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         g_hash_table_destroy(variant_type->fields_by_tag);
  58
  59         for (i = 0; i < variant_type->fields->len; i++) {
  60                 struct type_field *type_field =
  61                         &g_array_index(variant_type->fields,
  62                                        struct type_field, i);
  63                 type_unref(type_field->type);
  64         }
  65         g_array_free(variant_type->fields, true);
  66         g_free(variant_type);
  67 }
  68
  69 struct type_variant *variant_type_new(const char *name)
  70 {
  71         struct type_variant *variant_type;
  72         struct type *type;
  73
  74         variant_type = g_new(struct type_variant, 1);
  75         type = &variant_type->p;
  76         variant_type->fields_by_tag = g_hash_table_new(g_direct_hash,
  77                                                        g_direct_equal);
  78         variant_type->fields = g_array_sized_new(FALSE, TRUE,
  79                                                  sizeof(struct type_field),
  80                                                  DEFAULT_NR_STRUCT_FIELDS);
  81         type->name = g_quark_from_string(name);
  82         type->alignment = 1;
  83         type->copy = variant_copy;
  84         type->type_free = _variant_type_free;
  85         type->declaration_new = _variant_declaration_new;
  86         type->declaration_free = _variant_declaration_free;
  87         type->ref = 1;
  88         return variant_type;
  89 }
  90
  91 static
  92 struct declaration *
  93         _variant_declaration_new(struct type *type,
  94                                  struct declaration_scope *parent_scope)
  95 {
  96         struct type_variant *variant_type =
  97                 container_of(type, struct type_variant, p);
  98         struct declaration_variant *variant;
  99         unsigned long i;
 100
 101         variant = g_new(struct declaration_variant, 1);
 102         type_ref(&variant_type->p);
 103         variant->p.type = type;
 104         variant->type = variant_type;
 105         variant->p.ref = 1;
 106         variant->scope = new_declaration_scope(parent_scope);
 107         variant->fields = g_array_sized_new(FALSE, TRUE,
 108                                             sizeof(struct field),
 109                                             DEFAULT_NR_STRUCT_FIELDS);
 110         g_array_set_size(variant->fields, variant_type->fields->len);
 111         for (i = 0; i < variant_type->fields->len; i++) {
 112                 struct type_field *type_field =
 113                         &g_array_index(variant_type->fields,
 114                                        struct type_field, i);
 115                 struct field *field = &g_array_index(variant->fields,
 116                                                      struct field, i);
 117
 118                 field->name = type_field->name;
 119                 field->declaration =
 120                         type_field->type->declaration_new(type_field->type,
 121                                                           variant->scope);
 122         }
 123         variant->current_field = NULL;
 124         return &variant->p;
 125 }
 126
 127 static
 128 void _variant_declaration_free(struct declaration *declaration)
 129 {
 130         struct declaration_variant *variant =
 131                 container_of(declaration, struct declaration_variant, p);
 132         unsigned long i;
 133
 134         assert(variant->fields->len == variant->type->fields->len);
 135         for (i = 0; i < variant->fields->len; i++) {
 136                 struct field *field = &g_array_index(variant->fields,
 137                                                      struct field, i);
 138                 declaration_unref(field->declaration);
 139         }
 140         free_declaration_scope(variant->scope);
 141         type_unref(variant->p.type);
 142         g_free(variant);
 143 }
 144
 145 void variant_type_add_field(struct type_variant *variant_type,
 146                             const char *tag_name,
 147                             struct type *tag_type)
 148 {
 149         struct type_field *field;
 150         unsigned long index;
 151
 152         g_array_set_size(variant_type->fields, variant_type->fields->len + 1);
 153         index = variant_type->fields->len - 1;  /* last field (new) */
 154         field = &g_array_index(variant_type->fields, struct type_field, index);
 155         field->name = g_quark_from_string(tag_name);
 156         type_ref(tag_type);
 157         field->type = tag_type;
 158         /* Keep index in hash rather than pointer, because array can relocate */
 159         g_hash_table_insert(variant_type->fields_by_tag,
 160                             (gpointer) (unsigned long) field->name,
 161                             (gpointer) index);
 162         /*
 163          * Alignment of variant is based on the alignment of its currently
 164          * selected choice, so we leave variant alignment as-is (statically
 165          * speaking).
 166          */
 167 }
 168
 169 struct type_field *
 170 struct_type_get_field_from_tag(struct type_variant *variant_type, GQuark tag)
 171 {
 172         unsigned long index;
 173
 174         index = (unsigned long) g_hash_table_lookup(variant_type->fields_by_tag,
 175                                                     (gconstpointer) (unsigned long) tag);
 176         return &g_array_index(variant_type->fields, struct type_field, index);
 177 }
 178
 179 /*
 180  * tag_instance is assumed to be an enumeration.
 181  */
 182 int variant_declaration_set_tag(struct declaration_variant *variant,
 183                                 struct declaration *enum_tag)
 184 {
 185         struct declaration_enum *_enum =
 186                 container_of(variant->enum_tag, struct declaration_enum, p);
 187         struct type_enum *enum_type = _enum->type;
 188         int missing_field = 0;
 189         unsigned long i;
 190
 191         /*
 192          * Strictly speaking, each enumerator must map to a field of the
 193          * variant. However, we are even stricter here by requiring that each
 194          * variant choice map to an enumerator too. We then validate that the
 195          * number of enumerators equals the number of variant choices.
 196          */
 197         if (variant->type->fields->len != enum_get_nr_enumerators(enum_type))
 198                 return -EPERM;
 199
 200         for (i = 0; i < variant->type->fields->len; i++) {
 201                 struct type_field *field_type =
 202                         &g_array_index(variant->type->fields,
 203                                        struct type_field, i);
 204                 if (!enum_quark_to_range_set(enum_type, field_type->name)) {
 205                         missing_field = 1;
 206                         break;
 207                 }
 208         }
 209         if (missing_field)
 210                 return -EPERM;
 211
 212         /*
 213          * Check the enumeration: it must map each value to one and only one
 214          * enumerator tag.
 215          * TODO: we should also check that each range map to one and only one
 216          * tag. For the moment, we will simply check this dynamically in
 217          * variant_type_get_current_field().
 218          */
 219
 220         /* Set the enum tag field */
 221         variant->enum_tag = enum_tag;
 222         return 0;
 223 }
 224
 225 /*
 226  * field returned only valid as long as the field structure is not appended to.
 227  */
 228 struct field *variant_get_current_field(struct declaration_variant *variant)
 229 {
 230         struct declaration_enum *_enum =
 231                 container_of(variant->enum_tag, struct declaration_enum, p);
 232         struct type_variant *variant_type = variant->type;
 233         unsigned long index;
 234         GArray *tag_array;
 235         GQuark tag;
 236
 237         tag_array = _enum->value;
 238         /*
 239          * The 1 to 1 mapping from enumeration to value should have been already
 240          * checked. (see TODO above)
 241          */
 242         assert(tag_array->len == 1);
 243         tag = g_array_index(tag_array, GQuark, 0);
 244         index = (unsigned long) g_hash_table_lookup(variant_type->fields_by_tag,
 245                                                     (gconstpointer) (unsigned long) tag);
 246         variant->current_field = &g_array_index(variant->fields, struct field, index);
 247         return variant->current_field;
 248 }