-
+
Arrays
+
+
Quoting array elements.
+ As shown above, when writing an array literal value you may write double
+ quotes around any individual array
+ element. You must do so if the element value would otherwise
+ confuse the array-value parser. For example, elements containing curly
+ braces, commas, double quotes, backslashes, or white space must be
+ double-quoted. To put a double quote or backslash in an array element
+ value, precede it with a backslash.
+
+
+
+
+ Remember that what you write in an SQL query will first be interpreted
+ as a string literal, and then as an array. This doubles the number of
+ backslashes you need. For example, to insert a text array
+ value containing a backslash and a double quote, you'd need to write
+INSERT ... VALUES ('{"\\\\","\\""}');
+
+ The string-literal processor removes one level of backslashes, so that
+ what arrives at the array-value parser looks like {"\\","\""}.
+ In turn, the strings fed to the text datatype's input routine
+ become \ and " respectively. (If we were working
+ with a datatype whose input routine also treated backslashes specially,
+ bytea for example, we might need as many as eight backslashes
+ in the query to get one backslash into the stored array element.)
+
+
+
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.71 2001/10/25 05:49:43 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.72 2001/11/29 21:02:41 tgl Exp $
*
*-------------------------------------------------------------------------
*/
* If element type is pass-by-ref, the Datums point to palloc'd values.
* *nbytes is set to the amount of data space needed for the array,
* including alignment padding but not including array header overhead.
+ * CAUTION: the contents of "arrayStr" may be modified!
*---------------------------------------------------------------------------
*/
static Datum *
char *p,
*tmp,
*retval,
- **values,
- delim[2];
+ **values;
+ bool *needquotes;
int nitems,
overall_length,
i,
j,
k,
-#ifndef TCL_ARRAYS
- l,
-#endif
indx[MAXDIM];
int ndim,
*dim;
system_cache_lookup(element_type, false, &typlen, &typbyval,
&typdelim, &typelem, &typoutput, &typalign);
fmgr_info(typoutput, &outputproc);
- sprintf(delim, "%c", typdelim);
ndim = ARR_NDIM(v);
dim = ARR_DIMS(v);
nitems = ArrayGetNItems(ndim, dim);
if (nitems == 0)
{
- retval = (char *) palloc(3);
- retval[0] = '{';
- retval[1] = '}';
- retval[2] = '\0';
+ retval = pstrdup("{}");
PG_RETURN_CSTRING(retval);
}
+ /*
+ * Convert all values to string form, count total space needed
+ * (including any overhead such as escaping backslashes),
+ * and detect whether each item needs double quotes.
+ */
+ values = (char **) palloc(nitems * sizeof(char *));
+ needquotes = (bool *) palloc(nitems * sizeof(bool));
p = ARR_DATA_PTR(v);
overall_length = 1; /* [TRH] don't forget to count \0 at end. */
- values = (char **) palloc(nitems * sizeof(char *));
for (i = 0; i < nitems; i++)
{
Datum itemvalue;
+ bool nq;
itemvalue = fetch_att(p, typbyval, typlen);
values[i] = DatumGetCString(FunctionCall3(&outputproc,
else
p += INTALIGN(*(int32 *) p);
- /*
- * For the pair of double quotes
- */
- if (!typbyval)
- overall_length += 2;
-
+ /* count data plus backslashes; detect chars needing quotes */
+ nq = (values[i][0] == '\0'); /* force quotes for empty string */
for (tmp = values[i]; *tmp; tmp++)
{
+ char ch = *tmp;
+
overall_length += 1;
+ if (ch == '"' || ch == '\\')
+ {
+ nq = true;
#ifndef TCL_ARRAYS
- if (*tmp == '"')
overall_length += 1;
#endif
+ }
+ else if (ch == '{' || ch == '}' || ch == typdelim ||
+ isspace((unsigned char) ch))
+ nq = true;
}
+
+ needquotes[i] = nq;
+
+ /* Count the pair of double quotes, if needed */
+ if (nq)
+ overall_length += 2;
+
+ /* and the comma */
overall_length += 1;
}
*/
for (i = j = 0, k = 1; i < ndim; k *= dim[i++], j += k);
- p = (char *) palloc(overall_length + 2 * j);
- retval = p;
+ retval = (char *) palloc(overall_length + 2 * j);
+ p = retval;
+
+#define APPENDSTR(str) (strcpy(p, (str)), p += strlen(p))
+#define APPENDCHAR(ch) (*p++ = (ch), *p = '\0')
- strcpy(p, "{");
+ APPENDCHAR('{');
for (i = 0; i < ndim; indx[i++] = 0);
j = 0;
k = 0;
do
{
for (i = j; i < ndim - 1; i++)
- strcat(p, "{");
+ APPENDCHAR('{');
- /*
- * Surround anything that is not passed by value in double quotes.
