granicus.if.org Git - postgresql/blob - src/backend/nodes/read.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * read.c--
   4  *        routines to convert a string (legal ascii representation of node) back
   5  *        to nodes
   6  *
   7  * Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/nodes/read.c,v 1.9 1998/01/07 15:32:31 momjian Exp $
  12  *
  13  * HISTORY
  14  *        AUTHOR                        DATE                    MAJOR EVENT
  15  *        Andrew Yu                     Nov 2, 1994             file creation
  16  *
  17  *-------------------------------------------------------------------------
  18  */
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <ctype.h>
  22 #include "postgres.h"
  23 #include "nodes/pg_list.h"
  24 #include "nodes/readfuncs.h"
  25 #include "utils/elog.h"
  26
  27 /*
  28  * stringToNode -
  29  *        returns a Node with a given legal ascii representation
  30  */
  31 void       *
  32 stringToNode(char *str)
  33 {
  34         void       *retval;
  35
  36         lsptok(str, NULL);                      /* set the string used in lsptok */
  37         retval = nodeRead(true);        /* start reading */
  38
  39         return retval;
  40 }
  41
  42 /*****************************************************************************
  43  *
  44  * the lisp token parser
  45  *
  46  *****************************************************************************/
  47
  48 #define RIGHT_PAREN (1000000 + 1)
  49 #define LEFT_PAREN      (1000000 + 2)
  50 #define PLAN_SYM        (1000000 + 3)
  51 #define AT_SYMBOL       (1000000 + 4)
  52 #define ATOM_TOKEN      (1000000 + 5)
  53
  54 /*
  55  * nodeTokenType -
  56  *        returns the type of the node token contained in token.
  57  *        It returns one of the following valid NodeTags:
  58  *              T_Integer, T_Float, T_String
  59  *        and some of its own:
  60  *              RIGHT_PAREN, LEFT_PAREN, PLAN_SYM, AT_SYMBOL, ATOM_TOKEN
  61  *
  62  *        Assumption: the ascii representation is legal
  63  */
  64 static NodeTag
  65 nodeTokenType(char *token, int length)
  66 {
  67         NodeTag         retval = 0;
  68
  69         /*
  70          * Check if the token is a number (decimal or integer, positive or
  71          * negative
  72          */
  73         if (isdigit(*token) ||
  74                 (length >= 2 && *token == '-' && isdigit(*(token + 1))))
  75         {
  76
  77                 /*
  78                  * skip the optional '-' (i.e. negative number)
  79                  */
  80                 if (*token == '-')
  81                 {
  82                         token++;
  83                 }
  84
  85                 /*
  86                  * See if there is a decimal point
  87                  */
  88
  89                 for (; length && *token != '.'; token++, length--);
  90
  91                 /*
  92                  * if there isn't, token's an int, otherwise it's a float.
  93                  */
  94
  95                 retval = (*token != '.') ? T_Integer : T_Float;
  96         }
  97         else if (isalpha(*token) || *token == '_' ||
  98                          (token[0] == '<' && token[1] == '>'))
  99                 retval = ATOM_TOKEN;
 100         else if (*token == '(')
 101                 retval = LEFT_PAREN;
 102         else if (*token == ')')
 103                 retval = RIGHT_PAREN;
 104         else if (*token == '@')
 105                 retval = AT_SYMBOL;
 106         else if (*token == '\"')
 107                 retval = T_String;
 108         else if (*token == '{')
 109                 retval = PLAN_SYM;
 110         return (retval);
 111 }
 112
 113 /*
 114  * Works kinda like strtok, except it doesn't put nulls into string.
 115  *
 116  * Returns the length in length instead.  The string can be set without
 117  * returning a token by calling lsptok with length == NULL.
 118  *
 119  */
 120 char       *
 121 lsptok(char *string, int *length)
 122 {
 123         static char *local_str;
 124         char       *ret_string;
 125
 126         if (string != NULL)
 127         {
 128                 local_str = string;
 129                 if (length == NULL)
 130                 {
 131                         return (NULL);
 132                 }
 133         }
 134
 135         for (; *local_str == ' '
 136                  || *local_str == '\n'
 137                  || *local_str == '\t'; local_str++);
 138
 139         /*
 140          * Now pointing at next token.
