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
  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         unsigned long i;
  39
  40         fsrc->variant_begin(src, variant_type);
  41         fdest->variant_begin(dest, variant_type);
  42
  43         field = variant_get_current_field(variant);
  44         field_type = field->type->p.type;
  45         field_type->copy(dest, fdest, src, fsrc, &field->type->p);
  46
  47         fsrc->variant_end(src, variant_type);
  48         fdest->variant_end(dest, variant_type);
  49 }
  50
  51 static
  52 void _variant_type_free(struct type *type)
  53 {
  54         struct type_variant *variant_type =
  55                 container_of(type, struct type_variant, p);
  56         unsigned long i;
  57
  58         g_hash_table_destroy(variant_type->fields_by_tag);
  59
  60         for (i = 0; i < variant_type->fields->len; i++) {
  61                 struct field *type_field =
  62                         &g_array_index(variant_type->fields,
  63                                        struct type_field, i);
  64                 type_unref(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 {
  72         struct type_variant *variant_type;
  73         struct type *type;
  74         int ret;
  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         type->name = g_quark_from_string(name);
  84         type->alignment = 1;
  85         type->copy = variant_copy;
  86         type->type_free = _variant_type_free;
  87         type->declaration_new = _variant_declaration_new;
  88         type->declaration_free = _variant_declaration_free;
  89         type->ref = 1;
  90
  91         if (type->name) {
  92                 ret = register_type(type);
  93                 if (ret)
  94                         goto error_register;
  95         }
  96         return variant_type;
  97
  98 error_register:
  99         g_hash_table_destroy(variant_type->fields_by_tag);
 100         g_array_free(variant_type->fields, true);
 101         g_free(variant_type);
 102         return NULL;
 103 }
 104
 105 static
 106 struct declaration *
 107         _variant_declaration_new(struct type *type,
 108                                  struct declaration_scope *parent_scope)
 109 {
 110         struct type_variant *variant_type =
 111                 container_of(type, struct type_variant, p);
 112         struct declaration_variant *variant;
 113
 114         variant = g_new(struct declaration_variant, 1);
 115         type_ref(&variant_type->p);
 116         variant->p.type = variant_type;
 117         variant->p.ref = 1;
 118         variant->scope = new_declaration_scope(parent_scope);
 119         variant->fields = g_array_sized_new(FALSE, TRUE,
 120                                             sizeof(struct field),
 121                                             DEFAULT_NR_STRUCT_FIELDS);
 122         variant->current_field = NULL;
 123         return &variant->p;
 124 }
 125
 126 static
 127 void variant_declaration_free(struct declaration *declaration)
 128 {
 129         struct declaration_variant *variant =
 130                 container_of(declaration, struct declaration_variant, p);
 131         unsigned long i;
 132
 133         for (i = 0; i < variant->fields->len; i++) {
 134                 struct field *field = &g_array_index(variant->fields,
 135                                                      struct field, i);
 136                 declaration_unref(field->declaration);
 137         }
 138         free_declaration_scope(variant->scope);
 139         type_unref(variant->p.type);
 140         g_free(variant);
 141 }
 142
 143 void variant_type_add_field(struct type_variant *variant_type,
 144                             const char *tag_name,
 145                             struct type *tag_type)
 146 {
 147         struct type_field *field;
 148         unsigned long index;
 149
 150         g_array_set_size(variant_type->fields, variant_type->fields->len + 1);
 151         index = variant_type->fields->len - 1;  /* last field (new) */
 152         field = &g_array_index(variant_type->fields, struct type_field, index);
 153         field->name = g_quark_from_string(tag_name);
 154         type_ref(tag_type);
 155         field->type = tag_type;
 156         /* Keep index in hash rather than pointer, because array can relocate */
 157         g_hash_table_insert(variant_type->fields_by_name,
 158                             (gpointer) (unsigned long) field->name,
 159                             (gpointer) index);
 160         /*
 161          * Alignment of variant is based on the alignment of its currently
 162          * selected choice, so we leave variant alignment as-is (statically
 163          * speaking).
 164          */
 165 }
 166
 167 struct type_field *
 168 struct_type_get_field_from_tag(struct type_variant *variant_type, GQuark tag)
 169 {
 170         unsigned long index;
 171
 172         index = (unsigned long) g_hash_table_lookup(variant_type->fields_by_tag,
 173                                                     (gconstpointer) (unsigned long) tag);
 174         return &g_array_index(variant_type->fields, struct type_field, index);
 175 }
 176
 177 /*
 178  * tag_instance is assumed to be an enumeration.
 179  */
 180 int variant_declaration_set_tag(struct declaration_variant *variant,
 181                                 struct declaration *enum_tag)
 182 {
 183         struct declaration_enum *_enum =
 184                 container_of(variant->enum_tag, struct declaration_enum, p);
 185         struct type_enum *enum_type = _enum->type;
 186         int missing_field = 0;
 187         unsigned long i;
 188
 189         /*
 190          * Strictly speaking, each enumerator must map to a field of the
 191          * variant. However, we are even stricter here by requiring that each
 192          * variant choice map to an enumerator too. We then validate that the
 193          * number of enumerators equals the number of variant choices.
 194          */
 195         if (variant->type->fields->len != enum_get_nr_enumerators(enum_type))
 196                 return -EPERM;
 197
 198         for (i = 0; i < variant->type->fields->len; i++) {
 199                 struct type_field *field_type =
 200                         &g_array_index(variant->type->fields,
 201                                        struct type_field, i);
 202                 if (!enum_quark_to_range_set(enum_type, field_type->name)) {
 203                         missing_field = 1;
 204                         break;
 205                 }
 206         }
 207         if (missing_field)
 208                 return -EPERM;
 209
 210         /*
 211          * Check the enumeration: it must map each value to one and only one
 212          * enumerator tag.
 213          * TODO: we should also check that each range map to one and only one
 214          * tag. For the moment, we will simply check this dynamically in
 215          * variant_type_get_current_field().
 216          */
 217
 218         /* Set the enum tag field */
 219         variant->enum_tag = enum_tag;
 220         return 0;
 221 }
 222
 223 /*
 224  * field returned only valid as long as the field structure is not appended to.
 225  */
 226 struct field *variant_get_current_field(struct declaration_variant *variant)
 227 {
 228         struct declaration_enum *_enum =
 229                 container_of(variant->enum_tag, struct declaration_enum, p);
 230         struct variant_type *variant_type = variant->type;
 231         unsigned long index;
 232         GArray *tag_array;
 233         GQuark tag;
 234
 235         tag_array = _enum->value;
 236         /*
 237          * The 1 to 1 mapping from enumeration to value should have been already
 238          * checked. (see TODO above)
 239          */
 240         assert(tag_array->len == 1);
 241         tag = g_array_index(tag_array, GQuark, 0);
 242         index = (unsigned long) g_hash_table_lookup(variant_type->fields_by_tag,
 243                                                     (gconstpointer) (unsigned long) tag);
 244         variant->current_field = &g_array_index(variant->fields, struct field, index);
 245         return variant->current_field;
 246 }