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/*-------------------------------------------------------------------------
*
* keywords.c
* lexical token lookup for key words in PostgreSQL
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/common/keywords.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#ifndef FRONTEND
#include "parser/gramparse.h"
#define PG_KEYWORD(a,b,c) {a,b,c},
#else
#include "common/keywords.h"
/*
* We don't need the token number for frontend uses, so leave it out to avoid
* requiring backend headers that won't compile cleanly here.
*/
#define PG_KEYWORD(a,b,c) {a,0,c},
#endif /* FRONTEND */
const ScanKeyword ScanKeywords[] = {
#include "parser/kwlist.h"
};
const int NumScanKeywords = lengthof(ScanKeywords);
/*
* ScanKeywordLookup - see if a given word is a keyword
*
* The table to be searched is passed explicitly, so that this can be used
* to search keyword lists other than the standard list appearing above.
*
* Returns a pointer to the ScanKeyword table entry, or NULL if no match.
*
* The match is done case-insensitively. Note that we deliberately use a
* dumbed-down case conversion that will only translate 'A'-'Z' into 'a'-'z',
* even if we are in a locale where tolower() would produce more or different
* translations. This is to conform to the SQL99 spec, which says that
* keywords are to be matched in this way even though non-keyword identifiers
* receive a different case-normalization mapping.
*/
const ScanKeyword *
ScanKeywordLookup(const char *text,
const ScanKeyword *keywords,
int num_keywords)
{
int len,
i;
char word[NAMEDATALEN];
const ScanKeyword *low;
const ScanKeyword *high;
len = strlen(text);
/* We assume all keywords are shorter than NAMEDATALEN. */
if (len >= NAMEDATALEN)
return NULL;
/*
* Apply an ASCII-only downcasing. We must not use tolower() since it may
* produce the wrong translation in some locales (eg, Turkish).
*/
for (i = 0; i < len; i++)
{
char ch = text[i];
if (ch >= 'A' && ch <= 'Z')
ch += 'a' - 'A';
word[i] = ch;
}
word[len] = '\0';
/*
* Now do a binary search using plain strcmp() comparison.
*/
low = keywords;
high = keywords + (num_keywords - 1);
while (low <= high)
{
const ScanKeyword *middle;
int difference;
middle = low + (high - low) / 2;
difference = strcmp(middle->name, word);
if (difference == 0)
return middle;
else if (difference < 0)
low = middle + 1;
else
high = middle - 1;
}
return NULL;
}
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