Formatter for printing ReportNode

commons/src/main/java/com/powsybl/commons/report/Formatter.java

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) 2025, RTE (http://www.rte-france.com)
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+package com.powsybl.commons.report;
+
+/**
+ * @author Florian Dupuy {@literal <florian.dupuy at rte-france.com>}
+ */
+@FunctionalInterface
+public interface Formatter {
+    Formatter DEFAULT = t -> t.getValue().toString();
+
+    String format(TypedValue value);
+}

commons/src/main/java/com/powsybl/commons/report/ReportNode.java

@@ -88,7 +88,17 @@ static ReportNodeBuilder newRootReportNode() {
      * corresponding values, either contained in current node or in one of its parents.
      * @return the message
      */
-    String getMessage();
+    default String getMessage() {
+        return getMessage(Formatter.DEFAULT);
+    }
+
+    /**
+     * Get the message of current node, replacing <code>${key}</code> references in the message template with the
+     * corresponding values, either contained in current node or in one of its parents.
+     * @param formatter the formatter to use to transform any value into a string
+     * @return the message
+     */
+    String getMessage(Formatter formatter);
 
     /**
      * Get the values which belong to current node (does not include the inherited values)
@@ -138,17 +148,35 @@ static ReportNodeBuilder newRootReportNode() {
 
     /**
      * Print to given path the current report node and its descendants
-     * @param path the writer to write to
+     * @param path the path to write to
      */
     default void print(Path path) throws IOException {
+        print(path, Formatter.DEFAULT);
+    }
+
+    /**
+     * Print to given path the current report node and its descendants
+     * @param path the path to write to
+     * @param formatter the formatter to use to print values
+     */
+    default void print(Path path, Formatter formatter) throws IOException {
         try (Writer writer = Files.newBufferedWriter(path, StandardCharsets.UTF_8)) {
-            print(writer);
+            print(writer, formatter);
         }
     }
 
     /**
      * Print to given writer the current report node and its descendants
      * @param writer the writer to write to
      */
-    void print(Writer writer) throws IOException;
+    default void print(Writer writer) throws IOException {
+        print(writer, Formatter.DEFAULT);
+    }
+
+    /**
+     * Print to given writer the current report node and its descendants
+     * @param writer the writer to write to
+     * @param formatter the formatter to use to print values
+     */
+    void print(Writer writer, Formatter formatter) throws IOException;
 }

commons/src/main/java/com/powsybl/commons/report/ReportNodeImpl.java

@@ -109,14 +109,14 @@ public Map<String, TypedValue> getValues() {
     }
 
     @Override
-    public String getMessage() {
+    public String getMessage(Formatter formatter) {
         return Optional.ofNullable(getTreeContext().getDictionary().get(messageKey))
-                .map(messageTemplate -> new StringSubstitutor(vk -> getValueAsString(vk).orElse(null)).replace(messageTemplate))
+                .map(messageTemplate -> new StringSubstitutor(vk -> getValueAsString(vk, formatter).orElse(null)).replace(messageTemplate))
                 .orElse("(missing message key in dictionary)");
     }
 
-    public Optional<String> getValueAsString(String valueKey) {
-        return getValue(valueKey).map(TypedValue::getValue).map(Object::toString);
+    public Optional<String> getValueAsString(String valueKey, Formatter formatter) {
+        return getValue(valueKey).map(formatter::format);
     }
 
     @Override
@@ -183,24 +183,24 @@ public List<ReportNode> getChildren() {
     }
 
     @Override
-    public void print(Writer writer) throws IOException {
-        print(writer, "");
+    public void print(Writer writer, Formatter formatter) throws IOException {
+        print(writer, "", formatter);
     }
 
-    private void print(Writer writer, String indentationStart) throws IOException {
+    private void print(Writer writer, String indentationStart, Formatter formatter) throws IOException {
         if (children.isEmpty()) {
-            print(writer, indentationStart, "");
+            print(writer, indentationStart, "", formatter);
         } else {
-            print(writer, indentationStart, "+ ");
+            print(writer, indentationStart, "+ ", formatter);
             String childrenIndent = indentationStart + "   ";
             for (ReportNodeImpl child : children) {
-                child.print(writer, childrenIndent);
+                child.print(writer, childrenIndent, formatter);
             }
         }
     }
 
