Let's define our minimal framework
const prand = require('pure-rand');
class Random {
constructor(rng) {
this.rng = rng;
}
next(min, max) {
const g = prand.uniformIntDistribution(min, max, this.rng);
this.rng = g[1];
return g[0];
}
}
function map(g, mapper) {
return {
generate(mrng) {
const value = g.generate(mrng);
return mapper(value);
}
};
}
const miniFc = {}
miniFc.integer = (min, max) => {
return {
generate(mrng) {
return mrng.next(min, max);
}
};
}
miniFc.boolean = () => map(
miniFc.integer(0, 1),
Boolean
)
miniFc.character = () => map(
miniFc.integer(0, 25),
n => String.fromCharCode(97 + n)
)
miniFc.tuple = (...itemGenerators) => {
return {
generate(mrng) {
return itemGenerators.map(g => g.generate(mrng));
}
};
}
miniFc.array = (itemGenerator) => {
return {
generate(mrng) {
const size = mrng.next(0, 10);
const content = [];
for (let index = 0 ; index !== size ; ++index) {
content.push(itemGenerator.generate(mrng));
}
return content;
}
};
}
miniFc.string = () => map(
miniFc.array(miniFc.character()),
characters => characters.join('')
)
miniFc.dictionary = (valueGenerator) => map(
miniFc.array(
miniFc.tuple(
miniFc.string(),
valueGenerator
)
),
Object.fromEntries
)
Let's use it!
const seed = 0;
const mrng = new Random(prand.xoroshiro128plus(seed));
const generator = miniFc.array(miniFc.character());
console.log(generator.generate(mrng));
console.log(generator.generate(mrng));
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