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293 lines
6.1 KiB
C
293 lines
6.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* read.c--
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* routines to convert a string (legal ascii representation of node) back
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* to nodes
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/nodes/read.c,v 1.13 1998/09/01 03:23:01 momjian Exp $
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*
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* HISTORY
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* AUTHOR DATE MAJOR EVENT
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* Andrew Yu Nov 2, 1994 file creation
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*
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*-------------------------------------------------------------------------
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*/
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#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#include "postgres.h"
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#include "nodes/pg_list.h"
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#include "nodes/readfuncs.h"
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#include "utils/elog.h"
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/*
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* stringToNode -
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* returns a Node with a given legal ascii representation
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*/
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void *
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stringToNode(char *str)
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{
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void *retval;
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lsptok(str, NULL); /* set the string used in lsptok */
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retval = nodeRead(true); /* start reading */
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return retval;
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}
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/*****************************************************************************
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*
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* the lisp token parser
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*
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*****************************************************************************/
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#define RIGHT_PAREN (1000000 + 1)
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#define LEFT_PAREN (1000000 + 2)
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#define PLAN_SYM (1000000 + 3)
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#define AT_SYMBOL (1000000 + 4)
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#define ATOM_TOKEN (1000000 + 5)
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/*
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* nodeTokenType -
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* returns the type of the node token contained in token.
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* It returns one of the following valid NodeTags:
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* T_Integer, T_Float, T_String
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* and some of its own:
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* RIGHT_PAREN, LEFT_PAREN, PLAN_SYM, AT_SYMBOL, ATOM_TOKEN
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*
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* Assumption: the ascii representation is legal
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*/
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static NodeTag
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nodeTokenType(char *token, int length)
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{
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NodeTag retval = 0;
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/*
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* Check if the token is a number (decimal or integer, positive or
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* negative
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*/
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if (isdigit(*token) ||
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(length >= 2 && *token == '-' && isdigit(*(token + 1))))
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{
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/*
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* skip the optional '-' (i.e. negative number)
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*/
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if (*token == '-')
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token++;
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/*
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* See if there is a decimal point
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*/
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for (; length && *token != '.'; token++, length--);
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/*
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* if there isn't, token's an int, otherwise it's a float.
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*/
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retval = (*token != '.') ? T_Integer : T_Float;
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}
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else if (isalpha(*token) || *token == '_' ||
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(token[0] == '<' && token[1] == '>'))
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retval = ATOM_TOKEN;
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else if (*token == '(')
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retval = LEFT_PAREN;
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else if (*token == ')')
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retval = RIGHT_PAREN;
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else if (*token == '@')
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retval = AT_SYMBOL;
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else if (*token == '\"')
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retval = T_String;
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else if (*token == '{')
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retval = PLAN_SYM;
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return retval;
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}
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/*
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* Works kinda like strtok, except it doesn't put nulls into string.
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*
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* Returns the length in length instead. The string can be set without
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* returning a token by calling lsptok with length == NULL.
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*
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*/
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char *
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lsptok(char *string, int *length)
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{
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static char *local_str;
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char *ret_string;
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if (string != NULL)
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{
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local_str = string;
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if (length == NULL)
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return NULL;
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}
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for (; *local_str == ' '
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|| *local_str == '\n'
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|| *local_str == '\t'; local_str++);
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/*
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* Now pointing at next token.
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*/
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ret_string = local_str;
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if (*local_str == '\0')
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return NULL;
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*length = 1;
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if (*local_str == '"')
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{
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for (local_str++; *local_str != '"'; (*length)++, local_str++)
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;
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(*length)++;
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local_str++;
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}
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/* NULL */
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else if (local_str[0] == '<' && local_str[1] == '>')
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{
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*length = 0;
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local_str += 2;
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}
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else if (*local_str == ')' || *local_str == '(' ||
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*local_str == '}' || *local_str == '{')
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local_str++;
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else
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{
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for (; *local_str != ' '
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&& *local_str != '\n'
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&& *local_str != '\t'
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&& *local_str != '{'
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&& *local_str != '}'
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&& *local_str != '('
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&& *local_str != ')'; local_str++, (*length)++);
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(*length)--;
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}
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return ret_string;
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}
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/*
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* This guy does all the reading.
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*
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* Secrets: He assumes that lsptok already has the string (see below).
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* Any callers should set read_car_only to true.
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*/
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void *
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nodeRead(bool read_car_only)
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{
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char *token;
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NodeTag type;
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Node *this_value = NULL,
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*return_value = NULL;
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int tok_len;
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char tmp;
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bool make_dotted_pair_cell = false;
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token = lsptok(NULL, &tok_len);
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if (token == NULL)
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return NULL;
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type = nodeTokenType(token, tok_len);
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switch (type)
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{
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case PLAN_SYM:
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this_value = parsePlanString();
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token = lsptok(NULL, &tok_len);
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if (token[0] != '}')
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return NULL;
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if (!read_car_only)
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make_dotted_pair_cell = true;
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else
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make_dotted_pair_cell = false;
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break;
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case LEFT_PAREN:
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if (!read_car_only)
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{
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List *l = makeNode(List);
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lfirst(l) = nodeRead(false);
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lnext(l) = nodeRead(false);
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this_value = (Node *) l;
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}
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else
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this_value = nodeRead(false);
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break;
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case RIGHT_PAREN:
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this_value = NULL;
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break;
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case AT_SYMBOL:
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break;
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case ATOM_TOKEN:
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if (!strncmp(token, "<>", 2))
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{
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this_value = NULL;
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/*
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* It might be NULL but it is an atom!
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*/
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if (read_car_only)
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make_dotted_pair_cell = false;
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else
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make_dotted_pair_cell = true;
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}
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else
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{
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tmp = token[tok_len];
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token[tok_len] = '\0';
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this_value = (Node *) pstrdup(token); /* !attention! not a
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* Node. use with
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* caution */
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token[tok_len] = tmp;
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make_dotted_pair_cell = true;
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}
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break;
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case T_Float:
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tmp = token[tok_len];
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token[tok_len] = '\0';
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this_value = (Node *) makeFloat(atof(token));
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token[tok_len] = tmp;
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make_dotted_pair_cell = true;
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break;
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case T_Integer:
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tmp = token[tok_len];
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token[tok_len] = '\0';
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this_value = (Node *) makeInteger(atoi(token));
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token[tok_len] = tmp;
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make_dotted_pair_cell = true;
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break;
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case T_String:
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tmp = token[tok_len - 1];
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token[tok_len - 1] = '\0';
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token++;
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this_value = (Node *) makeString(token); /* !! not strdup'd */
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token[tok_len - 2] = tmp;
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make_dotted_pair_cell = true;
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break;
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default:
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elog(ERROR, "nodeRead: Bad type %d", type);
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break;
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}
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if (make_dotted_pair_cell)
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{
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List *l = makeNode(List);
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lfirst(l) = this_value;
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if (!read_car_only)
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lnext(l) = nodeRead(false);
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else
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lnext(l) = NULL;
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return_value = (Node *) l;
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}
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else
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return_value = this_value;
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return return_value;
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}
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