[composer][samplecode]Add writeSampleCode method

src/main/java/com/google/api/generator/gapic/composer/samplecode/BUILD.bazel

@@ -13,6 +13,8 @@ java_library(
         ":samplecode_files",
     ],
     deps = [
+        "//src/main/java/com/google/api/generator/engine/ast",
+        "//src/main/java/com/google/api/generator/engine/writer",
         "@google_java_format_all_deps//jar",
     ],
 )

src/main/java/com/google/api/generator/gapic/composer/samplecode/SampleCodeWriter.java

@@ -0,0 +1,35 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.api.generator.gapic.composer.samplecode;
+
+import com.google.api.generator.engine.ast.Statement;
+import com.google.api.generator.engine.writer.JavaWriterVisitor;
+import java.util.Arrays;
+import java.util.List;
+
+public final class SampleCodeWriter {
+
+  public static String writeSampleCode(Statement ... statement) {
+    return writeSampleCode(Arrays.asList(statement));
+  }
+
+  public static String writeSampleCode(List<Statement> statements) {
+    JavaWriterVisitor visitor = new JavaWriterVisitor();
+    for (Statement statement : statements) {
+      statement.accept(visitor);
+    }
+    return SampleCodeJavaFormatter.format(visitor.write());
+  }
+}

src/test/java/com/google/api/generator/gapic/composer/samplecode/BUILD.bazel

@@ -4,6 +4,7 @@ package(default_visibility = ["//visibility:public"])
 
 TESTS = [
     "SampleCodeJavaFormatterTest",
+    "SampleCodeWriterTest"
 ]
 
 filegroup(
@@ -19,7 +20,9 @@ filegroup(
         "//src/main/java/com/google/api/generator/engine/ast",
         "//src/main/java/com/google/api/generator/engine/writer",
         "//src/main/java/com/google/api/generator/gapic/composer/samplecode",
+        "//src/main/java/com/google/api/generator/gapic/model",
         "@com_google_truth_truth//jar",
         "@junit_junit//jar",
+        "@com_google_api_gax_java//gax",
     ],
 ) for test_name in TESTS]

src/test/java/com/google/api/generator/gapic/composer/samplecode/SampleCodeWriterTest.java

@@ -0,0 +1,84 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.api.generator.gapic.composer.samplecode;
+
+import static junit.framework.TestCase.assertEquals;
+
+import com.google.api.gax.rpc.ClientSettings;
+import com.google.api.generator.engine.ast.AssignmentExpr;
+import com.google.api.generator.engine.ast.ConcreteReference;
+import com.google.api.generator.engine.ast.Expr;
+import com.google.api.generator.engine.ast.ExprStatement;
+import com.google.api.generator.engine.ast.MethodInvocationExpr;
+import com.google.api.generator.engine.ast.PrimitiveValue;
+import com.google.api.generator.engine.ast.Reference;
+import com.google.api.generator.engine.ast.TypeNode;
+import com.google.api.generator.engine.ast.Statement;
+import com.google.api.generator.engine.ast.TryCatchStatement;
+import com.google.api.generator.engine.ast.ValueExpr;
+import com.google.api.generator.engine.ast.Variable;
+import com.google.api.generator.engine.ast.VariableExpr;
+import com.google.api.generator.gapic.model.Method;
+import java.lang.reflect.Array;
+import java.util.Arrays;
+import org.junit.Test;
+
+public class SampleCodeWriterTest {
+  @Test
+  public void writeSampleCode_statements() {
+    TypeNode settingType = TypeNode.withReference(ConcreteReference.withClazz(ClientSettings.class));
+    Variable aVar = Variable.builder().setName("clientSettings").setType(settingType).build();
+    VariableExpr aVarExpr = VariableExpr.withVariable(aVar);
+    MethodInvocationExpr aValueExpr = MethodInvocationExpr.builder()
+        .setExprReferenceExpr(MethodInvocationExpr.builder()
+        .setMethodName("newBuilder")
+        .setStaticReferenceType(settingType)
+        .build())
+        .setReturnType(settingType)
+        .setMethodName("build")
+        .build();
+    AssignmentExpr assignmentExpr = AssignmentExpr.builder()
+        .setVariableExpr(aVarExpr.toBuilder().setIsDecl(true).build())
+        .setValueExpr(aValueExpr)
+        .build();
+    Statement sampleStatement = TryCatchStatement.builder()
+        .setTryResourceExpr(createAssignmentExpr("aBool", "false", TypeNode.BOOLEAN))
+        .setTryBody(Arrays.asList(ExprStatement.withExpr(createAssignmentExpr("x", "3", TypeNode.INT))))
+        .setIsSampleCode(true)
+        .build();
+    String result = SampleCodeWriter.writeSampleCode(
+        ExprStatement.withExpr(assignmentExpr),
+            sampleStatement);
+    String expected = "ClientSettings clientSettings = ClientSettings.newBuilder().build();\n"
+        + "try (boolean aBool = false) {\n"
+        + "  int x = 3;\n"
+        + "}";
+    assertEquals(expected, result);
+  }
+
+  private AssignmentExpr createAssignmentExpr(String varName, String varValue, TypeNode type) {
+    Variable variable = Variable.builder().setName(varName).setType(type).build();
+    VariableExpr variableExpr =
+        VariableExpr.builder()
+            .setVariable(variable)
+            .setIsDecl(true)
+            .build();
+    return AssignmentExpr.builder()
+        .setVariableExpr(variableExpr)
+        .setValueExpr(ValueExpr.withValue(PrimitiveValue.builder().setType(type).setValue(varValue).build()))
+        .build();
+  }
+
+}