feat: ! to signify negative values

MikeIbberson · Feb 3, 2020 · 41cae41 · 41cae41
1 parent 52a3e43
commit 41cae41
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Showing 4 changed files with 41 additions and 12 deletions.
diff --git a/lib/__tests__/comparison.test.js b/lib/__tests__/comparison.test.js
@@ -8,9 +8,11 @@ const exp = [
   'language=EN',
   'bestFriend.name=jon',
   'colleague.age=*',
+  '!colour',
 ];
 
 const stub = {
+  colour: null,
   foo: 'bar',
   age: 21,
   language: 'en',
@@ -29,6 +31,7 @@ describe('Comparison', () => {
       expect(Comparison.isValid('<')).toBeTruthy();
       expect(Comparison.isValid('>=')).toBeTruthy();
       expect(Comparison.isValid('<=')).toBeTruthy();
+      expect(Comparison.isValid('!foo')).toBeTruthy();
     });
   });
 
@@ -38,7 +41,9 @@ describe('Comparison', () => {
 
     it('should return falsy', () =>
       expect(
-        new Comparison(['age>22', 'language=FR']).eval(stub),
+        new Comparison(['age>22', 'language=FR', 'color=red']).eval(
+          stub,
+        ),
       ).toBeFalsy());
   });
 
@@ -52,6 +57,7 @@ describe('Comparison', () => {
           { language: /EN/gi },
           { 'bestFriend.name': /jon/gi },
           { 'colleague.age': { $exists: true } },
+          { 'colour': { $or: [{ $exists: false }, { $eq: null }] } },
         ],
       }));
 

diff --git a/lib/__tests__/utils.test.js b/lib/__tests__/utils.test.js
@@ -97,4 +97,15 @@ describe('Utils', () => {
     it('should return truthy on equal value', () =>
       expect(Utils.isGreaterThanOrEqualTo(1, 2)).toBeFalsy());
   });
+
+  describe('isEmpty', () => {
+    it('should return truthy on null', () =>
+      expect(Utils.isEmpty(null)).toBeTruthy());
+
+    it('should return truthy on undefined', () =>
+      expect(Utils.isEmpty(undefined)).toBeTruthy());
+
+    it('should return falsy on false', () =>
+      expect(Utils.isEmpty(false)).toBeFalsy());
+  });
 });
diff --git a/lib/index.js b/lib/index.js
@@ -6,6 +6,7 @@ const {
   isLessThan,
   isGreaterThanOrEqualTo,
   isLessThanOrEqualTo,
+  isEmpty,
   cast,
 } = require('./utils');
 
@@ -19,6 +20,7 @@ const ops = {
 
 const getAssignment = {
   'equals': cast,
+  'isEmpty': cast,
   'isLessThan': (v) => ({
     $lt: cast(v),
   }),
@@ -37,18 +39,23 @@ const keys = Object.keys(ops);
 const re = new RegExp(`[${keys.map((v) => `(${v})`).join('')}]`, 'i');
 
 const hasLength = (v) => Array.isArray(v) && v.length;
+const hasNegation = (v) => typeof v === 'string' && v.startsWith('!');
 
 const getOp = (v) =>
-  keys.reduce(
-    (a, c) =>
-      v.includes(c) && !hasLength(a)
-        ? v
-            .split(re)
-            .filter(Boolean)
-            .concat(ops[c])
-        : a,
-    [],
-  );
+  hasNegation(v)
+    ? // reference the cast function conditionals
+      // this leverages how wildcards work, just the inverse
+      [v.replace('!', ''), '!', isEmpty]
+    : keys.reduce(
+        (a, c) =>
+          v.includes(c) && !hasLength(a)
+            ? v
+                .split(re)
+                .filter(Boolean)
+                .concat(ops[c])
+            : a,
+        [],
+      );
 
 class Comparison {
   constructor(exp, locale = 'en') {
@@ -57,7 +64,7 @@ class Comparison {
   }
 
   static isValid(v) {
-    return re.test(v);
+    return hasNegation(v) || re.test(v);
   }
 
   get eligible() {

diff --git a/lib/utils.js b/lib/utils.js
@@ -90,19 +90,24 @@ const isLessThanOrEqualTo = (a, b, locale) =>
 
 const cast = (v) => {
   if (v === '*') return { $exists: true };
+  if (v === '!') return { $or: [{ $exists: false }, { $eq: null }] };
 
   const test = validate(v);
   if (test.date()) return v;
   if (test.numeric()) return parseFloat(v);
   return new RegExp(v, 'i');
 };
 
+const isEmpty = (v) =>
+  v === undefined || v === null || v === 'undefined' || v === 'null';
+
 module.exports = {
   equals,
   isGreaterThan,
   isLessThan,
   isGreaterThanOrEqualTo,
   isLessThanOrEqualTo,
+  isEmpty,
   validate,
   cast,
 };