public static void main( String[] args)
{
if ( DEBUGGING )
{
System.out.println(Boyer.indexOf("dogcatwombat","cat"));
System.out.println("dogcatwombat".indexOf("cat"));
System.out.println(Boyer.indexOf("crtcamccmcarogcatwombat","cat"));
System.out.println("crtcamccmcarogcatwombat".indexOf("cat"));
System.out.println(Boyer.indexOf("dogcatwombat",""));
System.out.println("dogcatwombat".indexOf(""));
System.out.println(Boyer.indexOf("",""));
System.out.println("".indexOf(""));
System.out.println(Boyer.indexOf("","abcde"));
System.out.println("".indexOf("abcde"));
System.out.println(Boyer.indexOf("dogcatwombat","cow"));
System.out.println("dogcatwombat".indexOf("cow"));
String s = "create table foo (created_date datetime default sysdate not null)";
System.out.println(s.indexOf("create", 10));
System.out.println(Boyer.indexOf(s, "create", 10));
try
{
// O P E N
// Any file of sample characters
File f = new File ("C:/temp/temp.txt");
int size = (int) f.length();
FileReader fr;
fr = new FileReader(f);
// R E A D
char[] ca = new char[size];
int charsRead = fr.read(ca);
s = new String(ca);
long start;
long stop;
int result = 0;
start = System.currentTimeMillis();
for ( int i=0; i<1000; i++ )
{
// Need to make different so optimiser will actually do
// the work repeatedly.
// search for strings like "efficiency9" that probably won't be there.
result = Boyer.indexOf(ca,"efficiency"+i%10);
}
System.out.println("Boyer.indexOf(char[]): " + result);
stop = System.currentTimeMillis();
System.out.println("Elapsed:"
+ (stop-start));
// benchmark Boyer.indexOf
start = System.currentTimeMillis();
for ( int i=0; i<1000; i++ )
{
// Need to make different so optimiser will actually do
// the work repeatedly.
result = Boyer.indexOf(s,"efficiency"+i%10);
}
System.out.println("Boyer.indexOf(String): " + result);
stop = System.currentTimeMillis();
System.out.println("Elapsed:"
+ (stop-start));
// Benchmark String.indexOf
start = System.currentTimeMillis();
for ( int i=0; i<1000; i++ )
{
result = s.indexOf("efficiency"+i%10);
}
System.out.println("String.indexOf: " + result);
stop = System.currentTimeMillis();
System.out.println("Elapsed:"
+ (stop-start));
// C L O S E
fr.close();
}
catch ( IOException e )
{
return;
}
} // end if debugging
} // end main
} // end class Boyer
/**
* Calculate how many chars you can skip
* to the right if you find a mismatch.
* It depends on what character is at
* the end of the word when you find a mismatch.
* We must match the pattern, char by char, right to left.
* Only called after degenerate cases,
* (e.g. null, zero-length and 1-length Pattern) are eliminated.
*/
private final void analysePattern ()
{
if ( pattern.equals(prevPattern) )
{
return;
}
// get pattern in fast-to-access charArray form
patternArray = pattern.toCharArray();
// Calculate how many slots we can skip to the right
// depending on which char is at the end of the word
// when we find a match.
// Recycle old array if possible.
if ( skip == null ) skip = new int [256];
for ( int i=0; i<256; i++ )
{
skip[i] = lenPat;
} // end for
for ( int i=0; i<lenPat-1; i++ )
{
// The following line is the key to the whole algorithm.
// It also deals with repeating letters in the pattern.
// It works conservatively, considering only the last
// instance of repeating letter.
// We exclude the last letter of the pattern, because we are
// only concerned with what to do on a mismatch.
skip[patternArray[i] & 0xff] = lenPat-i-1;
} // end for
prevPattern = pattern;
} // end analysePattern
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