Add array sum and contains

circuits/array.circom

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+/*
+    Copyright 2018 0KIMS association.
+
+    This file is part of circom (Zero Knowledge Circuit Compiler).
+
+    circom is a free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    circom is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+    License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with circom. If not, see <https://www.gnu.org/licenses/>.
+*/
+pragma circom 2.0.0;
+
+include "comparators.circom";
+
+template Sum(n) {
+    signal input in[n];
+    signal output out;
+
+    signal cumulative[n];
+    cumulative[0] <== in[0];
+
+    for (var i = 1; i < n; i++) {
+        cumulative[i] <== cumulative[i - 1] + in[i];
+    }
+
+    out <== cumulative[n - 1];
+}
+
+template Contains(n) {
+    signal input in[n];
+    signal input value;
+    signal cumulative[n];
+    signal output out;
+
+    cumulative[0] <== in[0] - value;
+
+    for (var i = 1; i < n; i++) {
+        cumulative[i] <== cumulative[i - 1] * (in[i] - value);
+    }
+
+    component isZero = IsZero();
+    isZero.in <== cumulative[n - 1];
+
+    out <== isZero.out;
+}

test/array.js

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+const chai = require("chai");
+const path = require("path");
+const F1Field = require("ffjavascript").F1Field;
+const Scalar = require("ffjavascript").Scalar;
+exports.p = Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617");
+const Fr = new F1Field(exports.p);
+
+const wasm_tester = require("circom_tester").wasm;
+
+const assert = chai.assert;
+
+describe.only("Array test", function ()  {
+
+    this.timeout(100000);
+
+    it("Should create a sum circuit", async() => {
+        const circuit = await wasm_tester(path.join(__dirname, "circuits", "array_sum_test.circom"));
+
+        let witness;
+        witness = await circuit.calculateWitness({ "in": [7, 3, 6, 4]}, true);
+        assert(Fr.eq(Fr.e(witness[0]), Fr.e(1)));
+        assert(Fr.eq(Fr.e(witness[1]), Fr.e(20)));
+
+        witness = await circuit.calculateWitness({ "in": [2, 1, 5, 4]}, true);
+        assert(Fr.eq(Fr.e(witness[0]), Fr.e(1)));
+        assert(Fr.eq(Fr.e(witness[1]), Fr.e(12)));
+    });
+
+    it("Should create a contains circuit", async() => {
+        const circuit = await wasm_tester(path.join(__dirname, "circuits", "array_contains_test.circom"));
+
+        let witness;
+        witness = await circuit.calculateWitness({ "in": [7, 3, 6, 4], "value": 3}, true);
+        assert(Fr.eq(Fr.e(witness[0]), Fr.e(1)));
+        assert(Fr.eq(Fr.e(witness[1]), Fr.e(1)));
+
+        witness = await circuit.calculateWitness({ "in": [7, 3, 7, 4], "value": 7}, true);
+        assert(Fr.eq(Fr.e(witness[0]), Fr.e(1)));
+        assert(Fr.eq(Fr.e(witness[1]), Fr.e(1)));
+
+        witness = await circuit.calculateWitness({ "in": [7, 3, 6, 4], "value": 5}, true);
+        assert(Fr.eq(Fr.e(witness[0]), Fr.e(1)));
+        assert(Fr.eq(Fr.e(witness[1]), Fr.e(0)));
+
+        witness = await circuit.calculateWitness({ "in": [7, 5, 6, 4], "value": 3}, true);
+        assert(Fr.eq(Fr.e(witness[0]), Fr.e(1)));
+        assert(Fr.eq(Fr.e(witness[1]), Fr.e(0)));
+    });
+});

test/circuits/array_contains_test.circom

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+pragma circom 2.0.0;
+
+include "../../circuits/array.circom";
+
+component main = Contains(4);

test/circuits/array_sum_test.circom

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+pragma circom 2.0.0;
+
+include "../../circuits/array.circom";
+
+component main = Sum(4);