295 lines
9.4 KiB
TypeScript
295 lines
9.4 KiB
TypeScript
/// SPDX-License-Identifier: GPL-3.0-or-later
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/// SPDX-FileCopyrightText: Copyright © 2016-2023 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
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import { Turn } from "./actor.js";
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import { Bytes, Dictionary, DoubleFloat, embed, IdentityMap, is, isEmbedded, Record, SingleFloat, Tuple, stringify } from "@preserves/core";
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import type { Assertion, Handle, Ref } from "./actor.js";
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import type { SturdyValue } from "../transport/sturdy.js";
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import {
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Alts,
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Caveat,
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Lit,
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PAnd,
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PAtom,
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PBind,
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PCompound,
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PDiscard,
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PNot,
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PEmbedded,
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Pattern,
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Rewrite,
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TRef,
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Template,
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_embedded,
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} from '../gen/sturdy.js';
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export * from '../gen/sturdy.js';
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export type Bindings = Array<Assertion>;
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export function match(p: Pattern, v: Assertion): Bindings | null {
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let bindings: Bindings = [];
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function walk(p: Pattern, v: Assertion): boolean {
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switch (p._variant) {
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case 'PDiscard':
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return true;
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case 'PAtom':
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switch (p.value._variant) {
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case 'Boolean': return typeof v === 'boolean';
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case 'ByteString': return Bytes.isBytes(v);
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case 'Double': return DoubleFloat.isDouble(v);
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case 'Float': return SingleFloat.isSingle(v);
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case 'SignedInteger': return typeof v === 'number';
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case 'String': return typeof v === 'string';
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case 'Symbol': return typeof v === 'symbol';
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}
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case 'PEmbedded':
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return isEmbedded(v);
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case 'PBind':
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if (walk(p.value.pattern, v)) {
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bindings.push(v);
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return true;
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}
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return false;
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case 'PAnd':
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for (const pp of p.value.patterns) {
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if (!walk(pp, v)) return false;
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}
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return true;
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case 'PNot': {
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const savedBindings = bindings;
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bindings = [];
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const result = !walk(p.value.pattern, v)
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bindings = savedBindings;
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return result;
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}
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case 'Lit':
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return is(p.value.value, v);
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case 'PCompound': switch (p.value._variant) {
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case 'rec': {
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if (!Record.isRecord<Assertion, Tuple<Assertion>, Ref>(v)) return false;
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if (!is(p.value.label, v.label)) return false;
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if (p.value.fields.length !== v.length) return false;
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let index = 0;
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for (const pp of p.value.fields) {
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if (!walk(pp, v[index++])) return false;
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}
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return true;
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}
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case 'arr': {
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if (!Array.isArray(v)) return false;
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if ('label' in v) return false;
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if (p.value.items.length !== v.length) return false;
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let index = 0;
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for (const pp of p.value.items) {
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if (!walk(pp, v[index++])) return false;
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}
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return true;
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}
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case 'dict':{
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if (!Dictionary.isDictionary<Ref, Assertion>(v)) return false;
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for (const [key, pp] of p.value.entries.entries()) {
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const vv = v.get(key);
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if (vv === void 0) return false;
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if (!walk(pp, vv)) return false;
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}
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return true;
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}
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}
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default:
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((_p : never) => {})(p);
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return false;
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}
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}
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return walk(p, v) ? bindings : null;
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}
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export function instantiate(t: Template, b: Bindings): Assertion {
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function walk(t: Template): Assertion {
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switch (t._variant) {
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case 'TAttenuate': {
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const v = walk(t.value.template);
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if (!isEmbedded(v)) {
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throw new Error(`Attempt to attenuate non-capability: ${stringify(v)}`);
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}
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const r = v.embeddedValue;
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return embed(attenuate(r, ... t.value.attenuation));
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}
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case 'TRef': {
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const n = t.value.binding;
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const v = b[n];
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if (v === void 0) throw new Error(`Unbound reference: ${n}`);
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return v;
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}
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case 'Lit':
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return t.value.value;
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case 'TCompound':
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switch (t.value._variant) {
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case 'rec': {
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const v = [] as unknown as Record<Assertion, Assertion[], Ref>;
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v.label = t.value.label;
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t.value.fields.forEach(tt => v.push(walk(tt)));
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return v;
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}
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case 'arr':
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return t.value.items.map(walk);
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case 'dict': {
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const v = new Dictionary<Ref, Assertion>();
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t.value.entries.forEach((tt, key) => v.set(key, walk(tt)));
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return v;
