added Javascript support for Triggers' source

h2/src/docsrc/help/help.csv

@@ -735,6 +735,7 @@ The class must be available in the classpath of the database engine
 
 The sourceCodeString must define a single method with no parameters that returns ""org.h2.api.Trigger"".
 See CREATE ALIAS for requirements regarding the compilation.
+Alternatively, it can be a javascript (see javax.script.ScriptEngineManager) that returns ""org.h2.api.Trigger"". In that case the source must begin by ""//javascript"".
 
 BEFORE triggers are called after data conversion is made, default values are set,
 null and length constraint checks have been made;
@@ -773,6 +774,7 @@ This command commits an open transaction in this connection.
 ","
 CREATE TRIGGER TRIG_INS BEFORE INSERT ON TEST FOR EACH ROW CALL ""MyTrigger"";
 CREATE TRIGGER TRIG_SRC BEFORE INSERT ON TEST AS $$org.h2.api.Trigger create() { return new MyTrigger(""constructorParam""); } $$;
+CREATE TRIGGER TRIG_SCRIPT BEFORE INSERT ON TEST AS $$//javascript\nreturn new Packages.MyTrigger(""constructorParam""); $$;
 "
 "Commands (DDL)","CREATE USER","
 CREATE USER [ IF NOT EXISTS ] newUserName

h2/src/main/org/h2/schema/TriggerObject.java

@@ -5,7 +5,6 @@
  */
 package org.h2.schema;
 
-import java.lang.reflect.Method;
 import java.sql.Connection;
 import java.sql.SQLException;
 
@@ -94,11 +93,7 @@ public class TriggerObject extends SchemaObjectBase {
             String fullClassName = Constants.USER_PACKAGE + ".trigger." + getName();
             compiler.setSource(fullClassName, triggerSource);
             try {
-                Method m = compiler.getMethod(fullClassName);
-                if (m.getParameterTypes().length > 0) {
-                    throw new IllegalStateException("No parameters are allowed for a trigger");
-                }
-                return (Trigger) m.invoke(null);
+                return (Trigger) compiler.invoke(fullClassName);
             } catch (DbException e) {
                 throw e;
             } catch (Exception e) {

h2/src/main/org/h2/util/SourceCompiler.java

@@ -24,6 +24,14 @@ import java.net.URI;
 import java.security.SecureClassLoader;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.Map;
+
+import javax.script.Bindings;
+import javax.script.Compilable;
+import javax.script.CompiledScript;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+import javax.script.SimpleBindings;
 import javax.tools.FileObject;
 import javax.tools.ForwardingJavaFileManager;
 import javax.tools.JavaCompiler;
@@ -33,6 +41,7 @@ import javax.tools.JavaFileObject.Kind;
 import javax.tools.SimpleJavaFileObject;
 import javax.tools.StandardJavaFileManager;
 import javax.tools.ToolProvider;
+
 import org.h2.api.ErrorCode;
 import org.h2.engine.Constants;
 import org.h2.engine.SysProperties;
@@ -65,6 +74,8 @@ public class SourceCompiler {
      */
     final HashMap<String, Class<?>> compiled = New.hashMap();
 
+    final Map<String, CompiledScript> compiledScripts = New.hashMap();
+
     /**
      * Whether to use the ToolProvider.getSystemJavaCompiler().
      */
@@ -168,6 +179,32 @@ public class SourceCompiler {
         return source.startsWith("//groovy") || source.startsWith("@groovy");
     }
 
