docs: standalone runnable PoC of the grammar engine (#467)#489
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A single self-contained Kotlin file (stdlib only, no IntelliJ/project deps) under poc/ that models the new engine so it can be run and stepped through without Gradle: kotlin poc/GrammarEnginePoc.kt # or: kotlinc poc/GrammarEnginePoc.kt -include-runtime -d /tmp/poc.jar && java -jar /tmp/poc.jar # or: open in IntelliJ and Run main() Mirrors the real grammar/ classes (Parse/Stuck/Matcher, Seq/Alt/ZeroOrMore/ZeroOrOne, Lit/Choice/Whitespace, validate, nextTokenChoices) and main() demonstrates: the greedy completeness win, validation + error localization, completion as the same expected-set question, and the raw ParseStep stream you'd see in a debugger. Lives outside the source sets, so it is not compiled into the plugin. Refs #467 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Moved GrammarEnginePoc.kt to src/main/kotlin so IntelliJ runs main() directly, and
reworked it as a teaching aid (this branch is not merged/shipped):
- Seq.parse rewritten with the sequence { } builder (lazy, but plain for-loops + yield
instead of flatMap/map), with clearer names (waysToHere / soFar) and the snapshot
comment explaining why the lazy block must close over a captured value.
- Added eager List-based twins SeqEager / ZeroOrMoreEager that build the full result
up front (no laziness) to make the logic and the recursion easier to follow.
- Demos: eager vs lazy produce identical validate() results; and the eager twin builds
the whole ambiguous space (all 4 full parses of "aaa") where lazy validate stops at
the first.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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What
A single self-contained Kotlin file —
poc/GrammarEnginePoc.kt— that models the new grammar engine with no IntelliJ or project dependencies (Kotlin stdlib only), so you can run it and step through it in a debugger without Gradle.Run it
What it shows
It mirrors the real
grammar/classes (Parse/Stuck/Matcher,Seq/Alt/ZeroOrMore/ZeroOrOne,Lit/Choice/Whitespace,validate,nextTokenChoices) andmain()walks through four demos:Seq(ZeroOrMore("a"), "a")accepts"aa"(the case a single greedy match fails).AF_BOGUS→SemanticError;AF_INET, AF_INET6→SyntaxError(furthest=7, expected=[<ws>]).nextTokenChoices("")/("~")/("AF_INET ")showing "what can come next" is the same expected-set question.ParseStepstream — what you'd actually see in a debugger.Sample output:
The header comment explains the two core ideas (list-of-successes; failure-as-a-value) and maps the PoC names back to the real classes.
Refs #467
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