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 /* TODO: `libcpp/mkdeps.cc` wants JSON writing support for p1689r5 output;
  34    extract this code and move to libiberty.  */
  35
  36 namespace json
  37 {
  38
  39 /* Forward decls of json::value and its subclasses (using indentation
  40    to denote inheritance.  */
  41
  42 class value;
  43   class object;
  44   class array;
  45   class float_number;
  46   class integer_number;
  47   class string;
  48   class literal;
  49
  50 /* An enum for discriminating the subclasses of json::value.  */
  51
  52 enum kind
  53 {
  54   /* class json::object.  */
  55   JSON_OBJECT,
  56
  57   /* class json::array.  */
  58   JSON_ARRAY,
  59
  60   /* class json::integer_number.  */
  61   JSON_INTEGER,
  62
  63   /* class json::float_number.  */
  64   JSON_FLOAT,
  65
  66   /* class json::string.  */
  67   JSON_STRING,
  68
  69   /* class json::literal uses these three values to identify the
  70      particular literal.  */
  71   JSON_TRUE,
  72   JSON_FALSE,
  73   JSON_NULL
  74 };
  75
  76 /* Base class of JSON value.  */
  77
  78 class value
  79 {
  80  public:
  81   virtual ~value () {}
  82   virtual enum kind get_kind () const = 0;
  83   virtual void print (pretty_printer *pp) const = 0;
  84
  85   void dump (FILE *) const;
  86 };
  87
  88 /* Subclass of value for objects: a collection of key/value pairs
  89    preserving the ordering in which keys were inserted.
  90
  91    Preserving the order eliminates non-determinism in the output,
  92    making it easier for the user to compare repeated invocations.  */
  93
  94 class object : public value
  95 {
  96  public:
  97   ~object ();
  98
  99   enum kind get_kind () const final override { return JSON_OBJECT; }
 100   void print (pretty_printer *pp) const final override;
 101
 102   void set (const char *key, value *v);
 103   value *get (const char *key) const;
 104
 105  private:
 106   typedef hash_map <char *, value *,
 107     simple_hashmap_traits<nofree_string_hash, value *> > map_t;
 108   map_t m_map;
 109
 110   /* Keep track of order in which keys were inserted.  */
 111   auto_vec <const char *> m_keys;
 112 };
 113
 114 /* Subclass of value for arrays.  */
 115
 116 class array : public value
 117 {
 118  public:
 119   ~array ();
 120
 121   enum kind get_kind () const final override { return JSON_ARRAY; }
 122   void print (pretty_printer *pp) const final override;
 123
 124   void append (value *v);
 125
 126  private:
 127   auto_vec<value *> m_elements;
 128 };
 129
 130 /* Subclass of value for floating-point numbers.  */
 131
 132 class float_number : public value
 133 {
 134  public:
 135   float_number (double value) : m_value (value) {}
 136
 137   enum kind get_kind () const final override { return JSON_FLOAT; }
 138   void print (pretty_printer *pp) const final override;
 139
 140   double get () const { return m_value; }
 141
 142  private:
 143   double m_value;
 144 };
 145
 146 /* Subclass of value for integer-valued numbers.  */
 147
 148 class integer_number : public value
 149 {
 150  public:
 151   integer_number (long value) : m_value (value) {}
 152
 153   enum kind get_kind () const final override { return JSON_INTEGER; }
 154   void print (pretty_printer *pp) const final override;
 155
 156   long get () const { return m_value; }
 157
 158  private:
 159   long m_value;
 160 };
 161
 162
 163 /* Subclass of value for strings.  */
 164
 165 class string : public value
 166 {
 167  public:
 168   explicit string (const char *utf8);
 169   string (const char *utf8, size_t len);
 170   ~string () { free (m_utf8); }
 171
 172   enum kind get_kind () const final override { return JSON_STRING; }
 173   void print (pretty_printer *pp) const final override;
 174
 175   const char *get_string () const { return m_utf8; }
 176   size_t get_length () const { return m_len; }
 177
 178  private:
 179   char *m_utf8;
 180   size_t m_len;
 181 };
 182
 183 /* Subclass of value for the three JSON literals "true", "false",
 184    and "null".  */
 185
 186 class literal : public value
 187 {
 188  public:
 189   literal (enum kind kind) : m_kind (kind) {}
 190
 191   /* Construct literal for a boolean value.  */
 192   literal (bool value): m_kind (value ? JSON_TRUE : JSON_FALSE) {}
 193
 194   enum kind get_kind () const final override { return m_kind; }
 195   void print (pretty_printer *pp) const final override;
 196
 197  private:
 198   enum kind m_kind;
 199 };
 200
 201 } // namespace json
 202
 203 #endif  /* GCC_JSON_H  */