Javac内核源码

/* * Copyright (c) 1999, 2010, Oracle and/or its affiliates. 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. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.sun.tools.javac.comp; import java.util.*; import com.sun.tools.javac.code.*; import com.sun.tools.javac.jvm.*; import com.sun.tools.javac.tree.*; import com.sun.tools.javac.util.*; import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition; import com.sun.tools.javac.util.List; import com.sun.tools.javac.code.Symbol.*; import com.sun.tools.javac.tree.JCTree.*; import com.sun.tools.javac.code.Type.*; import com.sun.tools.javac.jvm.Target; import static com.sun.tools.javac.code.Flags.*; import static com.sun.tools.javac.code.Kinds.*; import static com.sun.tools.javac.code.TypeTags.*; import static com.sun.tools.javac.jvm.ByteCodes.*; /** This pass translates away some syntactic sugar: inner classes, * class literals, assertions, foreach loops, etc. * * <p><b>This is NOT part of any supported API. * 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 Lower extends TreeTranslator { protected static final Context.Key<Lower> lowerKey = new Context.Key<Lower>(); public static Lower instance(Context context) { Lower instance = context.get(lowerKey); if (instance == null) instance = new Lower(context); return instance; } private Name.Table names; private Log log; private Symtab syms; private Resolve rs; private Check chk; private Attr attr; private TreeMaker make; private DiagnosticPosition make_pos; private ClassWriter writer; private ClassReader reader; private ConstFold cfolder; private Target target; private Source source; private boolean allowEnums; private final Name dollarAssertionsDisabled; private final Name classDollar; private Types types; private boolean debugLower; protected Lower(Context context) { context.put(lowerKey, this); names = Name.Table.instance(context); log = Log.instance(context); syms = Symtab.instance(context); rs = Resolve.instance(context); chk = Check.instance(context); attr = Attr.instance(context); make = TreeMaker.instance(context); writer = ClassWriter.instance(context); reader = ClassReader.instance(context); cfolder = ConstFold.instance(context); target = Target.instance(context); source = Source.instance(context); allowEnums = source.allowEnums(); dollarAssertionsDisabled = names. fromString(target.syntheticNameChar() + "assertionsDisabled"); classDollar = names. fromString("class" + target.syntheticNameChar()); types = Types.instance(context); Options options = Options.instance(context); debugLower = options.get("debuglower") != null; } /** The currently enclosing class. */ ClassSymbol currentClass; /** A queue of all translated classes. */ ListBuffer<JCTree> translated; /** Environment for symbol lookup, set by translateTopLevelClass. */ Env<AttrContext> attrEnv; /** A hash table mapping syntax trees to their ending source positions. */ Map<JCTree, Integer> endPositions; /************************************************************************** * Global mappings *************************************************************************/ /** A hash table mapping local classes to their definitions. */ Map<ClassSymbol, JCClassDecl> classdefs; /** A hash table mapping virtual accessed symbols in outer subclasses * to the actually referred symbol in superclasses. */ Map<Symbol,Symbol> actualSymbols; /** The current method definition. */ JCMethodDecl currentMethodDef; /** The current method symbol. */ MethodSymbol currentMethodSym; /** The currently enclosing outermost class definition. */ JCClassDecl outermostClassDef; /** The currently enclosing outermost member definition. */ JCTree outermostMemberDef; /** A navigator class for assembling a mapping from local class symbols * to class definition trees. * There is only one case; all other cases simply traverse down the tree. */ class ClassMap extends TreeScanner { /** All encountered class defs are entered into classdefs table. */ public void visitClassDef(JCClassDecl tree) { classdefs.put(tree.sym, tree); super.visitClassDef(tree); } } ClassMap classMap = new ClassMap(); /** Map a class symbol to its definition. * @param c The class symbol of which we want to determine the definition. */ JCClassDecl classDef(ClassSymbol c) { // First lookup the class in the classdefs table. JCClassDecl def = classdefs.get(c); if (def == null && outermostMemberDef != null) { // If this fails, traverse outermost member definition, entering all // local classes into classdefs, and try again. classMap.scan(outermostMemberDef); def = classdefs.get(c); } if (def == null) { // If this fails, traverse outermost class definition, entering all // local classes into classdefs, and try again. classMap.scan(outermostClassDef); def = classdefs.get(c); } return def; } /** A hash table mapping class symbols to lists of free variables. * accessed by them. Only free variables of the method immediately containing * a class are associated with that class. */ Map<ClassSymbol,List<VarSymbol>> freevarCache; /** A navigator class for collecting the free variables accessed * from a local class. * There is only one case; all other cases simply traverse down the tree. */ class FreeVarCollector extends TreeScanner { /** The owner of the local class. */ Symbol owner; /** The local class. */ ClassSymbol clazz; /** The list of owner's variables accessed from within the local class, * without any duplicates. */ List<VarSymbol> fvs; FreeVarCollector(ClassSymbol clazz) { this.clazz = clazz; this.owner = clazz.owner; this.fvs = List.nil(); } /** Add free variable to fvs list unless it is already there. */ private void addFreeVar(VarSymbol v) { for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail) if (l.head == v) return; fvs = fvs.prepend(v); } /** Add all free variables of class