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Doc update from Roberto Mello: improved versions of instr() examples.

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This commit is contained in:
Tom Lane 2001-03-23 22:07:50 +00:00
parent e458ebfd21
commit 3311e250cd
1 changed files with 86 additions and 92 deletions
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178
doc/src/sgml/plsql.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.24 2001/03/17 18:08:14 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.25 2001/03/23 22:07:50 tgl Exp $
-->
<chapter id="plpgsql">
@ -2407,13 +2407,6 @@ WITH (isstrict, iscachable);
This function should probably be integrated into the core.
</comment>
<para>
The third function (that takes 4 parameters) is implemented in
PL/Tcl but I plan on porting it to PL/pgSQL so in case we want to
include it in OpenACS we don't need to require PL/Tcl. Plus
PL/pgSQL should be more efficient.
</para>
<programlisting>
--
-- instr functions that mimic Oracle's counterpart
@ -2424,127 +2417,128 @@ WITH (isstrict, iscachable);
-- not passed, assume 1 (search starts at first character).
--
-- by Roberto Mello (rmello@fslc.usu.edu)
-- modified by Robert Gaszewski (graszew@poland.com)
-- Licensed under the GPL v2 or later.
--
DROP FUNCTION instr(varchar, varchar);
CREATE FUNCTION instr(varchar, varchar) RETURNS integer AS '
DROP FUNCTION instr(varchar,varchar);
CREATE FUNCTION instr(varchar,varchar) RETURNS integer AS '
DECLARE
pos integer;
BEGIN
pos:= instr($1, $2, 1);
pos:= instr($1,$2,1);
RETURN pos;
END;
' LANGUAGE 'plpgsql';
' language 'plpgsql';
DROP FUNCTION instr(varchar, varchar, integer);
CREATE FUNCTION instr(varchar, varchar, integer) RETURNS integer AS '
DROP FUNCTION instr(varchar,varchar,integer);
CREATE FUNCTION instr(varchar,varchar,integer) RETURNS integer AS '
DECLARE
string ALIAS FOR $1;
string_to_search ALIAS FOR $2;
beg_index ALIAS FOR $3;
pos integer NOT NULL DEFAULT 0;
ending integer;
temp_str varchar;
beg integer;
length integer;
temp_int integer;
ss_length integer;
BEGIN
IF beg_index > 0 THEN
-- Get substring from 1 to beg_index
temp_str := substring(string FROM beg_index);
pos := position(string_to_search IN temp_str);
temp_str := substring(string FROM beg_index);
pos := position(string_to_search IN temp_str);
IF pos = 0 THEN
RETURN 0;
ELSE
RETURN pos + beg_index - 1;
END IF;
ELSE
ss_length := char_length(string_to_search);
length := char_length(string);
beg := length + beg_index - ss_length + 2;
WHILE beg > 0 LOOP
temp_str := substring(string FROM beg FOR ss_length);
pos := position(string_to_search IN temp_str);
IF pos > 0 THEN
RETURN beg;
END IF;
beg := beg - 1;
END LOOP;
RETURN 0;
END IF;
END;
' language 'plpgsql';
--
-- Written by Robert Gaszewski (graszew@poland.com)
-- Licensed under the GPL v2 or later.
--
DROP FUNCTION instr(varchar,varchar,integer,integer);
CREATE FUNCTION instr(varchar,varchar,integer,integer) RETURNS integer AS '
DECLARE
string ALIAS FOR $1;
string_to_search ALIAS FOR $2;
beg_index ALIAS FOR $3;
occur_index ALIAS FOR $4;
pos integer NOT NULL DEFAULT 0;
occur_number integer NOT NULL DEFAULT 0;
temp_str varchar;
beg integer;
i integer;
length integer;
ss_length integer;
BEGIN
IF beg_index > 0 THEN
beg := beg_index;
temp_str := substring(string FROM beg_index);
FOR i IN 1..occur_index LOOP
pos := position(string_to_search IN temp_str);
IF i = 1 THEN
beg := beg + pos - 1;
ELSE
beg := beg + pos;
END IF;
temp_str := substring(string FROM beg + 1);
END LOOP;
IF pos = 0 THEN
RETURN 0;
ELSE
RETURN pos + beg_index - 1;
RETURN beg;
END IF;
ELSE
ss_length := char_length(string_to_search);
length := char_length(string);
beg := length + beg_index - ss_length + 2;
IF beg_index = -1 THEN
ending := length;
beg := ending;
temp_int := 1;
ELSE
ending := length - abs(beg_index);
beg := ending;
temp_int := ending - beg;
END IF;
WHILE pos = 0 AND beg &lt;&gt; 1 LOOP
temp_str := substring(string FROM beg FOR temp_int);
WHILE beg > 0 LOOP
temp_str := substring(string FROM beg FOR ss_length);
pos := position(string_to_search IN temp_str);
-- Keep moving left
IF pos > 0 THEN
occur_number := occur_number + 1;
IF occur_number = occur_index THEN
RETURN beg;
END IF;
END IF;
beg := beg - 1;
temp_int := (ending - beg) + 1;
END LOOP;
END IF;
IF pos = 0 THEN
RETURN 0;
ELSE
RETURN beg + 1;
END IF;
END;
' LANGUAGE 'plpgsql';
--
-- The next one (where all four params are passed) is in PL/Tcl
-- because I had no more patience to do it in PL/pgSQL.
-- It'd probably be faster in PL/pgSQL (that being the reason why
-- I implemented the first two functions in PL/pgSQL) so someday I'll do it.
--
DROP FUNCTION instr(varchar, varchar, integer, integer);
CREATE FUNCTION instr(varchar, varchar, integer, integer) RETURNS integer AS '
set string1 $1
set string2 $2
set n $3
set m $4
if { $n > 0 } {
set pos [string first $string2 $string1 [expr $n -1]]
if { $pos < 0 } {
return 0
} else {
for { set i 1 } { $i < $m } { incr i } {
set pos [string first $string2 $string1 [expr $pos + 1]]
if { $pos < 0 } {
return 0
}
}
}
}
if { $n < 0 } {
set pos [string last $string2 $string1 [expr [string length $string1] + $n]]
if { $pos < 0 } {
return 0
} else {
for { set i 1 } { $i < $m } { incr i } {
# n is negative so we add
set pos [string last $string2 $string1 [expr $pos - 1]]
if { $pos < 0 } {
return 0
}
}
}
}
if { $pos < 0 } {
return 0
} else {
return [expr $pos + 1]
}
' LANGUAGE 'pltcl';
' language 'plpgsql';
</programlisting>
</sect3>
</sect2>