* In order to provide a custom object with methods, one may return a {@link IDynamicLuaObject}, or an arbitrary * class with {@link LuaFunction} annotations. Anything else will be converted to {@code nil}. + *
+ * Shared objects in a {@link MethodResult} will preserve their sharing when converted to Lua values. For instance, + * {@code Map m = new HashMap(); return MethodResult.of(m, m); } will return two values {@code a}, {@code b} + * where {@code a == b}. The one exception to this is Java's singleton collections ({@link List#of()}, + * {@link Set#of()} and {@link Map#of()}), which are always converted to new table. This is not true for other + * singleton collections, such as those provided by {@link Collections} or Guava. * * @param value The value to return to the calling Lua function. * @return A method result which returns immediately with the given value. diff --git a/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java b/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java index 2b97f00fb..5d51e55e0 100644 --- a/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java +++ b/projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java @@ -13,6 +13,7 @@ import dan200.computercraft.core.Logging; import dan200.computercraft.core.computer.TimeoutState; import dan200.computercraft.core.methods.LuaMethod; import dan200.computercraft.core.methods.MethodSupplier; +import dan200.computercraft.core.util.LuaUtil; import dan200.computercraft.core.util.Nullability; import dan200.computercraft.core.util.SanitisedError; import org.slf4j.Logger; @@ -183,10 +184,35 @@ public class CobaltLuaMachine implements ILuaMachine { return ValueFactory.valueOf(bytes); } + // Don't share singleton values, and instead convert them to a new table. + if (LuaUtil.isSingletonCollection(object)) return new LuaTable(); + if (values == null) values = new IdentityHashMap<>(1); var result = values.get(object); if (result != null) return result; + var wrapped = toValueWorker(object, values); + if (wrapped == null) { + LOG.warn(Logging.JAVA_ERROR, "Received unknown type '{}', returning nil.", object.getClass().getName()); + return Constants.NIL; + } + + values.put(object, wrapped); + return wrapped; + } + + /** + * Convert a complex Java object (such as a collection or Lua object) to a Lua value. + *
+ * This is a worker function for {@link #toValue(Object, IdentityHashMap)}, which handles the actual construction
+ * of values, without reading/writing from the value map.
+ *
+ * @param object The object to convert.
+ * @param values The map of Java to Lua values.
+ * @return The converted value, or {@code null} if it could not be converted.
+ * @throws LuaError If the value could not be converted.
+ */
+ private @Nullable LuaValue toValueWorker(Object object, IdentityHashMap
+ * These collections are treated specially by {@link ILuaMachine} implementations: we skip sharing for them, and
+ * create a new table each time.
+ *
+ * @param value The value to test.
+ * @return Whether this is a singleton collection.
+ */
+ public static boolean isSingletonCollection(Object value) {
+ return value == EMPTY_LIST || value == EMPTY_SET || value == EMPTY_MAP;
+ }
}
diff --git a/projects/core/src/test/java/dan200/computercraft/core/computer/ComputerTest.java b/projects/core/src/test/java/dan200/computercraft/core/computer/ComputerTest.java
index 98124fc89..674816828 100644
--- a/projects/core/src/test/java/dan200/computercraft/core/computer/ComputerTest.java
+++ b/projects/core/src/test/java/dan200/computercraft/core/computer/ComputerTest.java
@@ -5,11 +5,14 @@
package dan200.computercraft.core.computer;
import com.google.common.io.CharStreams;
+import dan200.computercraft.api.lua.ILuaAPI;
+import dan200.computercraft.api.lua.LuaFunction;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
+import java.util.List;
import java.util.Objects;
import static java.time.Duration.ofSeconds;
@@ -30,6 +33,26 @@ public class ComputerTest {
});
}
+ @Test
+ public void testDuplicateObjects() {
+ class CustomApi implements ILuaAPI {
+ @Override
+ public String[] getNames() {
+ return new String[]{ "custom" };
+ }
+
+ @LuaFunction
+ public final Object[] getObjects() {
+ return new Object[]{ List.of(), List.of() };
+ }
+ }
+
+ ComputerBootstrap.run("""
+ local x, y = custom.getObjects()
+ assert(x ~= y)
+ """, i -> i.addApi(new CustomApi()), 50);
+ }
+
public static void main(String[] args) throws Exception {
var stream = ComputerTest.class.getClassLoader().getResourceAsStream("benchmark.lua");
try (var reader = new InputStreamReader(Objects.requireNonNull(stream), StandardCharsets.UTF_8)) {
diff --git a/projects/core/src/test/resources/test-rom/spec/apis/os_spec.lua b/projects/core/src/test/resources/test-rom/spec/apis/os_spec.lua
index 562dcc7ff..95a50b369 100644
--- a/projects/core/src/test/resources/test-rom/spec/apis/os_spec.lua
+++ b/projects/core/src/test/resources/test-rom/spec/apis/os_spec.lua
@@ -188,4 +188,31 @@ describe("The os library", function()
expect.error(os.loadAPI, nil):eq("bad argument #1 (string expected, got nil)")
end)
end)
+
+ describe("os.queueEvent", function()
+ local function roundtrip(...)
+ local event_name = ("event_%08x"):format(math.random(1, 0x7FFFFFFF))
+ os.queueEvent(event_name, ...)
+ return select(2, os.pullEvent(event_name))
+ end
+
+ it("preserves references in tables", function()
+ local tbl = {}
+ local xs = roundtrip({ tbl, tbl })
+ expect(xs[1]):eq(xs[2])
+ end)
+
+ it("does not preserve references in separate args", function()
+ -- I'm not sure I like this behaviour, but it is what CC has always done.
+ local tbl = {}
+ local xs, ys = roundtrip(tbl, tbl)
+ expect(xs):ne(ys)
+ end)
+
+ it("clones objects", function()
+ local tbl = {}
+ local xs = roundtrip(tbl)
+ expect(xs):ne(tbl)
+ end)
+ end)
end)
diff --git a/projects/core/src/test/resources/test-rom/spec/modules/cc/internal/syntax/lexer_spec.md b/projects/core/src/test/resources/test-rom/spec/modules/cc/internal/syntax/lexer_spec.md
index 8cb2e646f..9d5af0531 100644
--- a/projects/core/src/test/resources/test-rom/spec/modules/cc/internal/syntax/lexer_spec.md
+++ b/projects/core/src/test/resources/test-rom/spec/modules/cc/internal/syntax/lexer_spec.md
@@ -19,7 +19,7 @@ We can lex some basic comments:
```
```txt
-1:1-1:37 COMMENT -- A basic singleline comment
+1:1-1:29 COMMENT -- A basic singleline comment
2:1-2:27 COMMENT --[ Not a multiline comment
3:1-3:34 COMMENT --[= Also not a multiline comment!
```