treeinfo.java

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	    throw new AssertionError();
	}
    }

    /** Find the position for reporting an error about a symbol, where
     *  that symbol is defined somewhere in the given tree. */
    public static int positionFor(final Symbol sym, final JCTree tree) {
        JCTree decl = declarationFor(sym, tree);
        return ((decl != null) ? decl : tree).pos;
    }

    /** Find the position for reporting an error about a symbol, where
     *  that symbol is defined somewhere in the given tree. */
    public static DiagnosticPosition diagnosticPositionFor(final Symbol sym, final JCTree tree) {
        JCTree decl = declarationFor(sym, tree);
        return ((decl != null) ? decl : tree).pos();
    }

    /** Find the declaration for a symbol, where
     *  that symbol is defined somewhere in the given tree. */
    public static JCTree declarationFor(final Symbol sym, final JCTree tree) {
	class DeclScanner extends TreeScanner {
            JCTree result = null;
            public void scan(JCTree tree) {
                if (tree!=null && result==null)
                    tree.accept(this);
            }
	    public void visitTopLevel(JCCompilationUnit that) {
		if (that.packge == sym) result = that;
		else super.visitTopLevel(that);
	    }
	    public void visitClassDef(JCClassDecl that) {
		if (that.sym == sym) result = that;
		else super.visitClassDef(that);
	    }
	    public void visitMethodDef(JCMethodDecl that) {
		if (that.sym == sym) result = that;
		else super.visitMethodDef(that);
	    }
	    public void visitVarDef(JCVariableDecl that) {
		if (that.sym == sym) result = that;
		else super.visitVarDef(that);
	    }
	}
	DeclScanner s = new DeclScanner();
	tree.accept(s);
	return s.result;
    }

    public static Env<AttrContext> scopeFor(JCTree node, JCCompilationUnit unit) {
	return scopeFor(pathFor(node, unit));
    }

    public static Env<AttrContext> scopeFor(List<JCTree> path) {
	// TODO: not implemented yet
	throw new UnsupportedOperationException("not implemented yet");
    }

    public static List<JCTree> pathFor(final JCTree node, final JCCompilationUnit unit) {
	class Result extends Error {
	    static final long serialVersionUID = -5942088234594905625L;
	    List<JCTree> path;
	    Result(List<JCTree> path) {
		this.path = path;
	    }
	}
	class PathFinder extends TreeScanner {
	    List<JCTree> path = List.nil();
	    public void scan(JCTree tree) {
		if (tree != null) {
		    path = path.prepend(tree);
		    if (tree == node)
			throw new Result(path);
		    super.scan(tree);
		    path = path.tail;
		}
	    }
	}
	try {
	    new PathFinder().scan(unit);
	} catch (Result result) {
	    return result.path;
	}
        return List.nil();
    }
    
    /** Return the statement referenced by a label.
     *  If the label refers to a loop or switch, return that switch
     *  otherwise return the labelled statement itself
     */
    public static JCTree referencedStatement(JCLabeledStatement tree) {
	JCTree t = tree;
	do t = ((JCLabeledStatement) t).body;
	while (t.getTag() == JCTree.LABELLED);
	switch (t.getTag()) {
	case JCTree.DOLOOP: case JCTree.WHILELOOP: case JCTree.FORLOOP: case JCTree.FOREACHLOOP: case JCTree.SWITCH:
	    return t;
	default:
	    return tree;
	}
    }

    /** Skip parens and return the enclosed expression
     */
    public static JCExpression skipParens(JCExpression tree) {
	while (tree.getTag() == JCTree.PARENS) {
	    tree = ((JCParens) tree).expr;
	}
	return tree;
    }

    /** Skip parens and return the enclosed expression
     */
    public static JCTree skipParens(JCTree tree) {
	if (tree.getTag() == JCTree.PARENS)
	    return skipParens((JCParens)tree);
	else
	    return tree;
    }

    /** Return the types of a list of trees.
     */
    public static List<Type> types(List<? extends JCTree> trees) {
	ListBuffer<Type> ts = new ListBuffer<Type>();
	for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
	    ts.append(l.head.type);
	return ts.toList();
    }

    /** If this tree is an identifier or a field or a parameterized type,
     *  return its name, otherwise return null.
     */
    public static Name name(JCTree tree) {
	switch (tree.getTag()) {
	case JCTree.IDENT:
	    return ((JCIdent) tree).name;
	case JCTree.SELECT:
	    return ((JCFieldAccess) tree).name;
	case JCTree.TYPEAPPLY:
	    return name(((JCTypeApply) tree).clazz);
	default:
	    return null;
	}
    }

