/*     ____ ____  ____ ____  ______                                     *\
**    / __// __ \/ __// __ \/ ____/    SOcos COmpiles Scala             **
**  __\_ \/ /_/ / /__/ /_/ /\_ \       (c) 2002, LAMP/EPFL              **
** /_____/\____/\___/\____/____/                                        **
**                                                                      **
** $Id$
\*                                                                      */

package scalac.util;

import java.util.HashMap;

public final class Name {

/** address in the name memory
 */
    public final int index;

    private final String string;

/** hashtable for finding term names quickly
 */
    private static HashMap/*<String,TermName>*/ terms = new HashMap();

    private final Name term;
    private Name type;

/** Constructor
 */
    private Name(String string, Name dual) {
        this.string = string;
        this.index = dual != null ? dual.index + 1 : 2 * terms.size();
        this.term = dual != null ? dual : this;
        this.type = dual != null ? this : null;
        if (dual == null) terms.put(string, this);
    }

/** create a term name from the bytes in cs[offset..offset+len-1].
 *  assume that bytes are in ascii format.
 */
    public static Name fromAscii(byte cs[], int offset, int len) {
        return fromString(SourceRepresentation.ascii2string(cs, offset, len));
    }

/** create a name from the bytes in cs[offset..offset+len-1];
 *  assume that characters are in source format
 */
    public static Name fromSource(byte cs[], int offset, int len) {
        byte[]  ascii = new byte[len * 2];
        int alen = SourceRepresentation.source2ascii(cs, offset, len, ascii);
        return fromAscii(ascii, 0, alen);
    }

/** create a name from the characters in string s
 */
    public static Name fromString(String s) {
        Object value = terms.get(s);
        if (value != null) return (Name)value;
        return new Name(s, null);
    }

/** return the string representation of this name
 */
    public String toString() {
        return string;
    }

/** is this name a term name?
 */
    public boolean isTermName() {
        return this == term;
    }

/** is this name a type name?
 */
    public boolean isTypeName() {
        return this == type;
    }

/** create a term name corresponding to this name
 */
    public Name toTermName() {
        return term;
    }

/** create a type name corresponding to this name
 */
    public Name toTypeName() {
        return type != null ? type : (type = new Name(string, this));
    }

/** return the string hash value of this name
 */
    public int hashCode() {
        return index;
    }

/** returns the length of this name
 */
    public int length() {
        return string.length();
    }

/** returns i'th char of this name
 */
    public char charAt(int i) {
        return string.charAt(i);
    }

/** returns first occurrence of char c in this name, -1 if not found
 */
    public int indexOf(char c) {
        return indexOf(c, 0);
    }

/** returns first occurrence of char c in this name from `start', -1 if not found
 */
    public int indexOf(char c, int start) {
        return string.indexOf(c, start);
    }

/** returns last occurrence of char c in this name, -1 if not found.
 */
    public int lastIndexOf(char c) {
        return string.lastIndexOf(c);
    }

/** does this name start with prefix?
 */
    public boolean startsWith(Name prefix) {
        return string.startsWith(prefix.string);
    }

/** does this name end with suffix?
 */
    public boolean endsWith(Name suffix) {
        return string.endsWith(suffix.string);
    }

/** returns the subName starting at position start, excluding position end
 */
    public Name subName(int start, int end) {
        return fromString(string.substring(start, end));
    }

/** returns the concatenation of this name and n
 */
    public Name append(Name n) {
        return fromString(string + n.string);
    }

/** is this name a variable identifier?
 */
    public boolean isVariable() {
        char first = string.charAt(0);
        return ((first >= 'a' && first <= 'z') || first == '_') &&
            this != Names.null_ &&
            this != Names.true_ &&
            this != Names.false_;
    }

    public static final Name ERROR = Name.fromString("<error>");
    static { ERROR.type = ERROR; }

/** precedence of this name
 */
    public int precedence() {
        if (this == ERROR)
            return -1;
        char ch = string.charAt(0);
        if (((ch >= 'A') && (ch <= 'Z')) ||
            ((ch >= 'a') && (ch <= 'z')))
            return 1;
        switch (ch) {
            case '|':
                return 2;
            case '^':
                return 3;
            case '&':
                return 4;
            case '<':
            case '>':
                return 5;
            case '=':
            case '!':
                return 6;
            case ':':
                return 7;
            case '+':
            case '-':
                return 8;
            case '*':
            case '/':
            case '%':
                return 9;
            default:
                return 10;
        }
    }

/** is this operator left associative
 */
    public boolean isLeftAssoc() {
        int length = string.length();
        return length > 0 && string.charAt(length - 1) != ':';
    }
}