Add Memento pattern source generator for classes, structs, and records #88
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- Created MementoAttribute with configuration options - Implemented MementoGenerator for class/struct/record class/record struct - Generated immutable memento structs with Capture and RestoreNew methods - Generated optional caretaker classes for undo/redo history - Added diagnostic support (PKMEM001-PKMEM006) - All 13 generator tests passing Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
- Created EditorStateDemo showing text editor with undo/redo - Created GameStateDemo showing game state save/load - Added comprehensive README with usage examples - Moved MementoAttribute to Abstractions project for accessibility - Fixed generator to skip computed/read-only properties - All 13 generator tests passing Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
- Added null checks for FirstOrDefault in test assertions - Fixed potential NullReferenceException in generated source access - All 13 Memento tests passing Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
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[WIP] Add source generator for Memento pattern implementation
Add Memento pattern source generator for classes, structs, and records
Jan 20, 2026
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Dependency Review✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.Scanned FilesNone |
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Test Results0 tests 0 ✅ 0s ⏱️ Results for commit bb0a281. |
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🔍 PR Validation ResultsVersion: `` ✅ Validation Steps
📊 ArtifactsDry-run artifacts have been uploaded and will be available for 7 days. This comment was automatically generated by the PR validation workflow. |
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Codecov Report❌ Patch coverage is Additional details and impacted files@@ Coverage Diff @@
## main #88 +/- ##
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+ Coverage 86.81% 89.73% +2.91%
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Files 139 143 +4
Lines 11295 11867 +572
Branches 1548 1610 +62
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+ Hits 9806 10649 +843
- Misses 1101 1218 +117
+ Partials 388 0 -388
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Implements a compile-time source generator that produces complete Memento pattern implementations for classes, structs, record classes, and record structs with optional undo/redo caretaker.
Generated Components
Capture(in TOriginator)andRestoreNew()methodsConfiguration
Type Support
RestoreNew()returning new instancesRestore(originator)(in-place) andRestoreNew()Member Selection
Usage Example
Implementation Details
Demos
EditorStateDemo: Text editor with undo/redo using record classGameStateDemo: Game state save/load with mutable class and in-place restoreOriginal prompt
This section details on the original issue you should resolve
<issue_title>Generator: Create Memento Pattern (supports class/struct/record + optional undo/redo caretaker)</issue_title>
<issue_description>## Summary
Add a source generator that produces a complete implementation of the Memento pattern for consumer types — including classes, structs, record classes, and record structs — focused on:
Motivation / Problem
Memento implementations are repetitive and correctness-sensitive:
This is ideal for source generation: emit correct, optimized code once, consistently.
Supported Originator Kinds (must-have)
The generator must support:
classstructrecord classrecord structEach kind has different restore semantics:
Mutable originators (class/struct with settable members)
Immutable originators (records with
initor positional parameters)restore should support returning a new instance:
RestoreNew(...)orApply(...)optionally support
with-expression restore when feasible:with { ... }for the included membersWe should not force mutation on records that are designed to be immutable.
Proposed User Experience
Minimal: snapshot only
Generated (shape):
Snapshot + caretaker (undo/redo)
Generated:
Notes
Member Selection
Support both modes:
Include-all (default, configurable)
Include-explicit
[MementoInclude]Attributes:
[Memento][MementoIgnore][MementoInclude]Capture Strategies for Mutable References (footgun prevention)
Default strategy should be explicit and safe:
stringtreated as safe immutableByReferencewith a warning unless configured otherwisePer-member strategy attribute:
Strategies:
ByReferenceClone(requires a known mechanism)DeepCopy(only when generator can safely emit it)Serialize(opt-in, future)Custom(partial hook)Restore Semantics (by originator type)
For class / struct (mutable)
Generate both:
void Restore(TOriginator originator)(in-place)TOriginator RestoreNew()(convenience)For record class / record struct
Generate:
TOriginator RestoreNew()(always)Apply(TOriginator originator)only if the record has writable members (rare / discouraged)Additionally:
if feasible, prefer
with-expression:originator with { Prop = value, ... }otherwise, use the best available constructor/positional parameters:
The generator must emit diagnostics if it cannot safely construct a new record instance.
Caretaker Generation (Undo/Redo)
Caretaker should be optional and support dete...
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