[ < < < Home ] [ < < Reference Start ] [ < Reference Contents ]
[ < Previous=PDGREPPE Expression Parts ] [ Next=PDGREPPE Groups > ]
PDGREPPE Search Operators

An operator is a way of dealing with something.  In
this case, it is a logical OR or logical AND Boolean operator.

A Boolean operator is a way of evaluating one or more
expressions for being True (|) or False (O).

TRUTH TABLES for OR and AND Operators show what result (True or
False) is obtained for two or more ME's.

A "|" represents True.
A "O" represents False.

OR Truth Table

ME0  |	ME1	Result

O	O	False
O	|	TRUE
|	O	TRUE
|	|	TRUE

AND Truth Table

ME0  &	ME1	Result

O	O	False
O	|	False
|	O	False
|	|	TRUE

OR Operations:

 |	OR  ME0|ME1 : ME0 Or  ME1 is in same area (Greatest width)

 ~	OR  ME0~ME1 : ME0 Or  ME1 is in same area (Shortest width)

An OR operation is TRUE if ME0 *** OR *** ME1 is TRUE.

An OR operation is FALSE if both ME0 *** AND *** ME1 are FALSE.

Important:

Also, since pattern matching in a OR/AND Group happens in direct
CONTEXT to the remainder of the pattern to be matched:

An OR operation "ME0 OR ME1" is TRUE providing that

ME0 *** OR *** ME1 is TRUE

AND the remainder of the pattern also PASSES beyond a successful
match to ME0 and/or ME1.

An OR operation "ME0 OR ME1" is FALSE if the pattern after a
successful match to ME0 or ME1 is FALSE.

TRUTH TABLES for OR and AND Operators show what result (True or
False symbolised by | or O) is obtained for two or more ME's.

OR Truth Table

ME0  |	ME1	Result

O	O	False
O	|	TRUE
|	O	TRUE
|	|	TRUE

If TRUE, the longest ME found becomes part of the matched area.

The OR operator is used to test 2 possible patterns for at least
one of the patterns matching in the same area.

The pattern <ME0> is tested against the current area and then
the pattern <ME1> is tested in the same area.

The match returned will be the one with the GREATEST width if
using the regular OR of "|".  Otherwise with "~", it is match
with the SHORTEST width.  And importantly, the match
returned will be the one that passes any remainder of the
pattern beyond the OR group.


	pdgreppe -Hjc "MAGIC|fixed" file_id.diz


...OR "|" in "MAGIC|fixed" finds lines in file_id.diz that have
string "MAGIC" OR "fixed".


	pdgreppe -Hjc "MAGIC|MA" file_id.diz


...WIDEST OR "|" in "MAGIC|MA" finds lines in file_id.diz that
have string "MAGIC" OR "MA" with the WIDEST of the matches shown
as the result.


	pdgreppe -Hjc "MAGIC~MA" file_id.diz


...THINNEST OR as "~" in "MAGIC~MA" finds lines in file_id.diz
that have string "MAGIC" OR "MA" with the THINNEST of the
matches shown as the result.

AND Operations:

 &	AND ME0&ME1 : ME0 And ME1 are in SAME area

An AND operation is TRUE if ME0 and ME1 are TRUE.
An AND operation is FALSE if ME0 or ME1 are FALSE.

AND Truth Table

ME0  &	ME1	Result

O	O	False
O	|	False
|	O	False
|	|	TRUE

If TRUE, the area shared becomes part of the matched area.

Also if TRUE : ME0 and ME1 have the SAME MATCH WIDTH.

The AND operator is used to test 2 possible patterns BOTH
matching in the same area and having the SAME WIDTH.

The pattern <ME0> is tested against the current area and if it
does match then the pattern <ME1> is tested in the same area.


	pdgreppe -Hjc "^.*Search.*&^.*pattern.*" file_id.diz


...AND "&" in "^.*Search.*&^.*pattern.*" finds any line in
file_id.diz with strings "Search" AND "pattern".

Combinations of OR/AND sequences

Results for combinations of OR/AND sequences take on final
result values from left to right.

The OR and AND operators are of equal precedence and evaluate
left to right.

For example:

	A|B&C

is evaluated left-to-right like a section

	{A|B}

then

	<whatever {A|B}'s result was> & C.

Or a pattern

	A&B|C

is evaluated left-to-right like a section

	{A&B}

then

	<whatever {A&B}'s result was> | C.

Here are Truth Tables for combinations of OR/AND sequences:

Truth Table(ME0|ME1&ME2)

ME0  |	ME1  &	ME2	Result

O	O	O	False
O	O	|	False
O	|	O	False
O	|	|	TRUE
|	O	O	False
|	O	|	TRUE
|	|	O	False
|	|	|	TRUE

Truth Table(ME0&ME1|ME2)

ME0  &	ME1  |	ME2	Result

O	O	O	False
O	O	|	TRUE
O	|	O	False
O	|	|	TRUE
|	O	O	False
|	O	|	TRUE
|	|	O	TRUE
|	|	|	TRUE

See also:

CutBefore ":b" and CutAfter ":a" effects in Controls.

Marked Group data match values "%<n>" or "%<VName>" for matching
to previous found areas are CONSEQUTIVE and CUMULATIVE when
being evaluated by OR/AND sequences.

So patterns like

	.*(body).*&.*(loves).*

or

	.*(body).*|.*(loves).*

will have both of the marked groups for (body) and/or (loves)
counted as passes.  They will reference areas for a data string
like

	Everybody loves somebody sometime.

So if further search or substitution references are made to
these as %0 or %1 then the areas are both available.

NOTE:

When searching for SOF (`) or EOF (') Start or End of File
or other Zero_Width positions in OR/AND operations, these
will be part of any width matched.  The Shortest OR operator
(~) can locate any of these, except EOF:

A Zero_Width EOF (`) OR/AND term cannot be located separate
from any other match that occurs at the End of File.
[ < < < Home ] [ < < Reference Start ] [ < Reference Contents ]
[ < Previous=PDGREPPE Expression Parts ] [ Next=PDGREPPE Groups > ]