Add function compare blocks (#3682)

* Add function compareBlockNumbers(a, b)

No tests yet; BigNumber values not presently included

* Fix format of fn declaration & add to exports

* Finish fixing format of fn declaration

* refactor exisiting pr

* update changelog

* more tests

* more tests

* move to web3-utils

* fix if clause

Co-authored-by: wbt <wbt@users.noreply.github.com>
Co-authored-by: Frankie <frankie.diamond@gmail.com>

CHANGELOG.md

@@ -271,6 +271,7 @@ Released with 1.0.0-beta.37 code base.
 ### Added
 
 - Support for typescript files (.ts) to be writtern alongside regular .js files (#3652)
+- Add compareBlock function that allows for complex block comparisons (#3682)
 
 ### Changed
 

packages/web3-utils/src/index.js

@@ -27,7 +27,7 @@ var ethjsUnit = require('ethjs-unit');
 var utils = require('./utils.js');
 var soliditySha3 = require('./soliditySha3.js');
 var randombytes = require('randombytes');
-
+var BN = require('bn.js');
 
 
 /**
@@ -316,6 +316,62 @@ var toChecksumAddress = function (address) {
     return checksumAddress;
 };
 
+/**
+ * Returns -1 if a<b, 1 if a>b; 0 if a == b.
+ * For more details on this type of function, see
+ * developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort
+ *
+ * @method compareBlockNumbers
+ *
+ * @param {String|Number|BN} a
+ *
+ * @param {String|Number|BN} b
+ *
+ * @returns {Number} -1, 0, or 1
+ */
+var compareBlockNumbers = function(a, b) {
+    if (a == b) {
+        return 0;
+    } else if (("genesis" == a || "earliest" == a || 0 == a) && ("genesis" == b || "earliest" ==  b || 0 == b)) {
+        return 0;
+    } else if ("genesis" == a || "earliest" == a) {
+        // b !== a, thus a < b
+        return -1;
+    } else if ("genesis" == b || "earliest" == b) {
+        // b !== a, thus a > b
+        return 1;
+    } else if (a == "latest") {
+        if (b == "pending") {
+            return -1;
+        } else {
+            // b !== ("pending" OR "latest"), thus a > b
+            return 1;
+        }
+    } else if (b === "latest") {
+        if (a == "pending") {
+            return 1;
+        } else {
+            // b !== ("pending" OR "latest"), thus a > b
+            return -1 
+        }
+    } else if (a == "pending") {
+        // b (== OR <) "latest", thus a > b
+        return 1;
+    } else if (b == "pending") {
+        return -1;
+    } else {
+        let bnA = new BN(a);
+        let bnB = new BN(b);
+        if(bnA.lt(bnB)) {
+            return -1;
+        } else if(bnA.eq(bnB)) {
+            return 0;
+        } else {
+            return 1;
+        }
+    }
+};
+
 module.exports = {
     _fireError: _fireError,
     _jsonInterfaceMethodToString: _jsonInterfaceMethodToString,
@@ -379,5 +435,7 @@ module.exports = {
     isContractAddressInBloom: utils.isContractAddressInBloom,
     isTopic: utils.isTopic,
     isTopicInBloom: utils.isTopicInBloom,
-    isInBloom: utils.isInBloom
+    isInBloom: utils.isInBloom,
+
+    compareBlockNumbers: compareBlockNumbers
 };

test/utils.compareBlockNumbers.js

@@ -0,0 +1,58 @@
+const chai = require('chai');
+const assert = chai.assert;
+const BN = require('bn.js');
+const formatters = require('../packages/web3-utils/src/index.js');
+
+const pending = "pending";
+const latest = "latest";
+const genesis = "genesis";
+const earliest = "earliest";
+
+const tests = [
+    // Base cases for numbers
+    { input: {a: 1, b: 1}, result: 0 },
+    { input: {a: 1, b: 2}, result: -1 },
+    { input: {a: 2, b: 1}, result: 1 },
+    // Base cases for BN
+    { input: {a: new BN(1), b: new BN(1)}, result: 0 },
+    { input: {a: new BN(1), b: new BN(2)}, result: -1 },
+    { input: {a: new BN(2), b: new BN(1)}, result: 1 },
+    // Base cases for numbers vs BN
+    { input: {a: new BN(1), b: 1}, result: 0 },
+    { input: {a: new BN(1), b: 2}, result: -1 },
+    { input: {a: new BN(2), b: 1}, result: 1 },
+    // Base cases for strings (sanity)
+    { input: {a: genesis, b: earliest}, result: 0 },
+    { input: {a: genesis, b: 0}, result: 0 },
+    { input: {a: earliest, b: 0}, result: 0 },
+    { input: {a: latest, b: latest}, result: 0 },
+    { input: {a: pending, b: pending}, result: 0 },
+    // Complex Strings
+    // Genesis
+    { input: {a: earliest, b: 2}, result: -1 },    
+    { input: {a: earliest, b: new BN(2)}, result: -1 },
+    { input: {a: earliest, b: latest}, result: -1 },
+    { input: {a: earliest, b: pending}, result: -1 },
+    { input: {a: genesis, b: 2}, result: -1 },    
+    { input: {a: genesis, b: new BN(2)}, result: -1 },
+    { input: {a: genesis, b: latest}, result: -1 },
+    { input: {a: genesis, b: pending}, result: -1 },
+    // latest
+    { input: {a: latest, b: 0}, result: 1 },
+    { input: {a: latest, b: new BN(1)}, result: 1 },
+    { input: {a: latest, b: pending}, result: -1 },
+    // pending 
+    { input: {a: pending, b: 0}, result: 1 },
+    { input: {a: pending, b: new BN(1)}, result: 1 },
+];
+
+describe('formatters', function () {
+    describe('compare blocknumbers', function () {
+        tests.forEach(function(test){
+            it('should return the correct value', function () {
+                assert.deepEqual(formatters.compareBlockNumbers(test.input.a, test.input.b), test.result);
+            });
+        });
+    });
+
+});