Differentiate nil values from missing keys in Map.Has - #172
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Previously, Map.Has was implemented as !m.Get(selector).IsNil(). Because Get returns a Value wrapping nil when a key either does not exist or exists with a nil value, Has returned false for keys that were explicitly set to nil or slice indices containing nil elements. This prevented callers from differentiating between non-existent keys and keys mapped to nil/null. Introduce a path traversal helper has that checks for map key presence and array index bounds rather than checking whether the retrieved value is non-nil. Update Map.Has to use has so that existing keys with nil values evaluate to true.
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Summary
Fixes #131
Previously,
Map.Has(selector)was implemented as!m.Get(selector).IsNil(). BecauseGetreturns aValuecontainingnilwhenever a key does not exist or exists with anilvalue,Hasreturnedfalsefor keys explicitly set tonilor slice indices containingnil. This prevented callers from differentiating between missing keys and keys mapped tonil/null.This change adds a path traversal helper
hasinaccessors.gothat verifies key presence in maps (_, ok := cur[thisSel]) and index boundaries in slices (0 <= index < len(array)).Map.Hasnow delegates tohas, correctly returningtruefor existing keys and indices withnilvalues.Checklist
task testtask lint