 141          */
 142         ret_string = local_str;
 143         if (*local_str == '\0')
 144                 return (NULL);
 145         *length = 1;
 146
 147         if (*local_str == '"')
 148         {
 149                 for (local_str++; *local_str != '"'; (*length)++, local_str++)
 150                         ;
 151                 (*length)++;
 152                 local_str++;
 153         }
 154                         /* NULL */
 155         else if (local_str[0] == '<' && local_str[1] == '>' )
 156         {
 157                 *length = 0;
 158                 local_str += 2;
 159         }
 160         else if (*local_str == ')' || *local_str == '(' ||
 161                          *local_str == '}' || *local_str == '{')
 162         {
 163                 local_str++;
 164         }
 165         else
 166         {
 167                 for (; *local_str != ' '
 168                          && *local_str != '\n'
 169                          && *local_str != '\t'
 170                          && *local_str != '{'
 171                          && *local_str != '}'
 172                          && *local_str != '('
 173                          && *local_str != ')'; local_str++, (*length)++);
 174                 (*length)--;
 175         }
 176         return (ret_string);
 177 }
 178
 179 /*
 180  * This guy does all the reading.
 181  *
 182  * Secrets:  He assumes that lsptok already has the string (see below).
 183  * Any callers should set read_car_only to true.
 184  */
 185 void       *
 186 nodeRead(bool read_car_only)
 187 {
 188         char       *token;
 189         NodeTag         type;
 190         Node       *this_value = NULL,
 191                            *return_value = NULL;
 192         int                     tok_len;
 193         char            tmp;
 194         bool            make_dotted_pair_cell = false;
 195
 196         token = lsptok(NULL, &tok_len);
 197
 198         if (token == NULL)
 199                 return (NULL);
 200
 201         type = nodeTokenType(token, tok_len);
 202
 203         switch (type)
 204         {
 205                 case PLAN_SYM:
 206                         this_value = parsePlanString();
 207                         token = lsptok(NULL, &tok_len);
 208                         if (token[0] != '}')
 209                                 return (NULL);
 210
 211                         if (!read_car_only)
 212                                 make_dotted_pair_cell = true;
 213                         else
 214                                 make_dotted_pair_cell = false;
 215                         break;
 216                 case LEFT_PAREN:
 217                         if (!read_car_only)
 218                         {
 219                                 List       *l = makeNode(List);
 220
 221                                 lfirst(l) = nodeRead(false);
 222                                 lnext(l) = nodeRead(false);
 223                                 this_value = (Node *) l;
 224                         }
 225                         else
 226                         {
 227                                 this_value = nodeRead(false);
 228                         }
 229                         break;
 230                 case RIGHT_PAREN:
 231                         this_value = NULL;
 232                         break;
 233                 case AT_SYMBOL:
 234                         break;
 235                 case ATOM_TOKEN:
 236                         if (!strncmp(token, "<>", 2))
 237                         {
 238                                 this_value = NULL;
 239
 240                                 /*
 241                                  * It might be NULL but it is an atom!
 242                                  */
 243                                 if (read_car_only)
 244                                 {
 245                                         make_dotted_pair_cell = false;
 246                                 }
 247                                 else
 248                                 {
 249                                         make_dotted_pair_cell = true;
 250                                 }
 251                         }
 252                         else
 253                         {
 254                                 tmp = token[tok_len];
 255                                 token[tok_len] = '\0';
 256                                 this_value = (Node *) pstrdup(token);   /* !attention! not a
 257                                                                                                                  * Node. use with
 258                                                                                                                  * caution */
 259                                 token[tok_len] = tmp;
 260                                 make_dotted_pair_cell = true;
 261                         }
 262                         break;
 263                 case T_Float:
 264                         tmp = token[tok_len];
 265                         token[tok_len] = '\0';
 266                         this_value = (Node *) makeFloat(atof(token));
 267                         token[tok_len] = tmp;
 268                         make_dotted_pair_cell = true;
 269                         break;
 270                 case T_Integer:
 271                         tmp = token[tok_len];
 272                         token[tok_len] = '\0';
 273                         this_value = (Node *) makeInteger(atoi(token));
 274                         token[tok_len] = tmp;
 275                         make_dotted_pair_cell = true;
 276                         break;
 277                 case T_String:
 278                         tmp = token[tok_len - 1];
 279                         token[tok_len - 1] = '\0';
 280                         token++;
 281                         this_value = (Node *) makeString(token);        /* !! not strdup'd */
 282                         token[tok_len - 2] = tmp;
 283                         make_dotted_pair_cell = true;
 284                         break;
 285                 default:
 286                         elog(ABORT, "nodeRead: Bad type %d", type);
 287                         break;
 288         }
 289         if (make_dotted_pair_cell)
 290         {
 291                 List       *l = makeNode(List);
 292
 293                 lfirst(l) = this_value;
 294
 295                 if (!read_car_only)
 296                 {
 297                         lnext(l) = nodeRead(false);
 298                 }
 299                 else
 300                 {
 301                         lnext(l) = NULL;
 302                 }
 303                 return_value = (Node *) l;
 304         }
 305         else
 306         {
 307                 return_value = this_value;
 308         }
 309         return (return_value);
 310 }