115 lines
2.7 KiB
C
115 lines
2.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* keywords.c
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* lexical token lookup for key words in PostgreSQL
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*
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*
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* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
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* Portions 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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* src/common/keywords.c
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef FRONTEND
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#include "postgres.h"
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#else
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#include "postgres_fe.h"
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#endif
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#ifndef FRONTEND
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#include "parser/gramparse.h"
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#define PG_KEYWORD(a,b,c) {a,b,c},
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#else
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#include "common/keywords.h"
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/*
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* We don't need the token number for frontend uses, so leave it out to avoid
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* requiring backend headers that won't compile cleanly here.
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*/
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#define PG_KEYWORD(a,b,c) {a,0,c},
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#endif /* FRONTEND */
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const ScanKeyword ScanKeywords[] = {
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#include "parser/kwlist.h"
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};
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const int NumScanKeywords = lengthof(ScanKeywords);
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/*
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* ScanKeywordLookup - see if a given word is a keyword
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*
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* The table to be searched is passed explicitly, so that this can be used
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* to search keyword lists other than the standard list appearing above.
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*
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* Returns a pointer to the ScanKeyword table entry, or NULL if no match.
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*
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* The match is done case-insensitively. Note that we deliberately use a
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* dumbed-down case conversion that will only translate 'A'-'Z' into 'a'-'z',
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* even if we are in a locale where tolower() would produce more or different
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* translations. This is to conform to the SQL99 spec, which says that
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* keywords are to be matched in this way even though non-keyword identifiers
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* receive a different case-normalization mapping.
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*/
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const ScanKeyword *
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ScanKeywordLookup(const char *text,
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const ScanKeyword *keywords,
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int num_keywords)
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{
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int len,
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i;
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char word[NAMEDATALEN];
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const ScanKeyword *low;
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const ScanKeyword *high;
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len = strlen(text);
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/* We assume all keywords are shorter than NAMEDATALEN. */
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if (len >= NAMEDATALEN)
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return NULL;
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/*
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* Apply an ASCII-only downcasing. We must not use tolower() since it may
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* produce the wrong translation in some locales (eg, Turkish).
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*/
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for (i = 0; i < len; i++)
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{
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char ch = text[i];
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if (ch >= 'A' && ch <= 'Z')
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ch += 'a' - 'A';
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word[i] = ch;
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}
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word[len] = '\0';
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/*
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* Now do a binary search using plain strcmp() comparison.
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*/
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low = keywords;
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high = keywords + (num_keywords - 1);
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while (low <= high)
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{
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const ScanKeyword *middle;
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int difference;
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middle = low + (high - low) / 2;
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difference = strcmp(middle->name, word);
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if (difference == 0)
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return middle;
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else if (difference < 0)
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low = middle + 1;
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else
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high = middle - 1;
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}
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return NULL;
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}
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