feature: strict_variables, working on #9

src/scope.js

@@ -1,20 +1,30 @@
 const _ = require('lodash');
 const lexical = require('./lexical.js');
 
-var scope = {
-    get: function(str) {
-        var ctx = {};
-        for (var i = this.scopes.length - 1; i >= 0; i--) {
-            if(str === undefined){
+var Scope = {
+    safeGet: function(str) {
+        var i;
+        // get all
+        if (str === undefined) {
+            var ctx = {};
+            for (i = this.scopes.length - 1; i >= 0; i--) {
                 _.merge(ctx, this.scopes[i]);
             }
+            return ctx;
+        }
+        // get one path
+        for (i = this.scopes.length - 1; i >= 0; i--) {
             var v = _.get(this.scopes[i], str);
             if (v !== undefined) return v;
-            if(str === undefined){
-                return ctx;
-            }
         }
     },
+    get: function(str){
+        var val = this.safeGet(str);
+        if (val === undefined && this.opts.strict) {
+            throw new Error(`[strict_variables] undefined variable: ${str}`);
+        }
+        return val;
+    },
     set: function(k, v) {
         _.set(this.scopes[this.scopes.length - 1], k, v);
         return this;
@@ -28,8 +38,13 @@ var scope = {
     }
 };
 
-exports.factory = function(_ctx) {
-    var ctx = Object.create(scope);
-    ctx.scopes = [_ctx || {}];
-    return ctx;
+exports.factory = function(_ctx, opts) {
+    opts = _.defaults(opts, {
+        strict: false
+    });
+
+    var scope = Object.create(Scope);
+    scope.opts = opts;
+    scope.scopes = [_ctx || {}];
+    return scope;
 };