src/frontend/grammar.y

   1 /*
   2  * SysDB - src/frontend/grammar.y
   3  * Copyright (C) 2013 Sebastian 'tokkee' Harl <sh@tokkee.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  16  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  17  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  18  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
  19  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 %{
  29
  30 #include "frontend/connection-private.h"
  31 #include "frontend/parser.h"
  32 #include "frontend/grammar.h"
  33
  34 #include "core/store.h"
  35 #include "core/store-private.h"
  36
  37 #include "utils/error.h"
  38 #include "utils/llist.h"
  39
  40 #include <stdio.h>
  41 #include <string.h>
  42
  43 int
  44 sdb_fe_yylex(YYSTYPE *yylval, YYLTYPE *yylloc, sdb_fe_yyscan_t yyscanner);
  45
  46 sdb_fe_yyextra_t *
  47 sdb_fe_yyget_extra(sdb_fe_yyscan_t scanner);
  48
  49 void
  50 sdb_fe_yyerror(YYLTYPE *lval, sdb_fe_yyscan_t scanner, const char *msg);
  51
  52 /* quick access to the current parse tree */
  53 #define pt sdb_fe_yyget_extra(scanner)->parsetree
  54
  55 /* quick access to the parser mode */
  56 #define parser_mode sdb_fe_yyget_extra(scanner)->mode
  57
  58 %}
  59
  60 %pure-parser
  61 %lex-param {sdb_fe_yyscan_t scanner}
  62 %parse-param {sdb_fe_yyscan_t scanner}
  63 %locations
  64 %error-verbose
  65 %expect 0
  66 %name-prefix "sdb_fe_yy"
  67
  68 %union {
  69         char *str;
  70
  71         sdb_llist_t     *list;
  72         sdb_conn_node_t *node;
  73
  74         sdb_store_matcher_t *m;
  75 }
  76
  77 %start statements
  78
  79 %token SCANNER_ERROR
  80
  81 %token AND OR NOT WHERE
  82 %token CMP_EQUAL CMP_NEQUAL CMP_REGEX CMP_NREGEX
  83
  84 %token FETCH LIST LOOKUP
  85
  86 %token <str> IDENTIFIER STRING
  87
  88 /* Precedence (lowest first): */
  89 %left OR
  90 %left AND
  91 %left NOT
  92 %left CMP_EQUAL CMP_NEQUAL
  93 %left CMP_REGEX CMP_NREGEX
  94 %left '(' ')'
  95 %left '.'
  96
  97 %type <list> statements
  98 %type <node> statement
  99         fetch_statement
 100         list_statement
 101         lookup_statement
 102         expression
 103
 104 %type <m> matcher
 105         compare_matcher
 106
 107 %destructor { free($$); } <str>
 108 %destructor { sdb_object_deref(SDB_OBJ($$)); } <node> <m>
 109
 110 %%
 111
 112 statements:
 113         statements ';' statement
 114                 {
 115                         /* only accept this in default parse mode */
 116                         if (parser_mode != SDB_PARSE_DEFAULT) {
 117                                 sdb_fe_yyerror(&yylloc, scanner,
 118                                                 YY_("syntax error, unexpected statement, "
 119                                                         "expecting expression"));
 120                                 sdb_object_deref(SDB_OBJ($3));
 121                                 YYABORT;
 122                         }
 123
 124                         if ($3) {
 125                                 sdb_llist_append(pt, SDB_OBJ($3));
 126                                 sdb_object_deref(SDB_OBJ($3));
 127                         }
 128                 }
 129         |
 130         statement
 131                 {
 132                         /* only accept this in default parse mode */
 133                         if (parser_mode != SDB_PARSE_DEFAULT) {
 134                                 sdb_fe_yyerror(&yylloc, scanner,
 135                                                 YY_("syntax error, unexpected statement, "
 136                                                         "expecting expression"));
 137                                 sdb_object_deref(SDB_OBJ($1));
 138                                 YYABORT;
 139                         }
 140
 141                         if ($1) {
 142                                 sdb_llist_append(pt, SDB_OBJ($1));
 143                                 sdb_object_deref(SDB_OBJ($1));
 144                         }
 145                 }
 146         |
 147         expression
 148                 {
 149                         /* only accept this in expression parse mode */
 150                         if (! (parser_mode & SDB_PARSE_EXPR)) {
 151                                 sdb_fe_yyerror(&yylloc, scanner,
 152                                                 YY_("syntax error, unexpected expression, "
 153                                                         "expecting statement"));
 154                                 sdb_object_deref(SDB_OBJ($1));
 155                                 YYABORT;
 156                         }
 157
 158                         if ($1) {
 159                                 sdb_llist_append(pt, SDB_OBJ($1));
 160                                 sdb_object_deref(SDB_OBJ($1));
 161                         }
 162                 }
 163         ;
 164
 165 statement:
 166         fetch_statement
 167         |
 168         list_statement
 169         |
 170         lookup_statement
 171         |
 172         /* empty */
 173                 {
 174                         $$ = NULL;
 175                 }
 176         ;
 177
 178 /*
 179  * FETCH <hostname>;
 180  *
 181  * Retrieve detailed information about a single host.
