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Cosmetic improvements in ltree code.

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Add more comments in ltree.h, and correct a misstatement or two.

Use a symbol, rather than hardwired constants, for the maximum length
of an ltree label.  The max length is still hardwired in the associated
error messages, but I want to clean that up as part of a separate patch
to improve the error messages.
This commit is contained in:
Tom Lane
2020-03-29 19:14:15 -04:00
parent 122b0ccfef
commit 2743d9ae4a
2 changed files with 45 additions and 15 deletions
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41
contrib/ltree/ltree.h
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@ -7,9 +7,19 @@
#include "tsearch/ts_locale.h"
#include "utils/memutils.h"
/* ltree */
/*
* We want the maximum length of a label to be encoding-independent, so
* set it somewhat arbitrarily at 255 characters (not bytes), while using
* uint16 fields to hold the byte length.
*/
#define LTREE_LABEL_MAX_CHARS 255
typedef struct
{
uint16 len;
uint16 len; /* label string length in bytes */
char name[FLEXIBLE_ARRAY_MEMBER];
} ltree_level;
@ -19,7 +29,8 @@ typedef struct
typedef struct
{
int32 vl_len_; /* varlena header (do not touch directly!) */
uint16 numlevel;
uint16 numlevel; /* number of labels */
/* Array of maxalign'd ltree_level structs follows: */
char data[FLEXIBLE_ARRAY_MEMBER];
} ltree;
@ -30,25 +41,35 @@ typedef struct
/* lquery */
/* lquery_variant: one branch of some OR'ed alternatives */
typedef struct
{
int32 val;
uint16 len;
int32 val; /* CRC of label string */
uint16 len; /* label string length in bytes */
uint8 flag; /* see LVAR_xxx flags below */
char name[FLEXIBLE_ARRAY_MEMBER];
} lquery_variant;
/*
* Note: these macros contain too many MAXALIGN calls and so will sometimes
* overestimate the space needed for an lquery_variant. However, we can't
* change it without breaking on-disk compatibility for lquery.
*/
#define LVAR_HDRSIZE MAXALIGN(offsetof(lquery_variant, name))
#define LVAR_NEXT(x) ( (lquery_variant*)( ((char*)(x)) + MAXALIGN(((lquery_variant*)(x))->len) + LVAR_HDRSIZE ) )
#define LVAR_ANYEND 0x01
#define LVAR_INCASE 0x02
#define LVAR_SUBLEXEME 0x04
#define LVAR_ANYEND 0x01 /* '*' flag: prefix match */
#define LVAR_INCASE 0x02 /* '@' flag: case-insensitive match */
#define LVAR_SUBLEXEME 0x04 /* '%' flag: word-wise match */
/*
* In an lquery_level, "flag" contains the union of the variants' flags
* along with possible LQL_xxx flags; so those bit sets can't overlap.
*/
typedef struct
{
uint16 totallen; /* total length of this level, in bytes */
uint16 flag; /* see LQL_xxx flags below */
uint16 flag; /* see LQL_xxx and LVAR_xxx flags */
uint16 numvar; /* number of variants; 0 means '*' */
uint16 low; /* minimum repeat count for '*' */
uint16 high; /* maximum repeat count for '*' */
@ -60,7 +81,7 @@ typedef struct
#define LQL_NEXT(x) ( (lquery_level*)( ((char*)(x)) + MAXALIGN(((lquery_level*)(x))->totallen) ) )
#define LQL_FIRST(x) ( (lquery_variant*)( ((char*)(x))+LQL_HDRSIZE ) )
#define LQL_NOT 0x10
#define LQL_NOT 0x10 /* level has '!' (NOT) prefix */
#ifdef LOWER_NODE
#define FLG_CANLOOKSIGN(x) ( ( (x) & ( LQL_NOT | LVAR_ANYEND | LVAR_SUBLEXEME ) ) == 0 )
@ -73,7 +94,7 @@ typedef struct
{
int32 vl_len_; /* varlena header (do not touch directly!) */
uint16 numlevel; /* number of lquery_levels */
uint16 firstgood;
uint16 firstgood; /* number of leading simple-match levels */
uint16 flag; /* see LQUERY_xxx flags below */
/* Array of maxalign'd lquery_level structs follows: */
char data[FLEXIBLE_ARRAY_MEMBER];