Object property accessor API update (#485)

* Simplify function names

* Add delete and swap functions

* Remove custom setter

Not currently part of the expected use cases.

* Add documentation

* Update tests

* Add delete test functions

* Update tests to use fresh objects

* Add swap test functions

* Add empty tests

* Disable delete on arrays
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toasted-nutbread 2020-05-02 12:57:42 -04:00 committed by GitHub
parent 5a61c311ad
commit 401fe9f8d0
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2 changed files with 269 additions and 44 deletions

View File

@ -16,15 +16,27 @@
*/ */
/** /**
* Class used to get and set generic properties of an object by using path strings. * Class used to get and mutate generic properties of an object by using path strings.
*/ */
class ObjectPropertyAccessor { class ObjectPropertyAccessor {
constructor(target, setter=null) { /**
* Create a new accessor for a specific object.
* @param target The object which the getter and mutation methods are applied to.
* @returns A new ObjectPropertyAccessor instance.
*/
constructor(target) {
this._target = target; this._target = target;
this._setter = (typeof setter === 'function' ? setter : null);
} }
getProperty(pathArray, pathLength) { /**
* Gets the value at the specified path.
* @param pathArray The path to the property on the target object.
* @param pathLength How many parts of the pathArray to use.
* This parameter is optional and defaults to the length of pathArray.
* @returns The value found at the path.
* @throws An error is thrown if pathArray is not valid for the target object.
*/
get(pathArray, pathLength) {
let target = this._target; let target = this._target;
const ii = typeof pathLength === 'number' ? Math.min(pathArray.length, pathLength) : pathArray.length; const ii = typeof pathLength === 'number' ? Math.min(pathArray.length, pathLength) : pathArray.length;
for (let i = 0; i < ii; ++i) { for (let i = 0; i < ii; ++i) {
@ -37,24 +49,89 @@ class ObjectPropertyAccessor {
return target; return target;
} }
setProperty(pathArray, value) { /**
if (pathArray.length === 0) { * Sets the value at the specified path.
throw new Error('Invalid path'); * @param pathArray The path to the property on the target object.
} * @param value The value to assign to the property.
* @throws An error is thrown if pathArray is not valid for the target object.
*/
set(pathArray, value) {
const ii = pathArray.length - 1;
if (ii < 0) { throw new Error('Invalid path'); }
const target = this.getProperty(pathArray, pathArray.length - 1); const target = this.get(pathArray, ii);
const key = pathArray[pathArray.length - 1]; const key = pathArray[ii];
if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) { if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) {
throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`); throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`);
} }
if (this._setter !== null) {
this._setter(target, key, value, pathArray);
} else {
target[key] = value; target[key] = value;
} }
/**
* Deletes the property of the target object at the specified path.
* @param pathArray The path to the property on the target object.
* @throws An error is thrown if pathArray is not valid for the target object.
*/
delete(pathArray) {
const ii = pathArray.length - 1;
if (ii < 0) { throw new Error('Invalid path'); }
const target = this.get(pathArray, ii);
const key = pathArray[ii];
if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) {
throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`);
}
if (Array.isArray(target)) {
throw new Error('Invalid type');
}
delete target[key];
}
/**
* Swaps two properties of an object or array.
* @param pathArray1 The path to the first property on the target object.
* @param pathArray2 The path to the second property on the target object.
* @throws An error is thrown if pathArray1 or pathArray2 is not valid for the target object,
* or if the swap cannot be performed.
*/
swap(pathArray1, pathArray2) {
const ii1 = pathArray1.length - 1;
if (ii1 < 0) { throw new Error('Invalid path 1'); }
const target1 = this.get(pathArray1, ii1);
const key1 = pathArray1[ii1];
if (!ObjectPropertyAccessor.isValidPropertyType(target1, key1)) { throw new Error(`Invalid path 1: ${ObjectPropertyAccessor.getPathString(pathArray1)}`); }
const ii2 = pathArray2.length - 1;
if (ii2 < 0) { throw new Error('Invalid path 2'); }
const target2 = this.get(pathArray2, ii2);
const key2 = pathArray2[ii2];
if (!ObjectPropertyAccessor.isValidPropertyType(target2, key2)) { throw new Error(`Invalid path 2: ${ObjectPropertyAccessor.getPathString(pathArray2)}`); }
const value1 = target1[key1];
const value2 = target2[key2];
target1[key1] = value2;
try {
target2[key2] = value1;
} catch (e) {
// Revert
try {
target1[key1] = value1;
} catch (e2) {
// NOP
}
throw e;
}
} }
/**
* Converts a path string to a path array.
* @param pathArray The path array to convert.
* @returns A string representation of pathArray.
*/
static getPathString(pathArray) { static getPathString(pathArray) {
const regexShort = /^[a-zA-Z_][a-zA-Z0-9_]*$/; const regexShort = /^[a-zA-Z_][a-zA-Z0-9_]*$/;
let pathString = ''; let pathString = '';
@ -86,6 +163,12 @@ class ObjectPropertyAccessor {
return pathString; return pathString;
} }
/**
* Converts a path array to a path string. For the most part, the format of this string
* matches Javascript's notation for property access.
* @param pathString The path string to convert.
* @returns An array representation of pathString.
*/
static getPathArray(pathString) { static getPathArray(pathString) {
const pathArray = []; const pathArray = [];
let state = 'empty'; let state = 'empty';
@ -201,6 +284,14 @@ class ObjectPropertyAccessor {
return pathArray; return pathArray;
} }
/**
* Checks whether an object or array has the specified property.
* @param object The object to test.
* @param property The property to check for existence.
* This value should be a string if the object is a non-array object.
* For arrays, it should be an integer.
* @returns true if the property exists, otherwise false.
*/
static hasProperty(object, property) { static hasProperty(object, property) {
switch (typeof property) { switch (typeof property) {
case 'string': case 'string':
@ -222,6 +313,14 @@ class ObjectPropertyAccessor {
} }
} }
/**
* Checks whether a property is valid for the given object
* @param object The object to test.
* @param property The property to check for existence.
* @returns true if the property is correct for the given object type, otherwise false.
* For arrays, this means that the property should be a positive integer.
* For non-array objects, the property should be a string.
*/
static isValidPropertyType(object, property) { static isValidPropertyType(object, property) {
switch (typeof property) { switch (typeof property) {
case 'string': case 'string':

