Lucas WintherandClaude Opus 5.5
820b378929
Baba.undo() restores the level before the last step or move (board snapshot: objects in age order with ids, the id counter, and won; rules recompiled). place clears the history. SpellGrid's undo throws/panics 'not supported'. stackAt / stack_at lists a tile's kinds oldest first, on Baba and SpellGrid. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
18 lines
2.4 KiB
Markdown
18 lines
2.4 KiB
Markdown
# Module 8 reference engine (TypeScript)
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The course's own engine as of the end of Module 8. Part I's card engine is unchanged, and all of its tests still pass. The Part II engine in `src/engine/puzzle/` now moves objects: each `YOU` object's move is planned in full, push chain and all, and only then committed. Module 7's reference was the starting point, so a diff between the two shows what this module adds.
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- `cards/` (at the package root; not in this directory): Part I's card data, a copy of `course/cards/` staged by `tools/verify-references.mjs`. Part II doesn't read it.
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- `src/engine/puzzle/`: the Part II engine. It names no noun: the engine's own words are the operators `IS`, `AND`, `NOT`, the meta-noun `TEXT`, the property `PUSH` of the base rule `TEXT IS PUSH`, and from Module 8 the property `YOU`, which picks the objects that move.
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- `grid.ts`: the level format, object kinds and the board. Module 8 adds `Board.find`, `Board.remove`, `Board.shift`, `Board.at` and `Kind.format` (the kind as placed, for `kindsAt`).
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- `movement.ts` (new): validate, then commit. `Planner` (`tryMove`, `stayingAt`, `destroy`, `has`), `Step`, `Plan`, `Response` and `Dir`. The planner reads the board and plans one step at a time; for each step it runs content's movement responses in order, and rolls back everything a step added if a response blocks it. The edge of the level blocks every step, and an object that has already stepped in the same move can't step again.
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- `level.ts`: a level in play. Module 8 adds `Level.moveYou`: the `YOU` objects move one at a time, furthest ahead first, each planned and then committed, and an object steps at most once per move (a `YOU` object that an earlier move carried along doesn't start its own); the rules are reparsed once at the end. `hasProperty` is `false` for a destroyed object.
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- `word.ts`, `parse.ts`, `resolve.ts`: unchanged.
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- `index.ts`: the module's exports.
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- The rest of `src/engine/`: Part I, unchanged.
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- `src/content/movement.ts` (new) and `src/content/index.ts`: the movement responses, in the order the engine runs them: `OPEN`/`SHUT`, `PUSH`, `STOP`. What a property does when something moves is content, not engine.
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- `src/content/words.json`: Module 8 adds `OPEN` and `SHUT`.
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- `src/harness.ts`: the adapter the course tests call. Module 8 adds `move`, `posOf`, `kindsAt` and `stackAt` on `Baba`.
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Run it with the module's tests: `node tools/verify-references.mjs 08` from the course repository.
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