component_model_meta 0.16.0

//! Component model unified derive macro implementation

use macro_tools ::prelude :: *;
use macro_tools :: { attr, diag };

/// Generate `ComponentModel` derive implementation
/// 
/// This macro combines all existing component model derives :
/// - `Assign` : Basic component assignment
/// - `ComponentsAssign` : Multiple component assignment from tuples  
/// - `ComponentFrom` : Create objects from single components
/// - `FromComponents` : Create objects from multiple components
#[ allow(clippy ::too_many_lines, clippy ::manual_let_else, clippy ::explicit_iter_loop) ]
pub fn component_model( input: proc_macro ::TokenStream ) -> Result< proc_macro2 ::TokenStream, syn ::Error >
{
  let original_input = input.clone();
  let parsed = syn ::parse :: < syn ::DeriveInput >( input )?;
  
  // Extract debug attribute if present (Design Rule: Proc Macros Must Have debug Attribute)
  let debug = attr ::has_debug( parsed.attrs.iter() )?;
  
  let struct_name = &parsed.ident;
  let generics = &parsed.generics;
  let ( impl_generics, ty_generics, where_clause ) = generics.split_for_impl();
  
  // Only work with structs for now
  let data_struct = match &parsed.data
  {
  syn ::Data ::Struct( data_struct ) => data_struct,
  _ => return Err( syn_err!( parsed.span(), "ComponentModel can only be applied to structs" ) ),
 };

  // Extract field information
  let fields = match &data_struct.fields
  {
  syn ::Fields ::Named( fields ) => &fields.named,
  _ => return Err( syn_err!( parsed.span(), "ComponentModel requires named fields" ) ),
 };

  let mut result = proc_macro2 ::TokenStream ::new();

  // Collect unique field types to avoid conflicts
  let mut seen_types = std ::collections ::HashSet ::new();
  let mut unique_fields = Vec ::new();
  
  for field in fields.iter()
  {
  let field_type = &field.ty;
  let type_string = quote ::quote!( #field_type ).to_string();
  
  if seen_types.insert( type_string )
  {
   unique_fields.push( field );
 }
 }

  // Generate field-specific methods for ALL fields to avoid type ambiguity
  for field in fields.iter()
  {
  let field_name = field.ident.as_ref().unwrap();
  let field_type = &field.ty;
  
  // Generate field-specific assignment methods to avoid type ambiguity
  let field_name_str = field_name.to_string();
  let clean_field_name =  if field_name_str.starts_with("r#") 
  {
   field_name_str.trim_start_matches("r#")
 } else {
   &field_name_str
 };
  let set_method_name = syn ::Ident ::new( &format!( "{clean_field_name}_set" ), field_name.span() );
  let with_method_name = syn ::Ident ::new( &format!( "{clean_field_name}_with" ), field_name.span() );
  
  let field_specific_methods =  if generics.params.is_empty() 
  {
   quote ::quote!
   {
  impl #struct_name
  {
   /// Field-specific setter method to avoid type ambiguity
   #[ inline( always ) ]
   pub fn #set_method_name < IntoT >( &mut self, component: IntoT )
   where
  IntoT: Into< #field_type >
   {
  self.#field_name = component.into();
 }
   
   /// Field-specific builder method for fluent pattern
   #[ inline( always ) ]
   #[ must_use ]
   pub fn #with_method_name < IntoT >( mut self, component: IntoT ) -> Self
   where
  IntoT: Into< #field_type >
   {
  self.#field_name = component.into();
  self
 }
 }
 }
 } else {
   quote ::quote!
   {
  impl #impl_generics #struct_name #ty_generics
  #where_clause
  {
   /// Field-specific setter method to avoid type ambiguity
   #[ inline( always ) ]
   pub fn #set_method_name < IntoT >( &mut self, component: IntoT )
   where
  IntoT: Into< #field_type >
   {
  self.#field_name = component.into();
 }
   
   /// Field-specific builder method for fluent pattern  
   #[ inline( always ) ]
   #[ must_use ]
   pub fn #with_method_name < IntoT >( mut self, component: IntoT ) -> Self
   where
  IntoT: Into< #field_type >
   {
  self.#field_name = component.into();
  self
 }
 }
 }
 };
  
  result.extend( field_specific_methods );
 }

  // Generate Assign implementations only for unique field types to avoid conflicts
  for field in unique_fields.iter()
  {
  let field_name = field.ident.as_ref().unwrap();
  let field_type = &field.ty;
  
  // Check if this is a popular type that needs special handling
  let _type_str = quote ::quote!( #field_type ).to_string();
  let popular_impls = crate ::popular_types ::generate_popular_type_assigns( 
   struct_name, 
   field_name, 
   field_type,
   generics,
   &impl_generics,
   &ty_generics,
   where_clause
 );
  
  if popular_impls.is_empty()
  {
   // Generate standard Assign implementation using Into trait for non-popular types
   let assign_impl =  if generics.params.is_empty() 
  {
  quote ::quote!
  {
   impl< IntoT > component_model_types ::Assign< #field_type, IntoT > for #struct_name
   where
  IntoT: Into< #field_type >
   {
  #[ inline( always ) ]
  fn assign( &mut self, component: IntoT )
  {
   self.#field_name = component.into();
 }
 }
 }
 } else {
  quote ::quote!
  {
   impl< #impl_generics, IntoT > component_model_types ::Assign< #field_type, IntoT > for #struct_name #ty_generics
   where
  IntoT: Into< #field_type >,
  #where_clause
   {
  #[ inline( always ) ]
  fn assign( &mut self, component: IntoT )
  {
   self.#field_name = component.into();
 }
 }
 }
 };
   
   result.extend( assign_impl );
 }
  else
  {
   // For popular types, generate specific implementations instead of generic Into
   for impl_tokens in popular_impls
   {
  result.extend( impl_tokens );
 }
 }
 }
  
  // Generate ComponentFrom implementations for unique field types
  for field in unique_fields.iter()
  {
  let field_name = field.ident.as_ref().unwrap();
  let field_type = &field.ty;
  
  let _component_from_impl = quote ::quote!
  {
   impl From< &#struct_name #ty_generics > for #field_type
   where
  #field_type: Clone,
  #where_clause
   {
  #[ inline( always ) ]
  fn from( src: &#struct_name #ty_generics ) -> Self
  {
   src.#field_name.clone()
 }
 }
 };
  
  // For now, skip to avoid conflicts with existing From implementations
  // TODO: Add proper conflict detection and resolution
  // result.extend( component_from_impl );
 }

  if debug
  {
  let about = format!("derive: ComponentModel\nstructure: {struct_name}");
  diag ::report_print(about, original_input, &result);
 }

  Ok( result )
}