v8/src/json-parser.h

// Copyright 2011 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_JSON_PARSER_H_
#define V8_JSON_PARSER_H_

#include "token.h"

namespace v8 {
namespace internal {

// A simple json parser.
class JsonParser BASE_EMBEDDED {
 public:
  static Handle<Object> Parse(Handle<String> source) {
    return JsonParser().ParseJson(source);
  }

  static const int kEndOfString = -1;

 private:
  // Parse a string containing a single JSON value.
  Handle<Object> ParseJson(Handle<String> source);

  inline void Advance() {
    position_++;
    if (position_ > source_length_) {
      c0_ = kEndOfString;
    } else if (is_sequential_ascii_) {
      c0_ = seq_source_->SeqAsciiStringGet(position_);
    } else {
      c0_ = source_->Get(position_);
    }
  }

  // The JSON lexical grammar is specified in the ECMAScript 5 standard,
  // section 15.12.1.1. The only allowed whitespace characters between tokens
  // are tab, carriage-return, newline and space.

  inline void AdvanceSkipWhitespace() {
    do {
      Advance();
    } while (c0_ == '\t' || c0_ == '\r' || c0_ == '\n' || c0_ == ' ');
  }

  inline void SkipWhitespace() {
    while (c0_ == '\t' || c0_ == '\r' || c0_ == '\n' || c0_ == ' ') {
      Advance();
    }
  }

  inline uc32 AdvanceGetChar() {
    Advance();
    return c0_;
  }

  // Checks that current charater is c.
  // If so, then consume c and skip whitespace.
  inline bool MatchSkipWhiteSpace(uc32 c) {
    if (c0_ == c) {
      AdvanceSkipWhitespace();
      return true;
    }
    return false;
  }

  // A JSON string (production JSONString) is subset of valid JavaScript string
  // literals. The string must only be double-quoted (not single-quoted), and
  // the only allowed backslash-escapes are ", /, \, b, f, n, r, t and
  // four-digit hex escapes (uXXXX). Any other use of backslashes is invalid.
  Handle<String> ParseJsonString() {
    return ScanJsonString<false>();
  }
  Handle<String> ParseJsonSymbol() {
    return ScanJsonString<true>();
  }
  template <bool is_symbol>
  Handle<String> ScanJsonString();
  // Slow version for unicode support, uses the first ascii_count characters,
  // as first part of a ConsString
  Handle<String> SlowScanJsonString();

  // A JSON number (production JSONNumber) is a subset of the valid JavaScript
  // decimal number literals.
  // It includes an optional minus sign, must have at least one
  // digit before and after a decimal point, may not have prefixed zeros (unless
  // the integer part is zero), and may include an exponent part (e.g., "e-10").
  // Hexadecimal and octal numbers are not allowed.
  Handle<Object> ParseJsonNumber();

  // Parse a single JSON value from input (grammar production JSONValue).
  // A JSON value is either a (double-quoted) string literal, a number literal,
  // one of "true", "false", or "null", or an object or array literal.
  Handle<Object> ParseJsonValue();

  // Parse a JSON object literal (grammar production JSONObject).
  // An object literal is a squiggly-braced and comma separated sequence
  // (possibly empty) of key/value pairs, where the key is a JSON string
  // literal, the value is a JSON value, and the two are separated by a colon.
  // A JSON array dosn't allow numbers and identifiers as keys, like a
  // JavaScript array.
  Handle<Object> ParseJsonObject();

  // Parses a JSON array literal (grammar production JSONArray). An array
  // literal is a square-bracketed and comma separated sequence (possibly empty)
  // of JSON values.
  // A JSON array doesn't allow leaving out values from the sequence, nor does
  // it allow a terminal comma, like a JavaScript array does.
  Handle<Object> ParseJsonArray();


  // Mark that a parsing error has happened at the current token, and
  // return a null handle. Primarily for readability.
  inline Handle<Object> ReportUnexpectedCharacter() {
    return Handle<Object>::null();
  }

  inline Isolate* isolate() { return isolate_; }

  static const int kInitialSpecialStringSize = 1024;


 private:
  Handle<String> source_;
  int source_length_;
  Handle<SeqAsciiString> seq_source_;

  bool is_sequential_ascii_;
  // begin and end position of scanned string or number
  int beg_pos_;
  int end_pos_;

  Isolate* isolate_;
  uc32 c0_;
  int position_;

  double number_;
};

} }  // namespace v8::internal

#endif  // V8_JSON_PARSER_H_