Add mode to throw on invalid property access, fixes mozilla#25

lib/Jexl.js

@@ -14,10 +14,11 @@ var Evaluator = require("./evaluator/Evaluator"),
  * xpath-like drilldown into native Javascript objects.
  * @constructor
  */
-function Jexl() {
+function Jexl(throwOnMissingProp) {
   this._customGrammar = null;
   this._lexer = null;
   this._transforms = {};
+  this._throwOnMissingProp = throwOnMissingProp || true;
 }
 
 /**
@@ -174,7 +175,12 @@ Jexl.prototype._eval = function(exp, context) {
   var self = this,
     grammar = this._getGrammar(),
     parser = new Parser(grammar),
-    evaluator = new Evaluator(grammar, this._transforms, context);
+    evaluator = new Evaluator(
+      grammar,
+      this._transforms,
+      context,
+      this._throwOnMissingProp
+    );
   return Promise.resolve().then(function() {
     parser.addTokens(self._getLexer().tokenize(exp));
     return evaluator.eval(parser.complete());

lib/evaluator/Evaluator.js

@@ -35,11 +35,20 @@ var handlers = require("./handlers");
  *      to resolve the value of a relative identifier.
  * @constructor
  */
-var Evaluator = function(grammar, transforms, context, relativeContext) {
+var Evaluator = function(
+  grammar,
+  transforms,
+  context,
+  relativeContext,
+  throwOnMissingProp
+) {
   this._grammar = grammar;
   this._transforms = transforms || {};
   this._context = context || {};
   this._relContext = relativeContext || this._context;
+  this._throwOnMissingProp = true;
+  throwOnMissingProp || false;
+  console.log("_tOMP", this._throwOnMissingProp);
 };
 
 /**
@@ -50,7 +59,12 @@ var Evaluator = function(grammar, transforms, context, relativeContext) {
 Evaluator.prototype.eval = function(ast) {
   var self = this;
   return Promise.resolve().then(function() {
-    return handlers[ast.type].call(self, ast);
+    try {
+      var retVal = handlers[ast.type].call(self, ast);
+    } catch (ex) {
+      console.log("handler threw: ", ex);
+    }
+    return retVal;
   });
 };
 

lib/evaluator/handlers.js

@@ -81,16 +81,31 @@ exports.FilterExpression = function(ast) {
  * @private
  */
 exports.Identifier = function(ast) {
+  let throwOnMissingProp = true; // this._throwOnMissingProp;
+
   if (ast.from) {
     return this.eval(ast.from).then(function(context) {
       if (Array.isArray(context)) context = context[0];
-      if (context === undefined) return undefined;
+      if (context === undefined) return undefined; // XXX deleteme?  testme?
+      if (throwOnMissingProp && !(ast.value in context)) {
+        throw new Error(
+          `stemmed context does not have an identifier named ${ast.value}`
+        );
+      }
+
       return context[ast.value];
     });
   } else {
-    return ast.relative
-      ? this._relContext[ast.value]
-      : this._context[ast.value];
+    const contextToCheck = ast.relative ? this._relContext : this._context;
+
+    console.log("b4");
+    if (throwOnMissingProp && !(ast.value in contextToCheck)) {
+      throw new Error(
+        `default context does not have an identifier named ${ast.value}`
+      );
+    }
+
+    return contextToCheck[ast.value];
   }
 };
 

test/evaluator/Evaluator.js

@@ -107,7 +107,19 @@ describe("Evaluator", function() {
   });
   it("should throw when transform does not exist", function() {
     var e = new Evaluator(grammar);
-    return e.eval(toTree('"hello"|world')).should.reject;
+    return e.eval(toTree('"hello"|world')).should.be.rejected;
+  });
+  it("should throw when top-level identifier doesn't exist in throw mode", function() {
+    console.log("about to pass in true");
+    var context = { foo: { baz: { bar: "dog" } } },
+      e = new Evaluator(grammar, null, context, null, true);
+    return e.eval(toTree("monkey")).should.be.rejected;
+  });
+  it("should throw when child identifier doesn't exist in throw mode", function() {
+    console.log("about to pass in true");
+    var context = { foo: { baz: { bar: "cat" } } },
+      e = new Evaluator(grammar, null, context, null, true);
+    return e.eval(toTree("foo.baz.monkey")).should.be.rejected;
   });
   it("should apply the DivFloor operator", function() {
     var e = new Evaluator(grammar);

vendor/mozjexl.jsm

@@ -300,10 +300,11 @@ var Evaluator = __webpack_require__(2),
  * xpath-like drilldown into native Javascript objects.
  * @constructor
  */
-function Jexl() {
+function Jexl(throwOnMissingProp) {
   this._customGrammar = null;
   this._lexer = null;
   this._transforms = {};
+  this._throwOnMissingProp = throwOnMissingProp || true;
 }
 
 /**
@@ -460,7 +461,12 @@ Jexl.prototype._eval = function(exp, context) {
   var self = this,
     grammar = this._getGrammar(),
     parser = new Parser(grammar),
-    evaluator = new Evaluator(grammar, this._transforms, context);
+    evaluator = new Evaluator(
+      grammar,
+      this._transforms,
+      context,
+      this._throwOnMissingProp
+    );
   return Promise.resolve().then(function() {
     parser.addTokens(self._getLexer().tokenize(exp));
     return evaluator.eval(parser.complete());
@@ -552,11 +558,20 @@ var handlers = __webpack_require__(3);
  *      to resolve the value of a relative identifier.
  * @constructor
  */
-var Evaluator = function(grammar, transforms, context, relativeContext) {
+var Evaluator = function(
+  grammar,
+  transforms,
+  context,
+  relativeContext,
+  throwOnMissingProp
+) {
   this._grammar = grammar;
   this._transforms = transforms || {};
   this._context = context || {};
   this._relContext = relativeContext || this._context;
+  this._throwOnMissingProp = true;
+  throwOnMissingProp || false;
+  console.log("_tOMP", this._throwOnMissingProp);
 };
 
 /**
@@ -567,7 +582,12 @@ var Evaluator = function(grammar, transforms, context, relativeContext) {
 Evaluator.prototype.eval = function(ast) {
   var self = this;
   return Promise.resolve().then(function() {
-    return handlers[ast.type].call(self, ast);
+    try {
+      var retVal = handlers[ast.type].call(self, ast);
+    } catch (ex) {
+      console.log("handler threw: ", ex);
+    }
+    return retVal;
   });
 };
 
@@ -762,16 +782,31 @@ exports.FilterExpression = function(ast) {
  * @private
  */
 exports.Identifier = function(ast) {
+  let throwOnMissingProp = true; // this._throwOnMissingProp;
+
   if (ast.from) {
     return this.eval(ast.from).then(function(context) {
       if (Array.isArray(context)) context = context[0];
-      if (context === undefined) return undefined;
+      if (context === undefined) return undefined; // XXX deleteme?  testme?
+      if (throwOnMissingProp && !(ast.value in context)) {
+        throw new Error(
+          `stemmed context does not have an identifier named ${ast.value}`
+        );
+      }
+
       return context[ast.value];
     });
   } else {
-    return ast.relative
-      ? this._relContext[ast.value]
-      : this._context[ast.value];
+    const contextToCheck = ast.relative ? this._relContext : this._context;
+
+    console.log("b4");
+    if (throwOnMissingProp && !(ast.value in contextToCheck)) {
+      throw new Error(
+        `default context does not have an identifier named ${ast.value}`
+      );
+    }
+
+    return contextToCheck[ast.value];
   }
 };