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Hash symbols and valueOf results #17
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conartist6
commented
Aug 24, 2020
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| hashed = nextHash(); | ||
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| symbolMap[sym] = hashed; |
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Note that this is technically a memory leak. I'm just hoping there's no reason that programmers would create an unbounded number of symbols.
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| if (o == null) { | ||
| return hashNullish(o); | ||
| } | ||
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| if (typeof o.hashCode === 'function') { | ||
| // Drop any high bits from accidentally long hash codes. | ||
| return smi(o.hashCode(o)); | ||
| } | ||
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| const v = valueOf(o); | ||
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| if (v == null) { | ||
| return hashNullish(v); | ||
| } |
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Can you explain why we are moving this code of out of the 'object' || 'function' case to the top of the method?
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Quite simply: require('moment')().valueOf(), which returns a number (the timestamp). The current code assumes incorrectly that the result of object.valueOf() is always an object.
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Oh, I see now you're tackling immutable-js#1643 as well in this PR. I was trying to figure out what this code had to do with symbols, but now it makes sense.
Methuselah96
approved these changes
Aug 27, 2020
This was referenced Nov 14, 2020
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Fixes an obvious bug:
TypeError: Cannot convert a Symbol value to a string, and also tries to avoid the cost of hash collisions between symbols.This is an alternative to immutable-js#1753, based primarily on this comment.