fixes #86 - new emitter extension to generate bean property paths. (#87)

* fixes #86 - new emitter extension to generate bean property paths.

* have the generated Field spec classes replicate the inheritance hierarchy instead of duplicating the fields, good advice @vojtechhabarta

* respect the exportKeyword setting.

* oops that was wrong

typescript-generator-core/src/main/java/cz/habarta/typescript/generator/ext/BeanPropertyPathExtension.java

@@ -0,0 +1,137 @@
+package cz.habarta.typescript.generator.ext;
+
+import java.util.*;
+import cz.habarta.typescript.generator.Settings;
+import cz.habarta.typescript.generator.TsType;
+import cz.habarta.typescript.generator.TsType.GenericReferenceType;
+import cz.habarta.typescript.generator.compiler.EnumKind;
+import cz.habarta.typescript.generator.compiler.EnumMemberModel;
+import cz.habarta.typescript.generator.emitter.EmitterExtension;
+import cz.habarta.typescript.generator.emitter.EmitterExtensionFeatures;
+import cz.habarta.typescript.generator.emitter.TsBeanModel;
+import cz.habarta.typescript.generator.emitter.TsEnumModel;
+import cz.habarta.typescript.generator.emitter.TsModel;
+import cz.habarta.typescript.generator.emitter.TsPropertyModel;
+
+/**
+ * Emitter which generates type-safe property path getters.
+ *
+ * Many javascript frameworks require that you specify "property paths"
+ * to extract data from objects. For instance, if you have a data model
+ * which is an array of items, and you want to display them in a grid,
+ * you can give column specifications as strings, like "field1.field2".
+ * With this emitter you can specify such paths like so:
+ * {@code ClassName.field1.field2.get()}
+ * Once you call {@code get()}, you get a string
+ * (in this case "field1.field2")
+ */
+public class BeanPropertyPathExtension extends EmitterExtension {
+
+    @Override
+    public EmitterExtensionFeatures getFeatures() {
+        final EmitterExtensionFeatures features = new EmitterExtensionFeatures();
+        features.generatesRuntimeCode = true;
+        return features;
+    }
+
+    @Override
+    public void emitElements(Writer writer, Settings settings, boolean exportKeyword, TsModel model) {
+        emitFieldsClass(writer, settings);
+
+        Set<TsBeanModel> emittedBeans = new HashSet<>();
+        for (TsBeanModel bean : model.getBeans()) {
+            emittedBeans.addAll(
+                writeBeanAndParentsFieldSpecs(writer, settings, model, emittedBeans, bean));
+        }
+        for (TsBeanModel bean : model.getBeans()) {
+            createBeanFieldConstant(writer, exportKeyword, bean);
+        }
+    }
+
+    private static void emitFieldsClass(Writer writer, Settings settings) {
+        List<String> fieldsClassLines = Arrays.asList(
+            "class Fields {",
+            "    protected parent: Fields | undefined;",
+            "    protected name: string | undefined;",
+            "    constructor(parent?: Fields, name?: string) {",
+            "        this.parent = parent;",
+            "        this.name = name;",
+            "    };",
+            "    get(): string | undefined {",
+            "        if (this.parent && this.parent.get()) {",
+            "            return this.name ? this.parent.get() + \".\" + this.name : this.parent.get();",
+            "        } else {",
+            "            return this.name;",
+            "        }",
+            "    }",
+            "}");
+        writer.writeIndentedLine("");
+        for (String fieldsClassLine : fieldsClassLines) {
+            writer.writeIndentedLine(fieldsClassLine.replace("    ", settings.indentString));
+        }
+    }
+
+    /**
+     * Emits a bean and its parent beans before if needed.
+     * Returns the list of beans that were emitted.
+     */
+    private static Set<TsBeanModel> writeBeanAndParentsFieldSpecs(
+        Writer writer, Settings settings, TsModel model, Set<TsBeanModel> emittedSoFar, TsBeanModel bean) {
+        if (emittedSoFar.contains(bean)) {
+            return new HashSet<>();
+        }
+        final TsBeanModel parentBean = getBeanModelByType(model, bean.getParent());
+        final Set<TsBeanModel> emittedBeans = parentBean != null
+            ? writeBeanAndParentsFieldSpecs(writer, settings, model, emittedSoFar, parentBean)
+            : new HashSet<TsBeanModel>();
+        final String parentClassName = parentBean != null
+            ? getBeanModelClassName(parentBean) + "Fields"
+            : "Fields";
+        writer.writeIndentedLine("");
+        writer.writeIndentedLine(
+            "class " + getBeanModelClassName(bean) + "Fields extends " + parentClassName + " {");
+        writer.writeIndentedLine(
+            settings.indentString + "constructor(parent?: Fields, name?: string) { super(parent, name); }");
+        for (TsPropertyModel property : bean.getProperties()) {
+            writeBeanProperty(writer, settings, model, bean, property);
+        }
+        writer.writeIndentedLine("}");
+
+        emittedBeans.add(bean);
+        return emittedBeans;
+    }
+
+    private static TsBeanModel getBeanModelByType(TsModel model, TsType type) {
+        for (TsBeanModel curBean : model.getBeans()) {
+            if (curBean.getName().equals(type)) {
+                return curBean;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * return a class name formatted for rendering in code
+     * as part of another class name (so, for generics, strip
+     * the type arguments)
+     */
+    private static String getBeanModelClassName(TsBeanModel bean) {
+        return bean.getName() instanceof GenericReferenceType
+            ? ((GenericReferenceType)bean.getName()).symbol.toString()
+            : bean.getName().toString();
+    }
+
+    private static void writeBeanProperty(
+        Writer writer, Settings settings, TsModel model, TsBeanModel bean,
+        TsPropertyModel property) {
+        TsBeanModel fieldBeanModel = getBeanModelByType(model, property.getTsType());
+        String fieldClassName = fieldBeanModel != null ? getBeanModelClassName(fieldBeanModel) : "";
+        writer.writeIndentedLine(
+            settings.indentString + property.getName() + " = new " + fieldClassName + "Fields(this, \"" + property.getName() + "\");");
+    }
+
+    private static void createBeanFieldConstant(Writer writer, boolean exportKeyword, TsBeanModel bean) {
+        writer.writeIndentedLine((exportKeyword ? "export " : "")
+            + "const " + getBeanModelClassName(bean) + " = new " + getBeanModelClassName(bean) + "Fields();");
+    }
+}