    /** If this tree is a qualified identifier, its return fully qualified name,
     *  otherwise return null.
     */
    public static Name fullName(JCTree tree) {
	tree = skipParens(tree);
	switch (tree.getTag()) {
	case JCTree.IDENT:
	    return ((JCIdent) tree).name;
	case JCTree.SELECT:
	    Name sname = fullName(((JCFieldAccess) tree).selected);
	    return sname == null ? null : sname.append('.', name(tree));
	default:
	    return null;
	}
    }

    public static Symbol symbolFor(JCTree node) {
	node = skipParens(node);
	switch (node.getTag()) {
	case JCTree.CLASSDEF:
	    return ((JCClassDecl) node).sym;
	case JCTree.METHODDEF:
	    return ((JCMethodDecl) node).sym;
	case JCTree.VARDEF:
	    return ((JCVariableDecl) node).sym;
	default:
	    return null;
	}
    }

    /** If this tree is an identifier or a field, return its symbol,
     *  otherwise return null.
     */
    public static Symbol symbol(JCTree tree) {
	tree = skipParens(tree);
	switch (tree.getTag()) {
	case JCTree.IDENT:
	    return ((JCIdent) tree).sym;
	case JCTree.SELECT:
	    return ((JCFieldAccess) tree).sym;
	case JCTree.TYPEAPPLY:
	    return symbol(((JCTypeApply) tree).clazz);
	default:
	    return null;
	}
    }

    /** Return true if this is a nonstatic selection. */
    public static boolean nonstaticSelect(JCTree tree) {
	tree = skipParens(tree);
	if (tree.getTag() != JCTree.SELECT) return false;
	JCFieldAccess s = (JCFieldAccess) tree;
	Symbol e = symbol(s.selected);
	return e == null || (e.kind != Kinds.PCK && e.kind != Kinds.TYP);
    }

    /** If this tree is an identifier or a field, set its symbol, otherwise skip.
     */
    public static void setSymbol(JCTree tree, Symbol sym) {
	tree = skipParens(tree);
	switch (tree.getTag()) {
	case JCTree.IDENT:
	    ((JCIdent) tree).sym = sym; break;
	case JCTree.SELECT:
	    ((JCFieldAccess) tree).sym = sym; break;
	default:
	}
    }

    /** If this tree is a declaration or a block, return its flags field,
     *  otherwise return 0.
     */
    public static long flags(JCTree tree) {
	switch (tree.getTag()) {
	case JCTree.VARDEF:
	    return ((JCVariableDecl) tree).mods.flags;
	case JCTree.METHODDEF:
	    return ((JCMethodDecl) tree).mods.flags;
	case JCTree.CLASSDEF:
	    return ((JCClassDecl) tree).mods.flags;
	case JCTree.BLOCK:
	    return ((JCBlock) tree).flags;
	default:
	    return 0;
	}
    }

    /** Return first (smallest) flag in `flags':
     *  pre: flags != 0
     */
    public static long firstFlag(long flags) {
	int flag = 1;
        while ((flag & StandardFlags) != 0 && (flag & flags) == 0)
	    flag = flag << 1;
        return flag;
    }

    /** Return flags as a string, separated by " ".
     */
    public static String flagNames(long flags) {
        return Flags.toString(flags & StandardFlags).trim();
    }

    /** Operator precedences values.
     */
    public static final int
        notExpression = -1,   // not an expression
        noPrec = 0,           // no enclosing expression
        assignPrec = 1,
	assignopPrec = 2,
	condPrec = 3,
	orPrec = 4,
	andPrec = 5,
	bitorPrec = 6,
	bitxorPrec = 7,
	bitandPrec = 8,
	eqPrec = 9,
	ordPrec = 10,
	shiftPrec = 11,
	addPrec = 12,
	mulPrec = 13,
	prefixPrec = 14,
	postfixPrec = 15,
	precCount = 16;


    /** Map operators to their precedence levels.
     */
    public static int opPrec(int op) {
	switch(op) {
	case JCTree.POS:
	case JCTree.NEG:
	case JCTree.NOT:
	case JCTree.COMPL:
	case JCTree.PREINC:
	case JCTree.PREDEC: return prefixPrec;
	case JCTree.POSTINC:
	case JCTree.POSTDEC:
	case JCTree.NULLCHK: return postfixPrec;
	case JCTree.ASSIGN: return assignPrec;
	case JCTree.BITOR_ASG:
	case JCTree.BITXOR_ASG:
	case JCTree.BITAND_ASG:
	case JCTree.SL_ASG:
	case JCTree.SR_ASG:
	case JCTree.USR_ASG:
	case JCTree.PLUS_ASG:
	case JCTree.MINUS_ASG:
	case JCTree.MUL_ASG:
	case JCTree.DIV_ASG:
	case JCTree.MOD_ASG: return assignopPrec;
        case JCTree.OR: return orPrec;
        case JCTree.AND: return andPrec;
        case JCTree.EQ:
        case JCTree.NE: return eqPrec;
        case JCTree.LT:
        case JCTree.GT:
        case JCTree.LE:
        case JCTree.GE: return ordPrec;
        case JCTree.BITOR: return bitorPrec;
        case JCTree.BITXOR: return bitxorPrec;
        case JCTree.BITAND: return bitandPrec;
        case JCTree.SL:
        case JCTree.SR:
        case JCTree.USR: return shiftPrec;
        case JCTree.PLUS:
        case JCTree.MINUS: return addPrec;
        case JCTree.MUL:
        case JCTree.DIV:
        case JCTree.MOD: return mulPrec;
	case JCTree.TYPETEST: return ordPrec;
	default: throw new AssertionError();
	}
    }

