feat(diagnostics): token and rule labels for expected-X messages - #73
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feat(diagnostics): token and rule labels for expected-X messages#73theoephraim wants to merge 1 commit into
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The emitted engine's $missing diagnostics name what was missing by its
grammar name: a token NUM reads as "expected 'NUM'", a rule Value as
"expected Value". For a language whose grammar names are internal
identifiers (DEC_VALUE_TEXT) that text leaks straight to editor users.
token(pattern, { label }) and rule(fn, { label }) substitute a display
string in exactly those messages and nowhere else: leaf tokenTypes,
ruleNameOf, the CST, and every derived artifact keep the grammar name,
so a grammar that adds labels parses byte-identically. A labelled token
renders bare (expected a number); an unlabelled one keeps the quoted
name, so existing output is unchanged.
Gate: test/diagnostic-labels.ts (tiny grammar plus TypeScript's Expr
rule relabelled, tree identity across labels).
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Token and rule labels for
expected …diagnosticsThe emitted engine's
$missingdiagnostics name what was missing by its grammar name: a tokenNUMreads asexpected 'NUM', a ruleValueasexpected Value. That is fine when grammar names are already words (Expr), and leaks internal identifiers to end users otherwise. We hit it porting env-spec (the dotenv dialect behind varlock): its tokens are things likeDEC_VALUE_TEXT, and those names would be the text an editor shows on every keystroke.token(pattern, { label: 'a number' })andrule(fn, { label: 'an expression' })substitute a display string in exactly those messages and nowhere else. LeaftokenTypes,ruleNameOf, the CST, and every derived artifact keep the grammar name, so a grammar that adds labels parses byte-identically. A labelled token renders bare (expected a number); an unlabelled one keeps the quoted grammar name, so existing output is unchanged (the emitted tables gainRULE_LABELSandK_LABELSnext toRULE_DISPLAYandK_NAMES;RULE_DISPLAYstill drives node names).Gate:
test/diagnostic-labels.ts(registered incore). It covers the tiny-grammar token case, TypeScript'sExprrule relabelled (const a = ;readsexpected an expression), tree identity across labels, the TextMate, tree-sitter, and language-configuration outputs byte-identical across labels, literal messages and related info unchanged, and the interpreter unaffected (it has no expected-X diagnostics). README gets one paragraph.npm run check: 50/50.