matcher.c

   1 /*
   2  * Copyright (C) 2013-2014 Jo-Philipp Wich <jow@openwrt.org>
   3  *
   4  * Permission to use, copy, modify, and/or distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #include "parser.h"
  18 #include "matcher.h"
  19
  20 static struct json_object *
  21 jp_match_next(struct jp_opcode *ptr,
  22               struct json_object *root, struct json_object *cur,
  23               jp_match_cb_t cb, void *priv);
  24
  25 static bool
  26 jp_json_to_op(struct json_object *obj, struct jp_opcode *op)
  27 {
  28         switch (json_object_get_type(obj))
  29         {
  30         case json_type_boolean:
  31                 op->type = T_BOOL;
  32                 op->num = json_object_get_boolean(obj);
  33                 return true;
  34
  35         case json_type_int:
  36                 op->type = T_NUMBER;
  37                 op->num = json_object_get_int(obj);
  38                 return true;
  39
  40         case json_type_string:
  41                 op->type = T_STRING;
  42                 op->str = (char *)json_object_get_string(obj);
  43                 return true;
  44
  45         default:
  46                 return false;
  47         }
  48 }
  49
  50 static bool
  51 jp_resolve(struct json_object *root, struct json_object *cur,
  52            struct jp_opcode *op, struct jp_opcode *res)
  53 {
  54         struct json_object *val;
  55
  56         switch (op->type)
  57         {
  58         case T_THIS:
  59                 val = jp_match(op, cur, NULL, NULL);
  60
  61                 if (val)
  62                         return jp_json_to_op(val, res);
  63
  64                 return false;
  65
  66         case T_ROOT:
  67                 val = jp_match(op, root, NULL, NULL);
  68
  69                 if (val)
  70                         return jp_json_to_op(val, res);
  71
  72                 return false;
  73
  74         default:
  75                 *res = *op;
  76                 return true;
  77         }
  78 }
  79
  80 static bool
  81 jp_cmp(struct jp_opcode *op, struct json_object *root, struct json_object *cur)
  82 {
  83         int delta;
  84         struct jp_opcode left, right;
  85
  86         if (!jp_resolve(root, cur, op->down, &left) ||
  87         !jp_resolve(root, cur, op->down->sibling, &right))
  88                 return false;
  89
  90         if (left.type != right.type)
  91                 return false;
  92
  93         switch (left.type)
  94         {
  95         case T_BOOL:
  96         case T_NUMBER:
  97                 delta = left.num - right.num;
  98                 break;
  99
 100         case T_STRING:
 101                 delta = strcmp(left.str, right.str);
 102                 break;
 103
 104         default:
 105                 return false;
 106         }
 107
 108         switch (op->type)
 109         {
 110         case T_EQ:
 111                 return (delta == 0);
 112
 113         case T_LT:
 114                 return (delta < 0);
 115
 116         case T_LE:
 117                 return (delta <= 0);
 118
 119         case T_GT:
 120                 return (delta > 0);
 121
 122         case T_GE:
 123                 return (delta >= 0);
 124
 125         case T_NE:
 126                 return (delta != 0);
 127
 128         default:
 129                 return false;
 130         }
 131 }
 132
 133 static bool
 134 jp_expr(struct jp_opcode *op, struct json_object *root, struct json_object *cur,
 135         int idx, const char *key, jp_match_cb_t cb, void *priv)
 136 {
 137         struct jp_opcode *sop;
 138
 139         switch (op->type)
 140         {
 141         case T_WILDCARD:
 142                 return true;
 143
 144         case T_EQ:
 145         case T_NE:
 146         case T_LT:
 147         case T_LE:
 148         case T_GT:
 149         case T_GE:
 150                 return jp_cmp(op, root, cur);
 151
 152         case T_ROOT:
 153                 return !!jp_match(op, root, NULL, NULL);
 154
 155         case T_THIS:
 156                 return !!jp_match(op, cur, NULL, NULL);
 157
 158         case T_NOT:
 159                 return !jp_expr(op->down, root, cur, idx, key, cb, priv);
 160
 161         case T_AND:
 162                 for (sop = op->down; sop; sop = sop->sibling)