View File

@ -40,29 +40,30 @@ function createTestObject() {
} }
function testGetProperty1() { function testGet1() {
const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object);
const data = [ const data = [
[[], object], [[], (object) => object],
[['0'], object['0']], [['0'], (object) => object['0']],
[['value1'], object.value1], [['value1'], (object) => object.value1],
[['value1', 'value2'], object.value1.value2], [['value1', 'value2'], (object) => object.value1.value2],
[['value1', 'value3'], object.value1.value3], [['value1', 'value3'], (object) => object.value1.value3],
[['value1', 'value4'], object.value1.value4], [['value1', 'value4'], (object) => object.value1.value4],
[['value5'], object.value5], [['value5'], (object) => object.value5],
[['value5', 0], object.value5[0]], [['value5', 0], (object) => object.value5[0]],
[['value5', 1], object.value5[1]], [['value5', 1], (object) => object.value5[1]],
[['value5', 2], object.value5[2]] [['value5', 2], (object) => object.value5[2]]
]; ];
for (const [pathArray, expected] of data) { for (const [pathArray, getExpected] of data) {
assert.strictEqual(accessor.getProperty(pathArray), expected); const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object);
const expected = getExpected(object);
assert.strictEqual(accessor.get(pathArray), expected);
} }
} }
function testGetProperty2() { function testGet2() {
const object = createTestObject(); const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object); const accessor = new ObjectPropertyAccessor(object);
@ -89,15 +90,12 @@ function testGetProperty2() {
]; ];
for (const [pathArray, message] of data) { for (const [pathArray, message] of data) {
assert.throws(() => accessor.getProperty(pathArray), {message}); assert.throws(() => accessor.get(pathArray), {message});
} }
} }
function testSetProperty1() { function testSet1() {
const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object);
const testValue = {}; const testValue = {};
const data = [ const data = [
['0'], ['0'],
@ -112,17 +110,21 @@ function testSetProperty1() {
]; ];
for (const pathArray of data) { for (const pathArray of data) {
accessor.setProperty(pathArray, testValue); const object = createTestObject();
assert.strictEqual(accessor.getProperty(pathArray), testValue); const accessor = new ObjectPropertyAccessor(object);
accessor.set(pathArray, testValue);
assert.strictEqual(accessor.get(pathArray), testValue);
} }
} }
function testSetProperty2() { function testSet2() {
const object = createTestObject(); const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object); const accessor = new ObjectPropertyAccessor(object);
const testValue = {}; const testValue = {};
const data = [ const data = [
[[], 'Invalid path'],
[[0], 'Invalid path: [0]'], [[0], 'Invalid path: [0]'],
[['0', 'invalid'], 'Invalid path: ["0"].invalid'], [['0', 'invalid'], 'Invalid path: ["0"].invalid'],
[['value1', 'value2', 0], 'Invalid path: value1.value2[0]'], [['value1', 'value2', 0], 'Invalid path: value1.value2[0]'],
@ -137,7 +139,127 @@ function testSetProperty2() {
]; ];
for (const [pathArray, message] of data) { for (const [pathArray, message] of data) {
assert.throws(() => accessor.setProperty(pathArray, testValue), {message}); assert.throws(() => accessor.set(pathArray, testValue), {message});
}
}
function testDelete1() {
const hasOwn = (object, property) => Object.prototype.hasOwnProperty.call(object, property);
const data = [
[['0'], (object) => !hasOwn(object, '0')],
