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refactor: lake: introduce lowerHexUInt64 (#13455)

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This PR adds a `lowerHexUInt64` utility to Lake which is used to
optimize `Hash.hex`.
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Mac Malone 2026-04-17 23:43:11 -04:00 • committed by GitHub
parent 592eb02bb2
commit 0fa749f71b
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2 changed files with 39 additions and 3 deletions
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6
src/lake/Lake/Build/Trace.lean
View file

@ -9,7 +9,7 @@ prelude
public import Lean.Data.Json
import Init.Data.Nat.Fold
meta import Init.Data.Nat.Fold
import Lake.Util.String
public import Lake.Util.String
public import Init.Data.String.Search
public import Init.Data.String.Extra
import Init.Data.Option.Coe
@ -141,8 +141,8 @@ public def ofHex? (s : String) : Option Hash :=
if s.utf8ByteSize = 16 && isHex s then ofHex s else none
/-- Returns the hash as 16-digit lowercase hex string. -/
public def hex (self : Hash) : String :=
lpad (String.ofList <| Nat.toDigits 16 self.val.toNat) '0' 16
@[inline] public def hex (self : Hash) : String :=
lowerHexUInt64 self.val
/-- Parse a hash from a string of decimal digits. -/
public def ofDecimal? (s : String) : Option Hash :=

36
src/lake/Lake/Util/String.lean
View file

@ -7,6 +7,7 @@ module
prelude
public import Init.Data.ToString.Basic
import Init.Data.UInt.Lemmas
import Init.Data.String.Basic
import Init.Data.Nat.Fold
@ -33,3 +34,38 @@ public def isHex (s : String) : Bool :=
65 ≤ c -- 'A'
else
false
def lowerHexByte (n : UInt8) : UInt8 :=
if n ≤ 9 then
n + 48 -- + '0'
else
n + 87 -- + ('a' - 10)
theorem isValidChar_of_lt_256 (h : n < 256) : isValidChar n :=
Or.inl <| Nat.lt_trans h (by decide)
def lowerHexChar (n : UInt8) : Char :=
⟨lowerHexByte n |>.toUInt32, isValidChar_of_lt_256 <|
UInt32.lt_iff_toNat_lt.mpr <| (lowerHexByte n).toNat_lt⟩
public def lowerHexUInt64 (n : UInt64) : String :=
String.ofByteArray (ByteArray.emptyWithCapacity 16) ByteArray.isValidUTF8_empty
|>.push (lowerHexChar (n >>> 60 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 56 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 52 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 48 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 44 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 40 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 36 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 32 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 28 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 24 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 20 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 16 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 12 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 8 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n >>> 4 &&& 0xf).toUInt8)
|>.push (lowerHexChar (n &&& 0xf).toUInt8)
-- sanity check
example : "0123456789abcdef" = lowerHexUInt64 0x0123456789abcdef := by decide