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"nb-javac" is a patched version of OpenJDK "javac", i.e., the Java compiler. This has long been part of NetBeans, providing a highly tuned Java compiler specifically for the Java editor i.e., parsing and lexing for features such as syntax coloring, code completion.
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/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
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package com.sun.tools.javac.comp;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.BindingSymbol;
import com.sun.tools.javac.resources.CompilerProperties.Errors;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.JCTree.JCGuardPattern;
import com.sun.tools.javac.tree.JCTree.Tag;
import com.sun.tools.javac.tree.TreeScanner;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.Log;
import static com.sun.tools.javac.code.Flags.CLASH;
public class MatchBindingsComputer extends TreeScanner {
public static final MatchBindings EMPTY = new MatchBindings(List.nil(), List.nil());
protected static final Context.Key matchBindingsComputerKey = new Context.Key<>();
private final Log log;
public static MatchBindingsComputer instance(Context context) {
MatchBindingsComputer instance = context.get(matchBindingsComputerKey);
if (instance == null)
instance = new MatchBindingsComputer(context);
return instance;
}
protected MatchBindingsComputer(Context context) {
this.log = Log.instance(context);
}
public MatchBindings conditional(JCTree tree, MatchBindings condBindings, MatchBindings trueBindings, MatchBindings falseBindings) {
if (condBindings == EMPTY &&
trueBindings == EMPTY &&
falseBindings == EMPTY) {
return EMPTY;
}
DiagnosticPosition pos = tree.pos();
//A pattern variable is introduced both by a when true, and by c when true:
List xTzT = intersection(pos, condBindings.bindingsWhenTrue, falseBindings.bindingsWhenTrue);
//A pattern variable is introduced both by a when false, and by b when true:
List xFyT = intersection(pos, condBindings.bindingsWhenFalse, trueBindings.bindingsWhenTrue);
//A pattern variable is introduced both by b when true, and by c when true:
List yTzT = intersection(pos, trueBindings.bindingsWhenTrue, falseBindings.bindingsWhenTrue);
//A pattern variable is introduced both by a when true, and by c when false:
List xTzF = intersection(pos, condBindings.bindingsWhenTrue, falseBindings.bindingsWhenFalse);
//A pattern variable is introduced both by a when false, and by b when false:
List xFyF = intersection(pos, condBindings.bindingsWhenFalse, trueBindings.bindingsWhenFalse);
//A pattern variable is introduced both by b when false, and by c when false:
List yFzF = intersection(pos, trueBindings.bindingsWhenFalse, falseBindings.bindingsWhenFalse);
//error recovery:
/* if e = "x ? y : z", then:
e.T = union(intersect(y.T, z.T), intersect(x.T, z.T), intersect(x.F, y.T))
e.F = union(intersect(y.F, z.F), intersect(x.T, z.F), intersect(x.F, y.F))
*/
List bindingsWhenTrue = union(pos, yTzT, xTzT, xFyT);
List bindingsWhenFalse = union(pos, yFzF, xTzF, xFyF);
return new MatchBindings(bindingsWhenTrue, bindingsWhenFalse);
}
public MatchBindings unary(JCTree tree, MatchBindings bindings) {
if (bindings == EMPTY || !tree.hasTag(Tag.NOT)) return bindings;
return new MatchBindings(bindings.bindingsWhenFalse, bindings.bindingsWhenTrue);
}
public MatchBindings binary(JCTree tree, MatchBindings lhsBindings, MatchBindings rhsBindings) {
switch (tree.getTag()) {
