https://issues.dlang.org/show_bug.cgi?id=15381
Issue ID: 15381
Summary: Allow hashes to use only lowest bits
Product: D
Version: D2
Hardware: All
OS: All
Status: NEW
Keywords: performance, spec
Severity: enhancement
Priority: P1
Component: druntime
Assignee: [email protected]
Reporter: [email protected]
It's a common situation that hash tables and other algorithms use only some
bits of a hash so all hash bits must equally represent the object (currently
not documented, filled as Issue 15380).
It may be useful to require an algorithm working with hashes cut only highest
bits (as current Druntime's associative array implementation does). This allows
e.g. unique indexed elements use its index as a hash (if I'm not missing
something regarding probabilities of usage patterns):
size_t toHash() { return myIndex; } // Will be allowed
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