circom/src/utils.js

const fnv = require("fnv-plus");
const bigInt = require("big-integer");

module.exports.ident =ident;

module.exports.extractSizes =extractSizes;
module.exports.flatArray = flatArray;
module.exports.csArr = csArr;
module.exports.subArray = subArray;
module.exports.accSizes = accSizes;
module.exports.fnvHash = fnvHash;
module.exports.stringifyBigInts = stringifyBigInts;
module.exports.unstringifyBigInts = unstringifyBigInts;

function ident(text) {
    let lines = text.split("\n");
    for (let i=0; i<lines.length; i++) {
        if (lines[i]) lines[i] = "    "+lines[i];
    }
    return lines.join("\n");
}

function extractSizes (o) {
    if (! Array.isArray(o)) return [];
    return [o.length, ...extractSizes(o[0])];
}

function flatArray(a) {
    var res = [];
    fillArray(res, a);
    return res;

    function fillArray(res, a) {
        if (Array.isArray(a)) {
            for (let i=0; i<a.length; i++) {
                fillArray(res, a[i]);
            }
        } else {
            res.push(a);
        }
    }
}

// Input [1,2,3]
// Returns " ,1 ,2, 3"
function csArr(_arr) {
    let S = "";
    const arr = _arr || [];
    for (let i=0; i<arr.length; i++) {
        S = " ,"+arr[i];
    }
    return S;
}

function subArray(value, sels) {
    if ((!sels) || (sels.length == 0)) return value;

    return subArray(value[sels[0]], sels.slice(1));
}

function accSizes(_sizes) {
    const sizes = _sizes || [];
    const accSizes = [1, 0];
    for (let i=sizes.length-1; i>=0; i--) {
        accSizes.unshift(accSizes[0]*sizes[i]);
    }
    return accSizes;
}

function fnvHash(str) {
    return fnv.hash(str, 64).hex();
}



function stringifyBigInts(o) {
    if ((typeof(o) == "bigint") || o.isZero !== undefined)  {
        return o.toString(10);
    } else if (Array.isArray(o)) {
        return o.map(stringifyBigInts);
    } else if (typeof o == "object") {
        const res = {};
        for (let k in o) {
            res[k] = stringifyBigInts(o[k]);
        }
        return res;
    } else {
        return o;
    }
}

function unstringifyBigInts(o) {
    if ((typeof(o) == "string") && (/^[0-9]+$/.test(o) ))  {
        return bigInt(o);
    } else if (Array.isArray(o)) {
        return o.map(unstringifyBigInts);
    } else if (typeof o == "object") {
        const res = {};
        for (let k in o) {
            res[k] = unstringifyBigInts(o[k]);
        }
        return res;
    } else {
        return o;
    }
}