+    private static boolean isJavascriptSource(String source) {
+        return source.startsWith("//javascript");
+    }
+
+    // whether the passed source should be compiled using javax.script.ScriptEngineManager
+    private static boolean isJavaxScriptSource(String source) {
+        return isJavascriptSource(source);
+    }
+
+    public CompiledScript getCompiledScript(String packageAndClassName) throws ScriptException {
+        CompiledScript compiledScript = compiledScripts.get(packageAndClassName);
+        if (compiledScript == null) {
+            String source = sources.get(packageAndClassName);
+            final String lang;
+            if (isJavascriptSource(source))
+                lang = "javascript";
+            else
+                throw new IllegalStateException("Unkown language for " + source);
+
+            final Compilable jsEngine = (Compilable) new ScriptEngineManager().getEngineByName(lang);
+            compiledScript = jsEngine.compile(source);
+            compiledScripts.put(packageAndClassName, compiledScript);
+        }
+        return compiledScript;
+    }
+
     /**
      * Get the first public static method of the given class.
      *
@@ -189,6 +226,24 @@ public class SourceCompiler {
         return null;
     }
 
+    public Object invoke(String className, final Object... args) throws Exception {
+        String source = sources.get(className);
+        if (isJavaxScriptSource(source)) {
+            final Bindings bindings = new SimpleBindings();
+            int i = 0;
+            for (final Object arg : args) {
+                bindings.put("arg" + i, arg);
+                i++;
+            }
+            return this.getCompiledScript(className).eval(bindings);
+        } else {
+            final Method m = this.getMethod(className);
+            if (m.getParameterTypes().length != args.length)
+                throw new IllegalStateException("Wrong number of parameters, " + args.length + " were pased but " + m.getParameterTypes().length + " were needed");
+            return m.invoke(null, args);
+        }
+    }
+
     /**
      * Compile the given class. This method tries to use the class
      * "com.sun.tools.javac.Main" if available. If not, it tries to run "javac"

h2/src/test/org/h2/test/db/TestTriggersConstraints.java

@@ -12,6 +12,7 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.Arrays;
 import java.util.HashSet;
+
 import org.h2.api.ErrorCode;
 import org.h2.api.Trigger;
 import org.h2.engine.Session;
@@ -50,6 +51,7 @@ public class TestTriggersConstraints extends TestBase implements Trigger {
         testTriggerBeforeSelect();
         testTriggerAlterTable();
         testTriggerAsSource();
+        testTriggerAsJavascript();
         testTriggers();
         testConstraints();
         testCheckConstraintErrorMessage();
@@ -471,15 +473,20 @@ public class TestTriggersConstraints extends TestBase implements Trigger {
 
     private void testTriggerAlterTable() throws SQLException {
         deleteDb("trigger");
-        testTrigger(false);
+        testTrigger(null);
     }
 
     private void testTriggerAsSource() throws SQLException {
         deleteDb("trigger");
-        testTrigger(true);
+        testTrigger("java");
+    }
+
+    private void testTriggerAsJavascript() throws SQLException {
+        deleteDb("trigger");
+        testTrigger("javascript");
     }
 
-    private void testTrigger(final boolean asSource) throws SQLException {
+    private void testTrigger(final String sourceLang) throws SQLException {
         final String callSeq = "call seq.nextval";
         Connection conn = getConnection("trigger");
         Statement stat = conn.createStatement();
@@ -490,12 +497,18 @@ public class TestTriggersConstraints extends TestBase implements Trigger {
         conn.setAutoCommit(false);
         Trigger t = new org.h2.test.db.TestTriggersConstraints.TestTriggerAlterTable();
         t.close();
-        if (asSource) {
+        if ("java".equals(sourceLang)) {
             String triggerClassName = this.getClass().getName() + "."
                     + TestTriggerAlterTable.class.getSimpleName();
             stat.execute("create trigger test_upd before insert on test "
                     + "as $$org.h2.api.Trigger create() " + "{ return new "
                     + triggerClassName + "(); } $$");
+        } else if ("javascript".equals(sourceLang)) {
+            String triggerClassName = this.getClass().getName() + "."
+                    + TestTriggerAlterTable.class.getSimpleName();
+            final String body = "//javascript\nnew Packages." + triggerClassName + "();";
+            stat.execute("create trigger test_upd before insert on test as $$"
+                    + body + " $$");
         } else {
             stat.execute("create trigger test_upd before insert on test call \""
                     + TestTriggerAlterTable.class.getName() + "\"");