Added with special form implementation in javascript

bryanjos · bryanjos · commit 2ac4963f9b34 · 2016-02-23T20:23:30.000-06:00
diff --git a/src/javascript/lib/core/special_forms.js b/src/javascript/lib/core/special_forms.js
@@ -140,10 +140,35 @@ function _try(do_fun, rescue_function, catch_fun, else_function, after_function)
   }
 }
 
+function _with(...args){
+  let argsToPass = [];
+
+  for(let i = 0; i < args.length; i++){
+    if(i === args.length - 1){
+      return args[i].apply(null, argsToPass);
+    }else{
+      let [pattern, func] = args[i];
+
+      let result = func.apply(null, argsToPass);
+
+      let patternResult = Patterns.match_no_throw(pattern, result);
+
+      if(patternResult == null){
+        return result;
+      }else{
+        argsToPass = argsToPass.concat(patternResult);
+      }
+    }
+  }
+
+  return null;
+}
+
 export default {
   _case,
   cond,
   map_update,
   _for,
-  _try
+  _try,
+  _with
 };
diff --git a/src/javascript/tests/with.spec.js b/src/javascript/tests/with.spec.js
@@ -0,0 +1,94 @@
+import Core from "../lib/core";
+const Patterns = Core.Patterns;
+const SpecialForms = Core.SpecialForms;
+const Tuple = Core.Tuple;
+
+import Enum from "../lib/enum";
+
+import chai from 'chai';
+var expect = chai.expect;
+
+const $ = Patterns.variable();
+
+function map_fetch(map, key){
+  if(key in map){
+    return new Tuple(Symbol.for('ok'), map[key]);
+  }
+
+  return Symbol.for('error');
+}
+
+describe('with', () => {
+
+  it('normal', () => {
+    /*
+     opts = %{width: 10, height: 15}
+
+     with {:ok, width} <- Map.fetch(opts, :width),
+          {:ok, height} <- Map.fetch(opts, :height),
+          do: {:ok, width * height}
+
+     {:ok, 150}
+     */
+
+    let opts = { width: 10, height: 15 };
+
+    let value = SpecialForms._with(
+      [new Tuple(Symbol.for('ok'), $), () => map_fetch(opts, "width")],
+      [new Tuple(Symbol.for('ok'), $), (width) => map_fetch(opts, "height")],
+      (width, height) => new Tuple(Symbol.for('ok'), width * height)
+    );
+
+    expect(value).to.eql(new Tuple(Symbol.for('ok'), 150));
+  });
+
+
+  it('without match', () => {
+    /*
+     opts = %{width: 10}
+
+     with {:ok, width} <- Map.fetch(opts, :width),
+          {:ok, height} <- Map.fetch(opts, :height),
+          do: {:ok, width * height}
+
+     :error
+     */
+
+    let opts = { width: 10 };
+
+    let value = SpecialForms._with(
+      [new Tuple(Symbol.for('ok'), $), () => map_fetch(opts, "width")],
+      [new Tuple(Symbol.for('ok'), $), (width) => map_fetch(opts, "height")],
+      (width, height) => new Tuple(Symbol.for('ok'), width * height)
+    );
+
+    expect(value).to.eql(Symbol.for('error'));
+  });
+
+
+  it('bare expression', () => {
+    /*
+     opts = %{width: 10}
+
+     with {:ok, width} <- Map.fetch(opts, :width),
+          double_width = width * 2,
+          {:ok, height} <- Map.fetch(opts, :height),
+          do: {:ok, double_width * height}
+
+     {:ok, 300}
+     */
+
+    let opts = { width: 10, height: 15 };
+
+    let value = SpecialForms._with(
+      [new Tuple(Symbol.for('ok'), $), () => map_fetch(opts, "width")],
+      [$, (width) => width * 2],
+      [new Tuple(Symbol.for('ok'), $), (width, double_width) => map_fetch(opts, "height")],
+      (width, double_width, height) => new Tuple(Symbol.for('ok'), double_width * height)
+    );
+
+    expect(value).to.eql(new Tuple(Symbol.for('ok'), 300));
+  });
+
+});
+
