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The Enter.java Java example source code
/*
* Copyright (c) 1999, 2013, 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 javax.tools.JavaFileObject;
import javax.tools.JavaFileManager;
import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Scope.*;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.code.Type.*;
import com.sun.tools.javac.jvm.*;
import com.sun.tools.javac.main.Option.PkgInfo;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.tree.JCTree.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.List;
import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Kinds.*;
/** This class enters symbols for all encountered definitions into
* the symbol table. The pass consists of two phases, organized as
* follows:
*
* <p>In the first phase, all class symbols are entered into their
* enclosing scope, descending recursively down the tree for classes
* which are members of other classes. The class symbols are given a
* MemberEnter object as completer.
*
* <p>In the second phase classes are completed using
* MemberEnter.complete(). Completion might occur on demand, but
* any classes that are not completed that way will be eventually
* completed by processing the `uncompleted' queue. Completion
* entails (1) determination of a class's parameters, supertype and
* interfaces, as well as (2) entering all symbols defined in the
* class into its scope, with the exception of class symbols which
* have been entered in phase 1. (2) depends on (1) having been
* completed for a class and all its superclasses and enclosing
* classes. That's why, after doing (1), we put classes in a
* `halfcompleted' queue. Only when we have performed (1) for a class
* and all it's superclasses and enclosing classes, we proceed to
* (2).
*
* <p>Whereas the first phase is organized as a sweep through all
* compiled syntax trees, the second phase is demand. Members of a
* class are entered when the contents of a class are first
* accessed. This is accomplished by installing completer objects in
* class symbols for compiled classes which invoke the member-enter
* phase for the corresponding class tree.
*
* <p>Classes migrate from one phase to the next via queues:
*
* <pre>{@literal
* class enter -> (Enter.uncompleted) --> member enter (1)
* -> (MemberEnter.halfcompleted) --> member enter (2)
* -> (Todo) --> attribute
* (only for toplevel classes)
* }</pre>
*
* <p>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 Enter extends JCTree.Visitor {
protected static final Context.Key<Enter> enterKey =
new Context.Key<Enter>();
Log log;
Symtab syms;
Check chk;
TreeMaker make;
ClassReader reader;
Annotate annotate;
MemberEnter memberEnter;
Types types;
Lint lint;
Names names;
JavaFileManager fileManager;
PkgInfo pkginfoOpt;
private final Todo todo;
public static Enter instance(Context context) {
Enter instance = context.get(enterKey);
if (instance == null)
instance = new Enter(context);
return instance;
}
protected Enter(Context context) {
context.put(enterKey, this);
log = Log.instance(context);
reader = ClassReader.instance(context);
make = TreeMaker.instance(context);
syms = Symtab.instance(context);
chk = Check.instance(context);
memberEnter = MemberEnter.instance(context);
types = Types.instance(context);
annotate = Annotate.instance(context);
lint = Lint.instance(context);
names = Names.instance(context);
predefClassDef = make.ClassDef(
make.Modifiers(PUBLIC),
syms.predefClass.name,
List.<JCTypeParameter>nil(),
null,
List.<JCExpression>nil(),
List.<JCTree>nil());
predefClassDef.sym = syms.predefClass;
todo = Todo.instance(context);
fileManager = context.get(JavaFileManager.class);
Options options = Options.instance(context);
pkginfoOpt = PkgInfo.get(options);
}
/** A hashtable mapping classes and packages to the environments current
* at the points of their definitions.
*/
Map<TypeSymbol,Env typeEnvs =
new HashMap<TypeSymbol,Env();
/** Accessor for typeEnvs
*/
public Env<AttrContext> getEnv(TypeSymbol sym) {
return typeEnvs.get(sym);
}
public Env<AttrContext> getClassEnv(TypeSymbol sym) {
Env<AttrContext> localEnv = getEnv(sym);
Env<AttrContext> lintEnv = localEnv;
while (lintEnv.info.lint == null)
lintEnv = lintEnv.next;
localEnv.info.lint = lintEnv.info.lint.augment(sym);
return localEnv;
}
/** The queue of all classes that might still need to be completed;
* saved and initialized by main().
