42 lines
1.5 KiB
JavaScript
42 lines
1.5 KiB
JavaScript
/* Call this with an empty Set object S, and it returns an entity E
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* from which properties can be extracted, and at any time S will
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* contain all of the property names that have been extracted from E.
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*/
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export function dependencyExtractor(destinationSet) {
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return new Proxy({}, {
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get: (target, property) => {
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destinationSet.add(property)
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return {checkingDependency: true}
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}
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})
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}
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/* Given a (template) type name, what the template parameter is,
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* a top level typer, and a library of templates,
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* produces a function that will extract the instantantion type from an
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* instance. Currently relies heavily on there being only unary templates.
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*
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* We should really be using the typed-function parser to do the
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* manipulations below, but at the moment we don't have access.
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*/
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export function generateTypeExtractor(
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type, param, topTyper, typeJoiner, templates)
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{
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type = type.trim()
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if (type.slice(0,3) === '...') {
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type = type.slice(3).trim()
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}
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if (type === param) return topTyper
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if (!(type.includes('<'))) return false // no template type to extract
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const base = type.split('<',1)[0]
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if (!(base in templates)) return false // unknown template
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const arg = type.slice(base.length+1, -1)
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const argExtractor = generateTypeExtractor(
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arg, param, topTyper, typeJoiner, templates)
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if (!argExtractor) return false
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return templates[base].spec.infer({
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typeOf: argExtractor,
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joinTypes: typeJoiner
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})
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}
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