antlrhashstring.java

来自「SRI international 发布的OAA框架软件」· Java 代码 · 共 98 行

package antlr_oaa;

/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/RIGHTS.html
 *
 * $Id: ANTLRHashString.java,v 1.1 2002/11/08 17:38:32 agno Exp $
 */

// class implements a String-like object whose sole purpose is to be
// entered into a lexer HashTable.  It uses a lexer object to get
// information about case sensitivity.

public class ANTLRHashString {
	// only one of s or buf is non-null
	private String s;
	private char[] buf;
	private int len;
	private CharScanner lexer;
	private static final int prime = 151;


	public ANTLRHashString(char[] buf, int length, CharScanner lexer) {
		this.lexer = lexer;
		setBuffer(buf, length);
	}
	// Hash strings constructed this way are unusable until setBuffer or setString are called.
	public ANTLRHashString(CharScanner lexer) {
		this.lexer = lexer;
	}
	public ANTLRHashString(String s, CharScanner lexer) {
		this.lexer = lexer;
		setString(s);
	}
	private final char charAt(int index) {
		return (s!=null) ? s.charAt(index) : buf[index];
	}
	// Return true if o is an ANTLRHashString equal to this.
	public boolean equals(Object o) {
		if (!(o instanceof ANTLRHashString) && !(o instanceof String)) {
			return false;
		}
		
		ANTLRHashString s;
		if ( o instanceof String ) {
			s = new ANTLRHashString((String)o,lexer);
		}
		else {
			s = (ANTLRHashString)o;
		}	
		int l = length();
		if (s.length() != l) {
			return false;
		}
		if (lexer.getCaseSensitiveLiterals()) {
			for (int i = 0; i < l; i++) {
				if (charAt(i) != s.charAt(i)) {
					return false;
				}
			}
		} else {
			for (int i = 0; i < l; i++) {
				if (lexer.toLower(charAt(i)) != lexer.toLower(s.charAt(i))) {
					return false;
				}
			}
		}
		return true;
	}
	public int hashCode() {
		int hashval = 0;
		int l = length();

		if (lexer.getCaseSensitiveLiterals()) {
			for (int i = 0; i < l; i++) {
				hashval = hashval * prime + charAt(i);
			}
		} else {
			for (int i = 0; i < l; i++) {
				hashval = hashval * prime + lexer.toLower(charAt(i));
			}
		}
		return hashval;
	}
	private final int length() {
		return (s!=null) ? s.length() : len;
	}
	public void setBuffer(char[] buf, int length) {
		this.buf = buf;
		this.len = length;
		s = null;
	}
	public void setString(String s) {
		this.s = s;
		buf = null;
	}
}