*/
ListBuffer<ClassSymbol> uncompleted;
/** A dummy class to serve as enclClass for toplevel environments.
*/
private JCClassDecl predefClassDef;
/* ************************************************************************
* environment construction
*************************************************************************/
/** Create a fresh environment for class bodies.
* This will create a fresh scope for local symbols of a class, referred
* to by the environments info.scope field.
* This scope will contain
* - symbols for this and super
* - symbols for any type parameters
* In addition, it serves as an anchor for scopes of methods and initializers
* which are nested in this scope via Scope.dup().
* This scope should not be confused with the members scope of a class.
*
* @param tree The class definition.
* @param env The environment current outside of the class definition.
*/
public Env<AttrContext> classEnv(JCClassDecl tree, Env env) {
Env<AttrContext> localEnv =
env.dup(tree, env.info.dup(new Scope(tree.sym)));
localEnv.enclClass = tree;
localEnv.outer = env;
localEnv.info.isSelfCall = false;
localEnv.info.lint = null; // leave this to be filled in by Attr,
// when annotations have been processed
return localEnv;
}
/** Create a fresh environment for toplevels.
* @param tree The toplevel tree.
*/
Env<AttrContext> topLevelEnv(JCCompilationUnit tree) {
Env<AttrContext> localEnv = new Env(tree, new AttrContext());
localEnv.toplevel = tree;
localEnv.enclClass = predefClassDef;
tree.namedImportScope = new ImportScope(tree.packge);
tree.starImportScope = new StarImportScope(tree.packge);
localEnv.info.scope = tree.namedImportScope;
localEnv.info.lint = lint;
return localEnv;
}
public Env<AttrContext> getTopLevelEnv(JCCompilationUnit tree) {
Env<AttrContext> localEnv = new Env(tree, new AttrContext());
localEnv.toplevel = tree;
localEnv.enclClass = predefClassDef;
localEnv.info.scope = tree.namedImportScope;
localEnv.info.lint = lint;
return localEnv;
}
/** The scope in which a member definition in environment env is to be entered
* This is usually the environment's scope, except for class environments,
* where the local scope is for type variables, and the this and super symbol
* only, and members go into the class member scope.
*/
Scope enterScope(Env<AttrContext> env) {
return (env.tree.hasTag(JCTree.Tag.CLASSDEF))
? ((JCClassDecl) env.tree).sym.members_field
: env.info.scope;
}
/* ************************************************************************
* Visitor methods for phase 1: class enter
*************************************************************************/
/** Visitor argument: the current environment.
*/
protected Env<AttrContext> env;
/** Visitor result: the computed type.
*/
Type result;
/** Visitor method: enter all classes in given tree, catching any
* completion failure exceptions. Return the tree's type.
*
* @param tree The tree to be visited.
* @param env The environment visitor argument.
*/
Type classEnter(JCTree tree, Env<AttrContext> env) {
Env<AttrContext> prevEnv = this.env;
try {
this.env = env;
tree.accept(this);
return result;
} catch (CompletionFailure ex) {
return chk.completionError(tree.pos(), ex);
} finally {
this.env = prevEnv;
}
}
/** Visitor method: enter classes of a list of trees, returning a list of types.
