refactor(#1534): Use composition to control generation behaviour

core/src/main/java/com/scottlogic/datahelix/generator/core/generation/DecisionTreeDataGenerator.java

@@ -17,9 +17,7 @@
 package com.scottlogic.datahelix.generator.core.generation;
 
 import com.google.inject.Inject;
-import com.google.inject.name.Named;
 import com.scottlogic.datahelix.generator.common.output.GeneratedObject;
-import com.scottlogic.datahelix.generator.core.profile.Profile;
 import com.scottlogic.datahelix.generator.core.config.detail.VisualiserLevel;
 import com.scottlogic.datahelix.generator.core.decisiontree.DecisionTree;
 import com.scottlogic.datahelix.generator.core.decisiontree.DecisionTreeFactory;
@@ -29,6 +27,7 @@
 import com.scottlogic.datahelix.generator.core.generation.databags.DataBag;
 import com.scottlogic.datahelix.generator.core.generation.visualiser.Visualiser;
 import com.scottlogic.datahelix.generator.core.generation.visualiser.VisualiserFactory;
+import com.scottlogic.datahelix.generator.core.profile.Profile;
 import com.scottlogic.datahelix.generator.core.walker.DecisionTreeWalker;
 
 import java.util.function.Supplier;
@@ -45,7 +44,6 @@ public class DecisionTreeDataGenerator implements DataGenerator {
     private final CombinationStrategy partitionCombiner;
     private final UpfrontTreePruner upfrontTreePruner;
     private final VisualiserFactory visualiserFactory;
-    private final long maxRows;
 
     @Inject
     public DecisionTreeDataGenerator(
@@ -56,8 +54,7 @@ public DecisionTreeDataGenerator(
         DataGeneratorMonitor monitor,
         CombinationStrategy combinationStrategy,
         UpfrontTreePruner upfrontTreePruner,
-        VisualiserFactory visualiserFactory,
-        @Named("config:maxRows") long maxRows) {
+        VisualiserFactory visualiserFactory) {
         this.decisionTreeGenerator = decisionTreeGenerator;
         this.treePartitioner = treePartitioner;
         this.treeOptimiser = optimiser;
@@ -66,13 +63,10 @@ public DecisionTreeDataGenerator(
         this.partitionCombiner = combinationStrategy;
         this.upfrontTreePruner = upfrontTreePruner;
         this.visualiserFactory = visualiserFactory;
-        this.maxRows = maxRows;
     }
 
     @Override
     public Stream<GeneratedObject> generateData(Profile profile) {
-        monitor.generationStarting();
-
         DecisionTree decisionTree = decisionTreeGenerator.analyse(profile);
         visualiseTree(decisionTree,  INITIAL_TREE_VISUALISER_TITLE);
 
@@ -87,10 +81,9 @@ public Stream<GeneratedObject> generateData(Profile profile) {
             .map(treeOptimiser::optimiseTree)
             .map(tree -> () -> treeWalker.walk(tree));
 
+        //noinspection RedundantCast
         return partitionCombiner.permute(partitionedDataBags)
-            .map(d->(GeneratedObject)d)
-            .limit(maxRows)
-            .peek(monitor::rowEmitted);
+            .map(d-> (GeneratedObject)d);
     }
 
     private void visualiseTree(DecisionTree decisionTree, String title) {

core/src/main/java/com/scottlogic/datahelix/generator/core/generation/LimitingDataGenerator.java

