Initial implementation of printing the AST as a JSON string. This...

src/prettyprinter.h

Index: src/prettyprinter.h
===================================================================
--- src/prettyprinter.h	(revision 3048)
+++ src/prettyprinter.h	(working copy)
@@ -46,14 +46,15 @@
   const char* PrintExpression(FunctionLiteral* program);
   const char* PrintProgram(FunctionLiteral* program);
 
+  void Print(const char* format, ...);
+
   // Print a node to stdout.
   static void PrintOut(AstNode* node);
 
   // Individual nodes
-#define DEF_VISIT(type)                         \
-  virtual void Visit##type(type* node);
-  AST_NODE_LIST(DEF_VISIT)
-#undef DEF_VISIT
+#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
+  AST_NODE_LIST(DECLARE_VISIT)
+#undef DECLARE_VISIT
 
  private:
   char* output_;  // output string buffer
@@ -62,7 +63,6 @@
 
  protected:
   void Init();
-  void Print(const char* format, ...);
   const char* Output() const { return output_; }
 
   virtual void PrintStatements(ZoneList<Statement*>* statements);
@@ -85,10 +85,9 @@
   const char* PrintProgram(FunctionLiteral* program);
 
   // Individual nodes
-#define DEF_VISIT(type)                         \
-  virtual void Visit##type(type* node);
-  AST_NODE_LIST(DEF_VISIT)
-#undef DEF_VISIT
+#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
+  AST_NODE_LIST(DECLARE_VISIT)
+#undef DECLARE_VISIT
  private:
   friend class IndentedScope;
   void PrintIndented(const char* txt);
@@ -112,6 +111,107 @@
   static int indent_;
 };
 
+
+// Forward declaration of helper classes.
+class TagScope;
+class AttributesScope;
+
+// Build a C string containing a JSON representation of a function's
+// AST. The representation is based on JsonML (www.jsonml.org).
+class JsonAstBuilder: public PrettyPrinter {
+ public:
+  JsonAstBuilder()
+      : indent_(0), top_tag_scope_(NULL), attributes_scope_(NULL) {
+  }
+  virtual ~JsonAstBuilder() {}
+
+  // Controls the indentation of subsequent lines of a tag body after
+  // the first line.
+  static const int kTagIndentSize = 2;
+
+  // Controls the indentation of subsequent lines of an attributes
+  // blocks's body after the first line.
+  static const int kAttributesIndentSize = 1;
+
+  // Construct a JSON representation of a function literal.
+  const char* BuildProgram(FunctionLiteral* program);
+
+  // Print text indented by the current indentation level.
+  void PrintIndented(const char* text) { Print("%*s%s", indent_, "", text); }
+
+  // Change the indentation level.
+  void increase_indent(int amount) { indent_ += amount; }
+  void decrease_indent(int amount) { indent_ -= amount; }
+
+  // The builder maintains a stack of opened AST node constructors.
+  // Each node constructor corresponds to a JsonML tag.
+  TagScope* tag() { return top_tag_scope_; }
+  void set_tag(TagScope* scope) { top_tag_scope_ = scope; }
+
+  // The builder maintains a pointer to the currently opened attributes
+  // of current AST node or NULL if the attributes are not opened.
+  AttributesScope* attributes() { return attributes_scope_; }
+  void set_attributes(AttributesScope* scope) { attributes_scope_ = scope; }
+
+  // Add an attribute to the currently opened attributes.
+  void AddAttribute(const char* name, Handle<String> value);
+  void AddAttribute(const char* name, const char* value);
+  void AddAttribute(const char* name, int value);
+  void AddAttribute(const char* name, bool value);
+
+  // AST node visit functions.
+#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
+  AST_NODE_LIST(DECLARE_VISIT)
+#undef DECLARE_VISIT
+
+ private:
+  int indent_;
+  TagScope* top_tag_scope_;
+  AttributesScope* attributes_scope_;
+
+  // Utility function used by AddAttribute implementations.
+  void AddAttributePrefix(const char* name);
+};
+
+
+// The JSON AST builder keeps a stack of open element tags (AST node
+// constructors from the current iteration point to the root of the
+// AST).  TagScope is a helper class to manage the opening and closing
+// of tags, the indentation of their bodies, and comma separating their
+// contents.
+class TagScope BASE_EMBEDDED {
+ public:
+  TagScope(JsonAstBuilder* builder, const char* name);
+  ~TagScope();
+
+  void use() { has_body_ = true; }
+
+ private:
+  JsonAstBuilder* builder_;
+  TagScope* next_;
+  bool has_body_;
+};
+
+
+// AttributesScope is a helper class to manage the opening and closing
+// of attribute blocks, the indentation of their bodies, and comma
+// separating their contents. JsonAstBuilder::AddAttribute adds an
+// attribute to the currently open AttributesScope. They cannot be
+// nested so the builder keeps an optional single scope rather than a
+// stack.
+class AttributesScope BASE_EMBEDDED {
+ public:
+  explicit AttributesScope(JsonAstBuilder* builder);
+  ~AttributesScope();
+
+  bool is_used() { return attribute_count_ > 0; }
+  void use() { ++attribute_count_; }
+
+ private:
+  JsonAstBuilder* builder_;
+  int attribute_count_;
+};
+
 #endif  // DEBUG
 
 } }  // namespace v8::internal