    static Tree.Kind tagToKind(int tag) {
        switch (tag) {
        // Postfix expressions
        case JCTree.POSTINC:           // _ ++
            return Tree.Kind.POSTFIX_INCREMENT;
        case JCTree.POSTDEC:           // _ --
            return Tree.Kind.POSTFIX_DECREMENT;

        // Unary operators
        case JCTree.PREINC:            // ++ _
            return Tree.Kind.PREFIX_INCREMENT;
        case JCTree.PREDEC:            // -- _
            return Tree.Kind.PREFIX_DECREMENT;
        case JCTree.POS:               // +
            return Tree.Kind.UNARY_PLUS;
        case JCTree.NEG:               // -
            return Tree.Kind.UNARY_MINUS;
        case JCTree.COMPL:             // ~
            return Tree.Kind.BITWISE_COMPLEMENT;
        case JCTree.NOT:               // !
            return Tree.Kind.LOGICAL_COMPLEMENT;

        // Binary operators

        // Multiplicative operators
        case JCTree.MUL:               // *
            return Tree.Kind.MULTIPLY;
        case JCTree.DIV:               // /
            return Tree.Kind.DIVIDE;
        case JCTree.MOD:               // %
            return Tree.Kind.REMAINDER;

        // Additive operators
        case JCTree.PLUS:              // +
            return Tree.Kind.PLUS;
        case JCTree.MINUS:             // -
            return Tree.Kind.MINUS;

        // Shift operators
        case JCTree.SL:                // <<
            return Tree.Kind.LEFT_SHIFT;
        case JCTree.SR:                // >>
            return Tree.Kind.RIGHT_SHIFT;
        case JCTree.USR:               // >>>
            return Tree.Kind.UNSIGNED_RIGHT_SHIFT;

        // Relational operators
        case JCTree.LT:                // <
            return Tree.Kind.LESS_THAN;
        case JCTree.GT:                // >
            return Tree.Kind.GREATER_THAN;
        case JCTree.LE:                // <=
            return Tree.Kind.LESS_THAN_EQUAL;
        case JCTree.GE:                // >=
            return Tree.Kind.GREATER_THAN_EQUAL;

        // Equality operators
        case JCTree.EQ:                // ==
            return Tree.Kind.EQUAL_TO;
        case JCTree.NE:                // !=
            return Tree.Kind.NOT_EQUAL_TO;

        // Bitwise and logical operators
        case JCTree.BITAND:            // &
            return Tree.Kind.AND;
        case JCTree.BITXOR:            // ^
            return Tree.Kind.XOR;
        case JCTree.BITOR:             // |
            return Tree.Kind.OR;

        // Conditional operators
        case JCTree.AND:               // &&
            return Tree.Kind.CONDITIONAL_AND;
        case JCTree.OR:                // ||
            return Tree.Kind.CONDITIONAL_OR;

        // Assignment operators
        case JCTree.MUL_ASG:           // *=
            return Tree.Kind.MULTIPLY_ASSIGNMENT;
        case JCTree.DIV_ASG:           // /=
            return Tree.Kind.DIVIDE_ASSIGNMENT;
        case JCTree.MOD_ASG:           // %=
            return Tree.Kind.REMAINDER_ASSIGNMENT;
        case JCTree.PLUS_ASG:          // +=
            return Tree.Kind.PLUS_ASSIGNMENT;
        case JCTree.MINUS_ASG:         // -=
            return Tree.Kind.MINUS_ASSIGNMENT;
        case JCTree.SL_ASG:            // <<=
            return Tree.Kind.LEFT_SHIFT_ASSIGNMENT;
        case JCTree.SR_ASG:            // >>=
            return Tree.Kind.RIGHT_SHIFT_ASSIGNMENT;
        case JCTree.USR_ASG:           // >>>=
            return Tree.Kind.UNSIGNED_RIGHT_SHIFT_ASSIGNMENT;
        case JCTree.BITAND_ASG:        // &=
            return Tree.Kind.AND_ASSIGNMENT;
        case JCTree.BITXOR_ASG:        // ^=
            return Tree.Kind.XOR_ASSIGNMENT;
        case JCTree.BITOR_ASG:         // |=
            return Tree.Kind.OR_ASSIGNMENT;

        // Null check (implementation detail), for example, __.getClass()
        case JCTree.NULLCHK:
            return Tree.Kind.OTHER;

        default:
            return null;
        }
    }
}