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extern crate alloc;
use facet_core::{Type, UserType};
use facet_path::PathStep;
use facet_reflect::Partial;
use crate::{DeserializeError, FormatDeserializer, FormatParser, ParseEvent, ScalarValue};
impl<'input, const BORROW: bool, P> FormatDeserializer<'input, BORROW, P>
where
P: FormatParser<'input>,
{
/// Deserialize a struct without flattened fields (simple case).
pub(crate) fn deserialize_struct_simple(
&mut self,
mut wip: Partial<'input, BORROW>,
) -> Result<Partial<'input, BORROW>, DeserializeError<P::Error>> {
use facet_core::Characteristic;
// Get struct fields for lookup (needed before hint)
let struct_def = match &wip.shape().ty {
Type::User(UserType::Struct(def)) => def,
_ => {
return Err(DeserializeError::Unsupported(format!(
"expected struct type but got {:?}",
wip.shape().ty
)));
}
};
// Hint to non-self-describing parsers how many fields to expect
self.parser.hint_struct_fields(struct_def.fields.len());
let struct_type_has_default = wip.shape().is(Characteristic::Default);
// Peek at the next event first to handle EOF and null gracefully
let maybe_event = self.parser.peek_event().map_err(DeserializeError::Parser)?;
// Handle EOF (empty input / comment-only files): use Default if available
if maybe_event.is_none() {
if struct_type_has_default {
wip = wip.set_default().map_err(DeserializeError::reflect)?;
return Ok(wip);
}
return Err(DeserializeError::UnexpectedEof { expected: "value" });
}
// Handle Scalar(Null): use Default if available
if let Some(ParseEvent::Scalar(ScalarValue::Null)) = &maybe_event
&& struct_type_has_default
{
let _ = self.expect_event("null")?;
wip = wip.set_default().map_err(DeserializeError::reflect)?;
return Ok(wip);
}
let event = self.expect_event("value")?;
if !matches!(event, ParseEvent::StructStart(_)) {
return Err(DeserializeError::TypeMismatch {
expected: "struct start",
got: format!("{event:?}"),
span: self.last_span,
path: None,
});
}
let deny_unknown_fields = wip.shape().has_deny_unknown_fields_attr();
// Track which fields have been set
let num_fields = struct_def.fields.len();
let mut fields_set = alloc::vec![false; num_fields];
let mut ordered_field_index = 0usize;
loop {
let event = self.expect_event("value")?;
trace!(
?event,
"deserialize_struct_simple: loop iteration, got event"
);
match event {
ParseEvent::StructEnd => {
break;
}
ParseEvent::OrderedField => {
// Non-self-describing formats emit OrderedField events in order
let idx = ordered_field_index;
ordered_field_index += 1;
if idx < num_fields {
// Track path for error reporting
self.push_path(PathStep::Field(idx as u32));
wip = wip
.begin_nth_field(idx)
.map_err(DeserializeError::reflect)?;
wip = match self.deserialize_into(wip) {
Ok(wip) => wip,
Err(e) => {
// Only add path if error doesn't already have one
// (inner errors already have more specific paths)
let result = if e.path().is_some() {
e
} else {
let path = self.path_clone();
e.with_path(path)
};
self.pop_path();
return Err(result);
}
};
wip = wip.end().map_err(DeserializeError::reflect)?;
self.pop_path();
fields_set[idx] = true;
}
}
ParseEvent::FieldKey(key) => {
trace!(?key, "deserialize_struct_simple: got FieldKey");
// Unit keys don't make sense for struct fields
let key_name = match &key.name {
Some(name) => name.as_ref(),
None => {
// Skip unit keys in struct context
self.parser.skip_value().map_err(DeserializeError::Parser)?;
continue;
}
};
// Look up field in struct fields by name/alias
let field_info = struct_def
.fields
.iter()
.enumerate()
.find(|(_, f)| Self::field_matches(f, key_name));
if let Some((idx, field)) = field_info {
trace!(
idx,
field_name = field.name,
"deserialize_struct_simple: matched field"
);
// Track path for error reporting
self.push_path(PathStep::Field(idx as u32));
wip = wip
.begin_nth_field(idx)
.map_err(DeserializeError::reflect)?;
wip = match self.deserialize_into(wip) {
Ok(wip) => wip,
Err(e) => {
// Only add path if error doesn't already have one
// (inner errors already have more specific paths)
let result = if e.path().is_some() {
e
} else {
let path = self.path_clone();
e.with_path(path)
};
self.pop_path();
return Err(result);
}
};
// Run validation on the field value before finalizing
#[cfg(feature = "validate")]
self.run_field_validators(field, &wip)?;
#[cfg(not(feature = "validate"))]
let _ = field;
wip = wip.end().map_err(DeserializeError::reflect)?;
self.pop_path();
fields_set[idx] = true;
continue;
}
if deny_unknown_fields {
return Err(DeserializeError::UnknownField {
field: key_name.to_owned(),
span: self.last_span,
path: None,
});
} else {
// Unknown field - skip it
trace!(field_name = ?key_name, "deserialize_struct_simple: skipping unknown field");
self.parser.skip_value().map_err(DeserializeError::Parser)?;
}
}
other => {
return Err(DeserializeError::TypeMismatch {
expected: "field key or struct end",
got: format!("{other:?}"),
span: self.last_span,
path: None,
});
}
}
}
// In deferred mode, skip validation - finish_deferred() will handle it.
// This allows formats like TOML to reopen tables and set more fields later.
if wip.is_deferred() {
return Ok(wip);
}
// Defaults for missing fields are applied automatically by facet-reflect's
// fill_defaults() when build() or end() is called.
Ok(wip)
}
}