20151108_01.md

ltree 支持的字符 ISALNUM

作者

digoal

日期

2015-11-08

标签

PostgreSQL , ltree , 字符

---

背景

ltree目前只支持alpha numeric，数字，字母，下划线。

postgres=# select text2ltree('abc.\<f');  
ERROR:  42601: syntax error at position 4  
LOCATION:  ltree_in, ltree_io.c:81  
  
postgres=# select text2ltree('abc._f');  
 text2ltree   
------------  
 abc._f  
(1 row)  

见代码ltree_in.

参考

1. contrib/ltree/ltree_io.c

#include <ctype.h>  
......  
Datum  
ltree_in(PG_FUNCTION_ARGS)  
{  
        char       *buf = (char *) PG_GETARG_POINTER(0);  
        char       *ptr;  
        nodeitem   *list,  
                           *lptr;  
        int                     num = 0,  
                                totallen = 0;  
        int                     state = LTPRS_WAITNAME;  
        ltree      *result;  
        ltree_level *curlevel;  
        int                     charlen;  
        int                     pos = 0;  
  
        ptr = buf;  
        while (*ptr)  
        {  
                charlen = pg_mblen(ptr);  
                if (charlen == 1 && t_iseq(ptr, '.'))  
                        num++;  
                ptr += charlen;  
        }  
  
        if (num + 1 > MaxAllocSize / sizeof(nodeitem))  
                ereport(ERROR,  
                                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),  
                         errmsg("number of levels (%d) exceeds the maximum allowed (%d)",  
                                        num + 1, (int) (MaxAllocSize / sizeof(nodeitem)))));  
        list = lptr = (nodeitem *) palloc(sizeof(nodeitem) * (num + 1));  
        ptr = buf;  
        while (*ptr)  
        {  
                charlen = pg_mblen(ptr);  
  
                if (state == LTPRS_WAITNAME)  
                {  
                        if (ISALNUM(ptr))  
                        {  
                                lptr->start = ptr;  
                                lptr->wlen = 0;  
                                state = LTPRS_WAITDELIM;  
                        }  
                        else  
                                UNCHAR;  
                }  
                else if (state == LTPRS_WAITDELIM)  
                {  
                        if (charlen == 1 && t_iseq(ptr, '.'))  
                        {  
                                lptr->len = ptr - lptr->start;  
                                if (lptr->wlen > 255)  
                                        ereport(ERROR,  
                                                        (errcode(ERRCODE_NAME_TOO_LONG),  
                                                         errmsg("name of level is too long"),  
                                                         errdetail("Name length is %d, must "  
                                                                           "be < 256, in position %d.",  
                                                                           lptr->wlen, pos)));  
  
                                totallen += MAXALIGN(lptr->len + LEVEL_HDRSIZE);  
                                lptr++;  
                                state = LTPRS_WAITNAME;  
                        }  
                        else if (!ISALNUM(ptr))  
                                UNCHAR;  
                }  
                else  
                        /* internal error */  
                        elog(ERROR, "internal error in parser");  
  
                ptr += charlen;  
                lptr->wlen++;  
                pos++;  
        }  
  
        if (state == LTPRS_WAITDELIM)  
        {  
                lptr->len = ptr - lptr->start;  
                if (lptr->wlen > 255)  
                        ereport(ERROR,  
                                        (errcode(ERRCODE_NAME_TOO_LONG),  
                                         errmsg("name of level is too long"),  
                                         errdetail("Name length is %d, must "  
                                                           "be < 256, in position %d.",  
                                                           lptr->wlen, pos)));  
  
                totallen += MAXALIGN(lptr->len + LEVEL_HDRSIZE);  
                lptr++;  
        }  
        else if (!(state == LTPRS_WAITNAME && lptr == list))  
                ereport(ERROR,  
                                (errcode(ERRCODE_SYNTAX_ERROR),  
                                 errmsg("syntax error"),  
                                 errdetail("Unexpected end of line.")));  
  
        result = (ltree *) palloc0(LTREE_HDRSIZE + totallen);  
        SET_VARSIZE(result, LTREE_HDRSIZE + totallen);  
        result->numlevel = lptr - list;  
        curlevel = LTREE_FIRST(result);  
        lptr = list;  
        while (lptr - list < result->numlevel)  
        {  
                curlevel->len = (uint16) lptr->len;  
                memcpy(curlevel->name, lptr->start, lptr->len);  
                curlevel = LEVEL_NEXT(curlevel);  
                lptr++;  
        }  
  
        pfree(list);  
        PG_RETURN_POINTER(result);  
}  

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