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/*--------------------------------------------------------------------
* Symbols referenced in this file:
* - ScanKeywords
* - NumScanKeywords
* - ScanKeywordLookup
*--------------------------------------------------------------------
*/
/*-------------------------------------------------------------------------
*
* keywords.c
* lexical token lookup for key words in PostgreSQL
*
*
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development PGGroup
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/common/keywords.c
*
*-------------------------------------------------------------------------
*/
#include "pg_functions.hpp"
#include <string.h>
#include <string>
#include <memory>
#include "parser/gramparse.hpp"
#define DUCKDB_BASE_STD
namespace duckdb_base_std {
using ::std::unique_ptr;
} // namespace duckdb_base_std
#include "parser/kwlist.hpp"
namespace duckdb_libpgquery {
/*
* 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 PGScanKeyword 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 PGScanKeyword *ScanKeywordLookup(const char *text, const PGScanKeyword *keywords, int num_keywords) {
int len, i;
const PGScanKeyword *low;
const PGScanKeyword *high;
len = strlen(text);
auto data = duckdb_base_std::unique_ptr<char[]>(new char[len + 1]);
auto word = data.get();
/* We assume all keywords are shorter than NAMEDATALEN. */
/*
* 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 PGScanKeyword *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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