json.h

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/* JSON trees
   Copyright (C) 2017-2024 Free Software Foundation, Inc.
   Contributed by David Malcolm <dmalcolm@redhat.com>.
 
This file is part of GCC.
 
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
 
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.
 
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */
 
#ifndef GCC_JSON_H
#define GCC_JSON_H
 
/* Implementation of JSON, a lightweight data-interchange format.
 
   See http://www.json.org/
   and http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf
   and https://tools.ietf.org/html/rfc7159
 
   Supports creating a DOM-like tree of json::value *, and then dumping
   json::value * to text.  */
 
/* TODO: `libcpp/mkdeps.cc` wants JSON writing support for p1689r5 output;
   extract this code and move to libiberty.  */
 
namespace json
{
 
/* Forward decls of json::value and its subclasses (using indentation
   to denote inheritance.  */
 
class value;
  class object;
  class array;
  class float_number;
  class integer_number;
  class string;
  class literal;
 
/* An enum for discriminating the subclasses of json::value.  */
 
enum kind
{
  /* class json::object.  */
  JSON_OBJECT,
 
  /* class json::array.  */
  JSON_ARRAY,
 
  /* class json::integer_number.  */
  JSON_INTEGER,
 
  /* class json::float_number.  */
  JSON_FLOAT,
 
  /* class json::string.  */
  JSON_STRING,
 
  /* class json::literal uses these three values to identify the
     particular literal.  */
  JSON_TRUE,
  JSON_FALSE,
  JSON_NULL
};
 
/* Base class of JSON value.  */
 
class value
{
 public:
  virtual ~value () {}
  virtual enum kind get_kind () const = 0;
  virtual void print (pretty_printer *pp, bool formatted) const = 0;
 
  void dump (FILE *, bool formatted) const;
};
 
/* Subclass of value for objects: a collection of key/value pairs
   preserving the ordering in which keys were inserted.
 
   Preserving the order eliminates non-determinism in the output,
   making it easier for the user to compare repeated invocations.  */
 
class object : public value
{
 public:
  ~object ();
 
  enum kind get_kind () const final override { return JSON_OBJECT; }
  void print (pretty_printer *pp, bool formatted) const final override;
 
  void set (const char *key, value *v);
  value *get (const char *key) const;
 
  void set_string (const char *key, const char *utf8_value);
  void set_integer (const char *key, long v);
  void set_float (const char *key, double v);
 
  /* Set to literal true/false.  */
  void set_bool (const char *key, bool v);
 
 private:
  typedef hash_map <char *, value *,
    simple_hashmap_traits<nofree_string_hash, value *> > map_t;
  map_t m_map;
 
  /* Keep track of order in which keys were inserted.  */
  auto_vec <const char *> m_keys;
};
 
/* Subclass of value for arrays.  */
 
class array : public value
{
 public:
  ~array ();
 
  enum kind get_kind () const final override { return JSON_ARRAY; }
  void print (pretty_printer *pp, bool formatted) const final override;
 
  void append (value *v);
 
 private:
  auto_vec<value *> m_elements;
};
 
/* Subclass of value for floating-point numbers.  */
 
class float_number : public value
{
 public:
  float_number (double value) : m_value (value) {}
 
  enum kind get_kind () const final override { return JSON_FLOAT; }
  void print (pretty_printer *pp, bool formatted) const final override;
 
  double get () const { return m_value; }
 
 private:
  double m_value;
};
 
/* Subclass of value for integer-valued numbers.  */
 
class integer_number : public value
{
 public:
  integer_number (long value) : m_value (value) {}
 
  enum kind get_kind () const final override { return JSON_INTEGER; }
  void print (pretty_printer *pp, bool formatted) const final override;
 
  long get () const { return m_value; }
 
 private:
  long m_value;
};
 
 
/* Subclass of value for strings.  */
 
class string : public value
{
 public:
  explicit string (const char *utf8);
  string (const char *utf8, size_t len);
  ~string () { free (m_utf8); }
 
  enum kind get_kind () const final override { return JSON_STRING; }
  void print (pretty_printer *pp, bool formatted) const final override;
 
  const char *get_string () const { return m_utf8; }
  size_t get_length () const { return m_len; }
 
 private:
  char *m_utf8;
  size_t m_len;
};
 
/* Subclass of value for the three JSON literals "true", "false",
   and "null".  */
 
class literal : public value
{
 public:
  literal (enum kind kind) : m_kind (kind) {}
 
  /* Construct literal for a boolean value.  */
  literal (bool value): m_kind (value ? JSON_TRUE : JSON_FALSE) {}
 
  enum kind get_kind () const final override { return m_kind; }
  void print (pretty_printer *pp, bool formatted) const final override;
 
 private:
  enum kind m_kind;
};
 
} // namespace json
 
#endif  /* GCC_JSON_H  */