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util: add isSafeAddition.

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Christopher Jeffrey 2017-06-17 18:19:12 -07:00
parent 5bf68a765f
commit be0e7e02d2
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1 changed files with 21 additions and 0 deletions
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21
lib/utils/util.js
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@ -200,6 +200,14 @@ if (Object.assign)
util.MAX_SAFE_INTEGER = 0x1fffffffffffff; util.MAX_SAFE_INTEGER = 0x1fffffffffffff;
/**
* Max safe addition (52 bits).
* @const {Number}
* @default
*/
util.MAX_SAFE_ADDITION = 0xfffffffffffff;
/** /**
* Test whether a number is below MAX_SAFE_INTEGER. * Test whether a number is below MAX_SAFE_INTEGER.
* @param {Number} value * @param {Number} value
@ -210,6 +218,19 @@ util.isSafeInteger = function isSafeInteger(value) {
return value >= -0x1fffffffffffff && value <= 0x1fffffffffffff; return value >= -0x1fffffffffffff && value <= 0x1fffffffffffff;
}; };
/**
* Test whether the result of a positive
* addition would be below MAX_SAFE_INTEGER.
* @param {Number} value
* @returns {Boolean}
*/
util.isSafeAddition = function isSafeAddition(a, b) {
assert(a >= 0);
assert(b >= 0);
return a <= util.MAX_SAFE_ADDITION && b <= util.MAX_SAFE_ADDITION;
};
/** /**
* Test whether a number is Number, * Test whether a number is Number,
* finite, and below MAX_SAFE_INTEGER. * finite, and below MAX_SAFE_INTEGER.