1 /*-------------------------------------------------------------------------
2 *
3 * keywords.c
4 * lexical token lookup for key words in PostgreSQL
5 *
6 *
7 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
9 *
10 *
11 * IDENTIFICATION
12 * src/common/keywords.c
13 *
14 *-------------------------------------------------------------------------
15 */
16 #ifndef FRONTEND
17 #include "postgres.h"
18 #else
19 #include "postgres_fe.h"
20 #endif
21
22 #ifndef FRONTEND
23
24 #include "parser/gramparse.h"
25
26 #define PG_KEYWORD(a,b,c) {a,b,c},
27
28 #else
29
30 #include "common/keywords.h"
31
32 /*
33 * We don't need the token number for frontend uses, so leave it out to avoid
34 * requiring backend headers that won't compile cleanly here.
35 */
36 #define PG_KEYWORD(a,b,c) {a,0,c},
37
38 #endif /* FRONTEND */
39
40
41 const ScanKeyword ScanKeywords[] = {
42 #include "parser/kwlist.h"
43 };
44
45 const int NumScanKeywords = lengthof(ScanKeywords);
46
47
48 /*
49 * ScanKeywordLookup - see if a given word is a keyword
50 *
51 * The table to be searched is passed explicitly, so that this can be used
52 * to search keyword lists other than the standard list appearing above.
53 *
54 * Returns a pointer to the ScanKeyword table entry, or NULL if no match.
55 *
56 * The match is done case-insensitively. Note that we deliberately use a
57 * dumbed-down case conversion that will only translate 'A'-'Z' into 'a'-'z',
58 * even if we are in a locale where tolower() would produce more or different
59 * translations. This is to conform to the SQL99 spec, which says that
60 * keywords are to be matched in this way even though non-keyword identifiers
61 * receive a different case-normalization mapping.
62 */
63 const ScanKeyword *
ScanKeywordLookup(const char * text,const ScanKeyword * keywords,int num_keywords)64 ScanKeywordLookup(const char *text,
65 const ScanKeyword *keywords,
66 int num_keywords)
67 {
68 int len,
69 i;
70 char word[NAMEDATALEN];
71 const ScanKeyword *low;
72 const ScanKeyword *high;
73
74 len = strlen(text);
75 /* We assume all keywords are shorter than NAMEDATALEN. */
76 if (len >= NAMEDATALEN)
77 return NULL;
78
79 /*
80 * Apply an ASCII-only downcasing. We must not use tolower() since it may
81 * produce the wrong translation in some locales (eg, Turkish).
82 */
83 for (i = 0; i < len; i++)
84 {
85 char ch = text[i];
86
87 if (ch >= 'A' && ch <= 'Z')
88 ch += 'a' - 'A';
89 word[i] = ch;
90 }
91 word[len] = '\0';
92
93 /*
94 * Now do a binary search using plain strcmp() comparison.
95 */
96 low = keywords;
97 high = keywords + (num_keywords - 1);
98 while (low <= high)
99 {
100 const ScanKeyword *middle;
101 int difference;
102
103 middle = low + (high - low) / 2;
104 difference = strcmp(middle->name, word);
105 if (difference == 0)
106 return middle;
107 else if (difference < 0)
108 low = middle + 1;
109 else
110 high = middle - 1;
111 }
112
113 return NULL;
114 }
115