Basic support for reading and writing JSON objects.

runtime/vm/json.h

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef VM_JSON_H_
+#define VM_JSON_H_
+
+#include "vm/allocation.h"
+#include "vm/globals.h"
+
+namespace dart {
+
+
+// A low level interface to tokenize JSON strings.
+class JSONScanner : ValueObject {
+ public:
+  enum Token {
+    TokenIllegal = 0,
+    TokenLBrace,
+    TokenRBrace,
+    TokenLBrack,
+    TokenRBrack,
+    TokenColon,
+    TokenComma,
+    TokenString,
+    TokenInteger,
+    TokenTrue,
+    TokenFalse,
+    TokenNull,
+    TokenEOM
+  };
+  explicit JSONScanner(const char* json_text);
+
+  void SetText(const char* json_text);
+  void Scan();
+  Token CurrentToken() const { return token_; }
+  bool EOM() const { return token_ == TokenEOM; }
+  const char* TokenChars() const { return token_start_; }
+  int TokenLen() const { return token_length_; }
+  bool IsStringLiteral(const char* literal) const;
+  void Skip(Token matching_token);
+
+ private:
+  bool IsLetter(char ch) const;
+  bool IsDigit(char ch) const;
+  bool IsLiteral(const char* literal);
+  void ScanNumber();
+  void ScanString();
+  void Recognize(Token t);
+
+  const char* current_pos_;
+  const char* token_start_;
+  int token_length_;
+  Token token_;
+};
+
+
+// JSONReader is a higher level interface that allows for lookup of
+// name-value pairs in JSON objects.
+class JSONReader : ValueObject {
+ public:
+  enum JSONType {
+    kString,
+    kInteger,
+    kObject,
+    kArray,
+    kLiteral,
+    kNone
+  };
+
+  explicit JSONReader(const char* json_object);
+  void Set(const char* json_object);
+
+  // Returns true if a pair with the given name was found.
+  bool Seek(const char* name);
+
+  // Returns true if a syntax error was found.
+  bool Error() const { return error_; }
+
+  JSONType Type() const;
+  const char* ValueChars() const {
+    return (Type() != kNone) ? scanner_.TokenChars() : NULL;
+  }
+  int ValueLen() const {
+    return (Type() != kNone) ? scanner_.TokenLen() : 0;
+  }
+  bool IsStringLiteral(const char* literal) const {
+    return scanner_.IsStringLiteral(literal);
+  }
+
+ private:
+  JSONScanner scanner_;
+  const char* json_object_;
+  bool error_;
+};
+
+
+// TextBuffer maintains a dynamic character buffer with a printf-style way to
+// append text.
+class TextBuffer : ValueObject {
+ public:
+  explicit TextBuffer(intptr_t buf_size);
+  ~TextBuffer();
+
+  intptr_t Printf(const char* format, ...);
+  void Clear();
+
+  char* buf() { return buf_; }
+
+ private:
+  void GrowBuffer(intptr_t len);
+  char* buf_;
+  intptr_t buf_size_;
+  intptr_t msg_len_;
+};
+
+}  // namespace dart
+
+#endif  // VM_JSON_H_