feat: implement rustdoc comment generation support

lib/codegen/fromcto/rust/rustvisitor.js

@@ -304,6 +304,7 @@ class RustVisitor {
      * @private
      */
     visitClassDeclaration(classDeclaration, parameters) {
+        this.writeDescription(classDeclaration, parameters, 0);
         parameters.fileWriter.writeLine(
             0,
             '#[derive(Debug, Clone, Serialize, Deserialize)]'
@@ -513,6 +514,8 @@ class RustVisitor {
             if (field.isOptional?.()) {
                 hashMapType = this.wrapAsOption(hashMapType);
             }
+            // Add description for HashMap fields
+            this.writeDescription(field, parameters, 1);
 
             // Generate serde attributes for HashMap with DateTime serialization support
             parameters.fileWriter.writeLine(1, '#[serde(');
@@ -607,6 +610,10 @@ class RustVisitor {
         }
 
         // Handle regular (non-HashMap) fields
+
+        // Add description for regular fields
+        this.writeDescription(field, parameters, 1);
+
         parameters.fileWriter.writeLine(1, '#[serde(');
         parameters.fileWriter.writeLine(2, `rename = "${field.name}",`);
         if (field.isOptional?.()) {
@@ -752,6 +759,7 @@ class RustVisitor {
         if (relationshipDeclaration.isOptional?.()) {
             type = `Option<${type}>`;
         }
+        this.writeDescription(relationshipDeclaration, parameters, 1);
 
         // Start serde attribute block
         parameters.fileWriter.writeLine(1, '#[serde(');
@@ -1327,6 +1335,31 @@ class RustVisitor {
 
         parameters.fileWriter.closeFile();
     }
+    /**
+     * Writes the description of a declaration or property as a Rust documentation comment.
+     * @param {Object} thing - the declaration or property
+     * @param {Object} parameters - the parameters
+     * @param {number} indent - the indentation level
+     * @private
+     */
+    writeDescription(thing, parameters, indent) {
+        if (thing.getDescription && thing.getDescription()) {
+            const description = thing.getDescription();
+            // Split by newline to handle multi-line comments cleanly
+            const lines = description.split(/\r?\n/);
+            lines.forEach(line => {
+                // Preserve leading whitespace (important for Markdown),
+                // but trim trailing whitespace. For blank lines, emit
+                // "///" without a trailing space.
+                const trimmedEnd = line.replace(/\s+$/, '');
+                if (trimmedEnd === '') {
+                    parameters.fileWriter.writeLine(indent, '///');
+                } else {
+                    parameters.fileWriter.writeLine(indent, `/// ${trimmedEnd}`);
+                }
+            });
+        }
+    }
 }
 
 module.exports = RustVisitor;