typescript-generator-core/src/test/java/cz/habarta/typescript/generator/ext/BeanPropertyPathExtensionTest.java

@@ -0,0 +1,49 @@
+package cz.habarta.typescript.generator.ext;
+
+import java.util.Arrays;
+import cz.habarta.typescript.generator.TypeProcessor;
+import cz.habarta.typescript.generator.DefaultTypeProcessor;
+import cz.habarta.typescript.generator.Settings;
+import cz.habarta.typescript.generator.compiler.ModelCompiler;
+import cz.habarta.typescript.generator.emitter.EmitterExtension;
+import cz.habarta.typescript.generator.emitter.TsModel;
+import cz.habarta.typescript.generator.ext.BeanPropertyPathExtension;
+import cz.habarta.typescript.generator.parser.Jackson2Parser;
+import cz.habarta.typescript.generator.parser.Model;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class BeanPropertyPathExtensionTest {
+
+    static class ClassA {
+        public String field1;
+        public ClassB field2;
+    }
+
+    static class ClassB {
+        public int field1;
+    }
+
+    @Test
+    public void basicTest() {
+        final StringBuilder data = new StringBuilder();
+        final EmitterExtension.Writer writer = new EmitterExtension.Writer() {
+            @Override
+            public void writeIndentedLine(String line) {
+                data.append(line + "\n");
+            }
+        };
+        final Settings settings = new Settings();
+        settings.sortDeclarations = true;
+        final TypeProcessor typeProcessor = new DefaultTypeProcessor();
+        final Model model = new Jackson2Parser(settings, typeProcessor).parseModel(ClassA.class);
+        final TsModel tsModel = new ModelCompiler(settings, typeProcessor).javaToTypeScript(model);
+        new BeanPropertyPathExtension().emitElements(writer, settings, false, tsModel);
+        String dataStr = data.toString();
+        Assert.assertEquals(29, dataStr.split("\n").length);
+        Assert.assertTrue(dataStr.contains("class ClassAFields"));
+        Assert.assertTrue(dataStr.contains("class ClassBFields"));
+    }
+}