Compaq AA-PWCBD-TE manual DEC Text Processing Utility Data Types Pattern Data Type

DEC Text Processing Utility Data Types

3.7 Pattern Data Type

To create a pattern, use DECTPU pattern operators (+, &, , @) to connect any of the following:

•String constants

•String variables

•Pattern variables

•Calls to pattern built-in procedures

•The following keywords:

ANCHOR BUFFER_BEGIN BUFFER_END LINE_BEGIN LINE_END PAGE_BREAK REMAIN UNANCHOR

•Parentheses (to enclose expressions)

Patterns can be simple or complex. A simple pattern can be composed of sets of strings connected by one of the pattern operators. The following example indicates that pat1 matches either the string "abc" or the string "def":

pat1 := "abc" "def";

If you connect two strings with the + operator, the result is a string rather than a pattern. For example, the following statement gives pat1 the string data type:

pat1 := "abc" + "def";

The SEARCH and SEARCH_QUIETLY built-in procedures accept such a string as a parameter.

A more complex pattern uses pattern built-in procedures and existing patterns to form a new pattern. The following example indicates that pat2 matches the string "abc" followed by the longest string that contains any characters from the string "12345":

pat2 := "abc" + SPAN ("12345");

Pat2 matches the string "abc123" in the text string "xyzabc123def".

Following are additional examples of statements that create complex patterns:

pat1 := any( "abc" );

pat2 := line_begin + remain; pat3 := "abc" "xes"; pat4 := pat1 + "12";

pat5 := "xes" @ var1; pat6 := "abc" & "123";

You can assign a pattern to a variable and then use the variable as a parameter for the SEARCH or SEARCH_QUIETLY built-in procedure. SEARCH or SEARCH_QUIETLY looks for the character sequences specified by the pattern that you use as a parameter. If SEARCH or SEARCH_QUIETLY finds a match

DEC Text Processing Utility Data Types 3–11