- * See above for more details.
- */
- if (!typbyval)
+ if (needquotes[k])
{
- strcat(p, "\"");
+ APPENDCHAR('"');
#ifndef TCL_ARRAYS
- l = strlen(p);
for (tmp = values[k]; *tmp; tmp++)
{
- if (*tmp == '"')
- p[l++] = '\\';
- p[l++] = *tmp;
+ char ch = *tmp;
+
+ if (ch == '"' || ch == '\\')
+ *p++ = '\\';
+ *p++ = ch;
}
- p[l] = '\0';
+ *p = '\0';
#else
- strcat(p, values[k]);
+ APPENDSTR(values[k]);
#endif
- strcat(p, "\"");
+ APPENDCHAR('"');
}
else
- strcat(p, values[k]);
+ APPENDSTR(values[k]);
pfree(values[k++]);
for (i = ndim - 1; i >= 0; i--)
indx[i] = (indx[i] + 1) % dim[i];
if (indx[i])
{
- strcat(p, delim);
+ APPENDCHAR(typdelim);
break;
}
else
- strcat(p, "}");
+ APPENDCHAR('}');
}
j = i;
} while (j != -1);
+#undef APPENDSTR
+#undef APPENDCHAR
+
pfree(values);
+ pfree(needquotes);
+
PG_RETURN_CSTRING(retval);
}
INSERT INTO arrtest (a, b[1][2][2], c, d[2][1])
VALUES ('{}', '{3,4}', '{foo,bar}', '{bar,foo}');
SELECT * FROM arrtest;
- a | b | c | d | e | f | g
--------------+-----------------+---------------+-------------------+---------------+-------------------+-----------------
- {1,2,3,4,5} | {{{0,0},{1,2}}} | {} | {} | | {} | {}
- {11,12,23} | {{3,4},{4,5}} | {"foobar"} | {{"elt1","elt2"}} | {"3.4","6.7"} | {"abc ","abcde"} | {"abc","abcde"}
- {} | {3,4} | {"foo","bar"} | {"bar","foo"} | | |
+ a | b | c | d | e | f | g
+-------------+-----------------+-----------+---------------+-----------+-----------------+-------------
+ {1,2,3,4,5} | {{{0,0},{1,2}}} | {} | {} | | {} | {}
+ {11,12,23} | {{3,4},{4,5}} | {foobar} | {{elt1,elt2}} | {3.4,6.7} | {"abc ",abcde} | {abc,abcde}
+ {} | {3,4} | {foo,bar} | {bar,foo} | | |
(3 rows)
SELECT arrtest.a[1],
c[1:2],
d[1:1][1:2]
FROM arrtest;
- a | b | c | d
-------------+-----------------+---------------+-------------------
- {1,2,3} | {{{0,0},{1,2}}} | |
- {11,12,23} | | {"foobar"} | {{"elt1","elt2"}}
- | | {"foo","bar"} |
+ a | b | c | d
+------------+-----------------+-----------+---------------
+ {1,2,3} | {{{0,0},{1,2}}} | |
+ {11,12,23} | | {foobar} | {{elt1,elt2}}
+ | | {foo,bar} |
(3 rows)
SELECT array_dims(a) AS a,array_dims(b) AS b,array_dims(c) AS c
SET c[2:2] = '{"new_word"}'
WHERE array_dims(c) is not null;
SELECT a,b,c FROM arrtest;
- a | b | c
----------------+-----------------------+-----------------------
+ a | b | c
+---------------+-----------------------+-------------------
{16,25,3,4,5} | {{{113,142},{1,147}}} | {}
- {} | {3,4} | {"foo","new_word"}
- {16,25,23} | {{3,4},{4,5}} | {"foobar","new_word"}
+ {} | {3,4} | {foo,new_word}
+ {16,25,23} | {{3,4},{4,5}} | {foobar,new_word}
(3 rows)
SELECT a[1:3],
c[1:2],
d[1:1][2:2]
FROM arrtest;
- a | b | c | d
-------------+-----------------------+-----------------------+------------
- {16,25,3} | {{{113,142},{1,147}}} | |
- | | {"foo","new_word"} |
- {16,25,23} | | {"foobar","new_word"} | {{"elt2"}}
+ a | b | c | d
+------------+-----------------------+-------------------+----------
+ {16,25,3} | {{{113,142},{1,147}}} | |
+ | | {foo,new_word} |
+ {16,25,23} | | {foobar,new_word} | {{elt2}}
(3 rows)
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