GROOVY-11923: Provide a groovy-csv optional module

settings.gradle

@@ -78,6 +78,7 @@ def subprojects = [
         'groovy-test-junit5',
         'groovy-test-junit6',
         'groovy-testng',
+        'groovy-csv',
         'groovy-toml',
         'groovy-typecheckers',
         'groovy-xml',

subprojects/groovy-csv/build.gradle

@@ -0,0 +1,35 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you 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.
+ */
+plugins {
+    id 'org.apache.groovy-library'
+}
+
+dependencies {
+    api rootProject
+    implementation "com.fasterxml.jackson.dataformat:jackson-dataformat-csv:${versions.jackson}"
+    implementation "com.fasterxml.jackson.core:jackson-databind:${versions.jackson}"
+    testImplementation projects.groovyTest
+    testRuntimeOnly "com.fasterxml.jackson.core:jackson-annotations:${versions.jacksonAnnotations}"
+    testRuntimeOnly projects.groovyAnt // for JavadocAssertionTests
+}
+
+groovyLibrary {
+    optionalModule()
+    withoutBinaryCompatibilityChecks()
+}

subprojects/groovy-csv/src/main/java/groovy/csv/CsvBuilder.java

@@ -0,0 +1,160 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you 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 groovy.csv;
+
+import com.fasterxml.jackson.dataformat.csv.CsvMapper;
+import com.fasterxml.jackson.dataformat.csv.CsvSchema;
+import groovy.lang.Writable;
+import org.apache.groovy.lang.annotation.Incubating;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.util.Collection;
+import java.util.Map;
+
+/**
+ * Builds CSV output from collections of maps or typed objects.
+ * <p>
+ * Example with maps:
+ * <pre><code class="groovyTestCase">
+ * def data = [[name: 'Alice', age: 30], [name: 'Bob', age: 25]]
+ * def csv = groovy.csv.CsvBuilder.toCsv(data)
+ * assert csv.contains('name,age')
+ * assert csv.contains('Alice,30')
+ * </code></pre>
+ *
+ * @since 6.0.0
+ */
+@Incubating
+public class CsvBuilder implements Writable {
+    private final CsvMapper mapper;
+    private char separator = ',';
+    private char quoteChar = '"';
+    private String content;
+
+    public CsvBuilder() {
+        this.mapper = new CsvMapper();
+    }
+
+    /**
+     * Set the column separator character (default: comma).
+     *
+     * @param separator the separator character
+     * @return this builder for chaining
+     */
+    public CsvBuilder setSeparator(char separator) {
+        this.separator = separator;
+        return this;
+    }
+
+    /**
+     * Set the quote character (default: double-quote).
+     *
+     * @param quoteChar the quote character
+     * @return this builder for chaining
+     */
+    public CsvBuilder setQuoteChar(char quoteChar) {
+        this.quoteChar = quoteChar;
+        return this;
+    }
+
+    /**
+     * Convert a collection of maps to CSV.
+     * The keys of the first map are used as column headers.
+     *
+     * @param data the collection of maps
+     * @return the CSV string
+     */
+    public static String toCsv(Collection<? extends Map<String, ?>> data) {
+        if (data == null || data.isEmpty()) {
+            return "";
+        }
+        CsvMapper csvMapper = new CsvMapper();
+        Map<String, ?> first = data.iterator().next();
+        CsvSchema.Builder schemaBuilder = CsvSchema.builder();
+        for (String key : first.keySet()) {
+            schemaBuilder.addColumn(key);
+        }
+        CsvSchema schema = schemaBuilder.build().withHeader();
+        try {
+            return csvMapper.writer(schema).writeValueAsString(data);
+        } catch (IOException e) {
+            throw new CsvRuntimeException(e);
+        }
+    }
+
+    /**
+     * Convert a collection of typed objects to CSV using Jackson databinding.
+     * Supports {@code @JsonProperty} and {@code @JsonFormat} annotations.
+     *
+     * @param data the collection of objects
+     * @param type the object type (used to derive the schema)
+     * @param <T> the object type
+     * @return the CSV string
+     */
+    public static <T> String toCsv(Collection<T> data, Class<T> type) {
+        if (data == null || data.isEmpty()) {
+            return "";
+        }
+        CsvMapper csvMapper = new CsvMapper();
+        CsvSchema schema = csvMapper.schemaFor(type).withHeader();
+        try {
+            return csvMapper.writer(schema).writeValueAsString(data);
+        } catch (IOException e) {
+            throw new CsvRuntimeException(e);
+        }
+    }
+
+    /**
+     * Build CSV from a collection of maps.
+     *
+     * @param data the collection of maps
+     * @return this builder
+     */
+    public CsvBuilder call(Collection<? extends Map<String, ?>> data) {
+        if (data == null || data.isEmpty()) {
+            this.content = "";
+            return this;
+        }
+        Map<String, ?> first = data.iterator().next();
+        CsvSchema.Builder schemaBuilder = CsvSchema.builder()
+                .setColumnSeparator(separator)
+                .setQuoteChar(quoteChar);
+        for (String key : first.keySet()) {
+            schemaBuilder.addColumn(key);
+        }
+        CsvSchema schema = schemaBuilder.build().withHeader();
+        try {
+            this.content = mapper.writer(schema).writeValueAsString(data);
+        } catch (IOException e) {
+            throw new CsvRuntimeException(e);
+        }
+        return this;
+    }
+
+    @Override
+    public String toString() {
+        return content != null ? content : "";
+    }
+
+    @Override
+    public Writer writeTo(Writer out) throws IOException {
+        return out.append(toString());
+    }
+}

subprojects/groovy-csv/src/main/java/groovy/csv/CsvRuntimeException.java

@@ -0,0 +1,44 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you 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 groovy.csv;
+
+import groovy.lang.GroovyRuntimeException;
+import org.apache.groovy.lang.annotation.Incubating;
+
+/**
+ * Represents runtime exception occurred when parsing or building CSV
+ *
+ * @since 6.0.0
+ */
+@Incubating
+public class CsvRuntimeException extends GroovyRuntimeException {
+    private static final long serialVersionUID = 2809672072790437945L;
+
+    public CsvRuntimeException(String msg) {
+        super(msg);
+    }
+
+    public CsvRuntimeException(Throwable cause) {
+        super(cause);
+    }
+
+    public CsvRuntimeException(String msg, Throwable cause) {
+        super(msg, cause);
+    }
+}