Add Random class with seed support.

CHANGELOG.md

@@ -43,6 +43,12 @@ Whitespace conventions:
     * `Hash#to_proc`
     * `Struct#dig`
 - Added safe navigator (`&.`) support. (#1532)
+- Added Random class with seed support. The following methods were reworked to use it:
+    * `Kernel.rand`
+    * `Kernel.srand`
+    * `Array#shuffle`
+    * `Array#shuffle!`
+    * `Array#sample`
 
 
 ### Changed

opal/corelib/array.rb

@@ -1901,7 +1901,7 @@ def shuffle!(rng = undefined)
           }
         }
         else {
-          j = Math.floor(Math.random() * i);
+          j = #{rand(`i`)};
         }
 
         tmp = self[--i];

opal/corelib/kernel.rb

@@ -1061,19 +1061,24 @@ def raise(exception = undefined, string = nil, _backtrace = nil)
   def rand(max = undefined)
     %x{
       if (max === undefined) {
-        return Math.random();
+        return #{Random::DEFAULT.rand};
       }
-      else if (max.$$is_range) {
-        var min = max.begin, range = max.end - min;
-        if(!max.exclude) range++;
 
-        return self.$rand(range) + min;
-      }
-      else {
-        return Math.floor(Math.random() *
-          Math.abs(#{Opal.coerce_to max, Integer, :to_int}));
+      if (max.$$is_number) {
+        if (max < 0) {
+          max = Math.abs(max);
+        }
+
+        if (max % 1 !== 0) {
+          max = max.$to_i();
+        }
+
+        if (max === 0) {
+          max = undefined;
+        }
       }
     }
+    Random::DEFAULT.rand(max)
   end
 
   def respond_to?(name, include_all = false)
@@ -1148,7 +1153,9 @@ def sleep(seconds = nil)
 
   alias sprintf format
 
-  alias srand rand
+  def srand(seed = Random.new_seed)
+    Random.srand(seed)
+  end
 
   def String(str)
     Opal.coerce_to?(str, String, :to_str) ||

opal/corelib/random.rb

@@ -0,0 +1,117 @@
+require 'corelib/random/seedrandom.js'
+
+class Random
+  attr_reader :seed, :state
+
+  def initialize(seed = Random.new_seed)
+    seed = Opal.coerce_to!(seed, Integer, :to_int)
+    @state = seed
+    reseed(seed)
+  end
+
+  def reseed(seed)
+    @seed = seed
+    `self.$rng = new Math.seedrandom(seed);`
+  end
+
+  `var $seed_generator = new Math.seedrandom('opal', { entropy: true });`
+
+  def self.new_seed
+    %x{
+      return Math.abs($seed_generator.int32());
+    }
+  end
+
+  def self.rand(limit = undefined)
+    DEFAULT.rand(limit)
+  end
+
+
+  def self.srand(n = Random.new_seed)
+    n = Opal.coerce_to!(n, Integer, :to_int)
+
+    previous_seed = DEFAULT.seed
+    DEFAULT.reseed(n)
+    previous_seed
+  end
+
+  DEFAULT = new(new_seed)
+
+  def ==(other)
+    return false unless Random === other
+
+    seed == other.seed && state == other.state
+  end
+
+  def bytes(length)
+    length = Opal.coerce_to!(length, Integer, :to_int)
+    length
+      .times
+      .map { rand(255).chr }
+      .join
+      .encode(Encoding::ASCII_8BIT)
+  end
+
+  def rand(limit = undefined)
+    %x{
+      function randomFloat() {
+        self.state++;
+        return self.$rng.quick();
+      }
+
+      function randomInt() {
+        return Math.floor(randomFloat() * limit);
+      }
+
+      function randomRange() {
+        var min = limit.begin,
+            max = limit.end;
+
+        if (min === nil || max === nil) {
+          return nil;
+        }
+
+        var length = max - min;
+
+        if (length < 0) {
+          return nil;
+        }
+
+        if (length === 0) {
+          return min;
+        }
+
+        if (max % 1 === 0 && min % 1 === 0 && !limit.exclude) {
+          length++;
+        }
+
+        return self.$rand(length) + min;
+      }
+
+      if (limit == null) {
+        return randomFloat();
+      } else if (limit.$$is_range) {
+        return randomRange();
+      } else if (limit.$$is_number) {
+        if (limit <= 0) {
+          #{raise ArgumentError, "invalid argument - #{limit}"}
+        }
+
+        if (limit % 1 === 0) {
+          // integer
+          return randomInt();
+        } else {
+          return randomFloat() * limit;
+        }
+      } else {
+        limit = #{Opal.coerce_to!(limit, Integer, :to_int)};
+
+        if (limit <= 0) {
+          #{raise ArgumentError, "invalid argument - #{limit}"}
+        }
+
+        return randomInt();
+      }
+    }
+  end
+end