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}
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}
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}
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}
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return walk(t);
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}
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export function rewrite(r: Rewrite, v: Assertion): Assertion | null {
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const bindings = match(r.pattern, v);
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if (bindings === null) return null;
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return instantiate(r.template, bindings);
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}
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export function examineAlternatives(cav: Caveat, v: Assertion): Assertion | null {
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switch (cav._variant) {
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case "Alts": {
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for (const r of cav.value.alternatives) {
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const w = rewrite(r, v);
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if (w !== null) return w;
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}
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return null;
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}
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case "Rewrite":
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return rewrite(cav.value, v);
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case "Reject":
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return (match(cav.value.pattern, v) !== null) ? null : v;
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case "unknown":
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return null;
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default:
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((_: never) => { throw new Error("bad caveat"); })(cav);
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}
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}
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export function runRewrites(a: Caveat[] | undefined, v: Assertion): Assertion | null {
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if (a !== void 0) {
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for (let i = a.length - 1; i >= 0; i--) {
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const caveat = a[i];
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const w = examineAlternatives(caveat, v);
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if (w === null) return null;
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v = w;
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}
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}
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return v;
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}
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export function rfilter(... patterns: Pattern[]): Caveat {
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const ps = patterns.map(p => Rewrite({
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pattern: Pattern.PBind(PBind(p)),
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template: Template.TRef(TRef(0))
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}));
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return ps.length === 1 ? Caveat.Rewrite(ps[0]) : Caveat.Alts(Alts(ps));
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}
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export function attenuate(ref: Ref, ... a: Caveat[]): Ref {
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if (a.length === 0) return ref;
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return { ... ref, attenuation: [... (ref.attenuation ?? []), ... a] };
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}
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export function forwarder(ref: Ref): { proxy: Ref, revoker: Ref } {
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let underlying: Ref | null = ref;
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let handleMap = new IdentityMap<Handle, Handle>();
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let proxy = Turn.ref({
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assert(assertion: Assertion, handle: Handle): void {
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if (underlying === null) return;
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handleMap.set(handle, Turn.active.assert(underlying, assertion));
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},
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retract(handle: Handle): void {
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if (underlying === null) return;
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Turn.active.retract(handleMap.get(handle));
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handleMap.delete(handle);
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},
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message(body: Assertion): void {
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if (underlying === null) return;
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Turn.active.message(underlying, body);
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},
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sync(peer: Ref): void {
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if (underlying === null) return;
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Turn.active._sync(underlying, peer);
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},
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});
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let revoker = Turn.ref({
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message(_body: Assertion): void {
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underlying = null;
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handleMap.forEach(h => Turn.active.retract(h));
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},
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});
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return { proxy, revoker };
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}
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export function pRec(label: SturdyValue, ... fields: Array<Pattern>): Pattern {
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return Pattern.PCompound(PCompound.rec({ label, fields }));
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}
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export function pArr(... items: Array<Pattern>): Pattern {
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return Pattern.PCompound(PCompound.arr(items));
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}
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export function pDict(... entries: [SturdyValue, Pattern][]): Pattern {
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return Pattern.PCompound(PCompound.dict(new Dictionary<_embedded, Pattern>(entries)));
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}
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export function pLit(value: SturdyValue): Pattern {
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return Pattern.Lit(Lit(value));
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}
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export function pNot(p: Pattern): Pattern {
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return Pattern.PNot(PNot(p));
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}
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export function pAnd(... ps: Pattern[]): Pattern {
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return Pattern.PAnd(PAnd(ps));
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}
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export function pBind(pattern: Pattern): Pattern {
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return Pattern.PBind(PBind(pattern));
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}
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export function pEmbedded(): Pattern {
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return Pattern.PEmbedded(PEmbedded());
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}
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export function pSymbol(): Pattern {
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return Pattern.PAtom(PAtom.Symbol());
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}
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export function pByteString(): Pattern {
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return Pattern.PAtom(PAtom.ByteString());
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}
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export function pString(): Pattern {
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return Pattern.PAtom(PAtom.String());
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}
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export function pSignedInteger(): Pattern {
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return Pattern.PAtom(PAtom.SignedInteger());
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}
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export function pDouble(): Pattern {
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return Pattern.PAtom(PAtom.Double());
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}
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export function pFloat(): Pattern {
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return Pattern.PAtom(PAtom.Float());
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}
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export function pBoolean(): Pattern {
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return Pattern.PAtom(PAtom.Boolean());
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}
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export function pDiscard(): Pattern {
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return Pattern.PDiscard(PDiscard());
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}
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