fersilva16

name: Tests

on:
  push:
    branches:
      - master
  pull_request:
    branches:
      - master

fersilva16

const assert = require('assert');

/**
 * @param {string} str
 */
const asb = ([fst, scd, ...tail]) => {
  if (fst === 'a' && scd === 'a') return asb([fst, ...tail]);
  if (fst === 'b' && !scd) return true;
  if (fst === 'a' && scd === 'b') return true;

fersilva16

const assert = require('assert');

/**
 * @param {string} str
 */
const asb = ([head, ...tail]) => {
  if (head === 'a') return asb(tail);
  if (head === 'b' && !tail.length) return true;

  return false;

fersilva16

// Or just get the last element!
type GetLast<XS extends unknown[]>
  = [never, ...XS][XS['length']];

// => never
type Empty = TakeLast<[]>;

// => 1
type OneEl = TakeLast<[1]>;

fersilva16

Hoje imagino que os steps do LR parser serão desta maneira:

Action	Stack	Remaining
Shift	(	λx.λy.x y) z
Shift	(λ	x.λy.x y) z
Shift	(λx	.λy.x y) z
Shift	(λx.	λy.x y) z
Shift	(λx.λ	y.x y) z
Shift	(λx.λy	.x y) z

fersilva16

const assert = require('assert');

const Value = (n) => ({ type: 'value', n });
const Sum = (a, b) => ({ type: 'sum', a, b });
const Prod = (a, b) => ({ type: 'prod', a, b });
const Div = (a, b) => ({ type: 'div', a, b });
const Sub = (a, b) => ({ type: 'sub', a, b });

const sliceLast = (a, n) => a.slice(n > a.length ? 0 : a.length - n, a.length);

fersilva16

Trying to parse: λx.λy.x x

Tokens: [Lambda, 'x', Dot, Lambda, 'y', Dot, 'x', Space, 'x']

Step	Op	State	Tokens
1	Start	[]	[Lambda, 'x', Dot, Lambda, 'y', Dot, 'x', Space, 'x']
2	Shift	[Lambda]	['x', Dot, Lambda, 'y', Dot, 'x', Space, 'x']
3	Reduce	[Lambda]	['x', Dot, Lambda, 'y', Dot, 'x', Space, 'x']
4	Shift	[Lambda, 'x']	[Dot, Lambda, 'y', Dot, 'x', Space, 'x']

fersilva16

#!/usr/bin/env bash

set -e

# complain to STDERR and exit with error
die()
{
    echo "$*" >&2
    print_usage
    exit 2