| // Copyright (C) 2016 the V8 project authors. All rights reserved. |
| // This code is governed by the BSD license found in the LICENSE file. |
| /*--- |
| esid: sec-addition-operator-plus-runtime-semantics-evaluation |
| es6id: 12.7.3.1 |
| description: > |
| Behavior when coercion via `Symbol.toPrimitive` yields a primitive value |
| info: | |
| [...] |
| 5. Let lprim be ? ToPrimitive(lval). |
| 6. Let rprim be ? ToPrimitive(rval). |
| 7. If Type(lprim) is String or Type(rprim) is String, then |
| a. Let lstr be ? ToString(lprim). |
| b. Let rstr be ? ToString(rprim). |
| c. Return the String that is the result of concatenating lstr and rstr. |
| 8. Let lnum be ? ToNumber(lprim). |
| 9. Let rnum be ? ToNumber(rprim). |
| 10. Return the result of applying the addition operation to lnum and rnum. |
| See the Note below 12.8.5. |
| |
| ES6 Section 7.1.1 ToPrimitive ( input [, PreferredType] ) |
| |
| [...] |
| 4. Let exoticToPrim be GetMethod(input, @@toPrimitive). |
| 5. ReturnIfAbrupt(exoticToPrim). |
| 6. If exoticToPrim is not undefined, then |
| a. Let result be Call(exoticToPrim, input, «hint»). |
| b. ReturnIfAbrupt(result). |
| c. If Type(result) is not Object, return result. |
| features: [Symbol.toPrimitive] |
| ---*/ |
| |
| var y = {}; |
| var retVal; |
| |
| y[Symbol.toPrimitive] = function() { |
| return retVal; |
| }; |
| |
| retVal = 86; |
| assert.sameValue(1 + y, 87); |
| assert.sameValue(y + 2, 88); |
| assert.sameValue('s' + y, 's86'); |
| assert.sameValue(y + 's', '86s'); |
| |
| retVal = 'str'; |
| assert.sameValue(0 + y, '0str'); |
| assert.sameValue(y + 0, 'str0'); |
| assert.sameValue('s' + y, 'sstr'); |
| assert.sameValue(y + 's', 'strs'); |
| |
| retVal = Symbol.toPrimitive; |
| assert.throws(TypeError, function() { |
| 0 + y; |
| }, 'ToNumber(Symbol): right-hand side'); |
| assert.throws(TypeError, function() { |
| y + 0; |
| }, 'ToNumber(Symbol): left-hand side'); |
| assert.throws(TypeError, function() { |
| '' + y; |
| }, 'ToString(Symbol): right-hand side'); |
| assert.throws(TypeError, function() { |
| y + ''; |
| }, 'ToString(Symbol): left-hand size'); |