po 22. 6. 2020 v 5:48 odesílatel Pavel Stehule <pavel.steh...@gmail.com>
napsal:
> Hi
>
> There is one user request for unescape function in core.
>
>
> https://stackoverflow.com/questions/20124393/convert-escaped-unicode-character-back-to-actual-character-in-postgresql/20125412?noredirect=1#comment110502526_20125412
>
> This request is about possibility that we do with string literal via
> functional interface instead string literals only
>
> I wrote plpgsql function, but built in function can be simpler:
>
> CREATE OR REPLACE FUNCTION public.unescape(text, text)
> RETURNS text
> LANGUAGE plpgsql
> AS $function$
> DECLARE result text;
> BEGIN
> EXECUTE format('SELECT U&%s UESCAPE %s',
> quote_literal(replace($1, '\u','^')),
> quote_literal($2)) INTO result;
> RETURN result;
> END;
> $function$
>
> postgres=# select unescape('Odpov\u011Bdn\u00E1 osoba','^');
> unescape -----------------
> Odpovědná osoba(1 row)
>
> What do you think about this?
>
I changed the name to more accurately "unicode_unescape". Patch is assigned
Regards
Pavel
> Regards
>
> Pavel
>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index b7c450ea29..365ea17946 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -3533,6 +3533,24 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>unicode_unescape</primary>
+ </indexterm>
+ <function>unicode_unescape</function> ( <parameter>string</parameter> <type>text</type>
+ <optional>, <parameter>escape_char</parameter> <type>text</type> </optional> )
+ <returnvalue>text</returnvalue>
+ </para>
+ <para>
+ Evaluate escaped unicode chars (4 or 6 digits) to chars.
+ </para>
+ <para>
+ <literal>unicode_unescape('\0441\043B\043E\043D')</literal>
+ <returnvalue>слон</returnvalue>
+ </para></entry>
+ </row>
+
</tbody>
</tgroup>
</table>
diff --git a/src/backend/parser/parser.c b/src/backend/parser/parser.c
index be86eb37fe..c7f94298c1 100644
--- a/src/backend/parser/parser.c
+++ b/src/backend/parser/parser.c
@@ -26,7 +26,6 @@
#include "parser/parser.h"
#include "parser/scansup.h"
-static bool check_uescapechar(unsigned char escape);
static char *str_udeescape(const char *str, char escape,
int position, core_yyscan_t yyscanner);
@@ -278,44 +277,6 @@ base_yylex(YYSTYPE *lvalp, YYLTYPE *llocp, core_yyscan_t yyscanner)
return cur_token;
}
-/* convert hex digit (caller should have verified that) to value */
-static unsigned int
-hexval(unsigned char c)
-{
- if (c >= '0' && c <= '9')
- return c - '0';
- if (c >= 'a' && c <= 'f')
- return c - 'a' + 0xA;
- if (c >= 'A' && c <= 'F')
- return c - 'A' + 0xA;
- elog(ERROR, "invalid hexadecimal digit");
- return 0; /* not reached */
-}
-
-/* is Unicode code point acceptable? */
-static void
-check_unicode_value(pg_wchar c)
-{
- if (!is_valid_unicode_codepoint(c))
- ereport(ERROR,
- (errcode(ERRCODE_SYNTAX_ERROR),
- errmsg("invalid Unicode escape value")));
-}
-
-/* is 'escape' acceptable as Unicode escape character (UESCAPE syntax) ? */
-static bool
-check_uescapechar(unsigned char escape)
-{
- if (isxdigit(escape)
- || escape == '+'
- || escape == '\''
- || escape == '"'
- || scanner_isspace(escape))
- return false;
- else
- return true;
-}
-
/*
* Process Unicode escapes in "str", producing a palloc'd plain string
*
diff --git a/src/backend/parser/scansup.c b/src/backend/parser/scansup.c
index 18169ec4f4..5a39edf450 100644
--- a/src/backend/parser/scansup.c
+++ b/src/backend/parser/scansup.c
@@ -228,3 +228,41 @@ scanner_isspace(char ch)
return true;
return false;
}
+
+/* convert hex digit (caller should have verified that) to value */
+unsigned int
+hexval(unsigned char c)
+{
+ if (c >= '0' && c <= '9')
+ return c - '0';
+ if (c >= 'a' && c <= 'f')