*/
<T extends JCTree> List classEnter(List trees, Env env) {
ListBuffer<Type> ts = new ListBuffer();
for (List<T> l = trees; l.nonEmpty(); l = l.tail) {
Type t = classEnter(l.head, env);
if (t != null)
ts.append(t);
}
return ts.toList();
}
@Override
public void visitTopLevel(JCCompilationUnit tree) {
JavaFileObject prev = log.useSource(tree.sourcefile);
boolean addEnv = false;
boolean isPkgInfo = tree.sourcefile.isNameCompatible("package-info",
JavaFileObject.Kind.SOURCE);
if (tree.pid != null) {
tree.packge = reader.enterPackage(TreeInfo.fullName(tree.pid));
if (tree.packageAnnotations.nonEmpty()
|| pkginfoOpt == PkgInfo.ALWAYS
|| tree.docComments != null) {
if (isPkgInfo) {
addEnv = true;
} else if (tree.packageAnnotations.nonEmpty()){
log.error(tree.packageAnnotations.head.pos(),
"pkg.annotations.sb.in.package-info.java");
}
}
} else {
tree.packge = syms.unnamedPackage;
}
tree.packge.complete(); // Find all classes in package.
Env<AttrContext> topEnv = topLevelEnv(tree);
// Save environment of package-info.java file.
if (isPkgInfo) {
Env<AttrContext> env0 = typeEnvs.get(tree.packge);
if (env0 == null) {
typeEnvs.put(tree.packge, topEnv);
} else {
JCCompilationUnit tree0 = env0.toplevel;
if (!fileManager.isSameFile(tree.sourcefile, tree0.sourcefile)) {
log.warning(tree.pid != null ? tree.pid.pos()
: null,
"pkg-info.already.seen",
tree.packge);
if (addEnv || (tree0.packageAnnotations.isEmpty() &&
tree.docComments != null &&
tree.docComments.hasComment(tree))) {
typeEnvs.put(tree.packge, topEnv);
}
}
}
for (Symbol q = tree.packge; q != null && q.kind == PCK; q = q.owner)
q.flags_field |= EXISTS;
Name name = names.package_info;
ClassSymbol c = reader.enterClass(name, tree.packge);
c.flatname = names.fromString(tree.packge + "." + name);
c.sourcefile = tree.sourcefile;
c.completer = null;
c.members_field = new Scope(c);
tree.packge.package_info = c;
}
classEnter(tree.defs, topEnv);
if (addEnv) {
todo.append(topEnv);
}
log.useSource(prev);
result = null;
}
@Override
public void visitClassDef(JCClassDecl tree) {
Symbol owner = env.info.scope.owner;
Scope enclScope = enterScope(env);
ClassSymbol c;
if (owner.kind == PCK) {
// We are seeing a toplevel class.
PackageSymbol packge = (PackageSymbol)owner;
for (Symbol q = packge; q != null && q.kind == PCK; q = q.owner)
q.flags_field |= EXISTS;
c = reader.enterClass(tree.name, packge);
packge.members().enterIfAbsent(c);
if ((tree.mods.flags & PUBLIC) != 0 && !classNameMatchesFileName(c, env)) {
log.error(tree.pos(),
"class.public.should.be.in.file", tree.name);
}
} else {
if (!tree.name.isEmpty() &&
!chk.checkUniqueClassName(tree.pos(), tree.name, enclScope)) {
result = null;
return;
}
if (owner.kind == TYP) {
// We are seeing a member class.
c = reader.enterClass(tree.name, (TypeSymbol)owner);
if ((owner.flags_field & INTERFACE) != 0) {
tree.mods.flags |= PUBLIC | STATIC;
}
} else {
// We are seeing a local class.
c = reader.defineClass(tree.name, owner);
c.flatname = chk.localClassName(c);
if (!c.name.isEmpty())
chk.checkTransparentClass(tree.pos(), c, env.info.scope);
}
}
tree.sym = c;
// Enter class into `compiled' table and enclosing scope.
if (chk.compiled.get(c.flatname) != null) {
duplicateClass(tree.pos(), c);
result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);
tree.sym = (ClassSymbol)result.tsym;
return;
}
chk.compiled.put(c.flatname, c);
enclScope.enter(c);
// Set up an environment for class block and store in `typeEnvs'
// table, to be retrieved later in memberEnter and attribution.
