langtools/src/share/classes/com/sun/tools/javac/tree/TreeInfo.java
changeset 10 06bc494ca11e
child 1206 3a05355982a9
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/src/share/classes/com/sun/tools/javac/tree/TreeInfo.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,863 @@
+/*
+ * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package com.sun.tools.javac.tree;
+
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.comp.AttrContext;
+import com.sun.tools.javac.comp.Env;
+import java.util.Map;
+import com.sun.tools.javac.util.*;
+import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
+import com.sun.tools.javac.code.*;
+import com.sun.tools.javac.tree.JCTree.*;
+
+import static com.sun.tools.javac.code.Flags.*;
+import com.sun.tools.javac.util.JCDiagnostic.SimpleDiagnosticPosition;
+
+/** Utility class containing inspector methods for trees.
+ *
+ *  <p><b>This is NOT part of any API supported by Sun Microsystems.  If
+ *  you write code that depends on this, you do so at your own risk.
+ *  This code and its internal interfaces are subject to change or
+ *  deletion without notice.</b>
+ */
+public class TreeInfo {
+    protected static final Context.Key<TreeInfo> treeInfoKey =
+        new Context.Key<TreeInfo>();
+
+    public static TreeInfo instance(Context context) {
+        TreeInfo instance = context.get(treeInfoKey);
+        if (instance == null)
+            instance = new TreeInfo(context);
+        return instance;
+    }
+
+    /** The names of all operators.
+     */
+    private Name[] opname = new Name[JCTree.MOD - JCTree.POS + 1];
+
+    private TreeInfo(Context context) {
+        context.put(treeInfoKey, this);
+
+        Name.Table names = Name.Table.instance(context);
+        opname[JCTree.POS     - JCTree.POS] = names.fromString("+");
+        opname[JCTree.NEG     - JCTree.POS] = names.hyphen;
+        opname[JCTree.NOT     - JCTree.POS] = names.fromString("!");
+        opname[JCTree.COMPL   - JCTree.POS] = names.fromString("~");
+        opname[JCTree.PREINC  - JCTree.POS] = names.fromString("++");
+        opname[JCTree.PREDEC  - JCTree.POS] = names.fromString("--");
+        opname[JCTree.POSTINC - JCTree.POS] = names.fromString("++");
+        opname[JCTree.POSTDEC - JCTree.POS] = names.fromString("--");
+        opname[JCTree.NULLCHK - JCTree.POS] = names.fromString("<*nullchk*>");
+        opname[JCTree.OR      - JCTree.POS] = names.fromString("||");
+        opname[JCTree.AND     - JCTree.POS] = names.fromString("&&");
+        opname[JCTree.EQ      - JCTree.POS] = names.fromString("==");
+        opname[JCTree.NE      - JCTree.POS] = names.fromString("!=");
+        opname[JCTree.LT      - JCTree.POS] = names.fromString("<");
+        opname[JCTree.GT      - JCTree.POS] = names.fromString(">");
+        opname[JCTree.LE      - JCTree.POS] = names.fromString("<=");
+        opname[JCTree.GE      - JCTree.POS] = names.fromString(">=");
+        opname[JCTree.BITOR   - JCTree.POS] = names.fromString("|");
+        opname[JCTree.BITXOR  - JCTree.POS] = names.fromString("^");
+        opname[JCTree.BITAND  - JCTree.POS] = names.fromString("&");
+        opname[JCTree.SL      - JCTree.POS] = names.fromString("<<");
+        opname[JCTree.SR      - JCTree.POS] = names.fromString(">>");
+        opname[JCTree.USR     - JCTree.POS] = names.fromString(">>>");
+        opname[JCTree.PLUS    - JCTree.POS] = names.fromString("+");
+        opname[JCTree.MINUS   - JCTree.POS] = names.hyphen;
+        opname[JCTree.MUL     - JCTree.POS] = names.asterisk;
+        opname[JCTree.DIV     - JCTree.POS] = names.slash;
+        opname[JCTree.MOD     - JCTree.POS] = names.fromString("%");
+    }
+
+
+    /** Return name of operator with given tree tag.
+     */
+    public Name operatorName(int tag) {
+        return opname[tag - JCTree.POS];
+    }
+
+    /** Is tree a constructor declaration?
+     */
+    public static boolean isConstructor(JCTree tree) {
+        if (tree.getTag() == JCTree.METHODDEF) {
+            Name name = ((JCMethodDecl) tree).name;
+            return name == name.table.init;
+        } else {
+            return false;
+        }
+    }
+
+    /** Is there a constructor declaration in the given list of trees?
