types/variant.c

   1 /*
   2  * variant.c
   3  *
   4  * BabelTrace - Variant Type Converter
   5  *
   6  * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to deal
  10  * in the Software without restriction, including without limitation the rights
  11  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12  * copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  */
  18
  19 #include <babeltrace/compiler.h>
  20 #include <babeltrace/format.h>
  21 #include <errno.h>
  22
  23 static
  24 struct declaration *_variant_declaration_new(struct type *type,
  25                                 struct declaration_scope *parent_scope);
  26 static
  27 void _variant_declaration_free(struct declaration *declaration);
  28
  29 void variant_copy(struct stream_pos *dest, const struct format *fdest,
  30                   struct stream_pos *src, const struct format *fsrc,
  31                   struct declaration *declaration)
  32 {
  33         struct declaration_variant *variant =
  34                 container_of(declaration, struct declaration_variant, p);
  35         struct type_variant *variant_type = variant->type;
  36         struct field *field;
  37         struct type *field_type;
  38
  39         fsrc->variant_begin(src, variant_type);
  40         fdest->variant_begin(dest, variant_type);
  41
  42         field = variant_get_current_field(variant);
  43         field_type = field->declaration->type;
  44         field_type->copy(dest, fdest, src, fsrc, field->declaration);
  45
  46         fsrc->variant_end(src, variant_type);
  47         fdest->variant_end(dest, variant_type);
  48 }
  49
  50 static
  51 void _variant_type_free(struct type *type)
  52 {
  53         struct type_variant *variant_type =
  54                 container_of(type, struct type_variant, p);
  55         unsigned long i;
  56
  57         free_type_scope(variant_type->scope);
  58         g_hash_table_destroy(variant_type->fields_by_tag);
  59
  60         for (i = 0; i < variant_type->fields->len; i++) {
  61                 struct type_field *type_field =
  62                         &g_array_index(variant_type->fields,
  63                                        struct type_field, i);
  64                 type_unref(type_field->type);
  65         }
  66         g_array_free(variant_type->fields, true);
  67         g_free(variant_type);
  68 }
  69
  70 struct type_variant *variant_type_new(const char *name,
  71                                       struct type_scope *parent_scope)
  72 {
  73         struct type_variant *variant_type;
  74         struct type *type;
  75
  76         variant_type = g_new(struct type_variant, 1);
  77         type = &variant_type->p;
  78         variant_type->fields_by_tag = g_hash_table_new(g_direct_hash,
  79                                                        g_direct_equal);
  80         variant_type->fields = g_array_sized_new(FALSE, TRUE,
  81                                                  sizeof(struct type_field),
  82                                                  DEFAULT_NR_STRUCT_FIELDS);
  83         variant_type->scope = new_type_scope(parent_scope);
  84         type->name = g_quark_from_string(name);
  85         type->alignment = 1;
  86         type->copy = variant_copy;
  87         type->type_free = _variant_type_free;
  88         type->declaration_new = _variant_declaration_new;
  89         type->declaration_free = _variant_declaration_free;
  90         type->ref = 1;
  91         return variant_type;
  92 }
  93
  94 static
  95 struct declaration *
  96         _variant_declaration_new(struct type *type,
  97                                  struct declaration_scope *parent_scope)
  98 {
  99         struct type_variant *variant_type =
 100                 container_of(type, struct type_variant, p);
 101         struct declaration_variant *variant;
 102         unsigned long i;
 103
 104         variant = g_new(struct declaration_variant, 1);
 105         type_ref(&variant_type->p);
 106         variant->p.type = type;
 107         variant->type = variant_type;
 108         variant->p.ref = 1;
 109         variant->scope = new_declaration_scope(parent_scope);
 110         variant->fields = g_array_sized_new(FALSE, TRUE,
 111                                             sizeof(struct field),
 112                                             DEFAULT_NR_STRUCT_FIELDS);
 113         g_array_set_size(variant->fields, variant_type->fields->len);
 114         for (i = 0; i < variant_type->fields->len; i++) {
 115                 struct type_field *type_field =
 116                         &g_array_index(variant_type->fields,
 117                                        struct type_field, i);
 118                 struct field *field = &g_array_index(variant->fields,
 119                                                      struct field, i);
 120
 121                 field->name = type_field->name;
 122                 field->declaration =
 123                         type_field->type->declaration_new(type_field->type,
 124                                                           variant->scope);
 125         }
 126         variant->current_field = NULL;
 127         return &variant->p;
 128 }
 129
 130 static
 131 void _variant_declaration_free(struct declaration *declaration)
