feat: add .exact event modifier (#5977)

Allow limiting the event to the exact system modifiers specified.
close #5976

src/compiler/codegen/events.js

@@ -87,6 +87,14 @@ function genHandler (
         if (keyCodes[key]) {
           keys.push(key)
         }
+      } else if (key === 'exact') {
+        const modifiers: ASTModifiers = (handler.modifiers: any)
+        genModifierCode += genGuard(
+          ['ctrl', 'shift', 'alt', 'meta']
+            .filter(keyModifier => !modifiers[keyModifier])
+            .map(keyModifier => `$event.${keyModifier}Key`)
+            .join('||')
+        )
       } else {
         keys.push(key)
       }

src/core/instance/proxy.js

@@ -29,7 +29,7 @@ if (process.env.NODE_ENV !== 'production') {
     Proxy.toString().match(/native code/)
 
   if (hasProxy) {
-    const isBuiltInModifier = makeMap('stop,prevent,self,ctrl,shift,alt,meta')
+    const isBuiltInModifier = makeMap('stop,prevent,self,ctrl,shift,alt,meta,exact')
     config.keyCodes = new Proxy(config.keyCodes, {
       set (target, key, value) {
         if (isBuiltInModifier(key)) {

test/unit/features/directives/on.spec.js

@@ -205,6 +205,96 @@ describe('Directive v-on', () => {
     expect(spy).toHaveBeenCalled()
   })
 
+  // ctrl, shift, alt, meta
+  it('should support system modifers', () => {
+    vm = new Vue({
+      el,
+      template: `
+        <div>
+          <input ref="ctrl" @keyup.ctrl="foo">
+          <input ref="shift" @keyup.shift="foo">
+          <input ref="alt" @keyup.alt="foo">
+          <input ref="meta" @keyup.meta="foo">
+        </div>
+      `,
+      methods: { foo: spy }
+    })
+
+    triggerEvent(vm.$refs.ctrl, 'keyup')
+    expect(spy.calls.count()).toBe(0)
+    triggerEvent(vm.$refs.ctrl, 'keyup', e => { e.ctrlKey = true })
+    expect(spy.calls.count()).toBe(1)
+
+    triggerEvent(vm.$refs.shift, 'keyup')
+    expect(spy.calls.count()).toBe(1)
+    triggerEvent(vm.$refs.shift, 'keyup', e => { e.shiftKey = true })
+    expect(spy.calls.count()).toBe(2)
+
+    triggerEvent(vm.$refs.alt, 'keyup')
+    expect(spy.calls.count()).toBe(2)
+    triggerEvent(vm.$refs.alt, 'keyup', e => { e.altKey = true })
+    expect(spy.calls.count()).toBe(3)
+
+    triggerEvent(vm.$refs.meta, 'keyup')
+    expect(spy.calls.count()).toBe(3)
+    triggerEvent(vm.$refs.meta, 'keyup', e => { e.metaKey = true })
+    expect(spy.calls.count()).toBe(4)
+  })
+
+  it('should support exact modifier', () => {
+    vm = new Vue({
+      el,
+      template: `
+        <div>
+          <input ref="ctrl" @keyup.exact="foo">
+        </div>
+      `,
+      methods: { foo: spy }
+    })
+
+    triggerEvent(vm.$refs.ctrl, 'keyup')
+    expect(spy.calls.count()).toBe(1)
+
+    triggerEvent(vm.$refs.ctrl, 'keyup', e => {
+      e.ctrlKey = true
+    })
+    expect(spy.calls.count()).toBe(1)
+
+    // should not trigger if has other system modifiers
+    triggerEvent(vm.$refs.ctrl, 'keyup', e => {
+      e.ctrlKey = true
+      e.altKey = true
+    })
+    expect(spy.calls.count()).toBe(1)
+  })
+
+  it('should support system modifers with exact', () => {
+    vm = new Vue({
+      el,
+      template: `
+        <div>
+          <input ref="ctrl" @keyup.ctrl.exact="foo">
+        </div>
+      `,
+      methods: { foo: spy }
+    })
+
+    triggerEvent(vm.$refs.ctrl, 'keyup')
+    expect(spy.calls.count()).toBe(0)
+
+    triggerEvent(vm.$refs.ctrl, 'keyup', e => {
+      e.ctrlKey = true
+    })
+    expect(spy.calls.count()).toBe(1)
+
+    // should not trigger if has other system modifiers
+    triggerEvent(vm.$refs.ctrl, 'keyup', e => {
+      e.ctrlKey = true
+      e.altKey = true
+    })
+    expect(spy.calls.count()).toBe(1)
+  })
+
   it('should support number keyCode', () => {
     vm = new Vue({
       el,
@@ -497,8 +587,8 @@ describe('Directive v-on', () => {
     }).not.toThrow()
   })
 
-  // GitHub Issue #5046
-  it('should support keyboard modifier', () => {
+  // Github Issue #5046
+  it('should support keyboard modifier for direction keys', () => {
     const spyLeft = jasmine.createSpy()
     const spyRight = jasmine.createSpy()
     const spyUp = jasmine.createSpy()

test/unit/modules/compiler/codegen.spec.js

@@ -312,6 +312,14 @@ describe('codegen', () => {
       '<input @click.meta="onClick">',
       `with(this){return _c('input',{on:{"click":function($event){if(!$event.metaKey)return null;onClick($event)}}})}`
     )
+    assertCodegen(
+      '<input @click.exact="onClick">',
+      `with(this){return _c('input',{on:{"click":function($event){if($event.ctrlKey||$event.shiftKey||$event.altKey||$event.metaKey)return null;onClick($event)}}})}`
+    )
+    assertCodegen(
+      '<input @click.ctrl.exact="onClick">',
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return null;if($event.shiftKey||$event.altKey||$event.metaKey)return null;onClick($event)}}})}`
+    )
   })
 
   it('generate events with multiple modifiers', () => {