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use proc_macro_error2::emit_error;
use proc_macro2::TokenStream as TokenStream2;
use quote::{ToTokens, format_ident, quote};
use std::collections::HashMap;
use crate::Model;
use crate::model::{AliasAttribute, Field, FieldAttributeOuter};
pub struct BuildMetadataGen<'a> {
model: &'a Model,
}
impl<'a> BuildMetadataGen<'a> {
pub fn new(model: &'a Model) -> Self {
Self { model }
}
fn is_clock_type(&self, ty: &syn::Type) -> bool {
match ty {
syn::Type::Path(type_path) => type_path
.path
.segments
.last()
.map(|segment| segment.ident == "Clock")
.unwrap_or(false),
_ => false,
}
}
fn is_float_type(&self, ty: &syn::Type) -> bool {
match ty {
syn::Type::Path(type_path) => {
let last = type_path.path.segments.last();
match last.map(|segment| segment.ident.to_string()) {
Some(ident) if ident == "f32" || ident == "f64" => true,
Some(ident) if ident == "Vec" => segment_has_float_arg(last),
Some(ident) if ident == "Option" => segment_has_float_arg(last),
Some(ident) if ident == "Box" => segment_has_float_arg(last),
_ => false,
}
}
syn::Type::Array(array) => self.is_float_type(&array.elem),
syn::Type::Reference(reference) => self.is_float_type(&reference.elem),
_ => false,
}
}
}
fn segment_has_float_arg(segment: Option<&syn::PathSegment>) -> bool {
let Some(segment) = segment else {
return false;
};
let syn::PathArguments::AngleBracketed(args) = &segment.arguments else {
return false;
};
args.args.iter().any(|arg| match arg {
syn::GenericArgument::Type(ty) => matches_float_type(ty),
_ => false,
})
}
fn matches_float_type(ty: &syn::Type) -> bool {
match ty {
syn::Type::Path(type_path) => type_path
.path
.segments
.last()
.map(|segment| matches!(segment.ident.to_string().as_str(), "f32" | "f64"))
.unwrap_or(false),
syn::Type::Array(array) => matches_float_type(&array.elem),
syn::Type::Reference(reference) => matches_float_type(&reference.elem),
_ => false,
}
}
impl ToTokens for BuildMetadataGen<'_> {
fn to_tokens(&self, tokens: &mut TokenStream2) {
let prefix_binding = quote! { prefix.unwrap_or("") };
// Build a map of field names to their assigned value references
let mut field_name_to_vr = HashMap::new();
let mut current_vr = 0u32; // Start at 0, will be added to vr_offset (1) to get actual VRs starting at 1
// First pass: assign VRs to all fields with variable attributes (excluding skipped ones)
for field in &self.model.fields {
if self.has_skip_attribute(field) {
// Skip fields with skip=true
continue;
}
for attr in &field.attrs {
match attr {
FieldAttributeOuter::Variable(_) => {
field_name_to_vr.insert(field.ident.to_string(), current_vr);
current_vr += 1;
}
FieldAttributeOuter::Alias(_) => {
// Ignore Alias attributes for now
}
FieldAttributeOuter::Child(_) => {
// Child fields are flattened in a later pass; VRs are assigned then
}
FieldAttributeOuter::Terminal(_) => {
// Terminals are handled separately
}
FieldAttributeOuter::Docstring(_) => {
// Skip docstrings
}
}
}
}
let mut variable_tokens = Vec::new();
let mut model_structure_tokens = Vec::new();
let vr_offset_tracking = quote! { let mut current_vr_offset = vr_offset; };
// Second pass: generate the actual variable definitions
for field in &self.model.fields {
if self.has_skip_attribute(field) {
// For fields with skip=true, don't generate anything
continue;
} else if self.is_child_field(field) {
// For child fields, recursively call build_metadata and prefix variable names
let field_type = &field.rust_type;
let field_name = field.ident.to_string();
let child_prefix_lit = self.child_prefix_literal(field, &field_name);
variable_tokens.push(quote! {
let child_prefix = format!("{}{}.", #prefix_binding, #child_prefix_lit);
let field_count = <#field_type as ::fmi_export::fmi3::Model>::build_metadata(
variables,
model_structure,
current_vr_offset,
Some(child_prefix.as_str())
);
current_vr_offset += field_count;
});
} else if self.has_no_variable_attributes(field) {
// For fields with no attributes, recursively call build_metadata
let field_type = &field.rust_type;
variable_tokens.push(quote! {
let field_count = <#field_type as ::fmi_export::fmi3::Model>::build_metadata(variables, model_structure, current_vr_offset, Some(#prefix_binding));
current_vr_offset += field_count;
});
} else {
// Generate variables for this field
for attr in &field.attrs {
match attr {
FieldAttributeOuter::Variable(var_attr) => {
let alias_attrs: Vec<&AliasAttribute> = field
.attrs
.iter()
.filter_map(|attr| match attr {
FieldAttributeOuter::Alias(alias_attr) => Some(alias_attr),