+ return c - 'a' + 0xA;
+ if (c >= 'A' && c <= 'F')
+ return c - 'A' + 0xA;
+ elog(ERROR, "invalid hexadecimal digit");
+ return 0; /* not reached */
+}
+
+/* is Unicode code point acceptable? */
+Oid
+check_unicode_value(pg_wchar c)
+{
+ if (!is_valid_unicode_codepoint(c))
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("invalid Unicode escape value")));
+}
+
+/* is 'escape' acceptable as Unicode escape character (UESCAPE syntax) ? */
+bool
+check_uescapechar(unsigned char escape)
+{
+ if (isxdigit(escape)
+ || escape == '+'
+ || escape == '\''
+ || escape == '"'
+ || scanner_isspace(escape))
+ return false;
+ else
+ return true;
+}
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 2eaabd6231..2934a1d9da 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -6139,3 +6139,202 @@ unicode_is_normalized(PG_FUNCTION_ARGS)
PG_RETURN_BOOL(result);
}
+
+/*
+ * Process Unicode escapes in "str"
+ *
+ * escape: the escape character to use
+ */
+static void
+udeescape(StringInfo str, const char *instr, size_t len, char escape)
+{
+ pg_wchar pair_first = 0;
+ char cbuf[MAX_UNICODE_EQUIVALENT_STRING + 1];
+
+ while (len > 0)
+ {
+ if (instr[0] == escape)
+ {
+ if (len >= 2 &&
+ instr[1] == escape)
+ {
+ if (pair_first)
+ goto invalid_pair;
+ appendStringInfoChar(str, escape);
+ instr += 2;
+ len -= 2;
+ }
+ else if (len >= 5 &&
+ isxdigit((unsigned char) instr[1]) &&
+ isxdigit((unsigned char) instr[2]) &&
+ isxdigit((unsigned char) instr[3]) &&
+ isxdigit((unsigned char) instr[4]))
+ {
+ pg_wchar unicode;
+
+ unicode = (hexval(instr[1]) << 12) +
+ (hexval(instr[2]) << 8) +
+ (hexval(instr[3]) << 4) +
+ hexval(instr[4]);
+ check_unicode_value(unicode);
+ if (pair_first)
+ {
+ if (is_utf16_surrogate_second(unicode))
+ {
+ unicode = surrogate_pair_to_codepoint(pair_first, unicode);
+ pair_first = 0;
+ }
+ else
+ goto invalid_pair;
+ }
+ else if (is_utf16_surrogate_second(unicode))
+ goto invalid_pair;
+
+ if (is_utf16_surrogate_first(unicode))
+ pair_first = unicode;
+ else
+ {
+ pg_unicode_to_server(unicode, (unsigned char *) cbuf);
+ appendStringInfoString(str, cbuf);
+ }
+ instr += 5;
+ len -= 5;
+ }
+ else if (len >= 8 &&
+ instr[1] == '+' &&
+ isxdigit((unsigned char) instr[2]) &&
+ isxdigit((unsigned char) instr[3]) &&
+ isxdigit((unsigned char) instr[4]) &&
+ isxdigit((unsigned char) instr[5]) &&
+ isxdigit((unsigned char) instr[6]) &&
+ isxdigit((unsigned char) instr[7]))
+ {
+ pg_wchar unicode;
+
+ unicode = (hexval(instr[2]) << 20) +
+ (hexval(instr[3]) << 16) +
+ (hexval(instr[4]) << 12) +
+ (hexval(instr[5]) << 8) +
+ (hexval(instr[6]) << 4) +
+ hexval(instr[7]);
+ check_unicode_value(unicode);
+ if (pair_first)
+ {
+ if (is_utf16_surrogate_second(unicode))
+ {
+ unicode = surrogate_pair_to_codepoint(pair_first, unicode);
+ pair_first = 0;
+ }
+ else
+ goto invalid_pair;
+ }
+ else if (is_utf16_surrogate_second(unicode))
+ goto invalid_pair;
+
+ if (is_utf16_surrogate_first(unicode))
+ pair_first = unicode;
+ else
+ {
+ pg_unicode_to_server(unicode, (unsigned char *) cbuf);
+ appendStringInfoString(str, cbuf);
+ }
+ instr += 8;
+ len -= 8;
+ }
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("invalid Unicode escape"),
+ errhint("Unicode escapes must be \\XXXX or \\+XXXXXX.")));
+ }
+ else
+ {
+ if (pair_first)
+ goto invalid_pair;
+
+ appendStringInfoChar(str, *instr++);
+ len--;
+ }
+ }
+
+ /* unfinished surrogate pair? */
+ if (pair_first)
+ goto invalid_pair;
+
+ return;
+
+invalid_pair:
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("invalid Unicode surrogate pair")));
+}
+
+/*
+ * Unescape unicode strings
+ */
+Datum
+unicode_uescape_with_escape_char(PG_FUNCTION_ARGS)
