222 lines
8.1 KiB
JavaScript
222 lines
8.1 KiB
JavaScript
/* Core of pocomath: create an instance */
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import typed from 'typed-function'
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export default class PocomathInstance {
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/* Disallowed names for ops; beware, this is slightly non-DRY
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* in that if a new top-level PocomathInstance method is added, its name
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* must be added to this list.
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*/
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static reserved = new Set(['install', 'importDependencies'])
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constructor(name) {
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this.name = name
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this._imps = {}
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this._affects = {}
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this._typed = typed.create()
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this._typed.clear()
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// Convenient hack for now, would remove when a real string type is added:
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this._typed.addTypes([{name: 'string', test: s => typeof s === 'string'}])
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}
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/**
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* (Partially) define one or more operations of the instance:
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*
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* @param {Object<string, Object<Signature, [string[], function]>>} ops
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* The only parameter ops gives the semantics of the operations to install.
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* The keys are operation names. The value for a key is an object
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* mapping (typed-function) signature strings to pairs of dependency
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* lists and implementation functions.
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*
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* A dependency list is a list of strings. Each string can either be the
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* name of a function that the corresponding implementation has to call,
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* or a specification of a particular signature of a function that it has
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* to call, in the form 'FN(SIGNATURE)'. Note the function name can be
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* the special value 'self' to indicate a recursive call to the given
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* operation (either with or without a particular signature.
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*
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* There are two cases for the implementation function. If the dependency
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* list is empty, it should be a function taking the arguments specified
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* by the signature and returning the value. Otherwise, it should be
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* a function taking an object with the dependency lists as keys and the
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* requested functions as values, to a function taking the arguments
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* specified by the signature and returning the value.
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*
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* Note that the "operation" named `Types` is special: it gives
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* types that must be installed in the instance. In this case, the keys
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* are type names, and the values are objects with a property 'test'
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* giving the predicate for the type, and properties for each type that can
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* be converted **to** this type, giving the corresponding conversion
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* function.
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*/
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install(ops) {
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for (const key in ops) this._installOp(key, ops[key])
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}
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/**
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* Import (and install) all dependencies of previously installed functions,
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* for the specified types.
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*
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* @param {string[]} types A list of type names
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*/
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async importDependencies(types) {
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const doneSet = new Set(['self']) // nothing to do for self dependencies
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while (true) {
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const requiredSet = new Set()
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/* Grab all of the known deps */
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for (const func in this._imps) {
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if (func === 'Types') continue
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for (const definition of Object.values(this._imps[func])) {
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for (const dependency of definition[0]) {
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const depName = dependency.split('(',1)[0]
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if (doneSet.has(depName)) continue
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requiredSet.add(depName)
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}
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}
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}
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if (requiredSet.size === 0) break
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for (const name of requiredSet) {
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for (const type of types) {
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try {
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const modName = `../${type}/${name}.mjs`
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const mod = await import(modName)
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this.install(mod)
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} catch (err) {
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// No such module, but that's OK
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}
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}
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doneSet.add(name)
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}
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}
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}
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/* Used internally by install, see the documentation there */
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_installOp(name, implementations) {
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if (name.charAt(0) === '_') {
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throw new SyntaxError(
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`Pocomath: Cannot install ${name}, `
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+ 'initial _ reserved for internal use.')
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}
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if (PocomathInstance.reserved.has(name)) {
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throw new SyntaxError(
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`Pocomath: the meaning of function '${name}' cannot be modified.`)
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}
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// new implementations, so set the op up to lazily recreate itself
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this._invalidate(name)
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const opImps = this._imps[name]
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for (const signature in implementations) {
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if (signature in opImps) {
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if (implementations[signature] === opImps[signature]) continue
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throw new SyntaxError(
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`Conflicting definitions of ${signature} for ${name}`)
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} else {
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opImps[signature] = implementations[signature]
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for (const dep of implementations[signature][0] || []) {
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const depname = dep.split('(', 1)[0]
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if (depname === 'self') continue
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if (!(depname in this._affects)) {
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this._affects[depname] = new Set()
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}
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this._affects[depname].add(name)
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}
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}
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}
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}
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/**
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* Reset an operation to require creation of typed-function,
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* and if it has no implementations so far, set them up.
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*/
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_invalidate(name) {
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const self = this
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Object.defineProperty(this, name, {
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configurable: true,
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get: () => self._bundle(name)
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})
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if (!(name in this._imps)) {
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this._imps[name] = {}
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}
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if (name in this._affects) {
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for (const ancestor of this._affects[name]) {
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this._invalidate(ancestor)
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}
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}
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}
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/**
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* Create a typed-function from the signatures for the given name and
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* assign it to the property with that name, returning it as well
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*/
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_bundle(name) {
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const imps = this._imps[name]
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if (!imps || Object.keys(imps).length === 0) {
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throw new SyntaxError(`No implementations for ${name}`)
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}
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this._ensureTypes()
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const tf_imps = {}
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for (const signature in imps) {
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const [deps, imp] = imps[signature]
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if (deps.length === 0) {
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tf_imps[signature] = imp
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} else {
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const refs = {}
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let self_referential = false
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for (const dep of deps) {
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// TODO: handle signature-specific dependencies
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if (dep.includes('(')) {
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throw new Error('signature specific reference unimplemented')
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}
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if (dep === 'self') {
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self_referential = true
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} else {
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refs[dep] = this[dep] // assume acyclic for now
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}
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}
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if (self_referential) {
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tf_imps[signature] = this._typed.referToSelf(self => {
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refs.self = self
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return imp(refs)
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})
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} else {
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tf_imps[signature] = imp(refs)
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}
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}
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}
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const tf = this._typed(name, tf_imps)
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Object.defineProperty(this, name, {configurable: true, value: tf})
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return tf
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}
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/**
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* Ensure that all of the requested types and conversions are actually
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* in the typed-function universe:
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*/
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_ensureTypes() {
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const newTypes = []
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const newTypeSet = new Set()
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const knownTypeSet = new Set()
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const conversions = []
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const typeSpec = this._imps.Types
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for (const name in this._imps.Types) {
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knownTypeSet.add(name)
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for (const from in typeSpec[name]) {
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if (from === 'test') continue;
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conversions.push(
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{from, to: name, convert: typeSpec[name][from]})
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}
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try { // Hack: work around typed-function #154
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this._typed._findType(name)
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} catch {
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newTypeSet.add(name)
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newTypes.push({name, test: typeSpec[name].test})
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}
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}
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this._typed.addTypes(newTypes)
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const newConversions = conversions.filter(
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item => (newTypeSet.has(item.from) || newTypeSet.has(item.to)) &&
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knownTypeSet.has(item.from) && knownTypeSet.has(item.to)
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)
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this._typed.addConversions(newConversions)
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}
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}
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