_ => None,
})
.collect();
let mut added_initial_unknown = false;
let var_token = self.generate_variable_definition(
field,
var_attr,
&field.ident.to_string(),
&field_name_to_vr,
&prefix_binding,
&alias_attrs,
);
variable_tokens.push(var_token);
// Generate model structure entries for derivatives
if let Some(derivative_ref) = &var_attr.derivative {
let derivative_name = derivative_ref.to_string();
if field_name_to_vr.contains_key(&derivative_name) {
let current_vr = field_name_to_vr[&field.ident.to_string()];
// Add this field (derivative) to continuous_state_derivative
model_structure_tokens.push(quote! {
model_structure.unknowns.push(::fmi::schema::fmi3::VariableDependency::ContinuousStateDerivative(::fmi::schema::fmi3::Fmi3Unknown {
annotations: None,
value_reference: current_vr_offset + #current_vr,
dependencies: None,
dependencies_kind: None,
}));
});
// Add this field to initial_unknown if it has initial = Calculated
if let Some(initial) = &var_attr.initial {
let initial_schema: ::fmi::fmi3::schema::Initial =
(*initial).into();
if matches!(
initial_schema,
::fmi::fmi3::schema::Initial::Calculated
) {
model_structure_tokens.push(quote! {
model_structure.unknowns.push(::fmi::schema::fmi3::VariableDependency::InitialUnknown(::fmi::schema::fmi3::Fmi3Unknown {
annotations: None,
value_reference: current_vr_offset + #current_vr,
dependencies: None,
dependencies_kind: None,
}));
});
added_initial_unknown = true;
}
}
}
}
// Generate outputs for fields with Output causality
if let Some(causality) = &var_attr.causality {
let causality_schema: ::fmi::fmi3::schema::Causality =
(*causality).into();
if matches!(
causality_schema,
::fmi::fmi3::schema::Causality::Output
) {
let current_vr = field_name_to_vr[&field.ident.to_string()];
// Find if any other field has this field as derivative
let mut derivative_vr = None;
for other_field in &self.model.fields {
for other_attr in &other_field.attrs {
if let FieldAttributeOuter::Variable(other_var_attr) =
other_attr
&& let Some(other_derivative_ref) =
&other_var_attr.derivative
&& other_derivative_ref == &field.ident
&& let Some(&other_vr) = field_name_to_vr
.get(&other_field.ident.to_string())
{
derivative_vr = Some(other_vr);
break;
}
}
if derivative_vr.is_some() {
break;
}
}
if let Some(dep_vr) = derivative_vr {
model_structure_tokens.push(quote! {
model_structure.unknowns.push(::fmi::schema::fmi3::VariableDependency::Output(::fmi::schema::fmi3::Fmi3Unknown {
annotations: None,
value_reference: current_vr_offset + #current_vr,
dependencies: Some(::fmi::schema::utils::AttrList(vec![current_vr_offset + #dep_vr])),
dependencies_kind: Some(::fmi::schema::utils::AttrList(vec![::fmi::schema::fmi3::DependenciesKind::Dependent])),
}));
});
} else {
// Output without dependencies
model_structure_tokens.push(quote! {
model_structure.unknowns.push(::fmi::schema::fmi3::VariableDependency::Output(::fmi::schema::fmi3::Fmi3Unknown {
annotations: None,
value_reference: current_vr_offset + #current_vr,
dependencies: None,
dependencies_kind: None,
}));
});
}
}
}
// Output clocks must be listed in InitialUnknowns
if let Some(causality) = &var_attr.causality {
let causality_schema: ::fmi::fmi3::schema::Causality =
(*causality).into();
if matches!(
causality_schema,
::fmi::fmi3::schema::Causality::Output
) && self.is_clock_type(&field.rust_type)
{
let current_vr = field_name_to_vr[&field.ident.to_string()];
model_structure_tokens.push(quote! {
model_structure.unknowns.push(::fmi::schema::fmi3::VariableDependency::InitialUnknown(::fmi::schema::fmi3::Fmi3Unknown {
annotations: None,
value_reference: current_vr_offset + #current_vr,
dependencies: None,
dependencies_kind: None,
}));
});
}
}
// Generate model structure entries for event indicators
if matches!(var_attr.event_indicator, Some(true)) {
let current_vr = field_name_to_vr[&field.ident.to_string()];
model_structure_tokens.push(quote! {
model_structure.unknowns.push(::fmi::schema::fmi3::VariableDependency::EventIndicator(::fmi::schema::fmi3::Fmi3Unknown {
annotations: None,
value_reference: current_vr_offset + #current_vr,
dependencies: None,
dependencies_kind: None,
}));
});
}
// Add any variable with initial=Calculated to InitialUnknowns
if !added_initial_unknown && let Some(initial) = &var_attr.initial {
let initial_schema: ::fmi::fmi3::schema::Initial =
(*initial).into();
if matches!(
initial_schema,
::fmi::fmi3::schema::Initial::Calculated
) {
// Skip clocked variables; the triggering clock handles initial unknowns.
