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65 lines
1.9 KiB
65 lines
1.9 KiB
3 years ago
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import { DataTypes, Cons, Nil } from './datatypes.js';
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import { Env } from './env.js';
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export class Evaluator {
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static async expand(sexp, macros) {
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if (sexp.type === DataTypes.Cons) {
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const op = await Evaluator.expand(sexp.car, macros)
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if (op.type === DataTypes.SpecialForm) {
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return await op.value(sexp.cdr, macros, macros);
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} else if (op.type === DataTypes.Macro) {
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return await op.value(
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await Cons.map(sexp.cdr,
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async o => await Evaluator.expand(o, macros)));
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// return (sexp.cdr.type === DataTypes.Nil
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// ? sexp.cdr
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// : Cons.reverse(await Cons.reduce(
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// sexp.cdr,
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// (p, o) => new Cons(await Evaluator.expand(o, macros), p),
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// new Nil())))
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// .then(opts => op.value(opts));
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} else if (sexp.type === DataTypes.Symbol) {
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return Env.find(macros, sexp.value) || sexp;
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}
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return sexp;
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}
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if (sexp.type === DataTypes.Symbol) {
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return Env.find(macros, sexp.value) || sexp;
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}
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return sexp;
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}
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static async eval(sexp, env, macros) {
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sexp = await Evaluator.expand(sexp, macros)
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if (sexp.type === DataTypes.Cons) {
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const op = await Evaluator.eval(sexp.car, env, macros)
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if (op.type === DataTypes.SpecialForm) {
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return await op.value(sexp.cdr, env, macros);
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} else if (op.type === DataTypes.Function) {
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return await op.value(await Cons.map(sexp.cdr, async o => Evaluator.eval(o, env, macros)));
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// return (sexp.cdr.type === DataTypes.Nil
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// ? Promise.resolve(sexp.cdr)
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// : Cons.reduce(
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// sexp.cdr,
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// (p, o) => p.then(v => Evaluator.eval(o, env, macros)
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// .then(ve => new Cons(ve, v))),
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// Promise.resolve(new Nil()))
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// .then(v => Cons.reverse(v)))
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// .then(opts => op.value(opts));
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}
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throw 'Illegal function call';
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}
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if (sexp.type === DataTypes.Symbol) {
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return Env.get(env, sexp.value);
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}
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return sexp;
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}
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}
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