feat(mapper): add convenience mapper method

javiercejudo · Feb 13, 2016 · 6b9eb90 · 6b9eb90
1 parent 7d801c2
commit 6b9eb90
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Showing 3 changed files with 66 additions and 38 deletions.
diff --git a/README.md b/README.md
@@ -35,24 +35,22 @@ fn.raw(d, 10, [2, 3/10]); // d(30)
 ## Use case: functional hex to dec
 
 ```js
-var R = require('ramda');
-var fn = require('positional-notation');
+const R = require('ramda');
+const fn = require('positional-notation');
 
-var symbols = {
+const symbols = {
   '0': '0', '1': '1', '2': '2', '3': '3', '4': '4', '5': '5', '6': '6', '7': '7', '8': '8', '9': '9',
   'A': '10', 'B': '11', 'C': '12', 'D': '13', 'E': '14', 'F': '15',
 };
 
-var posNotation = fn(Object.keys(symbols).length);
+const posNotation = fn(Object.keys(symbols).length);
 
-var hexToDec = R.pipe(
+const hexToDec = R.pipe(
   R.toUpper,
   R.split(''),
   R.reverse,
   R.map(R.prop(R.__, symbols)),
-  R.addIndex(R.map)(function(val, index) {
-    return posNotation([index, val]);
-  }),
+  R.addIndex(R.map)(fn.mapper(posNotation)),
   R.sum
 );
 

diff --git a/src/index.js b/src/index.js
@@ -13,13 +13,18 @@ var floatingAdapter = require('floating-adapter');
 
 var Decimal = pipe(times, pow)(coreArbitraryPrecision(floatingAdapter));
 var toDecimal = toDecimalFactory(Decimal);
+var curry3 = curryN(3);
 
-var positionalNotationRaw = curryN(3, function (d, base, posValPair) {
-  return d(base).pow(d(posValPair[0]))
-    .times(d(posValPair[1]));
+var positionalNotationRaw = curry3(function(d, base, pair) {
+  return d(base).pow(d(pair[0])).times(d(pair[1]));
 });
 
 var positionalNotation = curryN(2, pipe(positionalNotationRaw(toDecimal), Number));
+
 positionalNotation.raw = positionalNotationRaw;
 
+positionalNotation.mapper = curry3(function(f, val, index) {
+  return f([index, val]);
+});
+
 module.exports = positionalNotation;
diff --git a/test/spec.js b/test/spec.js
@@ -36,6 +36,7 @@ describe('positional notation', function() {
     var d = toDecimalFactory(Decimal);
 
     fn.raw(d, 60, [1, 32]).equals(d(1920)).should.be.exactly(true);
+    fn.raw(d, 60)([1, 32]).equals(d(1920)).should.be.exactly(true);
     fn.raw(d)(60, [1, 32]).equals(d(1920)).should.be.exactly(true);
     fn.raw(d)(60)([1, 32]).equals(d(1920)).should.be.exactly(true);
 
@@ -49,35 +50,59 @@ describe('positional notation', function() {
   });
 });
 
-describe('use case', function() {
-  var symbols = {
-    '0': '0', '1': '1', '2': '2', '3': '3', '4': '4', '5': '5', '6': '6', '7': '7', '8': '8', '9': '9',
-    'A': '10', 'B': '11', 'C': '12', 'D': '13', 'E': '14', 'F': '15',
+describe('use case: base any to any', function() {
+  var d = toDecimalFactory(Decimal);
+  Decimal.setPrecision(10000);
+
+  var symbols = R.pipe(
+    R.split(''),
+    R.toPairs,
+    R.fromPairs
+  )('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz');
+
+  var fromBase = function(d, base) {
+    return R.pipe(
+      R.split(''),
+      R.reverse,
+      R.map(R.prop(R.__, R.invertObj(symbols))),
+      R.addIndex(R.map)(fn.mapper(fn.raw(d, base))),
+      R.reduce(R.invoker(1, 'plus'), d(0))
+    );
   };
 
-  var posNotation = fn(Object.keys(symbols).length);
+  var toBase = function(d, base) {
+    return R.pipe(
+      function(decimal) {
+        return R.unfold(function(cur) {
+          return cur > 0 ? [d(cur).mod(d(base)).toString(), d(cur).div(d(base)).toString().split('.')[0]] : false;
+        }, decimal);
+      },
+      R.reverse,
+      R.map(R.prop(R.__, symbols)),
+      R.join('')
+    );
+  };
 
-  var hexToDec = R.pipe(
-    R.toUpper,
-    R.split(''),
-    R.reverse,
-    R.map(R.prop(R.__, symbols)),
-    R.addIndex(R.map)(function(val, index) {
-      return posNotation([index, val]);
-    }),
-    R.sum
-  );
-
-  it('hexadecimal to decimal', function() {
-    hexToDec('AB').should.be.exactly(171);
-
-    // https://github.com/NerdDiffer/all-your-base/blob/ce258b2ca1430dd506b2a9e326f00219e8f8673c/test/convert_spec.js#L73-L79
-    hexToDec('1556').should.be.exactly(5462);
-    hexToDec('AE91').should.be.exactly(44689);
-    hexToDec('512').should.be.exactly(1298);
-    hexToDec('7DE').should.be.exactly(2014);
-    hexToDec('20').should.be.exactly(32);
-    hexToDec('9C4').should.be.exactly(2500);
-    hexToDec('ff001d').should.be.exactly(16711709);
+  var convertBasesRaw = R.curryN(4, function(d, oldBase, newBase, n) {
+    return R.pipe(fromBase(d, oldBase), toBase(d, newBase))(n);
+  });
+
+  var convertBases = convertBasesRaw(d);
+
+  it('hexadecimal to binary', function() {
+    var hexToBin = convertBases(16, 2);
+
+    hexToBin('A').should.be.exactly('1010');
+  });
+
+  it('octal to duodecimal', function() {
+    convertBases(8, 12, '73').should.be.exactly('4B');
+  });
+
+  it('quinary to base 32', function() {
+    var quiToB32 = convertBases(5, 32);
+
+    quiToB32('2312124222213').should.be.exactly('JAVIER');
+    quiToB32('30333330434').should.be.exactly('TAOCP');
   });
 });