com.sun.tools.javac.code
Class Scope

java.lang.Object
  com.sun.tools.javac.code.Scope

Direct Known Subclasses:

Scope.DelegatedScope, Scope.ErrorScope, Scope.ImportScope

public class Scope
extends java.lang.Object

A scope represents an area of visibility in a Java program. The Scope class is a container for symbols which provides efficient access to symbols given their names. Scopes are implemented as hash tables. Scopes can be nested; the next field of a scope points to its next outer scope. Nested scopes can share their hash tables.

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.

Nested Class Summary

static class	Scope.DelegatedScope An empty scope, into which you can't place anything.
static class	Scope.Entry A class for scope entries.
static class	Scope.ErrorScope An error scope, for which the owner should be an error symbol.
static class	Scope.ImportScope

Field Summary

Scope.Entry	elems A linear list that also contains all entries in reverse order of appearance (i.e later entries are pushed on top).
static Scope	emptyScope A value for the empty scope.
(package private) int	hashMask Mask for hash codes, always equal to (table.length - 1).
private static int	INITIAL_SIZE The hash table's initial size.
Symbol.Level	level
int	nelems The number of elements in this scope.
Scope	next Next enclosing scope (with whom this scope may share a hashtable)
Symbol	owner The scope's owner.
private static Scope.Entry	sentinel Every hash bucket is a list of Entry's which ends in sentinel.
private int	shared The number of scopes that share this scope's hash table.
Scope.Entry[]	table A hash table for the scope's entries.

Constructor Summary

Scope(Scope next, Symbol owner, Scope.Entry[] table, Symbol.Level l)
Construct a new scope, within scope next, with given owner, using given table.

Scope(Symbol owner)
Construct a new scope, within scope next, with given owner, using a fresh table of length INITIAL_SIZE.

Scope(Symbol owner, int l)
Construct a new scope, within scope next, with given owner, using a fresh table of length INITIAL_SIZE.

Scope(Symbol owner, Symbol.Level l)
Construct a new scope, within scope next, with given owner, using a fresh table of length INITIAL_SIZE.

Method Summary

private void	copy(Scope.Entry e) Copy the given entry and all entries shadowed by it to table
private void	dble() Double size of hash table.
Scope	dup() Construct a fresh scope within this scope, with same owner, which shares its table with the outer scope.
Scope	dup(Symbol newOwner) Construct a fresh scope within this scope, with new owner, which shares its table with the outer scope.
Scope	dupUnshared() Construct a fresh scope within this scope, with same owner, with a new hash table, whose contents initially are those of the table of its outer scope.
void	enter(Symbol sym) Enter symbol sym in this scope.
void	enter(Symbol sym, Scope s)
void	enter(Symbol sym, Scope s, Scope origin) Enter symbol sym in this scope, but mark that it comes from given scope `s' accessed through `origin'.
void	enterIfAbsent(Symbol sym) Enter symbol sym in this scope if not already there.
java.lang.Iterable<Symbol>	getElements()
int	getLevel()
boolean	includes(Symbol c) Given a class, is there already a class with same fully qualified name in this (import) scope?
Scope	leave() Remove all entries of this scope from its table, if shared with next.
Scope.Entry	lookup(Name name) Return the entry associated with given name, starting in this scope and proceeding outwards.
(package private) Scope.Entry	makeEntry(Symbol sym, Scope.Entry shadowed, Scope.Entry sibling, Scope scope, Scope origin)
void	remove(Symbol sym) Remove symbol from this scope.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

shared

private int shared

The number of scopes that share this scope's hash table.

next

public Scope next

Next enclosing scope (with whom this scope may share a hashtable)

owner

public Symbol owner

The scope's owner.

table

public Scope.Entry[] table

A hash table for the scope's entries.

hashMask

int hashMask

Mask for hash codes, always equal to (table.length - 1).

elems

public Scope.Entry elems

A linear list that also contains all entries in reverse order of appearance (i.e later entries are pushed on top).

nelems

public int nelems

The number of elements in this scope.

level

public Symbol.Level level

sentinel

private static final Scope.Entry sentinel

Every hash bucket is a list of Entry's which ends in sentinel.

INITIAL_SIZE

private static final int INITIAL_SIZE

The hash table's initial size.

See Also:

Constant Field Values

emptyScope

public static final Scope emptyScope

A value for the empty scope.

Constructor Detail

Scope

Scope(Scope next,
      Symbol owner,
      Scope.Entry[] table,
      Symbol.Level l)

Construct a new scope, within scope next, with given owner, using given table. The table's length must be an exponent of 2.

Scope

public Scope(Symbol owner,
             Symbol.Level l)

Construct a new scope, within scope next, with given owner, using a fresh table of length INITIAL_SIZE.

Scope

public Scope(Symbol owner,
             int l)

Construct a new scope, within scope next, with given owner, using a fresh table of length INITIAL_SIZE.

Scope

public Scope(Symbol owner)

Construct a new scope, within scope next, with given owner, using a fresh table of length INITIAL_SIZE.

Method Detail

getLevel

public int getLevel()

dup

public Scope dup()

Construct a fresh scope within this scope, with same owner, which shares its table with the outer scope. Used in connection with method leave if scope access is stack-like in order to avoid allocation of fresh tables.

dup

public Scope dup(Symbol newOwner)

Construct a fresh scope within this scope, with new owner, which shares its table with the outer scope. Used in connection with method leave if scope access is stack-like in order to avoid allocation of fresh tables.

dupUnshared

public Scope dupUnshared()

Construct a fresh scope within this scope, with same owner, with a new hash table, whose contents initially are those of the table of its outer scope.

leave

public Scope leave()

Remove all entries of this scope from its table, if shared with next.

dble

private void dble()

Double size of hash table.

copy

private void copy(Scope.Entry e)

Copy the given entry and all entries shadowed by it to table

enter

public void enter(Symbol sym)

Enter symbol sym in this scope.

enter

public void enter(Symbol sym,
                  Scope s)

enter

public void enter(Symbol sym,
                  Scope s,
                  Scope origin)

Enter symbol sym in this scope, but mark that it comes from given scope `s' accessed through `origin'. The last two arguments are only used in import scopes.

makeEntry

Scope.Entry makeEntry(Symbol sym,
                      Scope.Entry shadowed,
                      Scope.Entry sibling,
                      Scope scope,
                      Scope origin)

remove

public void remove(Symbol sym)

Remove symbol from this scope. Used when an inner class attribute tells us that the class isn't a package member.

enterIfAbsent

public void enterIfAbsent(Symbol sym)

Enter symbol sym in this scope if not already there.

includes

public boolean includes(Symbol c)

Given a class, is there already a class with same fully qualified name in this (import) scope?

lookup

public Scope.Entry lookup(Name name)

Return the entry associated with given name, starting in this scope and proceeding outwards. If no entry was found, return the sentinel, which is characterized by having a null in both its scope and sym fields, whereas both fields are non-null for regular entries.

getElements

public java.lang.Iterable<Symbol> getElements()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object