--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/MatchBindingsComputer.java Wed Nov 27 09:00:01 2019 +0100
@@ -0,0 +1,216 @@
+/*
+ * Copyright (c) 2017, 2019, 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 com.sun.tools.javac.code.Flags;
+import com.sun.tools.javac.code.Symbol;
+import com.sun.tools.javac.code.Symbol.VarSymbol;
+import com.sun.tools.javac.code.Type;
+import com.sun.tools.javac.code.Types;
+import com.sun.tools.javac.resources.CompilerProperties.Errors;
+import com.sun.tools.javac.tree.JCTree;
+import com.sun.tools.javac.tree.JCTree.JCBinary;
+import com.sun.tools.javac.tree.JCTree.JCConditional;
+import com.sun.tools.javac.tree.JCTree.JCUnary;
+import com.sun.tools.javac.tree.JCTree.JCBindingPattern;
+import com.sun.tools.javac.tree.TreeScanner;
+import com.sun.tools.javac.util.Context;
+import com.sun.tools.javac.util.List;
+import com.sun.tools.javac.util.Log;
+import com.sun.tools.javac.util.Name;
+
+
+public class MatchBindingsComputer extends TreeScanner {
+ protected static final Context.Key<MatchBindingsComputer> matchBindingsComputerKey = new Context.Key<>();
+
+ private final Log log;
+ private final Types types;
+ boolean whenTrue;
+ List<BindingSymbol> bindings;
+
+ 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);
+ this.types = Types.instance(context);
+ }
+
+ public List<BindingSymbol> getMatchBindings(JCTree expression, boolean whenTrue) {
+ this.whenTrue = whenTrue;
+ this.bindings = List.nil();
+ scan(expression);
+ return bindings;
+ }
+
+ @Override
+ public void visitBindingPattern(JCBindingPattern tree) {
+ bindings = whenTrue ? List.of(tree.symbol) : List.nil();
+ }
+
+ @Override
+ public void visitBinary(JCBinary tree) {
+ switch (tree.getTag()) {
+ case AND:
+ // e.T = union(x.T, y.T)
+ // e.F = intersection(x.F, y.F)
+ scan(tree.lhs);
+ List<BindingSymbol> lhsBindings = bindings;
+ scan(tree.rhs);
+ List<BindingSymbol> rhsBindings = bindings;
+ bindings = whenTrue ? union(tree, lhsBindings, rhsBindings) : intersection(tree, lhsBindings, rhsBindings);
+ break;
+ case OR:
+ // e.T = intersection(x.T, y.T)
+ // e.F = union(x.F, y.F)
+ scan(tree.lhs);
+ lhsBindings = bindings;
+ scan(tree.rhs);
+ rhsBindings = bindings;
+ bindings = whenTrue ? intersection(tree, lhsBindings, rhsBindings) : union(tree, lhsBindings, rhsBindings);
+ break;
+ default:
+ super.visitBinary(tree);
+ break;
+ }
+ }
+
+ @Override
+ public void visitUnary(JCUnary tree) {
+ switch (tree.getTag()) {
+ case NOT:
+ // e.T = x.F // flip 'em
+ // e.F = x.T
+ whenTrue = !whenTrue;
+ scan(tree.arg);
+ whenTrue = !whenTrue;
+ break;
+ default:
+ super.visitUnary(tree);
+ break;
+ }
+ }
+
+ @Override
+ public void visitConditional(JCConditional tree) {
+ /* 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))
+ */
+ if (whenTrue) {
+ List<BindingSymbol> xT, yT, zT, xF;
+ scan(tree.cond);
+ xT = bindings;
+ scan(tree.truepart);
+ yT = bindings;
+ scan(tree.falsepart);
+ zT = bindings;
+ whenTrue = false;
+ scan(tree.cond);
+ xF = bindings;
+ whenTrue = true;
+ bindings = union(tree, intersection(tree, yT, zT), intersection(tree, xT, zT), intersection(tree, xF, yT));
+ } else {
+ List<BindingSymbol> xF, yF, zF, xT;
+ scan(tree.cond);
+ xF = bindings;
+ scan(tree.truepart);
+ yF = bindings;
+ scan(tree.falsepart);
+ zF = bindings;
+ whenTrue = true;
+ scan(tree.cond);
+ xT = bindings;
+ whenTrue = false;
+ bindings = union(tree, intersection(tree, yF, zF), intersection(tree, xT, zF), intersection(tree, xF, yF));
+ }
+ }
+
+ private List<BindingSymbol> intersection(JCTree tree, List<BindingSymbol> lhsBindings, List<BindingSymbol> 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<BindingSymbol> list = List.nil();
+ for (BindingSymbol v1 : lhsBindings) {
+ for (BindingSymbol v2 : rhsBindings) {
+ if (v1.name == v2.name) {
+ log.error(tree.pos(), Errors.MatchBindingExists);
+ list = list.append(v2);
+ }
+ }
+ }
+ return list;
+ }
+
+ @SafeVarargs
+ private final List<BindingSymbol> union(JCTree tree, List<BindingSymbol> lhsBindings, List<BindingSymbol> ... rhsBindings_s) {
+ // It is an error if for union(a,b), a and b contain the same name (disjoint union).
+ List<BindingSymbol> list = lhsBindings;
+ for (List<BindingSymbol> rhsBindings : rhsBindings_s) {
+ for (BindingSymbol v : rhsBindings) {
+ for (BindingSymbol ov : list) {
+ if (ov.name == v.name) {
+ log.error(tree.pos(), Errors.MatchBindingExists);
+ }
+ }
+ list = list.append(v);
+ }
+ }
+ return list;
+ }
+
+ @Override
+ public void scan(JCTree tree) {
+ bindings = List.nil();
+ super.scan(tree);
+ }
+
+ public static class BindingSymbol extends VarSymbol {
+
+ public BindingSymbol(Name name, Type type, Symbol owner) {
+ super(Flags.FINAL | Flags.HASINIT | Flags.MATCH_BINDING, name, type, owner);
+ }
+
+ public boolean isAliasFor(BindingSymbol b) {
+ return aliases().containsAll(b.aliases());
+ }
+
+ List<BindingSymbol> aliases() {
+ return List.of(this);
+ }
+
+ public void preserveBinding() {
+ flags_field |= Flags.MATCH_BINDING_TO_OUTER;
+ }
+
+ public boolean isPreserved() {
+ return (flags_field & Flags.MATCH_BINDING_TO_OUTER) != 0;
+ }
+ }
+
+}