Env<AttrContext> localEnv = classEnv(tree, env);
typeEnvs.put(c, localEnv);
// Fill out class fields.
c.completer = memberEnter;
c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree);
c.sourcefile = env.toplevel.sourcefile;
c.members_field = new Scope(c);
ClassType ct = (ClassType)c.type;
if (owner.kind != PCK && (c.flags_field & STATIC) == 0) {
// We are seeing a local or inner class.
// Set outer_field of this class to closest enclosing class
// which contains this class in a non-static context
// (its "enclosing instance class"), provided such a class exists.
Symbol owner1 = owner;
while ((owner1.kind & (VAR | MTH)) != 0 &&
(owner1.flags_field & STATIC) == 0) {
owner1 = owner1.owner;
}
if (owner1.kind == TYP) {
ct.setEnclosingType(owner1.type);
}
}
// Enter type parameters.
ct.typarams_field = classEnter(tree.typarams, localEnv);
// Add non-local class to uncompleted, to make sure it will be
// completed later.
if (!c.isLocal() && uncompleted != null) uncompleted.append(c);
// System.err.println("entering " + c.fullname + " in " + c.owner);//DEBUG
// Recursively enter all member classes.
classEnter(tree.defs, localEnv);
result = c.type;
}
//where
/** Does class have the same name as the file it appears in?
*/
private static boolean classNameMatchesFileName(ClassSymbol c,
Env<AttrContext> env) {
return env.toplevel.sourcefile.isNameCompatible(c.name.toString(),
JavaFileObject.Kind.SOURCE);
}
/** Complain about a duplicate class. */
protected void duplicateClass(DiagnosticPosition pos, ClassSymbol c) {
log.error(pos, "duplicate.class", c.fullname);
}
/** Class enter visitor method for type parameters.
* Enter a symbol for type parameter in local scope, after checking that it
* is unique.
*/
@Override
public void visitTypeParameter(JCTypeParameter tree) {
TypeVar a = (tree.type != null)
? (TypeVar)tree.type
: new TypeVar(tree.name, env.info.scope.owner, syms.botType);
tree.type = a;
if (chk.checkUnique(tree.pos(), a.tsym, env.info.scope)) {
env.info.scope.enter(a.tsym);
}
result = a;
}
/** Default class enter visitor method: do nothing.
*/
@Override
public void visitTree(JCTree tree) {
result = null;
}
/** Main method: enter all classes in a list of toplevel trees.
* @param trees The list of trees to be processed.
*/
public void main(List<JCCompilationUnit> trees) {
complete(trees, null);
}
/** Main method: enter one class from a list of toplevel trees and
* place the rest on uncompleted for later processing.
* @param trees The list of trees to be processed.
* @param c The class symbol to be processed.
*/
public void complete(List<JCCompilationUnit> trees, ClassSymbol c) {
annotate.enterStart();
ListBuffer<ClassSymbol> prevUncompleted = uncompleted;
if (memberEnter.completionEnabled) uncompleted = new ListBuffer<ClassSymbol>();
try {
// enter all classes, and construct uncompleted list
classEnter(trees, null);
// complete all uncompleted classes in memberEnter
if (memberEnter.completionEnabled) {
while (uncompleted.nonEmpty()) {
ClassSymbol clazz = uncompleted.next();
if (c == null || c == clazz || prevUncompleted == null)
clazz.complete();
else
// defer
prevUncompleted.append(clazz);
}
// if there remain any unimported toplevels (these must have
// no classes at all), process their import statements as well.
for (JCCompilationUnit tree : trees) {
if (tree.starImportScope.elems == null) {
JavaFileObject prev = log.useSource(tree.sourcefile);
Env<AttrContext> topEnv = topLevelEnv(tree);
memberEnter.memberEnter(tree, topEnv);
log.useSource(prev);
}
}
}
} finally {
uncompleted = prevUncompleted;
annotate.enterDone();
}
}
}
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