case AND: {
return andOperation(tree.pos(), lhsBindings, rhsBindings);
}
case OR: {
// e.T = intersection(x.T, y.T) (error recovery)
// e.F = union(x.F, y.F)
List bindingsWhenTrue = //error recovery
intersection(tree.pos(), lhsBindings.bindingsWhenTrue, rhsBindings.bindingsWhenTrue);
List bindingsWhenFalse =
union(tree.pos(), lhsBindings.bindingsWhenFalse, rhsBindings.bindingsWhenFalse);
return new MatchBindings(bindingsWhenTrue, bindingsWhenFalse);
}
}
return EMPTY;
}
public MatchBindings guardedPattern(JCGuardPattern tree, MatchBindings patternBindings, MatchBindings guardBindings) {
return andOperation(tree.pos(), patternBindings, guardBindings);
}
public MatchBindings andOperation(DiagnosticPosition pos, MatchBindings lhsBindings, MatchBindings rhsBindings) {
// e.T = union(x.T, y.T)
// e.F = intersection(x.F, y.F) (error recovery)
List bindingsWhenTrue =
union(pos, lhsBindings.bindingsWhenTrue, rhsBindings.bindingsWhenTrue);
List bindingsWhenFalse = //error recovery
intersection(pos, lhsBindings.bindingsWhenFalse, rhsBindings.bindingsWhenFalse);
return new MatchBindings(bindingsWhenTrue, bindingsWhenFalse);
}
public MatchBindings switchCase(JCTree tree, MatchBindings prevBindings, MatchBindings currentBindings) {
if (prevBindings == null)
return currentBindings;
if (prevBindings.nullPattern) {
return currentBindings;
}
if (currentBindings.nullPattern) {
return prevBindings;
}
return new MatchBindings(intersection(tree.pos(), prevBindings.bindingsWhenTrue, currentBindings.bindingsWhenTrue),
intersection(tree.pos(), prevBindings.bindingsWhenFalse, currentBindings.bindingsWhenFalse));
}
public MatchBindings finishBindings(JCTree tree, MatchBindings matchBindings) {
switch (tree.getTag()) {
case NOT: case AND: case OR: case BINDINGPATTERN:
case PARENTHESIZEDPATTERN: case GUARDPATTERN:
case PARENS: case TYPETEST:
case CONDEXPR: //error recovery:
return matchBindings;
default:
return MatchBindingsComputer.EMPTY;
}
}
public static class MatchBindings {
public final List bindingsWhenTrue;
public final List bindingsWhenFalse;
public final boolean nullPattern;
public MatchBindings(List bindingsWhenTrue, List bindingsWhenFalse) {
this(bindingsWhenTrue, bindingsWhenFalse, false);
}
public MatchBindings(List bindingsWhenTrue, List bindingsWhenFalse, boolean nullPattern) {
this.bindingsWhenTrue = bindingsWhenTrue;
this.bindingsWhenFalse = bindingsWhenFalse;
this.nullPattern = nullPattern;
}
}
private List intersection(DiagnosticPosition pos, List lhsBindings, List rhsBindings) {
// It is an error if, for intersection(a,b), if a and b contain the same variable name (may be eventually relaxed to merge variables of same type)
List list = List.nil();
for (BindingSymbol v1 : lhsBindings) {
for (BindingSymbol v2 : rhsBindings) {
if (v1.name == v2.name &&
(v1.flags() & CLASH) == 0 &&
(v2.flags() & CLASH) == 0) {
log.error(pos, Errors.MatchBindingExists);
v2.flags_field |= CLASH;
list = list.append(v2);
}
}
}
return list;
}
@SafeVarargs
private final List union(DiagnosticPosition pos, List lhsBindings, List ... rhsBindings_s) {
// It is an error if for union(a,b), a and b contain the same name (disjoint union).
List list = lhsBindings;
for (List rhsBindings : rhsBindings_s) {
for (BindingSymbol v : rhsBindings) {
for (BindingSymbol ov : list) {
if (ov.name == v.name &&
(ov.flags() & CLASH) == 0 &&
(v.flags() & CLASH) == 0) {
log.error(pos, Errors.MatchBindingExists);
v.flags_field |= CLASH;
}
}
list = list.append(v);
}
}
return list;
}
}