+     */
+    public static boolean hasConstructors(List<JCTree> trees) {
+        for (List<JCTree> l = trees; l.nonEmpty(); l = l.tail)
+            if (isConstructor(l.head)) return true;
+        return false;
+    }
+
+    /** Is statement an initializer for a synthetic field?
+     */
+    public static boolean isSyntheticInit(JCTree stat) {
+        if (stat.getTag() == JCTree.EXEC) {
+            JCExpressionStatement exec = (JCExpressionStatement)stat;
+            if (exec.expr.getTag() == JCTree.ASSIGN) {
+                JCAssign assign = (JCAssign)exec.expr;
+                if (assign.lhs.getTag() == JCTree.SELECT) {
+                    JCFieldAccess select = (JCFieldAccess)assign.lhs;
+                    if (select.sym != null &&
+                        (select.sym.flags() & SYNTHETIC) != 0) {
+                        Name selected = name(select.selected);
+                        if (selected != null && selected == selected.table._this)
+                            return true;
+                    }
+                }
+            }
+        }
+        return false;
+    }
+
+    /** If the expression is a method call, return the method name, null
+     *  otherwise. */
+    public static Name calledMethodName(JCTree tree) {
+        if (tree.getTag() == JCTree.EXEC) {
+            JCExpressionStatement exec = (JCExpressionStatement)tree;
+            if (exec.expr.getTag() == JCTree.APPLY) {
+                Name mname = TreeInfo.name(((JCMethodInvocation) exec.expr).meth);
+                return mname;
+            }
+        }
+        return null;
+    }
+
+    /** Is this a call to this or super?
+     */
+    public static boolean isSelfCall(JCTree tree) {
+        Name name = calledMethodName(tree);
+        if (name != null) {
+            Name.Table names = name.table;
+            return name==names._this || name==names._super;
+        } else {
+            return false;
+        }
+    }
+
+    /** Is this a call to super?
+     */
+    public static boolean isSuperCall(JCTree tree) {
+        Name name = calledMethodName(tree);
+        if (name != null) {
+            Name.Table names = name.table;
+            return name==names._super;
+        } else {
+            return false;
+        }
+    }
+
+    /** Is this a constructor whose first (non-synthetic) statement is not
+     *  of the form this(...)?
+     */
+    public static boolean isInitialConstructor(JCTree tree) {
+        JCMethodInvocation app = firstConstructorCall(tree);
+        if (app == null) return false;
+        Name meth = name(app.meth);
+        return meth == null || meth != meth.table._this;
+    }
+
+    /** Return the first call in a constructor definition. */
+    public static JCMethodInvocation firstConstructorCall(JCTree tree) {
+        if (tree.getTag() != JCTree.METHODDEF) return null;
+        JCMethodDecl md = (JCMethodDecl) tree;
+        Name.Table names = md.name.table;
+        if (md.name != names.init) return null;
+        if (md.body == null) return null;
+        List<JCStatement> stats = md.body.stats;
+        // Synthetic initializations can appear before the super call.
+        while (stats.nonEmpty() && isSyntheticInit(stats.head))
+            stats = stats.tail;
+        if (stats.isEmpty()) return null;
+        if (stats.head.getTag() != JCTree.EXEC) return null;
+        JCExpressionStatement exec = (JCExpressionStatement) stats.head;
+        if (exec.expr.getTag() != JCTree.APPLY) return null;
+        return (JCMethodInvocation)exec.expr;
+    }
+
+    /** Return true if a tree represents the null literal. */
+    public static boolean isNull(JCTree tree) {
+        if (tree.getTag() != JCTree.LITERAL)
+            return false;
+        JCLiteral lit = (JCLiteral) tree;
+        return (lit.typetag == TypeTags.BOT);
+    }
+
+    /** The position of the first statement in a block, or the position of
+     *  the block itself if it is empty.
+     */
+    public static int firstStatPos(JCTree tree) {
+        if (tree.getTag() == JCTree.BLOCK && ((JCBlock) tree).stats.nonEmpty())
+            return ((JCBlock) tree).stats.head.pos;
+        else
+            return tree.pos;
+    }
+
+    /** The end position of given tree, if it is a block with
+     *  defined endpos.