-    private void print(Writer writer, String indent, String prefix) throws IOException {
-        writer.append(indent).append(prefix).append(getMessage()).append(System.lineSeparator());
+    private void print(Writer writer, String indent, String prefix, Formatter formatter) throws IOException {
+        writer.append(indent).append(prefix).append(getMessage(formatter)).append(System.lineSeparator());
     }
 
     public static ReportNodeImpl parseJsonNode(JsonParser parser, ObjectMapper objectMapper, TreeContextImpl treeContext, ReportNodeVersion version) throws IOException {

commons/src/main/java/com/powsybl/commons/report/ReportNodeNoOp.java

@@ -45,7 +45,7 @@ public String getMessageTemplate() {
     }
 
     @Override
-    public String getMessage() {
+    public String getMessage(Formatter formatter) {
         return null;
     }
 
@@ -70,7 +70,7 @@ public void writeJson(JsonGenerator generator) throws IOException {
     }
 
     @Override
-    public void print(Writer writer) throws IOException {
+    public void print(Writer writer, Formatter formatter) throws IOException {
         // No-op
     }
 

commons/src/test/java/com/powsybl/commons/report/FormatterTest.java

@@ -0,0 +1,57 @@
+/**
+ * Copyright (c) 2025, RTE (http://www.rte-france.com)
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+package com.powsybl.commons.report;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Locale;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author Florian Dupuy {@literal <florian.dupuy at rte-france.com>}
+ */
+class FormatterTest {
+
+    @Test
+    void test() {
+        ReportNode root = ReportNode.newRootReportNode()
+                .withMessageTemplate("formatTest", """
+                        Formatter test message
+                        double default format: ${doubleDefaultFormat}
+                        double format based on type: ${doubleSpecificFormat}
+                        float format based on type: ${floatSpecificFormat}
+                        string default format: ${stringDefaultFormat}
+                        string format based on type: ${stringSpecificFormat}""")
+                .withUntypedValue("doubleDefaultFormat", 4.35684975)
+                .withTypedValue("doubleSpecificFormat", 4.4664798548, TypedValue.ACTIVE_POWER)
+                .withTypedValue("floatSpecificFormat", 0.6f, TypedValue.IMPEDANCE)
+                .withUntypedValue("stringDefaultFormat", "tiny")
+                .withTypedValue("stringSpecificFormat", "This is a sentence which needs to be truncated", "LONG_SENTENCE")
+                .build();
+        Formatter customFormatter = typedValue -> {
+            if (typedValue.getType().equals(TypedValue.ACTIVE_POWER) && typedValue.getValue() instanceof Double d) {
+                return String.format(Locale.CANADA_FRENCH, "%2.4f", d);
+            }
+            if (typedValue.getType().equals(TypedValue.IMPEDANCE) && typedValue.getValue() instanceof Float f) {
+                return String.format(Locale.CANADA_FRENCH, "%.2f", f);
+            }
+            if (typedValue.getType().equals("LONG_SENTENCE") && typedValue.getValue() instanceof String s) {
+                return s.substring(0, 18);
+            }
+            return typedValue.getValue().toString();
+        };
+        assertEquals("""
+                        Formatter test message
+                        double default format: 4.35684975
+                        double format based on type: 4,4665
+                        float format based on type: 0,60
+                        string default format: tiny
+                        string format based on type: This is a sentence""", root.getMessage(customFormatter));
+    }
+}

docs/user/functional_logs/export.md

@@ -47,17 +47,26 @@ An example of the current version 2.1 of the serialization is below:
 ```
 
 ## Display format
-In order to have an overview of a report node, two print methods are provided in the API:
-- for printing to a `Path`
+To get an overview of a report node, several print methods are provided in the API, with the possibility to provide your own `Formatter` -
+`Formatter` is a functional interface that specifies how to get a `String` from a `TypedValue`.
+- To print to a `Path`:
 ```java
 reportNode.print(path);
+reportNode.print(path, formatter);
 ```
-- for printing to a `Writer`
+- To print to a `Writer`:
 ```java
 reportNode.print(writer);
+reportNode.print(writer, formatter);
 ```
 
-The correspond multiline string of above example is below.
+In both cases, giving a custom formatter allows to do specific formatting based on types for instance.
+If no formatter is provided, the default one is used:
+```java
+typedValue -> typedValue.getValue().toString()
+```
+
+The corresponding multiline string of above example is below.
 The `+` character and the indentation are used to show the tree hierarchy.
 ```text
 + template with typed value