 163                         if (!jp_expr(sop, root, cur, idx, key, cb, priv))
 164                                 return false;
 165                 return true;
 166
 167         case T_OR:
 168         case T_UNION:
 169                 for (sop = op->down; sop; sop = sop->sibling)
 170                         if (jp_expr(sop, root, cur, idx, key, cb, priv))
 171                                 return true;
 172                 return false;
 173
 174         case T_STRING:
 175                 return (key && !strcmp(op->str, key));
 176
 177         case T_NUMBER:
 178                 return (idx == op->num);
 179
 180         default:
 181                 return false;
 182         }
 183 }
 184
 185 static struct json_object *
 186 jp_match_expr(struct jp_opcode *ptr,
 187               struct json_object *root, struct json_object *cur,
 188               jp_match_cb_t cb, void *priv)
 189 {
 190         int idx, len;
 191         struct json_object *tmp, *res = NULL;
 192
 193         switch (json_object_get_type(cur))
 194         {
 195         case json_type_object:
 196                 ; /* a label can only be part of a statement and a declaration is not a statement */
 197                 json_object_object_foreach(cur, key, val)
 198                 {
 199                         if (jp_expr(ptr, root, val, -1, key, cb, priv))
 200                         {
 201                                 tmp = jp_match_next(ptr->sibling, root, val, cb, priv);
 202
 203                                 if (tmp && !res)
 204                                         res = tmp;
 205                         }
 206                 }
 207
 208                 break;
 209
 210         case json_type_array:
 211                 len = json_object_array_length(cur);
 212
 213                 for (idx = 0; idx < len; idx++)
 214                 {
 215                         tmp = json_object_array_get_idx(cur, idx);
 216
 217                         if (jp_expr(ptr, root, tmp, idx, NULL, cb, priv))
 218                         {
 219                                 tmp = jp_match_next(ptr->sibling, root, tmp, cb, priv);
 220
 221                                 if (tmp && !res)
 222                                         res = tmp;
 223                         }
 224                 }
 225
 226                 break;
 227
 228         default:
 229                 break;
 230         }
 231
 232         return res;
 233 }
 234
 235 static struct json_object *
 236 jp_match_next(struct jp_opcode *ptr,
 237               struct json_object *root, struct json_object *cur,
 238               jp_match_cb_t cb, void *priv)
 239 {
 240         int idx;
 241         struct json_object *next = NULL;
 242
 243         if (!ptr)
 244         {
 245                 if (cb)
 246                         cb(cur, priv);
 247
 248                 return cur;
 249         }
 250
 251         switch (ptr->type)
 252         {
 253         case T_STRING:
 254         case T_LABEL:
 255                 if (json_object_object_get_ex(cur, ptr->str, &next))
 256                         return jp_match_next(ptr->sibling, root, next, cb, priv);
 257
 258                 break;
 259
 260         case T_NUMBER:
 261                 if (json_object_get_type(cur) == json_type_array)
 262                 {
 263                         idx = ptr->num;
 264
 265                         if (idx < 0)
 266                                 idx += json_object_array_length(cur);
 267
 268                         if (idx >= 0)
 269                                 next = json_object_array_get_idx(cur, idx);
 270
 271                         if (next)
 272                                 return jp_match_next(ptr->sibling, root, next, cb, priv);
 273                 }
 274
 275                 break;
 276
 277         default:
 278                 return jp_match_expr(ptr, root, cur, cb, priv);
 279         }
 280
 281         return NULL;
 282 }
 283
 284 struct json_object *
 285 jp_match(struct jp_opcode *path, json_object *jsobj,
 286          jp_match_cb_t cb, void *priv)
 287 {
 288         if (path->type == T_LABEL)
 289                 path = path->down;
 290
 291         return jp_match_next(path->down, jsobj, jsobj, cb, priv);
 292 }