 182  */
 183 fetch_statement:
 184         FETCH STRING
 185                 {
 186                         $$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
 187                                                 conn_fetch_t, conn_fetch_destroy));
 188                         CONN_FETCH($$)->name = strdup($2);
 189                         $$->cmd = CONNECTION_FETCH;
 190                         free($2); $2 = NULL;
 191                 }
 192         ;
 193
 194 /*
 195  * LIST;
 196  *
 197  * Returns a list of all hosts in the store.
 198  */
 199 list_statement:
 200         LIST
 201                 {
 202                         $$ = SDB_CONN_NODE(sdb_object_create_T(/* name = */ NULL,
 203                                                 sdb_conn_node_t));
 204                         $$->cmd = CONNECTION_LIST;
 205                 }
 206         ;
 207
 208 /*
 209  * LOOKUP <type> WHERE <expression>;
 210  *
 211  * Returns detailed information about <type> matching expression.
 212  */
 213 lookup_statement:
 214         LOOKUP IDENTIFIER WHERE expression
 215                 {
 216                         /* TODO: support other types as well */
 217                         if (strcasecmp($2, "hosts")) {
 218                                 char errmsg[strlen($2) + 32];
 219                                 snprintf(errmsg, sizeof(errmsg),
 220                                                 YY_("unknown table %s"), $2);
 221                                 sdb_fe_yyerror(&yylloc, scanner, errmsg);
 222                                 free($2); $2 = NULL;
 223                                 sdb_object_deref(SDB_OBJ($4));
 224                                 YYABORT;
 225                         }
 226
 227                         $$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
 228                                                 conn_lookup_t, conn_lookup_destroy));
 229                         CONN_LOOKUP($$)->matcher = CONN_MATCHER($4);
 230                         $$->cmd = CONNECTION_LOOKUP;
 231                         free($2); $2 = NULL;
 232                 }
 233         ;
 234
 235 expression:
 236         matcher
 237                 {
 238                         if (! $1) {
 239                                 /* TODO: improve error reporting */
 240                                 sdb_fe_yyerror(&yylloc, scanner,
 241                                                 YY_("syntax error, invalid expression"));
 242                                 YYABORT;
 243                         }
 244
 245                         $$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
 246                                                 conn_node_matcher_t, conn_matcher_destroy));
 247                         $$->cmd = CONNECTION_EXPR;
 248                         CONN_MATCHER($$)->matcher = $1;
 249                 }
 250         ;
 251
 252 matcher:
 253         '(' matcher ')'
 254                 {
 255                         $$ = $2;
 256                 }
 257         |
 258         matcher AND matcher
 259                 {
 260                         $$ = sdb_store_con_matcher($1, $3);
 261                         sdb_object_deref(SDB_OBJ($1));
 262                         sdb_object_deref(SDB_OBJ($3));
 263                 }
 264         |
 265         matcher OR matcher
 266                 {
 267                         $$ = sdb_store_dis_matcher($1, $3);
 268                         sdb_object_deref(SDB_OBJ($1));
 269                         sdb_object_deref(SDB_OBJ($3));
 270                 }
 271         |
 272         NOT matcher
 273                 {
 274                         $$ = sdb_store_inv_matcher($2);
 275                         sdb_object_deref(SDB_OBJ($2));
 276                 }
 277         |
 278         compare_matcher
 279                 {
 280                         $$ = $1;
 281                 }
 282         ;
 283
 284 /*
 285  * <object_type>.<object_attr> <op> <value>
 286  *
 287  * Parse matchers comparing object attributes with a value.
 288  */
 289 compare_matcher:
 290         IDENTIFIER '.' IDENTIFIER CMP_EQUAL STRING
 291                 {
 292                         $$ = sdb_store_matcher_parse_cmp($1, $3, "=", $5);
 293                         /* TODO: simplify memory management in the parser */
 294                         free($1); $1 = NULL;
 295                         free($3); $3 = NULL;
 296                         free($5); $5 = NULL;
 297                 }
 298         |
 299         IDENTIFIER '.' IDENTIFIER CMP_NEQUAL STRING
 300                 {
 301                         $$ = sdb_store_matcher_parse_cmp($1, $3, "!=", $5);
 302                         /* TODO: simplify memory management in the parser */
 303                         free($1); $1 = NULL;
 304                         free($3); $3 = NULL;
 305                         free($5); $5 = NULL;
 306                 }
 307         |
 308         IDENTIFIER '.' IDENTIFIER CMP_REGEX STRING
 309                 {
 310                         $$ = sdb_store_matcher_parse_cmp($1, $3, "=~", $5);
 311                         free($1); $1 = NULL;
 312                         free($3); $3 = NULL;
 313                         free($5); $5 = NULL;
 314                 }
 315         |
 316         IDENTIFIER '.' IDENTIFIER CMP_NREGEX STRING
 317                 {
 318                         $$ = sdb_store_matcher_parse_cmp($1, $3, "!~", $5);
 319                         free($1); $1 = NULL;
 320                         free($3); $3 = NULL;
 321                         free($5); $5 = NULL;
 322                 }
 323         ;
 324
 325 %%
 326
 327 /* XXX: on parse errors, allocated objects, strings, etc. need to be freed */
 328
 329 void
 330 sdb_fe_yyerror(YYLTYPE *lval, sdb_fe_yyscan_t scanner, const char *msg)
 331 {
 332         sdb_log(SDB_LOG_ERR, "frontend: parse error: %s", msg);
 333 } /* sdb_fe_yyerror */
 334
 335 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 336