String matching: Difference between revisions

=={{header|Component Pascal}}==

BlackBox Component Builder

<lang oberon2>

MODULE StringMatch;

IMPORT StdLog,Strings;

CONST

strSize = 1024;

patSize = 256;

TYPE

Matcher* = POINTER TO LIMITED RECORD

str: ARRAY strSize OF CHAR;

pat: ARRAY patSize OF CHAR;

pos: INTEGER

END;

PROCEDURE NewMatcher*(IN str: ARRAY OF CHAR): Matcher;

VAR

m: Matcher;

BEGIN

NEW(m);m.str := str$;m.pos:= 0;

RETURN m

END NewMatcher;

PROCEDURE (m: Matcher) Match*(IN pat: ARRAY OF CHAR): INTEGER,NEW;

VAR

pos: INTEGER;

BEGIN

m.pat := pat$;

pos := m.pos;

Strings.Find(m.str,m.pat,pos,m.pos);

RETURN m.pos

END Match;

PROCEDURE (m: Matcher) Next*(): INTEGER, NEW;

VAR

pos: INTEGER;

BEGIN

pos := m.pos + LEN(m.pat$);

Strings.Find(m.str,m.pat,pos,m.pos);

RETURN m.pos;

END Next;

(* Some Helper functions based on Strings module *)

PROCEDURE StartsWith(IN str: ARRAY OF CHAR;IN pat: ARRAY OF CHAR): BOOLEAN;

VAR

pos: INTEGER;

BEGIN

Strings.Find(str,pat,0,pos);

RETURN pos = 0

END StartsWith;

PROCEDURE Contains(IN str: ARRAY OF CHAR;IN pat: ARRAY OF CHAR; OUT pos: INTEGER): BOOLEAN;

BEGIN

Strings.Find(str,pat,0,pos);

RETURN pos >= 0

END Contains;

PROCEDURE EndsWith(IN str: ARRAY OF CHAR;IN pat: ARRAY OF CHAR): BOOLEAN;

VAR

pos: INTEGER;

BEGIN

Strings.Find(str,pat,0,pos);

RETURN pos + LEN(pat$) = LEN(str$)

END EndsWith;

PROCEDURE Do*;

CONST

aStr = "abcdefghijklmnopqrstuvwxyz";

VAR

pat: ARRAY 128 OF CHAR;

res: BOOLEAN;

at: INTEGER;

m: Matcher;

BEGIN

(* StartsWith *)

pat := "abc";

StdLog.String(aStr + " startsWith " + pat + " :>");StdLog.Bool(StartsWith(aStr,pat));StdLog.Ln;

pat := "cba";

StdLog.String(aStr + " startsWith " + pat + " :>");StdLog.Bool(StartsWith(aStr,pat));StdLog.Ln;

pat := "def";

StdLog.String(aStr + " startsWith " + pat + " :>");StdLog.Bool(StartsWith(aStr,pat));StdLog.Ln;

StdLog.Ln;

(* Contains *)

pat := 'def';

StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at));

StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln;

pat := 'efd';

StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at));

StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln;

pat := 'abc';

StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at));

StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln;

pat := 'xyz';

StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at));

StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln;

StdLog.Ln;

(* EndsWith *)

pat := 'xyz';

StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln;

pat := 'zyx';

StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln;

pat := 'abc';

StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln;

pat:= 'def';

StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln;

StdLog.Ln;

m := NewMatcher("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");

StdLog.String("Matching 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz' against 'abc':> ");

StdLog.Ln;

StdLog.String("Match at: ");StdLog.Int(m.Match("abc"));StdLog.Ln;

StdLog.String("Match at: ");StdLog.Int(m.Next());StdLog.Ln;

StdLog.String("Match at: ");StdLog.Int(m.Next());StdLog.Ln

END Do;

END StringMatch.

</lang>

Execute: ^Q StringMatching.Do <br/>

Output:

<pre>

abcdefghijklmnopqrstuvwxyz startsWith abc :> $TRUE

abcdefghijklmnopqrstuvwxyz startsWith cba :> $FALSE

abcdefghijklmnopqrstuvwxyz startsWith def :> $FALSE

abcdefghijklmnopqrstuvwxyz contains def :> $TRUE at: 3

abcdefghijklmnopqrstuvwxyz contains efd :> $FALSE at: -1

abcdefghijklmnopqrstuvwxyz contains abc :> $TRUE at: 0

abcdefghijklmnopqrstuvwxyz contains xyz :> $TRUE at: 23

abcdefghijklmnopqrstuvwxyz endsWith xyz :> $TRUE

abcdefghijklmnopqrstuvwxyz endsWith zyx :> $FALSE

abcdefghijklmnopqrstuvwxyz endsWith abc :> $FALSE

abcdefghijklmnopqrstuvwxyz endsWith def :> $FALSE

Matching 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz' against 'abc':>

Match at: 0

Match at: 26

Match at: -1

</pre>