Basic Object Comprehension Support

Parses and transpiles object comprehension syntax proposed in issue DanielXMoore#439

Tested only in limited contexts, of the 4 tests added one is failing

source/parser.hera

@@ -3284,6 +3284,20 @@ ObjectLiteral
   BracedObjectLiteral
   NestedImplicitObjectLiteral
   InlineObjectLiteral
+  ObjectComprehension
+
+ObjectComprehension
+  OpenBrace __ "for" _ Identifier:id _ "of" _ Expression:exp __ ObjectComprehensionProps:props __ CloseBrace ->
+    return ["(()=>{const _results = {};\n",
+             "for (const ", id, " of ", exp, ") {\n",
+             "Object.assign(_results, {\n",
+             props, "\n",
+             "})}; return _results})()"
+           ]
+
+ObjectComprehensionProps
+  (ComputedPropertyName __ ":" __ Expression __)+ ->
+    return $0.map(entry => entry.concat([","]))
 
 BracedObjectLiteral
   OpenBrace:open AllowAll ( BracedObjectLiteralContent __ CloseBrace )? RestoreAll ->

test/object-comprehensions.civet

@@ -0,0 +1,72 @@
+{ testCase } from ./helper.civet
+
+describe "object comprehensions", ->
+  testCase """
+    1
+    ---
+    { 
+    for x of [1, 2, 3]
+    [x]:  2 * x
+    [x * 2]: 4 * x
+    }
+    ---
+    (()=>{const _results = {};
+    for (const x of [1, 2, 3]) {
+    Object.assign(_results, {
+    [x]:  2 * x
+    ,[x * 2]: 4 * x
+    ,
+    })}; return _results})()
+  """
+
+  testCase """
+    scoping
+    ---
+    { 
+    for _results of [1]
+    [_results]:  2 * _results
+    [_results * 2]: 4 * _results
+    }
+    ---
+    (()=>{const _results = {};
+    for (const _results of [1]) {
+    Object.assign(_results, {
+    [_results]:  2 * _results
+    ,[_results * 2]: 4 * _results
+    ,
+    })}; return _results})()
+  """
+
+  testCase """
+    spacing 1
+    ---
+    { for x of [1]
+    [x]:  2 * x
+    [x * 2]: 4 * x
+    }
+    ---
+    (()=>{const _results = {};
+    for (const x of [1]) {
+    Object.assign(_results, {
+    [x]:  2 * x
+    ,[x * 2]: 4 * x
+    ,
+    })}; return _results})()
+  """
+
+  testCase """
+    spacing 2: indentation
+    ---
+    { for x of [1]
+      [x]:  2 * x
+      [x * 2]: 4 * x
+    }
+    ---
+    (()=>{const _results = {};
+    for (const x of [1]) {
+    Object.assign(_results, {
+    [x]:  2 * x
+    ,[x * 2]: 4 * x
+    ,
+    })}; return _results})()
+  """