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-rw-r--r--src/backend/nodes/read.c395
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diff --git a/src/backend/nodes/read.c b/src/backend/nodes/read.c
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-/*-------------------------------------------------------------------------
- *
- * read.c
- * routines to convert a string (legal ascii representation of node) back
- * to nodes
- *
- * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- *
- * IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/nodes/read.c,v 1.32 2002/06/20 20:29:29 momjian Exp $
- *
- * HISTORY
- * AUTHOR DATE MAJOR EVENT
- * Andrew Yu Nov 2, 1994 file creation
- *
- *-------------------------------------------------------------------------
- */
-#include "postgres.h"
-
-#include <ctype.h>
-#include <errno.h>
-
-#include "nodes/pg_list.h"
-#include "nodes/readfuncs.h"
-
-
-/* Static state for pg_strtok */
-static char *pg_strtok_ptr = NULL;
-
-
-/*
- * stringToNode -
- * returns a Node with a given legal ASCII representation
- */
-void *
-stringToNode(char *str)
-{
- char *save_strtok;
- void *retval;
-
- /*
- * We save and restore the pre-existing state of pg_strtok. This makes
- * the world safe for re-entrant invocation of stringToNode, without
- * incurring a lot of notational overhead by having to pass the
- * next-character pointer around through all the readfuncs.c code.
- */
- save_strtok = pg_strtok_ptr;
-
- pg_strtok_ptr = str; /* point pg_strtok at the string to read */
-
- retval = nodeRead(true); /* do the reading */
-
- pg_strtok_ptr = save_strtok;
-
- return retval;
-}
-
-/*****************************************************************************
- *
- * the lisp token parser
- *
- *****************************************************************************/
-
-/*
- * pg_strtok --- retrieve next "token" from a string.
- *
- * Works kinda like strtok, except it never modifies the source string.
- * (Instead of storing nulls into the string, the length of the token
- * is returned to the caller.)
- * Also, the rules about what is a token are hard-wired rather than being
- * configured by passing a set of terminating characters.
- *
- * The string is assumed to have been initialized already by stringToNode.
- *
- * The rules for tokens are:
- * * Whitespace (space, tab, newline) always separates tokens.
- * * The characters '(', ')', '{', '}' form individual tokens even
- * without any whitespace around them.
- * * Otherwise, a token is all the characters up to the next whitespace
- * or occurrence of one of the four special characters.
- * * A backslash '\' can be used to quote whitespace or one of the four
- * special characters, so that it is treated as a plain token character.
- * Backslashes themselves must also be backslashed for consistency.
- * Any other character can be, but need not be, backslashed as well.
- * * If the resulting token is '<>' (with no backslash), it is returned
- * as a non-NULL pointer to the token but with length == 0. Note that
- * there is no other way to get a zero-length token.
- *
- * Returns a pointer to the start of the next token, and the length of the
- * token (including any embedded backslashes!) in *length. If there are
- * no more tokens, NULL and 0 are returned.
- *
- * NOTE: this routine doesn't remove backslashes; the caller must do so
- * if necessary (see "debackslash").
- *
- * NOTE: prior to release 7.0, this routine also had a special case to treat
- * a token starting with '"' as extending to the next '"'. This code was
- * broken, however, since it would fail to cope with a string containing an
- * embedded '"'. I have therefore removed this special case, and instead
- * introduced rules for using backslashes to quote characters. Higher-level
- * code should add backslashes to a string constant to ensure it is treated
- * as a single token.
- */
-char *
-pg_strtok(int *length)
-{
- char *local_str; /* working pointer to string */
- char *ret_str; /* start of token to return */
-
- local_str = pg_strtok_ptr;
-
- while (*local_str == ' ' || *local_str == '\n' || *local_str == '\t')
- local_str++;
-
- if (*local_str == '\0')
- {
- *length = 0;
- pg_strtok_ptr = local_str;
- return NULL; /* no more tokens */
- }
-
- /*
- * Now pointing at start of next token.
- */
- ret_str = local_str;
-
- if (*local_str == '(' || *local_str == ')' ||
- *local_str == '{' || *local_str == '}')
- {
- /* special 1-character token */
- local_str++;
- }
- else
- {
- /* Normal token, possibly containing backslashes */
- while (*local_str != '\0' &&
- *local_str != ' ' && *local_str != '\n' &&
- *local_str != '\t' &&
- *local_str != '(' && *local_str != ')' &&
- *local_str != '{' && *local_str != '}')
- {
- if (*local_str == '\\' && local_str[1] != '\0')
- local_str += 2;
- else
- local_str++;
- }
- }
-
- *length = local_str - ret_str;
-
- /* Recognize special case for "empty" token */
- if (*length == 2 && ret_str[0] == '<' && ret_str[1] == '>')
- *length = 0;
-
- pg_strtok_ptr = local_str;
-
- return ret_str;
-}
-
-/*
- * debackslash -
- * create a palloc'd string holding the given token.
- * any protective backslashes in the token are removed.
- */
-char *
-debackslash(char *token, int length)
-{
- char *result = palloc(length + 1);
- char *ptr = result;
-
- while (length > 0)
- {
- if (*token == '\\' && length > 1)
- token++, length--;
- *ptr++ = *token++;
- length--;
- }
- *ptr = '\0';
- return result;
-}
-
-#define RIGHT_PAREN (1000000 + 1)
-#define LEFT_PAREN (1000000 + 2)
-#define PLAN_SYM (1000000 + 3)
-#define AT_SYMBOL (1000000 + 4)
-#define ATOM_TOKEN (1000000 + 5)
-
-/*
- * nodeTokenType -
- * returns the type of the node token contained in token.
