start with write

amqp_codegen/src/main.rs

@@ -1,9 +1,11 @@
 mod parser;
+mod write;
 
 use crate::parser::codegen_parser;
 use heck::ToUpperCamelCase;
 use std::fs;
 use strong_xml::XmlRead;
+use crate::write::codegen_write;
 
 #[derive(Debug, XmlRead)]
 #[xml(tag = "amqp")]
@@ -87,6 +89,7 @@ fn codegen(amqp: &Amqp) {
     codegen_domain_defs(amqp);
     codegen_class_defs(amqp);
     codegen_parser(amqp);
+    codegen_write(amqp);
 }
 
 fn codegen_domain_defs(amqp: &Amqp) {

amqp_codegen/src/write.rs

@@ -0,0 +1,48 @@
+use crate::{field_type, resolve_type_from_domain, snake_case, Amqp};
+use heck::ToUpperCamelCase;
+
+pub(crate) fn codegen_write(amqp: &Amqp) {
+    println!(
+        "mod write {{
+use super::*;
+use crate::classes::write_helper::*;
+use crate::error::TransError;
+use std::io::Write;
+
+pub fn write_method<W: Write>(class: Class, mut writer: W) -> Result<(), TransError> {{
+    match class {{"
+    );
+
+    for class in &amqp.classes {
+        let class_name = class.name.to_upper_camel_case();
+        let class_index = class.index;
+        for method in &class.methods {
+            let method_name = method.name.to_upper_camel_case();
+            let method_index = method.index;
+            println!("        Class::{class_name}({class_name}::{method_name} {{");
+            for field in &method.fields {
+                let field_name = snake_case(&field.name);
+                println!("            {field_name},");
+            }
+            println!("        }}) => {{");
+            println!("            writer.write_all(&[{class_index}, {method_index}])?;");
+            for field in &method.fields {
+                let field_name = snake_case(&field.name);
+                let field_type = resolve_type_from_domain(amqp, field_type(field));
+                if field_type == "bit" {
+                    println!("            todo!();");
+                } else {
+                    println!("            {field_type}({field_name}, &mut writer)?;");
+                }
+            }
+            println!("        }}");
+        }
+    }
+
+    println!(
+        "    }}
+    Ok(())
+}}
+}}"
+    );
+}