Merge pull request #24 from mstade/and

And
mstade · Jan 31, 2015 · db9c055 · db9c055
2 parents 61cac6a + a22e94d
commit db9c055
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Showing 5 changed files with 129 additions and 31 deletions.
diff --git a/index.js b/index.js
@@ -1,5 +1,6 @@
 module.exports =
-  { apply      : require('./lib/apply')
+  { and        : require('./lib/and')
+  , apply      : require('./lib/apply')
   , assert     : require('./lib/assert')
   , call       : require('./lib/call')
   , compose    : require('./lib/compose')

diff --git a/lib/and.js b/lib/and.js
@@ -0,0 +1,20 @@
+module.exports = require('./variadic')(and)
+
+function and(x, rest) {
+  if (x === undefined && isEmpty(rest)) return true
+
+  var result = val(x)
+
+  if (isnt(result) || isnt(rest)) return result
+
+  rest.every(function(x) {
+    return is(result = val(x))
+  })
+
+  return result
+}
+
+const isEmpty = require('./isEmpty')
+    , isnt    = require('./isnt')
+    , val     = require('./val')
+    , is      = require('./is')
diff --git a/lib/variadic.js b/lib/variadic.js
@@ -7,39 +7,46 @@ function variadic(fn) {
 
   switch (argc) {
     case -1 : return fn
-    case  0 : return function (rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  1 : return function (a, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  2 : return function (a, b, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  3 : return function (a, b, c, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  4 : return function (a, b, c, d, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  5 : return function (a, b, c, d, e, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  6 : return function (a, b, c, d, e, f, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  7 : return function (a, b, c, d, e, f, g, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  8 : return function (a, b, c, d, e, f, g, h, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case  9 : return function (a, b, c, d, e, f, g, h, i, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 10 : return function (a, b, c, d, e, f, g, h, i, j, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 11 : return function (a, b, c, d, e, f, g, h, i, j, k, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 12 : return function (a, b, c, d, e, f, g, h, i, j, k, l, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 13 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 14 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 15 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 16 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 17 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 18 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 19 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 20 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 21 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 22 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 23 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 24 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, rest) { return apply(fn, this, argc, slice(arguments)) }
-    case 25 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, rest) { return apply(fn, this, argc, slice(arguments)) }
-    default : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, rest) { return apply(fn, this, argc, slice(arguments)) }
+    case  0 : return function (rest) { return apply(fn, this, argc, arguments) }
+    case  1 : return function (a, rest) { return apply(fn, this, argc, arguments) }
+    case  2 : return function (a, b, rest) { return apply(fn, this, argc, arguments) }
+    case  3 : return function (a, b, c, rest) { return apply(fn, this, argc, arguments) }
+    case  4 : return function (a, b, c, d, rest) { return apply(fn, this, argc, arguments) }
+    case  5 : return function (a, b, c, d, e, rest) { return apply(fn, this, argc, arguments) }
+    case  6 : return function (a, b, c, d, e, f, rest) { return apply(fn, this, argc, arguments) }
+    case  7 : return function (a, b, c, d, e, f, g, rest) { return apply(fn, this, argc, arguments) }
+    case  8 : return function (a, b, c, d, e, f, g, h, rest) { return apply(fn, this, argc, arguments) }
+    case  9 : return function (a, b, c, d, e, f, g, h, i, rest) { return apply(fn, this, argc, arguments) }
+    case 10 : return function (a, b, c, d, e, f, g, h, i, j, rest) { return apply(fn, this, argc, arguments) }
+    case 11 : return function (a, b, c, d, e, f, g, h, i, j, k, rest) { return apply(fn, this, argc, arguments) }
+    case 12 : return function (a, b, c, d, e, f, g, h, i, j, k, l, rest) { return apply(fn, this, argc, arguments) }
+    case 13 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, rest) { return apply(fn, this, argc, arguments) }
+    case 14 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, rest) { return apply(fn, this, argc, arguments) }
+    case 15 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, rest) { return apply(fn, this, argc, arguments) }
+    case 16 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, rest) { return apply(fn, this, argc, arguments) }
+    case 17 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, rest) { return apply(fn, this, argc, arguments) }
+    case 18 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, rest) { return apply(fn, this, argc, arguments) }
+    case 19 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, rest) { return apply(fn, this, argc, arguments) }
+    case 20 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, rest) { return apply(fn, this, argc, arguments) }
+    case 21 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, rest) { return apply(fn, this, argc, arguments) }
+    case 22 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, rest) { return apply(fn, this, argc, arguments) }
+    case 23 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, rest) { return apply(fn, this, argc, arguments) }
+    case 24 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, rest) { return apply(fn, this, argc, arguments) }
+    case 25 : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, rest) { return apply(fn, this, argc, arguments) }
+    default : return function (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, rest) { return apply(fn, this, argc, arguments) }
   }
 }
 