 132 {
 133         struct declaration_variant *variant =
 134                 container_of(declaration, struct declaration_variant, p);
 135         unsigned long i;
 136
 137         assert(variant->fields->len == variant->type->fields->len);
 138         for (i = 0; i < variant->fields->len; i++) {
 139                 struct field *field = &g_array_index(variant->fields,
 140                                                      struct field, i);
 141                 declaration_unref(field->declaration);
 142         }
 143         free_declaration_scope(variant->scope);
 144         type_unref(variant->p.type);
 145         g_free(variant);
 146 }
 147
 148 void variant_type_add_field(struct type_variant *variant_type,
 149                             const char *tag_name,
 150                             struct type *tag_type)
 151 {
 152         struct type_field *field;
 153         unsigned long index;
 154
 155         g_array_set_size(variant_type->fields, variant_type->fields->len + 1);
 156         index = variant_type->fields->len - 1;  /* last field (new) */
 157         field = &g_array_index(variant_type->fields, struct type_field, index);
 158         field->name = g_quark_from_string(tag_name);
 159         type_ref(tag_type);
 160         field->type = tag_type;
 161         /* Keep index in hash rather than pointer, because array can relocate */
 162         g_hash_table_insert(variant_type->fields_by_tag,
 163                             (gpointer) (unsigned long) field->name,
 164                             (gpointer) index);
 165         /*
 166          * Alignment of variant is based on the alignment of its currently
 167          * selected choice, so we leave variant alignment as-is (statically
 168          * speaking).
 169          */
 170 }
 171
 172 struct type_field *
 173 struct_type_get_field_from_tag(struct type_variant *variant_type, GQuark tag)
 174 {
 175         unsigned long index;
 176
 177         index = (unsigned long) g_hash_table_lookup(variant_type->fields_by_tag,
 178                                                     (gconstpointer) (unsigned long) tag);
 179         return &g_array_index(variant_type->fields, struct type_field, index);
 180 }
 181
 182 /*
 183  * tag_instance is assumed to be an enumeration.
 184  */
 185 int variant_declaration_set_tag(struct declaration_variant *variant,
 186                                 struct declaration *enum_tag)
 187 {
 188         struct declaration_enum *_enum =
 189                 container_of(variant->enum_tag, struct declaration_enum, p);
 190         struct type_enum *enum_type = _enum->type;
 191         int missing_field = 0;
 192         unsigned long i;
 193
 194         /*
 195          * Strictly speaking, each enumerator must map to a field of the
 196          * variant. However, we are even stricter here by requiring that each
 197          * variant choice map to an enumerator too. We then validate that the
 198          * number of enumerators equals the number of variant choices.
 199          */
 200         if (variant->type->fields->len != enum_get_nr_enumerators(enum_type))
 201                 return -EPERM;
 202
 203         for (i = 0; i < variant->type->fields->len; i++) {
 204                 struct type_field *field_type =
 205                         &g_array_index(variant->type->fields,
 206                                        struct type_field, i);
 207                 if (!enum_quark_to_range_set(enum_type, field_type->name)) {
 208                         missing_field = 1;
 209                         break;
 210                 }
 211         }
 212         if (missing_field)
 213                 return -EPERM;
 214
 215         /*
 216          * Check the enumeration: it must map each value to one and only one
 217          * enumerator tag.
 218          * TODO: we should also check that each range map to one and only one
 219          * tag. For the moment, we will simply check this dynamically in
 220          * variant_type_get_current_field().
 221          */
 222
 223         /* Set the enum tag field */
 224         variant->enum_tag = enum_tag;
 225         return 0;
 226 }
 227
 228 /*
 229  * field returned only valid as long as the field structure is not appended to.
 230  */
 231 struct field *variant_get_current_field(struct declaration_variant *variant)
 232 {
 233         struct declaration_enum *_enum =
 234                 container_of(variant->enum_tag, struct declaration_enum, p);
 235         struct type_variant *variant_type = variant->type;
 236         unsigned long index;
 237         GArray *tag_array;
 238         GQuark tag;
 239
 240         tag_array = _enum->value;
 241         /*
 242          * The 1 to 1 mapping from enumeration to value should have been already
 243          * checked. (see TODO above)
 244          */
 245         assert(tag_array->len == 1);
 246         tag = g_array_index(tag_array, GQuark, 0);
 247         index = (unsigned long) g_hash_table_lookup(variant_type->fields_by_tag,
 248                                                     (gconstpointer) (unsigned long) tag);
 249         variant->current_field = &g_array_index(variant->fields, struct field, index);
 250         return variant->current_field;
 251 }