if var_attr
.clocks
.as_ref()
.is_none_or(|clocks| clocks.is_empty())
{
let current_vr = field_name_to_vr[&field.ident.to_string()];
model_structure_tokens.push(quote! {
model_structure.unknowns.push(::fmi::schema::fmi3::VariableDependency::InitialUnknown(::fmi::schema::fmi3::Fmi3Unknown {
annotations: None,
value_reference: current_vr_offset + #current_vr,
dependencies: None,
dependencies_kind: None,
}));
});
}
}
}
}
FieldAttributeOuter::Alias(_) => {
// Ignore Alias attributes for now
}
FieldAttributeOuter::Child(_) => {
// Child fields are handled separately
}
FieldAttributeOuter::Terminal(_) => {
// Terminals are handled separately
}
FieldAttributeOuter::Docstring(_) => {
// Skip docstrings
}
}
}
}
}
// Count how many variables this model defines
let own_variable_count = field_name_to_vr.len() as u32;
tokens.extend(quote! {
use ::fmi_export::fmi3::FmiVariableBuilder;
use ::fmi::schema::fmi3::AppendToModelVariables;
#vr_offset_tracking
#(#variable_tokens)*
#(#model_structure_tokens)*
current_vr_offset - vr_offset + #own_variable_count
});
}
}
impl BuildMetadataGen<'_> {
/// Check if a field has the skip attribute set to true
fn has_skip_attribute(&self, field: &Field) -> bool {
field
.attrs
.iter()
.any(|attr| matches!(attr, FieldAttributeOuter::Variable(var_attr) if var_attr.skip))
}
/// Check if a field has no variable attributes (ignoring docstrings and aliases)
fn has_no_variable_attributes(&self, field: &Field) -> bool {
!field
.attrs
.iter()
.any(|attr| matches!(attr, FieldAttributeOuter::Variable(_)))
}
fn is_child_field(&self, field: &Field) -> bool {
field
.attrs
.iter()
.any(|attr| matches!(attr, FieldAttributeOuter::Child(_)))
}
fn child_prefix_literal(&self, field: &Field, default_name: &str) -> syn::LitStr {
let prefix = field.attrs.iter().find_map(|attr| {
if let FieldAttributeOuter::Child(child_attr) = attr {
child_attr.prefix.as_deref()
} else {
None
}
});
let prefix = prefix.unwrap_or(default_name);
syn::LitStr::new(prefix, field.ident.span())
}
/// Generate a variable definition for a field
fn generate_variable_definition(
&self,
field: &Field,
var_attr: &crate::model::FieldAttribute,
var_name: &str,
field_name_to_vr: &HashMap<String, u32>,
prefix_binding: &TokenStream2,
alias_attrs: &[&AliasAttribute],
) -> TokenStream2 {
let field_type = &field.rust_type;
let current_vr = field_name_to_vr[var_name];
let is_float = self.is_float_type(&field.rust_type);
// Use the name attribute if specified, otherwise use the field name
let variable_name = var_attr
.name
.clone()
.unwrap_or_else(|| field.ident.to_string());
let variable_name_prefixed = quote! { format!("{}{}", #prefix_binding, #variable_name) };
// Build the variable definition
let mut builder_calls = Vec::new();
// Set causality if specified
if let Some(causality) = &var_attr.causality {
let causality_schema: fmi::fmi3::schema::Causality = (*causality).into();
let causality_str = format!("{:?}", causality_schema);
let causality_variant = format_ident!("{}", causality_str);
builder_calls.push(quote! {
.with_causality(::fmi::fmi3::schema::Causality::#causality_variant)
});
}
// Set variability if specified
if let Some(variability) = &var_attr.variability {
let variability_schema: fmi::fmi3::schema::Variability = (*variability).into();
let variability_str = format!("{:?}", variability_schema);
let variability_variant = format_ident!("{}", variability_str);
builder_calls.push(quote! {
.with_variability(::fmi::fmi3::schema::Variability::#variability_variant)
});
}
// Default variability based on FMI3 spec if not provided explicitly.