- * It returns one of the following valid NodeTags:
- * T_Integer, T_Float, T_String, T_BitString
- * and some of its own:
- * RIGHT_PAREN, LEFT_PAREN, PLAN_SYM, AT_SYMBOL, ATOM_TOKEN
- *
- * Assumption: the ascii representation is legal
- */
-static NodeTag
-nodeTokenType(char *token, int length)
-{
- NodeTag retval;
- char *numptr;
- int numlen;
-
- /*
- * Check if the token is a number
- */
- numptr = token;
- numlen = length;
- if (*numptr == '+' || *numptr == '-')
- numptr++, numlen--;
- if ((numlen > 0 && isdigit((unsigned char) *numptr)) ||
- (numlen > 1 && *numptr == '.' && isdigit((unsigned char) numptr[1])))
- {
- /*
- * Yes. Figure out whether it is integral or float; this requires
- * both a syntax check and a range check. strtol() can do both for
- * us. We know the token will end at a character that strtol will
- * stop at, so we do not need to modify the string.
- */
- long val;
- char *endptr;
-
- errno = 0;
- val = strtol(token, &endptr, 10);
- if (endptr != token + length || errno == ERANGE
-#ifdef HAVE_LONG_INT_64
- /* if long > 32 bits, check for overflow of int4 */
- || val != (long) ((int32) val)
-#endif
- )
- return T_Float;
- return T_Integer;
- }
-
- /*
- * these three cases do not need length checks, since pg_strtok() will
- * always treat them as single-byte tokens
- */
- else if (*token == '(')
- retval = LEFT_PAREN;
- else if (*token == ')')
- retval = RIGHT_PAREN;
- else if (*token == '{')
- retval = PLAN_SYM;
- else if (*token == '@' && length == 1)
- retval = AT_SYMBOL;
- else if (*token == '\"' && length > 1 && token[length - 1] == '\"')
- retval = T_String;
- else if (*token == 'b')
- retval = T_BitString;
- else
- retval = ATOM_TOKEN;
- return retval;
-}
-
-/*
- * nodeRead -
- * Slightly higher-level reader.
- *
- * This routine applies some semantic knowledge on top of the purely
- * lexical tokenizer pg_strtok(). It can read
- * * Value token nodes (integers, floats, or strings);
- * * Plan nodes (via parsePlanString() from readfuncs.c);
- * * Lists of the above.
- *
- * We assume pg_strtok is already initialized with a string to read (hence
- * this should only be invoked from within a stringToNode operation).
- * Any callers should set read_car_only to true.
- */
-void *
-nodeRead(bool read_car_only)
-{
- char *token;
- int tok_len;
- NodeTag type;
- Node *this_value,
- *return_value;
- bool make_dotted_pair_cell = false;
-
- token = pg_strtok(&tok_len);
-
- if (token == NULL)
- return NULL;
-
- type = nodeTokenType(token, tok_len);
-
- switch (type)
- {
- case PLAN_SYM:
- this_value = parsePlanString();
- token = pg_strtok(&tok_len);
- if (token == NULL || token[0] != '}')
- elog(ERROR, "nodeRead: did not find '}' at end of plan node");
- if (!read_car_only)
- make_dotted_pair_cell = true;
- else
- make_dotted_pair_cell = false;
- break;
- case LEFT_PAREN:
- if (!read_car_only)
- {
- List *l = makeNode(List);
-
- lfirst(l) = nodeRead(false);
- lnext(l) = nodeRead(false);
- this_value = (Node *) l;
- }
- else
- this_value = nodeRead(false);
- break;
- case RIGHT_PAREN:
- this_value = NULL;
- break;
- case AT_SYMBOL:
- this_value = NULL;
- break;
- case ATOM_TOKEN:
- if (tok_len == 0)
- {
- /* must be "<>" */
- this_value = NULL;
-
- /*
- * It might be NULL but it is an atom!
- */
- if (read_car_only)
- make_dotted_pair_cell = false;
- else
- make_dotted_pair_cell = true;
- }
- else
- {
- /* !attention! result is not a Node. Use with caution. */
- this_value = (Node *) debackslash(token, tok_len);
- make_dotted_pair_cell = true;
- }
- break;
- case T_Integer:
-
- /*
- * we know that the token terminates on a char atol will stop
- * at
- */
- this_value = (Node *) makeInteger(atol(token));
- make_dotted_pair_cell = true;
- break;
- case T_Float:
- {
- char *fval = (char *) palloc(tok_len + 1);
-
- memcpy(fval, token, tok_len);
- fval[tok_len] = '\0';
- this_value = (Node *) makeFloat(fval);
- make_dotted_pair_cell = true;
- }
- break;
- case T_String:
- /* need to remove leading and trailing quotes, and backslashes */
- this_value = (Node *) makeString(debackslash(token + 1, tok_len - 2));
- make_dotted_pair_cell = true;
- break;
- case T_BitString:
- {
- char *val = palloc(tok_len);
-
- /* skip leading 'b' */
- strncpy(val, token + 1, tok_len - 1);
- val[tok_len - 1] = '\0';
- this_value = (Node *) makeBitString(val);
- break;
- }
- default:
- elog(ERROR, "nodeRead: Bad type %d", type);
- this_value = NULL; /* keep compiler happy */
- break;
- }
- if (make_dotted_pair_cell)
- {
- List *l = makeNode(List);
-
- lfirst(l) = this_value;
-
- if (!read_car_only)
- lnext(l) = nodeRead(false);
- else
- lnext(l) = NULL;
- return_value = (Node *) l;
- }
- else
- return_value = this_value;
- return return_value;
-}
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