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use crate::ir::ids::FieldName;
use crate::ir::ops::{FieldWriteOp, SizeExpr, ValueExpr, WriteOp, WriteSeq};
use super::lowerer::CSharpLowerer;
impl<'a> CSharpLowerer<'a> {
/// Rewrites a [`WriteSeq`] so every reference to the encoded value's
/// instance resolves to `{binding}` instead of the default `this`.
/// Used for data enum variant fields, where the switch statement
/// binds each variant as `case Circle _v:` and field references must
/// go through `_v.Radius` rather than `this.Radius`.
pub(super) fn prefix_write_seq(seq: &WriteSeq, binding: &str) -> WriteSeq {
WriteSeq {
size: Self::prefix_size_expr(&seq.size, binding),
ops: seq
.ops
.iter()
.map(|op| Self::prefix_write_op(op, binding))
.collect(),
shape: seq.shape,
}
}
/// Applies the variant binding rewrite to one [`WriteOp`]. Inner
/// sequences for loop bodies (`Vec::element`, `Option::some`) are
/// intentionally not rewritten; they reference loop-bound names, not
/// the enclosing variant binding.
fn prefix_write_op(op: &WriteOp, binding: &str) -> WriteOp {
match op {
WriteOp::Primitive { primitive, value } => WriteOp::Primitive {
primitive: *primitive,
value: Self::prefix_value(value, binding),
},
WriteOp::String { value } => WriteOp::String {
value: Self::prefix_value(value, binding),
},
WriteOp::Bytes { value } => WriteOp::Bytes {
value: Self::prefix_value(value, binding),
},
WriteOp::Record { id, value, fields } => WriteOp::Record {
id: id.clone(),
value: Self::prefix_value(value, binding),
fields: fields
.iter()
.map(|f| FieldWriteOp {
name: f.name.clone(),
accessor: Self::prefix_value(&f.accessor, binding),
seq: Self::prefix_write_seq(&f.seq, binding),
})
.collect(),
},
WriteOp::Enum { id, value, layout } => WriteOp::Enum {
id: id.clone(),
value: Self::prefix_value(value, binding),
layout: layout.clone(),
},
WriteOp::Vec {
value,
element_type,
element,
layout,
} => WriteOp::Vec {
value: Self::prefix_value(value, binding),
element_type: element_type.clone(),
// `element` references the per-iteration loop binding
// (`item`), which belongs to the foreach the Vec writer
// emits around the enclosing variant scope. Rewriting it
// to `_v.item` would break the generated loop; leave the
// element seq untouched.
element: element.clone(),
layout: layout.clone(),
},
WriteOp::Option { value, some } => WriteOp::Option {
value: Self::prefix_value(value, binding),
// `some` is written inside an `if (field is { } v)` block
// where inner ops reference `v`, not the outer variant
// binding. Clone as-is, same as `Vec::element`.
some: some.clone(),
},
other => panic!(
"prefix_write_op: unsupported op for C# variant fields: {:?}",
other
),
}
}
/// Rewrites `Instance` references to `Var(binding)` and bare
/// `Named(field)` references to `Field(Var(binding), field)`.
/// Recursive `Field` references walk into their parent. `Var` is
/// unchanged.
fn prefix_value(value: &ValueExpr, binding: &str) -> ValueExpr {
match value {
ValueExpr::Instance => ValueExpr::Var(binding.to_string()),
ValueExpr::Named(name) => ValueExpr::Field(
Box::new(ValueExpr::Var(binding.to_string())),
FieldName::new(name),
),
ValueExpr::Var(_) => value.clone(),
ValueExpr::Field(parent, field) => {
ValueExpr::Field(Box::new(Self::prefix_value(parent, binding)), field.clone())
}
}
}
/// Applies the variant binding rewrite to a [`SizeExpr`]. Mirrors
/// [`Self::prefix_write_op`]'s carve-out for inner loop bodies
/// (`Vec::inner`, `Option::inner`).
fn prefix_size_expr(expr: &SizeExpr, binding: &str) -> SizeExpr {
match expr {
SizeExpr::Fixed(_) | SizeExpr::Runtime => expr.clone(),
SizeExpr::StringLen(v) => SizeExpr::StringLen(Self::prefix_value(v, binding)),
SizeExpr::BytesLen(v) => SizeExpr::BytesLen(Self::prefix_value(v, binding)),
SizeExpr::ValueSize(v) => SizeExpr::ValueSize(Self::prefix_value(v, binding)),
SizeExpr::WireSize { value, owner } => SizeExpr::WireSize {
value: Self::prefix_value(value, binding),
owner: owner.clone(),
},
SizeExpr::Sum(parts) => SizeExpr::Sum(
parts
.iter()
.map(|p| Self::prefix_size_expr(p, binding))
.collect(),
),
SizeExpr::VecSize {
value,
inner,
layout,
} => SizeExpr::VecSize {
value: Self::prefix_value(value, binding),
// `inner` uses the per-element loop variable (`item`) the
// encoded-array size lambda binds. The `_v` rewrite only
// applies to the enclosing variant field reference.
inner: inner.clone(),
layout: layout.clone(),
},
SizeExpr::OptionSize { value, inner } => SizeExpr::OptionSize {
value: Self::prefix_value(value, binding),
// `inner` references the unwrapped-option binding `v` that
// the size-option emit lambda introduces, not the enclosing
// variant field. Clone as-is, same as `VecSize::inner`.
inner: inner.clone(),
},
other => panic!(
"prefix_size_expr: unsupported expr for C# variant fields: {:?}",
other
),
}
}
}