gcc/json.h

   1 /* JSON trees
   2    Copyright (C) 2017-2023 Free Software Foundation, Inc.
   3    Contributed by David Malcolm <dmalcolm@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_JSON_H
  22 #define GCC_JSON_H
  23
  24 /* Implementation of JSON, a lightweight data-interchange format.
  25
  26    See http://www.json.org/
  27    and http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf
  28    and https://tools.ietf.org/html/rfc7159
  29
  30    Supports creating a DOM-like tree of json::value *, and then dumping
  31    json::value * to text.  */
  32
  33 namespace json
  34 {
  35
  36 /* Forward decls of json::value and its subclasses (using indentation
  37    to denote inheritance.  */
  38
  39 class value;
  40   class object;
  41   class array;
  42   class float_number;
  43   class integer_number;
  44   class string;
  45   class literal;
  46
  47 /* An enum for discriminating the subclasses of json::value.  */
  48
  49 enum kind
  50 {
  51   /* class json::object.  */
  52   JSON_OBJECT,
  53
  54   /* class json::array.  */
  55   JSON_ARRAY,
  56
  57   /* class json::integer_number.  */
  58   JSON_INTEGER,
  59
  60   /* class json::float_number.  */
  61   JSON_FLOAT,
  62
  63   /* class json::string.  */
  64   JSON_STRING,
  65
  66   /* class json::literal uses these three values to identify the
  67      particular literal.  */
  68   JSON_TRUE,
  69   JSON_FALSE,
  70   JSON_NULL
  71 };
  72
  73 /* Base class of JSON value.  */
  74
  75 class value
  76 {
  77  public:
  78   virtual ~value () {}
  79   virtual enum kind get_kind () const = 0;
  80   virtual void print (pretty_printer *pp) const = 0;
  81
  82   void dump (FILE *) const;
  83 };
  84
  85 /* Subclass of value for objects: a collection of key/value pairs
  86    preserving the ordering in which keys were inserted.
  87
  88    Preserving the order eliminates non-determinism in the output,
  89    making it easier for the user to compare repeated invocations.  */
  90
  91 class object : public value
  92 {
  93  public:
  94   ~object ();
  95
  96   enum kind get_kind () const final override { return JSON_OBJECT; }
  97   void print (pretty_printer *pp) const final override;
  98
  99   void set (const char *key, value *v);
 100   value *get (const char *key) const;
 101
 102  private:
 103   typedef hash_map <char *, value *,
 104     simple_hashmap_traits<nofree_string_hash, value *> > map_t;
 105   map_t m_map;
 106
 107   /* Keep track of order in which keys were inserted.  */
 108   auto_vec <const char *> m_keys;
 109 };
 110
 111 /* Subclass of value for arrays.  */
 112
 113 class array : public value
 114 {
 115  public:
 116   ~array ();
 117
 118   enum kind get_kind () const final override { return JSON_ARRAY; }
 119   void print (pretty_printer *pp) const final override;
 120
 121   void append (value *v);
 122
 123  private:
 124   auto_vec<value *> m_elements;
 125 };
 126
 127 /* Subclass of value for floating-point numbers.  */
 128
 129 class float_number : public value
 130 {
 131  public:
 132   float_number (double value) : m_value (value) {}
 133
 134   enum kind get_kind () const final override { return JSON_FLOAT; }
 135   void print (pretty_printer *pp) const final override;
 136
 137   double get () const { return m_value; }
 138
 139  private:
 140   double m_value;
 141 };
 142
 143 /* Subclass of value for integer-valued numbers.  */
 144
 145 class integer_number : public value
 146 {
 147  public:
 148   integer_number (long value) : m_value (value) {}
 149
 150   enum kind get_kind () const final override { return JSON_INTEGER; }
 151   void print (pretty_printer *pp) const final override;
 152
 153   long get () const { return m_value; }
 154
 155  private:
 156   long m_value;
 157 };
 158
 159
 160 /* Subclass of value for strings.  */
 161
 162 class string : public value
 163 {
 164  public:
 165   explicit string (const char *utf8);
 166   string (const char *utf8, size_t len);
 167   ~string () { free (m_utf8); }
 168
 169   enum kind get_kind () const final override { return JSON_STRING; }
 170   void print (pretty_printer *pp) const final override;
 171
 172   const char *get_string () const { return m_utf8; }
 173   size_t get_length () const { return m_len; }
 174
 175  private:
 176   char *m_utf8;
 177   size_t m_len;
 178 };
 179
 180 /* Subclass of value for the three JSON literals "true", "false",
 181    and "null".  */
 182
 183 class literal : public value
 184 {
 185  public:
 186   literal (enum kind kind) : m_kind (kind) {}
 187
 188   /* Construct literal for a boolean value.  */
 189   literal (bool value): m_kind (value ? JSON_TRUE : JSON_FALSE) {}
 190
 191   enum kind get_kind () const final override { return m_kind; }
 192   void print (pretty_printer *pp) const final override;
 193
 194  private:
 195   enum kind m_kind;
 196 };
 197
 198 } // namespace json
 199
 200 #endif  /* GCC_JSON_H  */