Parser now works with variables passed into scope

app/imports/parser/parseTree/AccessorNode.js

@@ -0,0 +1,46 @@
+import ParseNode from '/imports/parser/parseTree/ParseNode.js';
+import ErrorNode from '/imports/parser/parseTree/ErrorNode.js';
+import ConstantNode from '/imports/parser/parseTree/ConstantNode.js';
+
+export default class AccessorNode extends ParseNode {
+  constructor({name, path}) {
+    super(...arguments);
+    this.name = name;
+    this.path = path;
+  }
+  compile(scope){
+    let value = scope && scope[this.name];
+    // For objects, get their value
+    this.path.forEach(name => {
+      if (value === undefined) return;
+      value = value[name];
+    });
+    let type = typeof value;
+    if (type === 'string' || type === 'number' || type === 'boolean'){
+      return new ConstantNode({value, type, previousNodes: [this]});
+    } else if (type === 'undefined'){
+      return new AccessorNode({
+        name: this.name,
+        path: this.path,
+        previousNodes: [this],
+      });
+    } else {
+      throw new Meteor.Error(`Unexpected case: ${this.name} resolved to ${value}`);
+    }
+  }
+  reduce(scope){
+    let result = this.compile(scope);
+    if (result instanceof AccessorNode){
+      return new ErrorNode({
+        node: result,
+        error: `${this.toString()} could not be resolved`,
+        previousNodes: [result],
+      });
+    } else {
+      return result;
+    }
+  }
+  toString(){
+    return `${this.name}.${this.path.join('.')}`;
+  }
+}