ScannerSearchAlgorithm.java
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package org.hsqldb.lib;
import java.io.Reader;
import java.util.Scanner;
import java.util.logging.Logger;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
/**
* Provides a string search facility using a {@link Scanner}.
*
* @author Campbell Burnet (campbell-burnet@users dot sourceforge.net)
* @version 2.7.x
* @since 2.7.x
*/
public class ScannerSearchAlgorithm {
/**
* is 1024. This is the size above which it <i>may</i> be better to use
* {@link KMPSearchAlgorithm}.
*/
public static final int SUGGESTED_MAX_LITERAL_SIZE = 1024;
private static final Logger LOG = Logger.getLogger(
ScannerSearchAlgorithm.class.getName());
/**
* the given {@code reader} for the given {@code searchstr}.
*
* @param reader to search
* @param searchstr to find
* @param literal true to treat {@code searchstr} as a literal search
* term; false to treat {@code searchstr} as a regular
* expression.
* @return zero-based offset into stream at which {@code searchstr} is
* found; -1 if not found, {@code reader} is null, or
* {@code searchstr} is null; 0 if {@code searchstr.length() == 0
* && literal == true}.
* @throws IllegalStateException if a {@link Scanner} illegal state
* occurs
* @throws IllegalArgumentException if a {@link Scanner} illegal argument is
* encountered.
*/
public static long search(
Reader reader,
char[] searchstr,
boolean literal) {
if (reader == null || searchstr == null) {
return -1;
}
if (searchstr.length == 0 && literal) {
return 0;
}
return search(reader, new String(searchstr), literal);
}
/**
* the given {@code reader} for the given {@code searchstr}.
*
* @param reader to search
* @param searchstr to find
* @param literal true to treat {@code searchstr} as a literal search
* term; false to treat {@code searchstr} as a regular
* expression.
* @return zero-based offset into stream at which {@code searchstr} is
* found; -1 if not found, {@code reader} is null, or
* {@code searchstr} is null; 0 if {@code searchstr.length() == 0
* && literal == true}.
* @throws PatternSyntaxException if {@code searchstr} expression's syntax
* is invalid
* @throws IllegalStateException if a {@link Scanner} illegal state
* occurs
* @throws IllegalArgumentException if a {@link Scanner} illegal argument is
* encountered.
*/
public static long search(
Reader reader,
String searchstr,
boolean literal)
throws NullPointerException,
PatternSyntaxException,
IllegalStateException,
IllegalArgumentException {
if (reader == null || searchstr == null) {
return -1;
}
if (searchstr.length() == 0 && literal) {
return 0;
}
final String s = literal
? Pattern.quote(searchstr)
: searchstr;
final Pattern pattern = Pattern.compile(s);
return searchNoChecks(reader, pattern);
}
/**
* the given {@code reader} for the given {@code pattern}.
*
* @param reader to search
* @param pattern to find
* @return zero-based offset into stream at which {@code searchstr} is
* found; -1 if not found;
* @throws NullPointerException if {@code reader} is null or
* {@code pattern} is null.
* @throws IllegalStateException if a {@link Scanner} illegal state
* occurs
* @throws IllegalArgumentException if a {@link Scanner} illegal argument is
* encountered.
*/
public static long search(
Reader reader,
Pattern pattern)
throws IllegalStateException,
IllegalArgumentException {
if (reader == null || pattern == null) {
return -1;
}
return searchNoChecks(reader, pattern);
}
/**
* the given {@code reader} for the given {@code pattern}.
*
* @param reader to search
* @param pattern to find
* @return zero-based offset into stream at which {@code searchstr} is
* found; -1 if not found;
* @throws IllegalStateException if a {@link Scanner} illegal state
* occurs
* @throws IllegalArgumentException if a {@link Scanner} illegal argument is
* encountered.
*/
private static long searchNoChecks(
Reader reader,
Pattern pattern)
throws IllegalStateException,
IllegalArgumentException {
final Scanner scanner = new Scanner(reader);
final String token = scanner.findWithinHorizon(pattern, 0);
final long position = (token == null)
? -1
: scanner.match().start();
return position;
}
private ScannerSearchAlgorithm() {
assert false: "Pure Utility Class";
}
}