@@ -0,0 +1,27 @@
+package com.scottlogic.datahelix.generator.core.generation;
+
+import com.google.inject.Inject;
+import com.google.inject.name.Named;
+import com.scottlogic.datahelix.generator.common.output.GeneratedObject;
+import com.scottlogic.datahelix.generator.core.profile.Profile;
+
+import java.util.stream.Stream;
+
+public class LimitingDataGenerator implements DataGenerator {
+    private final DataGenerator dataGenerator;
+    private final long maxRows;
+
+    //created by DataGeneratorProvider
+    public LimitingDataGenerator(
+        DataGenerator dataGenerator,
+        long maxRows) {
+        this.dataGenerator = dataGenerator;
+        this.maxRows = maxRows;
+    }
+
+    @Override
+    public Stream<GeneratedObject> generateData(Profile profile) {
+        return dataGenerator.generateData(profile)
+            .limit(maxRows);
+    }
+}

core/src/main/java/com/scottlogic/datahelix/generator/core/generation/MonitoringDataGenerator.java

@@ -0,0 +1,28 @@
+package com.scottlogic.datahelix.generator.core.generation;
+
+import com.google.inject.Inject;
+import com.scottlogic.datahelix.generator.common.output.GeneratedObject;
+import com.scottlogic.datahelix.generator.core.profile.Profile;
+
+import java.util.stream.Stream;
+
+public class MonitoringDataGenerator implements DataGenerator {
+    private final DataGenerator dataGenerator;
+    private final DataGeneratorMonitor monitor;
+
+    //created by DataGeneratorProvider
+    public MonitoringDataGenerator(
+        DataGenerator dataGenerator,
+        DataGeneratorMonitor monitor) {
+        this.dataGenerator = dataGenerator;
+        this.monitor = monitor;
+    }
+
+    @Override
+    public Stream<GeneratedObject> generateData(Profile profile) {
+        monitor.generationStarting();
+
+        return dataGenerator.generateData(profile)
+            .peek(monitor::rowEmitted);
+    }
+}

core/src/main/java/com/scottlogic/datahelix/generator/core/guice/DataGeneratorProvider.java

@@ -0,0 +1,29 @@
+package com.scottlogic.datahelix.generator.core.guice;
+
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import com.google.inject.name.Named;
+import com.scottlogic.datahelix.generator.core.generation.*;
+
+public class DataGeneratorProvider implements Provider<DataGenerator> {
+    private final DataGenerator coreGenerator;
+    private final long maxRows;
+    private final DataGeneratorMonitor monitor;
+
+    @Inject
+    public DataGeneratorProvider(
+        DecisionTreeDataGenerator coreGenerator,
+        @Named("config:maxRows") long maxRows,
+        DataGeneratorMonitor monitor) {
+        this.coreGenerator = coreGenerator;
+        this.maxRows = maxRows;
+        this.monitor = monitor;
+    }
+
+    @Override
+    public DataGenerator get() {
+        return new MonitoringDataGenerator(
+            new LimitingDataGenerator(coreGenerator, maxRows),
+            monitor);
+    }
+}

core/src/main/java/com/scottlogic/datahelix/generator/core/guice/GeneratorModule.java

@@ -61,7 +61,7 @@ protected void configure() {
 
         // Bind known implementations - no user input required
         bind(DataGeneratorMonitor.class).to(AbstractDataGeneratorMonitor.class);
-        bind(DataGenerator.class).to(DecisionTreeDataGenerator.class);
+        bind(DataGenerator.class).toProvider(DataGeneratorProvider.class);
 
         bind(JavaUtilRandomNumberGenerator.class)
             .toInstance(new JavaUtilRandomNumberGenerator(OffsetDateTime.now().getNano()));

core/src/test/java/com/scottlogic/datahelix/generator/core/generation/DecisionTreeDataGeneratorTests.java

@@ -63,7 +63,6 @@ void setup() {
         combinationStrategy = Mockito.mock(CombinationStrategy.class);
         upfrontTreePruner = Mockito.mock(UpfrontTreePruner.class);
         visualiserFactory = Mockito.mock(VisualiserFactory.class);
-        long maxRows = 10;
         generator = new DecisionTreeDataGenerator(
             factory,
             treeWalker,
@@ -72,8 +71,7 @@ void setup() {
             monitor,
             combinationStrategy,
             upfrontTreePruner,
-            visualiserFactory,
-            maxRows
+            visualiserFactory
         );
     }