opal/corelib/random/seedrandom.js.rb

@@ -0,0 +1,8 @@
+class Random
+  %x{
+    /* jshint ignore:start */
+    /* seedrandom.min.js 2.4.1 https://github.com/davidbau/seedrandom + PR https://github.com/davidbau/seedrandom/pull/36 */
+    !function(a,b){function c(c,j,k){var n=[];j=1==j?{entropy:!0}:j||{};var s=g(f(j.entropy?[c,i(a)]:null==c?h():c,3),n),t=new d(n),u=function(){for(var a=t.g(m),b=p,c=0;a<q;)a=(a+c)*l,b*=l,c=t.g(1);for(;a>=r;)a/=2,b/=2,c>>>=1;return(a+c)/b};return u.int32=function(){return 0|t.g(4)},u.quick=function(){return t.g(4)/4294967296},u.double=u,g(i(t.S),a),(j.pass||k||function(a,c,d,f){return f&&(f.S&&e(f,t),a.state=function(){return e(t,{})}),d?(b[o]=a,c):a})(u,s,"global"in j?j.global:this==b,j.state)}function d(a){var b,c=a.length,d=this,e=0,f=d.i=d.j=0,g=d.S=[];for(c||(a=[c++]);e<l;)g[e]=e++;for(e=0;e<l;e++)g[e]=g[f=s&f+a[e%c]+(b=g[e])],g[f]=b;(d.g=function(a){for(var b,c=0,e=d.i,f=d.j,g=d.S;a--;)b=g[e=s&e+1],c=c*l+g[s&(g[e]=g[f=s&f+b])+(g[f]=b)];return d.i=e,d.j=f,c})(l)}function e(a,b){return b.i=a.i,b.j=a.j,b.S=a.S.slice(),b}function f(a,b){var c,d=[],e=typeof a;if(b&&"object"==e)for(c in a)if(a.hasOwnProperty(c))try{d.push(f(a[c],b-1))}catch(a){}return d.length?d:"string"==e?a:a+"\0"}function g(a,b){for(var c,d=a+"",e=0;e<d.length;)b[s&e]=s&(c^=19*b[s&e])+d.charCodeAt(e++);return i(b)}function h(){try{if(j)return i(j.randomBytes(l));var b=new Uint8Array(l);return(k.crypto||k.msCrypto).getRandomValues(b),i(b)}catch(b){var c=k.navigator,d=c&&c.plugins;return[+new Date,k,d,k.screen,i(a)]}}function i(a){return String.fromCharCode.apply(0,a)}var j,k=this,l=256,m=6,n=52,o="random",p=b.pow(l,m),q=b.pow(2,n),r=2*q,s=l-1;if(b["seed"+o]=c,g(b.random(),a),"object"==typeof module&&module.exports){module.exports=c;try{j=require("crypto")}catch(a){}}else"function"==typeof define&&define.amd&&define(function(){return c})}([],Math);
+    /* jshint ignore:end */
+  }
+end

opal/opal.rb

@@ -13,5 +13,6 @@
 require 'corelib/dir'
 require 'corelib/file'
 require 'corelib/process'
+require 'corelib/random'
 
 require 'corelib/unsupported'

spec/filters/unsupported/bignum.rb

@@ -49,4 +49,7 @@
   fails "Marshal.load for a Integer loads an Integer -2361183241434822606847"
   fails "Marshal.dump with a Bignum dumps a Bignum"
   fails "Marshal.dump with a Bignum dumps a Bignum"
+  fails "Random.new_seed returns a Bignum"
+  fails "Random.new uses a random seed value if none is supplied"
+  fails "Random#rand with Bignum typically returns a Bignum"
 end

spec/filters/unsupported/random.rb

@@ -0,0 +1,4 @@
+opal_filter "Random" do
+  fails "Random#bytes returns the same numeric output for a given seed accross all implementations and platforms"
+  fails "Random#bytes returns the same numeric output for a given huge seed accross all implementations and platforms"
+end

spec/opal/core/kernel/rand_spec.rb

@@ -12,10 +12,6 @@
     r.to_a.include?(rand(r)).should == true
   end
 
-  it "should convert negative number and convert to integer" do
-    rand(-0.1).should == 0
-  end
-
   it "returns a numeric in opal" do
     rand.should be_kind_of(Numeric)
     rand(77).should be_kind_of(Numeric)

spec/ruby_specs

@@ -82,6 +82,7 @@ ruby/core/proc
 ruby/core/range
 ruby/core/rational
 ruby/core/regexp
+ruby/core/random
 
 ruby/core/string
 !ruby/core/string/crypt_spec