[jrubyscripting] Inject script context as global (#15618)

Signed-off-by: Jimmy Tanagra <jcode@tanagra.id.au>

bundles/org.openhab.automation.jrubyscripting/src/main/java/org/openhab/automation/jrubyscripting/internal/JRubyEngineWrapper.java

@@ -0,0 +1,218 @@
+/**
+ * Copyright (c) 2010-2023 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.automation.jrubyscripting.internal;
+
+import java.io.Reader;
+import java.util.Objects;
+
+import javax.script.Bindings;
+import javax.script.Compilable;
+import javax.script.CompiledScript;
+import javax.script.Invocable;
+import javax.script.ScriptContext;
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineFactory;
+import javax.script.ScriptException;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.jruby.embed.jsr223.JRubyEngine;
+
+/**
+ * This is a wrapper for {@link JRubyEngine}.
+ * 
+ * The purpose of this class is to intercept the call to eval and save the context into
+ * a global variable for use in the helper library.
+ *
+ * @author Jimmy Tanagra - Initial contribution
+ */
+@NonNullByDefault
+public class JRubyEngineWrapper implements Compilable, Invocable, ScriptEngine {
+
+    private final JRubyEngine engine;
+
+    private static final String CONTEXT_VAR_NAME = "ctx";
+    private static final String GLOBAL_VAR_NAME = "$" + CONTEXT_VAR_NAME;
+
+    JRubyEngineWrapper(JRubyEngine engine) {
+        this.engine = Objects.requireNonNull(engine);
+    }
+
+    @Override
+    public CompiledScript compile(@Nullable String script) throws ScriptException {
+        return engine.compile(script);
+    }
+
+    @Override
+    public CompiledScript compile(@Nullable Reader reader) throws ScriptException {
+        return engine.compile(reader);
+    }
+
+    @Override
+    public Object eval(@Nullable String script, @Nullable ScriptContext context) throws ScriptException {
+        Object ctx = Objects.requireNonNull(context).getBindings(ScriptContext.ENGINE_SCOPE).get(CONTEXT_VAR_NAME);
+
+        if (ctx == null) {
+            return engine.eval(script, context);
+        }
+
+        context.setAttribute(GLOBAL_VAR_NAME, ctx, ScriptContext.ENGINE_SCOPE);
+        try {
+            return engine.eval(script, context);
+        } finally {
+            context.removeAttribute(GLOBAL_VAR_NAME, ScriptContext.ENGINE_SCOPE);
+        }
+    }
+
+    @Override
+    public Object eval(@Nullable Reader reader, @Nullable ScriptContext context) throws ScriptException {
+        Object ctx = Objects.requireNonNull(context).getBindings(ScriptContext.ENGINE_SCOPE).get(CONTEXT_VAR_NAME);
+
+        if (ctx == null) {
+            return engine.eval(reader, context);
+        }
+
+        context.setAttribute(GLOBAL_VAR_NAME, ctx, ScriptContext.ENGINE_SCOPE);
+        try {
+            return engine.eval(reader, context);
+        } finally {
+            context.removeAttribute(GLOBAL_VAR_NAME, ScriptContext.ENGINE_SCOPE);
+        }
+    }
+
+    @Override
+    public Object eval(@Nullable String script, @Nullable Bindings bindings) throws ScriptException {
+        Object ctx = Objects.requireNonNull(bindings).get(CONTEXT_VAR_NAME);
+
+        if (ctx == null) {
+            return engine.eval(script, bindings);
+        }
+
+        bindings.put(GLOBAL_VAR_NAME, ctx);
+        try {
+            return engine.eval(script, bindings);
+        } finally {
+            bindings.remove(GLOBAL_VAR_NAME);
+        }
+    }
+
+    @Override
+    public Object eval(@Nullable Reader reader, @Nullable Bindings bindings) throws ScriptException {
+        Object ctx = Objects.requireNonNull(bindings).get(CONTEXT_VAR_NAME);
+
+        if (ctx == null) {
+            return engine.eval(reader, bindings);
+        }
+
+        bindings.put(GLOBAL_VAR_NAME, ctx);
+        try {
+            return engine.eval(reader, bindings);
+        } finally {
+            bindings.remove(GLOBAL_VAR_NAME);
+        }
+    }
+
+    @Override
+    public Object eval(@Nullable String script) throws ScriptException {
+        Object ctx = getBindings(ScriptContext.ENGINE_SCOPE).get(CONTEXT_VAR_NAME);
+
+        if (ctx == null) {
+            return engine.eval(script);
+        }
+
+        getContext().setAttribute(GLOBAL_VAR_NAME, ctx, ScriptContext.ENGINE_SCOPE);
+        try {
+            return engine.eval(script);
+        } finally {
+            getContext().removeAttribute(GLOBAL_VAR_NAME, ScriptContext.ENGINE_SCOPE);
+        }
+    }
+
+    @Override
+    public Object eval(@Nullable Reader reader) throws ScriptException {
+        Object ctx = getBindings(ScriptContext.ENGINE_SCOPE).get(CONTEXT_VAR_NAME);
+
+        if (ctx == null) {
+            return engine.eval(reader);
+        }
+
+        getContext().setAttribute(GLOBAL_VAR_NAME, ctx, ScriptContext.ENGINE_SCOPE);
+        try {
+            return engine.eval(reader);
+        } finally {
+            getContext().removeAttribute(GLOBAL_VAR_NAME, ScriptContext.ENGINE_SCOPE);
+        }
+    }
+
+    @Override
+    public Object get(@Nullable String key) {
+        return engine.get(key);
+    }
+
+    @Override
+    public void put(@Nullable String key, @Nullable Object value) {
+        engine.put(key, value);
+    }
+
+    @Override
+    public Bindings getBindings(int scope) {
+        return engine.getBindings(scope);
+    }
+
+    @Override
+    public void setBindings(@Nullable Bindings bindings, int scope) {
+        engine.setBindings(bindings, scope);
+    }
+
+    @Override
+    public Bindings createBindings() {
+        return engine.createBindings();
+    }
+
+    @Override
+    public ScriptContext getContext() {
+        return engine.getContext();
+    }
+
+    @Override
+    public void setContext(@Nullable ScriptContext context) {
+        engine.setContext(context);
+    }
+
+    @Override
+    public ScriptEngineFactory getFactory() {
+        return engine.getFactory();
+    }
+
+    @Override
+    public Object invokeMethod(@Nullable Object receiver, @Nullable String method, Object @Nullable... args)
+            throws ScriptException, NoSuchMethodException {
+        return engine.invokeMethod(receiver, method, args);
+    }
+
+    @Override
+    public Object invokeFunction(@Nullable String method, Object @Nullable... args)
+            throws ScriptException, NoSuchMethodException {
+        return engine.invokeFunction(method, args);
+    }
+
+    @Override
+    public <T> T getInterface(@Nullable Class<T> returnType) {
+        return engine.getInterface(returnType);
+    }
+
+    @Override
+    public <T> T getInterface(@Nullable Object receiver, @Nullable Class<T> returnType) {
+        return engine.getInterface(receiver, returnType);
+    }
+}

bundles/org.openhab.automation.jrubyscripting/src/main/java/org/openhab/automation/jrubyscripting/internal/JRubyScriptEngineFactory.java

@@ -160,7 +160,7 @@ public class JRubyScriptEngineFactory extends AbstractScriptEngineFactory {
         }
         ScriptEngine engine = factory.getScriptEngine();
         configuration.configureRubyEnvironment(engine);
-        return engine;
+        return new JRubyEngineWrapper((org.jruby.embed.jsr223.JRubyEngine) engine);
     }
 
     @Override