+{
+ StringInfoData str;
+ text *input_text;
+ text *escchr_text;
+ text *result;
+ const char *escchr_ptr;
+
+ /* when input string is NULL, then result is NULL too */
+ if (PG_ARGISNULL(0))
+ PG_RETURN_NULL();
+
+ input_text = PG_GETARG_TEXT_PP(0);
+
+ if (PG_ARGISNULL(1))
+ ereport(ERROR,
+ (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+ errmsg("null value not allowed for escape char")));
+
+ escchr_text = PG_GETARG_TEXT_PP(1);
+ escchr_ptr = VARDATA_ANY(escchr_text);
+
+ if (VARSIZE_ANY_EXHDR(escchr_text) == 1 && !check_uescapechar(*escchr_ptr))
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("invalid Unicode escape character")));
+
+ initStringInfo(&str);
+
+ udeescape(&str,
+ VARDATA_ANY(input_text),
+ VARSIZE_ANY_EXHDR(input_text),
+ *escchr_ptr);
+
+ result = cstring_to_text_with_len(str.data, str.len);
+ pfree(str.data);
+
+ PG_RETURN_TEXT_P(result);
+}
+
+Datum
+unicode_uescape(PG_FUNCTION_ARGS)
+{
+ StringInfoData str;
+ text *input_text;
+ text *result;
+
+ /* when input string is NULL, then result is NULL too */
+ if (PG_ARGISNULL(0))
+ PG_RETURN_NULL();
+
+ input_text = PG_GETARG_TEXT_PP(0);
+
+ initStringInfo(&str);
+
+ udeescape(&str,
+ VARDATA_ANY(input_text),
+ VARSIZE_ANY_EXHDR(input_text),
+ '\\');
+
+ result = cstring_to_text_with_len(str.data, str.len);
+ pfree(str.data);
+
+ PG_RETURN_TEXT_P(result);
+}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 61f2c2f5b4..42792fca3c 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -10936,4 +10936,11 @@
proname => 'is_normalized', prorettype => 'bool', proargtypes => 'text text',
prosrc => 'unicode_is_normalized' },
+{ oid => '1136', descr => 'unescape Unicode chars in strings',
+ proname => 'unicode_unescape', prorettype => 'text', proargtypes => 'text text',
+ proisstrict => 'f', prosrc => 'unicode_uescape_with_escape_char' },
+
+{ oid => '1137', descr => 'unescape Unicode chars in strings',
+ proname => 'unicode_unescape', prorettype => 'text', proargtypes => 'text',
+ proisstrict => 't', prosrc => 'unicode_uescape' }
]
diff --git a/src/include/parser/scansup.h b/src/include/parser/scansup.h
index 7a6ee529ae..e1dc7b8a2a 100644
--- a/src/include/parser/scansup.h
+++ b/src/include/parser/scansup.h
@@ -15,6 +15,8 @@
#ifndef SCANSUP_H
#define SCANSUP_H
+#include "mb/pg_wchar.h"
+
extern char *scanstr(const char *s);
extern char *downcase_truncate_identifier(const char *ident, int len,
@@ -27,4 +29,10 @@ extern void truncate_identifier(char *ident, int len, bool warn);
extern bool scanner_isspace(char ch);
+extern unsigned int hexval(unsigned char c);
+
+extern Oid check_unicode_value(pg_wchar c);
+
+extern bool check_uescapechar(unsigned char escape);
+
#endif /* SCANSUP_H */
diff --git a/src/test/regress/expected/unicode.out b/src/test/regress/expected/unicode.out
index 2a1e903696..deb67b566b 100644
--- a/src/test/regress/expected/unicode.out
+++ b/src/test/regress/expected/unicode.out
@@ -79,3 +79,15 @@ ORDER BY num;
SELECT is_normalized('abc', 'def'); -- run-time error
ERROR: invalid normalization form: def
+SELECT unicode_unescape('\0441\043B\043E\043D');
+ unicode_unescape
+------------------
+ слон
+(1 row)
+
+SELECT unicode_unescape('d!0061t!+000061', '!');
+ unicode_unescape
+------------------
+ data
+(1 row)
+
diff --git a/src/test/regress/sql/unicode.sql b/src/test/regress/sql/unicode.sql
index ccfc6fa77a..fd99031a1a 100644
--- a/src/test/regress/sql/unicode.sql
+++ b/src/test/regress/sql/unicode.sql
@@ -30,3 +30,6 @@ FROM
ORDER BY num;
SELECT is_normalized('abc', 'def'); -- run-time error
+
+SELECT unicode_unescape('\0441\043B\043E\043D');
+SELECT unicode_unescape('d!0061t!+000061', '!');
