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