[['value1', 'value2'], (object) => !hasOwn(object.value1, 'value2')],
[['value1', 'value3'], (object) => !hasOwn(object.value1, 'value3')],
[['value1', 'value4'], (object) => !hasOwn(object.value1, 'value4')],
[['value1'], (object) => !hasOwn(object, 'value1')],
[['value5'], (object) => !hasOwn(object, 'value5')]
];
for (const [pathArray, validate] of data) {
const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object);
accessor.delete(pathArray);
assert.ok(validate(object));
}
}
function testDelete2() {
const data = [
[[], 'Invalid path'],
[[0], 'Invalid path: [0]'],
[['0', 'invalid'], 'Invalid path: ["0"].invalid'],
[['value1', 'value2', 0], 'Invalid path: value1.value2[0]'],
[['value1', 'value3', 'invalid'], 'Invalid path: value1.value3.invalid'],
[['value1', 'value4', 'invalid'], 'Invalid path: value1.value4.invalid'],
[['value1', 'value4', 0], 'Invalid path: value1.value4[0]'],
[['value5', 1, 'invalid'], 'Invalid path: value5[1].invalid'],
[['value5', 2, 'invalid'], 'Invalid path: value5[2].invalid'],
[['value5', 2, 0], 'Invalid path: value5[2][0]'],
[['value5', 2, 0, 'invalid'], 'Invalid path: value5[2][0]'],
[['value5', 2.5], 'Invalid index'],
[['value5', 0], 'Invalid type'],
[['value5', 1], 'Invalid type'],
[['value5', 2], 'Invalid type']
];
for (const [pathArray, message] of data) {
const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object);
assert.throws(() => accessor.delete(pathArray), {message});
}
}
function testSwap1() {
const data = [
[['0'], true],
[['value1', 'value2'], true],
[['value1', 'value3'], true],
[['value1', 'value4'], true],
[['value1'], false],
[['value5', 0], true],
[['value5', 1], true],
[['value5', 2], true],
[['value5'], false]
];
for (const [pathArray1, compareValues1] of data) {
for (const [pathArray2, compareValues2] of data) {
const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object);
const value1a = accessor.get(pathArray1);
const value2a = accessor.get(pathArray2);
accessor.swap(pathArray1, pathArray2);
if (!compareValues1 || !compareValues2) { continue; }
const value1b = accessor.get(pathArray1);
const value2b = accessor.get(pathArray2);
assert.deepStrictEqual(value1a, value2b);
assert.deepStrictEqual(value2a, value1b);
}
}
}
function testSwap2() {
const data = [
[[], [], false, 'Invalid path 1'],
[['0'], [], false, 'Invalid path 2'],
[[], ['0'], false, 'Invalid path 1'],
[[0], ['0'], false, 'Invalid path 1: [0]'],
[['0'], [0], false, 'Invalid path 2: [0]']
];
for (const [pathArray1, pathArray2, checkRevert, message] of data) {
const object = createTestObject();
const accessor = new ObjectPropertyAccessor(object);
let value1a;
let value2a;
if (checkRevert) {
try {
value1a = accessor.get(pathArray1);
value2a = accessor.get(pathArray2);
} catch (e) {
// NOP
}
}
assert.throws(() => accessor.swap(pathArray1, pathArray2), {message});
if (!checkRevert) { continue; }
const value1b = accessor.get(pathArray1);
const value2b = accessor.get(pathArray2);
assert.deepStrictEqual(value1a, value1b);
assert.deepStrictEqual(value2a, value2b);
} }
} }
@ -272,10 +394,14 @@ function testIsValidPropertyType() {
function main() { function main() {
testGetProperty1(); testGet1();
testGetProperty2(); testGet2();
testSetProperty1(); testSet1();
testSetProperty2(); testSet2();
testDelete1();
testDelete2();
testSwap1();
testSwap2();
testGetPathString1(); testGetPathString1();
testGetPathString2(); testGetPathString2();
testGetPathArray1(); testGetPathArray1();