+     */
+    public static int endPos(JCTree tree) {
+        if (tree.getTag() == JCTree.BLOCK && ((JCBlock) tree).endpos != Position.NOPOS)
+            return ((JCBlock) tree).endpos;
+        else if (tree.getTag() == JCTree.SYNCHRONIZED)
+            return endPos(((JCSynchronized) tree).body);
+        else if (tree.getTag() == JCTree.TRY) {
+            JCTry t = (JCTry) tree;
+            return endPos((t.finalizer != null)
+                          ? t.finalizer
+                          : t.catchers.last().body);
+        } else
+            return tree.pos;
+    }
+
+
+    /** Get the start position for a tree node.  The start position is
+     * defined to be the position of the first character of the first
+     * token of the node's source text.
+     * @param tree  The tree node
+     */
+    public static int getStartPos(JCTree tree) {
+        if (tree == null)
+            return Position.NOPOS;
+
+        switch(tree.getTag()) {
+        case(JCTree.APPLY):
+            return getStartPos(((JCMethodInvocation) tree).meth);
+        case(JCTree.ASSIGN):
+            return getStartPos(((JCAssign) tree).lhs);
+        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 getStartPos(((JCAssignOp) tree).lhs);
+        case(JCTree.OR): case(JCTree.AND): case(JCTree.BITOR):
+        case(JCTree.BITXOR): case(JCTree.BITAND): case(JCTree.EQ):
+        case(JCTree.NE): case(JCTree.LT): case(JCTree.GT):
+        case(JCTree.LE): case(JCTree.GE): case(JCTree.SL):
+        case(JCTree.SR): case(JCTree.USR): case(JCTree.PLUS):
+        case(JCTree.MINUS): case(JCTree.MUL): case(JCTree.DIV):
+        case(JCTree.MOD):
+            return getStartPos(((JCBinary) tree).lhs);
+        case(JCTree.CLASSDEF): {
+            JCClassDecl node = (JCClassDecl)tree;
+            if (node.mods.pos != Position.NOPOS)
+                return node.mods.pos;
+            break;
+        }
+        case(JCTree.CONDEXPR):
+            return getStartPos(((JCConditional) tree).cond);
+        case(JCTree.EXEC):
+            return getStartPos(((JCExpressionStatement) tree).expr);
+        case(JCTree.INDEXED):
+            return getStartPos(((JCArrayAccess) tree).indexed);
+        case(JCTree.METHODDEF): {
+            JCMethodDecl node = (JCMethodDecl)tree;
+            if (node.mods.pos != Position.NOPOS)
+                return node.mods.pos;
+            if (node.typarams.nonEmpty()) // List.nil() used for no typarams
+                return getStartPos(node.typarams.head);
+            return node.restype == null ? node.pos : getStartPos(node.restype);
+        }
+        case(JCTree.SELECT):
+            return getStartPos(((JCFieldAccess) tree).selected);
+        case(JCTree.TYPEAPPLY):
+            return getStartPos(((JCTypeApply) tree).clazz);
+        case(JCTree.TYPEARRAY):
+            return getStartPos(((JCArrayTypeTree) tree).elemtype);
+        case(JCTree.TYPETEST):
+            return getStartPos(((JCInstanceOf) tree).expr);
+        case(JCTree.POSTINC):
+        case(JCTree.POSTDEC):
+            return getStartPos(((JCUnary) tree).arg);
+        case(JCTree.VARDEF): {
+            JCVariableDecl node = (JCVariableDecl)tree;
+            if (node.mods.pos != Position.NOPOS) {
+                return node.mods.pos;
+            } else {
+                return getStartPos(node.vartype);
+            }
+        }
+        case(JCTree.ERRONEOUS): {
+            JCErroneous node = (JCErroneous)tree;
+            if (node.errs != null && node.errs.nonEmpty())
+                return getStartPos(node.errs.head);
+        }
+        }
+        return tree.pos;
+    }
+
+    /** The end position of given tree, given  a table of end positions generated by the parser
+     */
+    public static int getEndPos(JCTree tree, Map<JCTree, Integer> endPositions) {
+        if (tree == null)
+            return Position.NOPOS;
+
+        if (endPositions == null) {
+            // fall back on limited info in the tree
+            return endPos(tree);
+        }
+
+        Integer mapPos = endPositions.get(tree);
+        if (mapPos != null)
+            return mapPos;
+
+        switch(tree.getTag()) {
+        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 getEndPos(((JCAssignOp) tree).rhs, endPositions);
