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Mini Shell
Mini Shell
'use strict';
const unique = arr => arr.filter((v, i) => arr.lastIndexOf(v) === i);
const compact = arr => unique(arr).filter(Boolean);
module.exports = (action, data = {}, value = '') => {
let { past = [], present = '' } = data;
let rest, prev;
switch (action) {
case 'prev':
case 'undo':
rest = past.slice(0, past.length - 1);
prev = past[past.length - 1] || '';
return {
past: compact([value, ...rest]),
present: prev
};
case 'next':
case 'redo':
rest = past.slice(1);
prev = past[0] || '';
return {
past: compact([...rest, value]),
present: prev
};
case 'save':
return {
past: compact([...past, value]),
present: ''
};
case 'remove':
prev = compact(past.filter(v => v !== value));
present = '';
if (prev.length) {
present = prev.pop();
}
return {
past: prev,
present
};
default: {
throw new Error(`Invalid action: "${action}"`);
}
}
};
Zerion Mini Shell 1.0