SimpleSqlPatternMatcher.java

package jeql.command.db.sde;

public class SimpleSqlPatternMatcher {
  public static final int MATCH_EXACT = 0;
  public static final int MATCH_PREFIX = 1;
  public static final int MATCH_INFIX = 2;
  public static final int MATCH_SUFFIX = 3;
  public static final int MATCH_ANY = 4;

  private String pattern;
  private String fixedData;
  private String fixedDataLower = null;
  private int matchStrategy = MATCH_EXACT;

  public SimpleSqlPatternMatcher(String pattern) {
    this.pattern = pattern;
    prepare(pattern);
  }

  private void prepare(String pattern) {
    if (pattern.equals("%")) {
      matchStrategy = MATCH_ANY;
      return;
    }
    boolean hasPrefixWildCard = pattern.startsWith("%");
    boolean hasSuffixWildCard = pattern.endsWith("%");

    if (hasPrefixWildCard && hasSuffixWildCard && pattern.length() >= 2) {
      fixedData = pattern.substring(1, pattern.length() - 1);
      matchStrategy = MATCH_INFIX;
      return;
    }
    if (hasPrefixWildCard) {
      fixedData = pattern.substring(1, pattern.length());
      matchStrategy = MATCH_SUFFIX;
      return;
    }
    if (hasSuffixWildCard) {
      fixedData = pattern.substring(0, pattern.length() - 1);
      matchStrategy = MATCH_PREFIX;
      return;
    }
    fixedData = pattern;
    matchStrategy = MATCH_EXACT;
  }

  public boolean match(String input) {
    return match(input, fixedData);
  }

  public boolean matchIgnoreCase(String input) {
    if (fixedDataLower == null)
      fixedDataLower = fixedData.toLowerCase();
    String inputLower = input.toLowerCase();
    return match(inputLower, fixedDataLower);
  }

  private boolean match(String input, String fixedData) {
    switch (matchStrategy) {
    case MATCH_ANY:
      return true;
    case MATCH_EXACT:
      return fixedData.equals(input);
    case MATCH_PREFIX:
      return input.startsWith(fixedData);
    case MATCH_SUFFIX:
      return input.endsWith(fixedData);
    case MATCH_INFIX:
      return input.indexOf(fixedData) >= 0;
    }
    throw new IllegalStateException("Unknown match state");

  }
}