 function apply(fn, host, argc, argv) {
-  var rest = slice(argv, argc)
-  argv = slice(argv, 0, argc)
+  var rest = []
+
+  if (argv.length < argc) {
+    argv = slice(argv).concat(Array(argc - argv.length))
+  } else {
+    rest = slice(argv, argc)
+    argv = slice(argv, 0, argc)
+  }
+
   argv.push(rest)
 
   return fn.apply(host, argv)

diff --git a/test/and.js b/test/and.js
@@ -0,0 +1,50 @@
+const constantly = require('../lib/constantly')
+    , expect     = require('must')
+    , and        = require('../lib/and')
+
+describe('`and`', function() {
+  describe('given zero arguments', function() {
+    it('should return `true`', function() {
+      expect(and()).to.equal(true)
+    })
+  })
+
+  describe('given one argument', function() {
+    it('should return the value of that argument', function() {
+      expect(and(1)).to.equal(1)
+      expect(and(0)).to.equal(0)
+      expect(and(false)).to.equal(false)
+    })
+
+    describe('and when that argument is a function', function() {
+      it('should return the value of calling that function', function() {
+	expect(and(constantly('wibble'))).to.equal('wibble')
+      })
+    })
+  })
+
+  describe('given two or more arguments', function() {
+    describe('when the values of all arguments are logically true', function() {
+      it('should return the last supplied value', function() {
+	expect(and(0, 1, 2, 3)).to.equal(3)
+      })
+    })
+
+    describe('when any one argument is logically false', function() {
+      it('should return the value that was logically false', function() {
+	expect(and(0, null, 1)).to.equal(null)
+	expect(and(false, true, 1)).to.equal(false)
+	expect(and(0, true, undefined)).to.equal(undefined)
+      })
+    })
+
+    describe('when an argument is a function', function() {
+      it('should call the function and evaluate its return value', function() {
+	var called = false
+
+	expect(and(0, function() { return (called = true) }, 1, 'yup')).to.equal('yup')
+	expect(called).to.be.true
+      })
+    })
+  })
+})
diff --git a/test/variadic.js b/test/variadic.js
@@ -5,6 +5,7 @@ var variadic = require('../lib/variadic')
   , slice    = require('../lib/slice')
   , each     = require('../lib/each')
   , src      = require('../lib/src')
+  , is       = require('../lib/is')
 
 describe('`variadic`', function() {
   describe('given an argument `fn`', function() {
@@ -32,6 +33,25 @@ describe('`variadic`', function() {
         })
       })
 
+      describe('of arity 1', function() {
+
+        it('should return a 1-arity function', function() {
+          var fn = variadic(function(rest) {})
+          expect(fn).to.have.length(1)
+        })
+
+        describe('when called without arguments', function() {
+          it('should set `rest` to an empty array', function(done) {
+            var fn = variadic(function(rest) {
+              is(Array, rest) && expect(rest).to.have.length(0)
+              done()
+            })
+
+            fn()
+          })
+        })
+      })
+
       each(range(1, 28), function(n) {
         describe('of arity '+n, function() {
           var sig = slice('abcdefghijklmnopqrstuvwxyz', 0, n - 1).concat('rest')
@@ -49,7 +69,7 @@ describe('`variadic`', function() {
 
               while (args.length) {
                 var fn = Function.apply(Function, sig.concat(
-                  [ 'this.expect(arguments).to.have.length('+(args.length + 1)+')'
+                  [ 'this.expect(arguments).to.have.length('+sig.length+')'
                   , 'this.expect(rest).to.be.empty'
                   ].join('\n')
                 ))