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 WHERE
  82
  83 %token CMP_EQUAL CMP_REGEX
  84
  85 %token <str> IDENTIFIER STRING
  86 %token <node> FETCH LIST LOOKUP
  87
  88 %type <list> statements
  89 %type <node> statement
  90         fetch_statement
  91         list_statement
  92         lookup_statement
  93         expression
  94
  95 %type <m> compare_matcher
  96
  97 %%
  98
  99 statements:
 100         statements ';' statement
 101                 {
 102                         /* only accept this in default parse mode */
 103                         if (parser_mode != SDB_PARSE_DEFAULT) {
 104                                 sdb_fe_yyerror(&yylloc, scanner,
 105                                                 YY_("syntax error, unexpected statement, "
 106                                                         "expecting expression"));
 107                                 YYABORT;
 108                         }
 109
 110                         if ($3) {
 111                                 sdb_llist_append(pt, SDB_OBJ($3));
 112                                 sdb_object_deref(SDB_OBJ($3));
 113                         }
 114                 }
 115         |
 116         statement
 117                 {
 118                         /* only accept this in default parse mode */
 119                         if (parser_mode != SDB_PARSE_DEFAULT) {
 120                                 sdb_fe_yyerror(&yylloc, scanner,
 121                                                 YY_("syntax error, unexpected statement, "
 122                                                         "expecting expression"));
 123                                 YYABORT;
 124                         }
 125
 126                         if ($1) {
 127                                 sdb_llist_append(pt, SDB_OBJ($1));
 128                                 sdb_object_deref(SDB_OBJ($1));
 129                         }
 130                 }
 131         |
 132         expression
 133                 {
 134                         /* only accept this in expression parse mode */
 135                         if (! (parser_mode & SDB_PARSE_EXPR)) {
 136                                 sdb_fe_yyerror(&yylloc, scanner,
 137                                                 YY_("syntax error, unexpected expression, "
 138                                                         "expecting statement"));
 139                                 YYABORT;
 140                         }
 141
 142                         if ($1) {
 143                                 sdb_llist_append(pt, SDB_OBJ($1));
 144                                 sdb_object_deref(SDB_OBJ($1));
 145                         }
 146                 }
 147         ;
 148
 149 statement:
 150         fetch_statement
 151         |
 152         list_statement
 153         |
 154         lookup_statement
 155         |
 156         /* empty */
 157                 {
 158                         $$ = NULL;
 159                 }
 160         ;
 161
 162 /*
 163  * FETCH <hostname>;
 164  *
 165  * Retrieve detailed information about a single host.
 166  */
 167 fetch_statement:
 168         FETCH STRING
 169                 {
 170                         $$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
 171                                                 conn_fetch_t, conn_fetch_destroy));
 172                         CONN_FETCH($$)->name = strdup($2);
 173                         $$->cmd = CONNECTION_FETCH;
 174                         free($2); $2 = NULL;
 175                 }
 176         ;
 177
 178 /*
 179  * LIST;
 180  *
 181  * Returns a list of all hosts in the store.
 182  */
 183 list_statement:
 184         LIST
 185                 {
 186                         $$ = SDB_CONN_NODE(sdb_object_create_T(/* name = */ NULL,
 187                                                 sdb_conn_node_t));
 188                         $$->cmd = CONNECTION_LIST;
 189                 }
 190         ;
 191
 192 /*
 193  * LOOKUP <type> WHERE <expression>;
 194  *
 195  * Returns detailed information about <type> matching expression.
 196  */
 197 lookup_statement:
 198         LOOKUP IDENTIFIER WHERE expression
 199                 {
 200                         /* TODO: support other types as well */
 201                         if (strcasecmp($2, "hosts")) {
 202                                 char errmsg[strlen($2) + 32];
 203                                 snprintf(errmsg, sizeof(errmsg),
 204                                                 YY_("unknown table %s"), $2);
 205                                 sdb_fe_yyerror(&yylloc, scanner, errmsg);
 206                                 YYABORT;
 207                         }
 208
 209                         $$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
 210                                                 conn_lookup_t, conn_lookup_destroy));
 211                         CONN_LOOKUP($$)->matcher = CONN_MATCHER($4);
 212                         $$->cmd = CONNECTION_LOOKUP;
 213                         free($2); $2 = NULL;
 214                 }
 215         ;
 216
 217 expression:
 218         compare_matcher
 219                 {
 220                         sdb_store_matcher_t *m = $1;
 221                         if (! m) {
 222                                 /* TODO: improve error reporting */
 223                                 sdb_fe_yyerror(&yylloc, scanner,
 224                                                 YY_("syntax error, invalid expression"));
 225                                 YYABORT;
 226                         }
 227
 228                         $$ = SDB_CONN_NODE(sdb_object_create_T(/* name = */ NULL,
 229                                                 conn_node_matcher_t));
 230                         $$->cmd = CONNECTION_EXPR;
 231
 232                         if (M(m)->type == MATCHER_HOST)
 233                                 CONN_MATCHER($$)->matcher = m;
 234                         else if (M(m)->type == MATCHER_SERVICE)
 235                                 CONN_MATCHER($$)->matcher = sdb_store_host_matcher(NULL,
 236                                                 /* name_re = */ NULL, /* service = */ m,
 237                                                 /* attr = */ NULL);
 238                         else if (M(m)->type == MATCHER_ATTR)
 239                                 CONN_MATCHER($$)->matcher = sdb_store_host_matcher(NULL,
 240                                                 /* name_re = */ NULL, /* service = */ NULL,
 241                                                 /* attr = */ m);
 242                 }
 243         ;
 244
 245 /*
 246  * <object_type>.<object_attr> <op> <value>
 247  *
 248  * Parse matchers comparing object attributes with a value.
 249  */
 250 compare_matcher:
 251         IDENTIFIER '.' IDENTIFIER CMP_EQUAL STRING
 252                 {
 253                         $$ = sdb_store_matcher_parse_cmp($1, $3, "=", $5);
 254                         /* TODO: simplify memory management in the parser */
 255                         free($1); $1 = NULL;
 256                         free($3); $3 = NULL;
 257                         free($5); $5 = NULL;
 258                 }
 259         |
 260         IDENTIFIER '.' IDENTIFIER CMP_REGEX STRING
 261                 {
 262                         $$ = sdb_store_matcher_parse_cmp($1, $3, "=~", $5);
 263                         free($1); $1 = NULL;
 264                         free($3); $3 = NULL;
 265                         free($5); $5 = NULL;
 266                 }
 267         ;
 268
 269 %%
 270
 271 void
 272 sdb_fe_yyerror(YYLTYPE *lval, sdb_fe_yyscan_t scanner, const char *msg)
 273 {
 274         sdb_log(SDB_LOG_ERR, "frontend: parse error: %s", msg);
 275 } /* sdb_fe_yyerror */
 276
 277 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 278