Began work on rewriting parser without object orientation

Parsing is expensive, if the parse tree can be stored on the DB it can 
save a lot of compute time, but mongo can't store Classes, so we 
re-write without classes

app/imports/parser/parseTree/index.js

@@ -0,0 +1,76 @@
+import resolve, {traverse, toString, mergeResolvedNodes} from '../resolve';
+
+const index = {
+  create({array, index}) {
+		return {
+      type: 'index',
+      array,
+      index,
+    }
+  },
+  resolve(fn, node, scope){
+    let index, array, rest;
+    let resolved = {};
+    ({result: index, ...rest} = resolve(fn, node.index, scope));
+    mergeResolvedNodes(resolved, rest);
+    ({result: array, ...rest} = resolve(fn, node.array, scope));
+    mergeResolvedNodes(resolved, rest);
+
+    if (
+      index.valueType === 'number' &&
+      Number.isInteger(index.value) &&
+      array.type === 'array'
+    ){
+      if (index.value < 1 || index.value > array.values.length){
+        mergeResolvedNodes(resolved, {
+          errors: [{
+            type: 'warning',
+            message: `Index of ${index.value} is out of range for an array` +
+              ` of length ${array.values.length}`,
+          }]
+        });
+      }
+      let selection = array.values[index.value - 1];
+      if (selection){
+        let result;
+        ({result, ...rest} = resolve(fn, selection, scope));
+        mergeResolvedNodes(resolved, rest)
+        return result;
+      }
+    } else if (fn === 'reduce'){
+      if (!(array instanceof ArrayNode)){
+        return new ErrorNode({
+          node: node,
+          error: 'Can not get the index of a non-array node: ' +
+            node.array.toString() + ' = ' + array.toString(),
+          context,
+        });
+      } else if (!index.isInteger){
+        return new ErrorNode({
+          node: node,
+          error: array.toString() + ' is not an integer index of the array',
+          context,
+        });
+      }
+    }
+    return new IndexNode({
+      index,
+      array,
+      previousNodes: [node],
+    });
+  },
+  toString(){
+    return `${node.array.toString()}[${node.index.toString()}]`;
+  },
+  traverse(fn){
+    fn(node);
+    node.array.traverse(fn);
+    node.index.traverse(fn);
+  },
+  replaceChildren(fn){
+    node.array = node.array.replaceNodes(fn);
+    node.index = node.index.replaceNodes(fn);
+  }
+}
+
+export default index;