RegExpr provides regular expression matching of text strings.

INTERFACE RegExpr;

TYPE T <: REFANY;

The special expression NIL matches every string.

PROCEDURE Compile (pattern: TEXT): T  RAISES {Error};

Translate the string pattern and return its internal form.

PROCEDURE Match (t: T;  txt: TEXT): BOOLEAN;

Returns TRUE if txt matches the pattern t.

PROCEDURE MatchSub (t: T;  READONLY str: ARRAY OF CHAR): BOOLEAN;

Returns TRUE if str matches the pattern t.

PROCEDURE MatchSubstring (t: T;  txt: TEXT;  pre, post: CARDINAL): BOOLEAN;

Returns TRUE if a matches the pattern t when the first pre characters and last post characters are dropped.

PROCEDURE SimpleString (t: T): TEXT;

Returns the string that matches t if it contains no non-trivial regular expression operators. Otherwise, returns NIL.

EXCEPTION Error (TEXT);

END RegExpr.

         pattern             matches
         -------------       ------------------------------------
         <expr1>|<expr2>     strings matching <expr1> or <expr2>
         <expr1>&<expr2>     strings matching <expr1> and <expr2>
         (expr)              strings matching <expr>
         *                   any string of zero or more characters
         @                   any single character
         \*                  the single character '*' (asterisk)
         \@                  the single character '@' (at sign)
         \|                  the single character '|' (vertical bar)
         \&                  the single character '&' (ampersand)
         \(                  the single character '(' (left parenthesis)
         \)                  the single character ')' (right parenthesis)
         \\                  the single character '\' (back slash)
         <char>              any other single character not mentioned above.