.getTypeDeclType(this);
139 
140   int FD;
141   SmallString<128> Filename;
142   if (std::error_code EC = llvm::sys::fs::createTemporaryFile(
143           Self.getAsString(), "dot", FD, Filename)) {
144     llvm::errs() << "Error: " << EC.message() << "\n";
145     return;
146   }
147 
148   llvm::errs() << "Writing '" << Filename << "'... ";
149 
150   llvm::raw_fd_ostream O(FD, true);
151 
152   InheritanceHierarchyWriter Writer(Context, O);
153   Writer.WriteGraph(Self);
154   llvm::errs() << " done. \n";
155 
156   O.close();
157 
158   // Display the graph
159   DisplayGraph(Filename);
160 }
161