Add support for explicit sparse lists and maps #599
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mtdowling
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kstich
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kstich
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jasdel
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The vast majority of all lists and maps in use today are dense, meaning they cannot contain null values. However, we have historically had no way to indicate that a list or map (value) supports nulls, so we had to assume that all lists and maps are sparse. This change makes it so that all lists and maps are considered dense by default, but services can opt-in to sparse lists using the `sparse` trait. This matters because it now allows languages that bake "null" into their type systems to provide better generated types. Given that nullability is now more abstract than just the box trait, I think that deprecating BoxIndex in favor of NullableIndex makes the concept more clear. BoxIndex still exists and can be used, but extends from NullableIndex.
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smithy-model/src/main/java/software/amazon/smithy/model/knowledge/NullableIndex.java
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The vast majority of all lists and maps in use today are dense, meaning
they cannot contain null values. However, we have historically had no
way to indicate that a list or map (value) supports nulls, so we had to
assume that all lists and maps are sparse. This change makes it so that
all lists and maps are considered dense by default, but services can
opt-in to sparse lists using the
sparsetrait. This matters because itnow allows languages that bake "null" into their type systems to provide
better generated types.
Issue #, if available:
Description of changes:
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.