Files

T

Michael Schimmel bf74795e01 Refactor: Implement Record Layouts and Optimized Field Access

Introduces a new `RecordLayout` system for efficient and type-safe
record handling.

Key changes:
- `RecordLayout` struct with `O(1)` field lookup using FMap
  optimization.
- Field accessors (`.name`) are now first-class callable values.
- Parser recognizes dot-prefixed identifiers as field accessors.
- Binder and TypeChecker handle field accessors.
- Optimizer transforms field accessor calls into specialized `GetField`
  nodes.
- VM executes `GetField` efficiently by directly accessing record
  values.
- Adds a new `records.myc` example showcasing record features.
- Improves comparison logic for records to use pointer equality for
  layout.

2026-02-26 21:38:20 +01:00

2.7 KiB

Raw Blame History

Plan: Record Layout & Optimized Field Access

This document outlines the implementation plan for porting Delphi's TKeywordMappingRegistry optimizations to the Rust-based Myc AST compiler and integrating first-class field accessors.

1. Core Data Structures (`src/ast/types.rs`)

RecordLayout (The Schema)

Concept: Replaces IKeywordMapping<IStaticType>.
Interning: Managed via a global OnceLock<Mutex<HashMap<..., Arc<RecordLayout>>>>.
FMap Optimization:
- Stores fields: Vec<(Keyword, StaticType)>.
- Maintains a lookup array Vec<i32> mapping Keyword.idx - first_key to the index in the fields array.
- Provides index_of(Keyword) -> Option<usize> with O(1) complexity.
Thread Safety: Uses Arc for global sharing across script threads.

Value & StaticType Updates

Value::Record points to an Arc<RecordLayout> and a flat Rc<Vec<Value>>.
Value::FieldAccessor(Keyword) added as a first-class callable value (e.g., .name).
StaticType::Record now holds Arc<RecordLayout>.

2. Compiler Pipeline

Parser (`src/ast/parser.rs`)

Identifiers starting with . (e.g., .age) are parsed as UntypedKind::FieldAccessor(Keyword).
This ensures interning happens immediately; strings are never used for field access in subsequent phases.

Binder (`src/ast/compiler/binder.rs`)

Maps UntypedKind::FieldAccessor to BoundKind::FieldAccessor.

TypeChecker (`src/ast/compiler/type_checker.rs`)

Analysis Only: When encountering Call { callee: FieldAccessor, args: [rec] }:
- Validates that rec is a Record.
- Uses RecordLayout::index_of to find the field's type.
- Sets the call's return type accordingly.
- Crucial: Does NOT modify the AST structure. It remains a Call.

Optimizer (`src/ast/compiler/optimizer/engine.rs`)

Transformation: Recognizes the Call { callee: FieldAccessor, ... } pattern.
Transforms it into a specialized BoundKind::GetField { rec, field: Keyword } node.

3. Execution (`src/ast/vm.rs`)

Optimized Path (`GetField`)

The VM executes GetField by:
1. Evaluating the record.
2. Calling layout.index_of(field) (O(1)).
3. Fetching the value from the flat array.

Functional Path (`FieldAccessor`)

If .field is passed as a value (e.g., (map .name users)), the VM treats the FieldAccessor value as a standard function that takes one argument and performs the lookup.

4. Benefits

Type Identity: Arc::ptr_eq allows instant type comparison.
Performance: Field access in loops is O(1) without hash lookups.
Safety: The TypeChecker remains a pure analysis phase as per design requirements.

2.7 KiB Raw Blame History

Plan: Record Layout & Optimized Field Access

1. Core Data Structures (src/ast/types.rs)

RecordLayout (The Schema)

Value & StaticType Updates

2. Compiler Pipeline

Parser (src/ast/parser.rs)

Binder (src/ast/compiler/binder.rs)

TypeChecker (src/ast/compiler/type_checker.rs)

Optimizer (src/ast/compiler/optimizer/engine.rs)

3. Execution (src/ast/vm.rs)

Optimized Path (GetField)

Functional Path (FieldAccessor)