Add function cache to reduce boilerplate

src/orchestrators/base.js

@@ -1,5 +1,6 @@
 const is = require('is')
 
+const cache = require('../services/cache_function')
 const NotImplementedError = require('../errors/not_implemented')
 const ValidationError = require('../errors/validation')
 
@@ -8,9 +9,9 @@ class BaseOrchestrator {
     this.querier = querier
 
     this.parser = this.buildParser()
-    this._parse = null
 
-    this._validate = null
+    this.validate = cache(this.validate, this)
+    this.parse = cache(this.parse, this)
   }
 
   get queryKey() {
@@ -50,11 +51,7 @@ class BaseOrchestrator {
       return null
     }
 
-    if (!this._parse) {
-      this._parse = this.parser.parse()
-    }
-
-    return this._parse
+    return this.parser.parse()
   }
 
   apply(values, querierMethod = null) {

src/orchestrators/filterer.js

@@ -31,14 +31,11 @@ class Filterer extends BaseOrchestrator {
       return true
     }
 
-    if (!this._validate) {
-      this._validate =
-        this.parser.validate() &&
-        this.querier.adapter.validator.validateFilters(this.parse()) &&
-        this.querier.validator.validate(this.parser.flatten(this.parse()))
-    }
-
-    return this._validate
+    return (
+      this.parser.validate() &&
+      this.querier.adapter.validator.validateFilters(this.parse()) &&
+      this.querier.validator.validate(this.parser.flatten(this.parse()))
+    )
   }
 
   run() {

src/orchestrators/pager.js

@@ -28,14 +28,11 @@ class Pager extends BaseOrchestrator {
       return true
     }
 
-    if (!this._validate) {
-      this._validate =
-        this.parser.validate() &&
-        this.querier.adapter.validator.validatePage(this.parse()) &&
-        this.querier.validator.validate(this.parser.flatten(this.parse()))
-    }
-
-    return this._validate
+    return (
+      this.parser.validate() &&
+      this.querier.adapter.validator.validatePage(this.parse()) &&
+      this.querier.validator.validate(this.parser.flatten(this.parse()))
+    )
   }
 
   run() {

src/orchestrators/sorter.js

@@ -28,14 +28,11 @@ class Sorter extends BaseOrchestrator {
       return true
     }
 
-    if (!this._validate) {
-      this._validate =
-        this.parser.validate() &&
-        this.querier.adapter.validator.validateSorts(this.parse()) &&
-        this.querier.validator.validate(this.parser.flatten(this.parse()))
-    }
-
-    return this._validate
+    return (
+      this.parser.validate() &&
+      this.querier.adapter.validator.validateSorts(this.parse()) &&
+      this.querier.validator.validate(this.parser.flatten(this.parse()))
+    )
   }
 
   run() {

src/parsers/base.js

@@ -1,3 +1,4 @@
+const cache = require('../services/cache_function')
 const NotImplementedError = require('../errors/not_implemented')
 const ParserValidator = require('../validators/parser')
 
@@ -13,7 +14,8 @@ class BaseParser {
       queryKey,
       query
     )
-    this._validate = null
+
+    this.validate = cache(this.validate, this)
   }
 
   buildKey(/* parsed */) {
@@ -48,11 +50,7 @@ class BaseParser {
   }
 
   validate() {
-    if (!this._validate) {
-      this._validate = this.validator.validate()
-    }
-
-    return this._validate
+    return this.validator.validate()
   }
 }
 

src/services/cache_function.js

@@ -0,0 +1,13 @@
+// Caches the return value of the first call to the function and returns that on
+// subsequent calls. Only works with functions without arguments.
+module.exports = (func, bind = undefined) => {
+  let cache = undefined
+
+  return () => {
+    if (cache === undefined) {
+      cache = func.call(bind)
+    }
+
+    return cache
+  }
+}

test/src/orchestrators/filterer.js

@@ -76,16 +76,6 @@ describe('validate', () => {
     expect(filterer.validate()).toBe(true)
   })
 
-  test('returns the cached `true` on subsequent calls', () => {
-    const filterer = new Filterer(
-      new TestQuerier({ filter: { test: 123 } }, knex('test'))
-    )
-
-    expect(filterer.validate()).toBe(true)
-    expect(filterer._validate).toBe(true)
-    expect(filterer.validate()).toBe(true)
-  })
-
   test('returns `true` if disabled', () => {
     const filterer = new Filterer(new TestQuerier({}, knex('test')))
 

test/src/orchestrators/pager.js

@@ -74,14 +74,6 @@ describe('validate', () => {
     expect(pager.validate()).toBe(true)
   })
 
-  test('returns the cached `true` on subsequent calls', () => {
-    const pager = new Pager(new TestQuerier({ page: 2 }, knex('test')))
-
-    expect(pager.validate()).toBe(true)
-    expect(pager._validate).toBe(true)
-    expect(pager.validate()).toBe(true)
-  })
-
   test('returns `true` if disabled', () => {
     const pager = new Pager(new TestQuerier({}, knex('test')))
 

test/src/orchestrators/sorter.js

@@ -74,14 +74,6 @@ describe('validate', () => {
     expect(sorter.validate()).toBe(true)
   })
 
-  test('returns the cached `true` on subsequent calls', () => {
-    const sorter = new Sorter(new TestQuerier({ sort: 'test' }, knex('test')))
-
-    expect(sorter.validate()).toBe(true)
-    expect(sorter._validate).toBe(true)
-    expect(sorter.validate()).toBe(true)
-  })
-
   test('returns `true` if disabled', () => {
     const sorter = new Sorter(new TestQuerier({}, knex('test')))
 

test/src/services/cache_function.js

@@ -0,0 +1,63 @@
+const cacheFunction = require('../../../src/services/cache_function')
+
+test('accepts/calls `func` and returns the value', () => {
+  const value = 'test123'
+  const func = jest.fn(() => value)
+
+  expect(cacheFunction(func)()).toEqual(value)
+  expect(func).toHaveBeenCalled()
+})
+
+test('accepts optional `bind` to set `this` for `func`', () => {
+  const value = {
+    value: 'test123',
+    test() {
+      return this.value
+    },
+  }
+
+  expect(cacheFunction(value.test, value)()).toEqual(value.value)
+})
+
+test('sets `this` to `undefined` for `func` if `bind` not set', () => {
+  const value = {
+    value: 'test123',
+    test() {
+      return this.value
+    },
+  }
+
+  expect(cacheFunction(value.test)()).toBeUndefined()
+})
+
+test('returns the cached value on subsequent calls', () => {
+  const value = 'test123'
+  const func = jest.fn(() => value)
+  const cachedFunc = cacheFunction(func)
+
+  expect(cachedFunc()).toEqual(value)
+  expect(cachedFunc()).toEqual(value)
+  expect(func).toHaveBeenCalledTimes(1)
+})
+
+test('does not cache the value if `undefined`', () => {
+  const value = undefined
+  const func = jest.fn(() => value)
+  const cachedFunc = cacheFunction(func)
+
+  expect(cachedFunc()).toEqual(value)
+  expect(cachedFunc()).toEqual(value)
+  expect(func).toHaveBeenCalledTimes(2)
+})
+
+test('does not cache the value if an error is thrown', () => {
+  const error = new Error('test123')
+  const func = jest.fn(() => {
+    throw error
+  })
+  const cachedFunc = cacheFunction(func)
+
+  expect(() => cachedFunc()).toThrow(error)
+  expect(() => cachedFunc()).toThrow(error)
+  expect(func).toHaveBeenCalledTimes(2)
+})