+        case(JCTree.OR): case(JCTree.AND): case(JCTree.BITOR):
+        case(JCTree.BITXOR): case(JCTree.BITAND): case(JCTree.EQ):
+        case(JCTree.NE): case(JCTree.LT): case(JCTree.GT):
+        case(JCTree.LE): case(JCTree.GE): case(JCTree.SL):
+        case(JCTree.SR): case(JCTree.USR): case(JCTree.PLUS):
+        case(JCTree.MINUS): case(JCTree.MUL): case(JCTree.DIV):
+        case(JCTree.MOD):
+            return getEndPos(((JCBinary) tree).rhs, endPositions);
+        case(JCTree.CASE):
+            return getEndPos(((JCCase) tree).stats.last(), endPositions);
+        case(JCTree.CATCH):
+            return getEndPos(((JCCatch) tree).body, endPositions);
+        case(JCTree.CONDEXPR):
+            return getEndPos(((JCConditional) tree).falsepart, endPositions);
+        case(JCTree.FORLOOP):
+            return getEndPos(((JCForLoop) tree).body, endPositions);
+        case(JCTree.FOREACHLOOP):
+            return getEndPos(((JCEnhancedForLoop) tree).body, endPositions);
+        case(JCTree.IF): {
+            JCIf node = (JCIf)tree;
+            if (node.elsepart == null) {
+                return getEndPos(node.thenpart, endPositions);
+            } else {
+                return getEndPos(node.elsepart, endPositions);
+            }
+        }
+        case(JCTree.LABELLED):
+            return getEndPos(((JCLabeledStatement) tree).body, endPositions);
+        case(JCTree.MODIFIERS):
+            return getEndPos(((JCModifiers) tree).annotations.last(), endPositions);
+        case(JCTree.SYNCHRONIZED):
+            return getEndPos(((JCSynchronized) tree).body, endPositions);
+        case(JCTree.TOPLEVEL):
+            return getEndPos(((JCCompilationUnit) tree).defs.last(), endPositions);
+        case(JCTree.TRY): {
+            JCTry node = (JCTry)tree;
+            if (node.finalizer != null) {
+                return getEndPos(node.finalizer, endPositions);
+            } else if (!node.catchers.isEmpty()) {
+                return getEndPos(node.catchers.last(), endPositions);
+            } else {
+                return getEndPos(node.body, endPositions);
+            }
+        }
+        case(JCTree.WILDCARD):
+            return getEndPos(((JCWildcard) tree).inner, endPositions);
+        case(JCTree.TYPECAST):
+            return getEndPos(((JCTypeCast) tree).expr, endPositions);
+        case(JCTree.TYPETEST):
+            return getEndPos(((JCInstanceOf) tree).clazz, endPositions);
+        case(JCTree.POS):
+        case(JCTree.NEG):
+        case(JCTree.NOT):
+        case(JCTree.COMPL):
+        case(JCTree.PREINC):
+        case(JCTree.PREDEC):
+            return getEndPos(((JCUnary) tree).arg, endPositions);
+        case(JCTree.WHILELOOP):
+            return getEndPos(((JCWhileLoop) tree).body, endPositions);
+        case(JCTree.ERRONEOUS): {
+            JCErroneous node = (JCErroneous)tree;
+            if (node.errs != null && node.errs.nonEmpty())
+                return getEndPos(node.errs.last(), endPositions);
+        }
+        }
+        return Position.NOPOS;
+    }
+
+
+    /** A DiagnosticPosition with the preferred position set to the
+     *  end position of given tree, if it is a block with
+     *  defined endpos.
+     */
+    public static DiagnosticPosition diagEndPos(final JCTree tree) {
+        final int endPos = TreeInfo.endPos(tree);
+        return new DiagnosticPosition() {
+            public JCTree getTree() { return tree; }
+            public int getStartPosition() { return TreeInfo.getStartPos(tree); }
+            public int getPreferredPosition() { return endPos; }
+            public int getEndPosition(Map<JCTree, Integer> endPosTable) {
+                return TreeInfo.getEndPos(tree, endPosTable);
+            }
+        };
+    }
+
+    /** The position of the finalizer of given try/synchronized statement.
+     */
+    public static int finalizerPos(JCTree tree) {
+        if (tree.getTag() == JCTree.TRY) {
+            JCTry t = (JCTry) tree;
+            assert t.finalizer != null;
+            return firstStatPos(t.finalizer);
+        } else if (tree.getTag() == JCTree.SYNCHRONIZED) {
+            return endPos(((JCSynchronized) tree).body);
+        } else {
+            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;
+        }
+    }
+}