if var_attr.variability.is_none()
&& let Some(causality) = &var_attr.causality
{
let causality_schema: ::fmi::fmi3::schema::Causality = (*causality).into();
let default_variability = match causality_schema {
::fmi::fmi3::schema::Causality::Parameter
| ::fmi::fmi3::schema::Causality::CalculatedParameter
| ::fmi::fmi3::schema::Causality::StructuralParameter => {
::fmi::fmi3::schema::Variability::Fixed
}
_ if is_float => ::fmi::fmi3::schema::Variability::Continuous,
_ => ::fmi::fmi3::schema::Variability::Discrete,
};
let variability_str = format!("{:?}", default_variability);
let variability_variant = format_ident!("{}", variability_str);
builder_calls.push(quote! {
.with_variability(::fmi::fmi3::schema::Variability::#variability_variant)
});
}
// Set interval variability if specified (for Clock variables)
if let Some(interval_variability) = &var_attr.interval_variability {
let interval_variability_schema: fmi::fmi3::schema::IntervalVariability =
(*interval_variability).into();
let interval_variability_str = format!("{:?}", interval_variability_schema);
let interval_variability_variant = format_ident!("{}", interval_variability_str);
builder_calls.push(quote! {
.with_interval_variability(
::fmi::fmi3::schema::IntervalVariability::#interval_variability_variant
)
});
}
// Set start value if specified
if let Some(start) = &var_attr.start {
builder_calls.push(quote! {
.with_start(#start)
});
}
// Set initial if specified
if let Some(initial) = &var_attr.initial {
let initial_schema: fmi::fmi3::schema::Initial = (*initial).into();
let initial_str = format!("{:?}", initial_schema);
let initial_variant = format_ident!("{}", initial_str);
builder_calls.push(quote! {
.with_initial(::fmi::fmi3::schema::Initial::#initial_variant)
});
}
// Set derivative if specified
if let Some(derivative_ref) = &var_attr.derivative {
let derivative_name = derivative_ref.to_string();
if let Some(&derivative_vr) = field_name_to_vr.get(&derivative_name) {
builder_calls.push(quote! {
.with_derivative(current_vr_offset + #derivative_vr)
});
}
}
// Set max_size if specified (for Binary variables)
if let Some(max_size) = var_attr.max_size {
builder_calls.push(quote! {
.with_max_size(#max_size)
});
}
// Set mime_type if specified (for Binary variables)
if let Some(mime_type) = &var_attr.mime_type {
builder_calls.push(quote! {
.with_mime_type(#mime_type)
});
}
// Set clocks if specified
if let Some(clocks) = &var_attr.clocks {
// Convert Vec<syn::Ident> to Vec<u32> by looking up VRs and adding vr_offset
let clock_vrs: Vec<u32> = clocks
.iter()
.filter_map(|clock_ident| {
let clock_name = clock_ident.to_string();
field_name_to_vr.get(&clock_name).map(|&vr| vr + 1) // Add 1 for vr_offset
})
.collect();
if !clock_vrs.is_empty() {
builder_calls.push(quote! {
.with_clocks(vec![#(#clock_vrs),*])
});
}
}
// Set description from field docstring or attribute
let description = if let Some(attr_desc) = &var_attr.description {
quote! { .with_description(#attr_desc) }
} else {
let field_desc = field.fold_description();
if !field_desc.is_empty() {
quote! { .with_description(#field_desc) }
} else {
quote! {}
}
};
let alias_tokens: Vec<TokenStream2> = alias_attrs
.iter()
.map(|alias_attr| {
if alias_attr.display_unit.is_some() && !is_float {
emit_error!(
field.ident,
"alias display_unit is only allowed for Float32/Float64 variables"
);
}
let alias_name_lit = syn::LitStr::new(&alias_attr.name, field.ident.span());
let alias_name_prefixed =
quote! { format!("{}{}", #prefix_binding, #alias_name_lit) };
let alias_description = alias_attr.description.as_ref().map_or_else(
|| quote! { None },
|desc| {
let desc_lit = syn::LitStr::new(desc, field.ident.span());
quote! { Some(#desc_lit.to_string()) }
},
);
let alias_display_unit = alias_attr.display_unit.as_ref().map_or_else(
|| quote! { None },
|display_unit| {
let display_unit_lit = syn::LitStr::new(display_unit, field.ident.span());
quote! { Some(#display_unit_lit.to_string()) }
},
);
if is_float {
quote! {
var.aliases.push(::fmi::schema::fmi3::FloatVariableAlias {
name: #alias_name_prefixed,
description: #alias_description,
display_unit: #alias_display_unit,
});
}
} else {
quote! {
var.aliases.push(::fmi::schema::fmi3::VariableAlias {
name: #alias_name_prefixed,
description: #alias_description,
});
}
}
})
.collect();
quote! {
let mut var = <#field_type as ::fmi_export::fmi3::FmiVariableBuilder>::variable(#variable_name_prefixed, current_vr_offset + #current_vr)
#description
#(#builder_calls)*
.finish();
#(#alias_tokens)*
var.append_to_variables(variables);
}
}
}