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math/rand/v2: rename various functions

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Int31 -> Int32
Int31n -> Int32N
Int63 -> Int64
Int63n -> Int64N
Intn -> IntN

The 31 and 63 are pedantic and confusing: the functions should
be named for the type they return, same as all the others.

The lower-case n is inconsistent with Go's usual CamelCase
and especially problematic because we plan to add 'func N'.
Capitalize the n.

For #61716.

Change-Id: Idb1a005a82f353677450d47fb612ade7a41fde69
Reviewed-on: https://go-review.googlesource.com/c/go/+/516857
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Russ Cox 2023-08-05 23:49:01 -04:00 • committed by Gopher Robot
parent 59f0ab4036
commit d42750b17c
9 changed files with 209 additions and 206 deletions
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96
src/math/rand/v2/rand.go
View file

@ -29,7 +29,7 @@ import (
//
// A Source is not safe for concurrent use by multiple goroutines.
type Source interface {
Int63() int64
Int64() int64
Seed(seed int64)
}
@ -38,7 +38,7 @@ type Source interface {
// the range [0, 1<<64) directly.
// If a Rand r's underlying Source s implements Source64,
// then r.Uint64 returns the result of one call to s.Uint64
// instead of making two calls to s.Int63.
// instead of making two calls to s.Int64.
type Source64 interface {
Source
Uint64() uint64
@ -92,66 +92,66 @@ func (r *Rand) Seed(seed int64) {
r.readPos = 0
}
// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
func (r *Rand) Int63() int64 { return r.src.Int63() }
// Int64 returns a non-negative pseudo-random 63-bit integer as an int64.
func (r *Rand) Int64() int64 { return r.src.Int64() }
// Uint32 returns a pseudo-random 32-bit value as a uint32.
func (r *Rand) Uint32() uint32 { return uint32(r.Int63() >> 31) }
func (r *Rand) Uint32() uint32 { return uint32(r.Int64() >> 31) }
// Uint64 returns a pseudo-random 64-bit value as a uint64.
func (r *Rand) Uint64() uint64 {
if r.s64 != nil {
return r.s64.Uint64()
}
return uint64(r.Int63())>>31 | uint64(r.Int63())<<32
return uint64(r.Int64())>>31 | uint64(r.Int64())<<32
}
// Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
func (r *Rand) Int31() int32 { return int32(r.Int63() >> 32) }
// Int32 returns a non-negative pseudo-random 31-bit integer as an int32.
func (r *Rand) Int32() int32 { return int32(r.Int64() >> 32) }
// Int returns a non-negative pseudo-random int.
func (r *Rand) Int() int {
u := uint(r.Int63())
u := uint(r.Int64())
return int(u << 1 >> 1) // clear sign bit if int == int32
}
// Int63n returns, as an int64, a non-negative pseudo-random number in the half-open interval [0,n).
// Int64N returns, as an int64, a non-negative pseudo-random number in the half-open interval [0,n).
// It panics if n <= 0.
func (r *Rand) Int63n(n int64) int64 {
func (r *Rand) Int64N(n int64) int64 {
if n <= 0 {
panic("invalid argument to Int63n")
panic("invalid argument to Int64N")
}
if n&(n-1) == 0 { // n is power of two, can mask
return r.Int63() & (n - 1)
return r.Int64() & (n - 1)
}
max := int64((1 << 63) - 1 - (1<<63)%uint64(n))
v := r.Int63()
v := r.Int64()
for v > max {
v = r.Int63()
v = r.Int64()
}
return v % n
}
// Int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n).
// Int32N returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n).
// It panics if n <= 0.
func (r *Rand) Int31n(n int32) int32 {
func (r *Rand) Int32N(n int32) int32 {
if n <= 0 {
panic("invalid argument to Int31n")
panic("invalid argument to Int32N")
}
if n&(n-1) == 0 { // n is power of two, can mask
return r.Int31() & (n - 1)
return r.Int32() & (n - 1)
}
max := int32((1 << 31) - 1 - (1<<31)%uint32(n))
v := r.Int31()
v := r.Int32()
for v > max {
v = r.Int31()
v = r.Int32()
}
return v % n
}
// int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n).
// n must be > 0, but int31n does not check this; the caller must ensure it.
// int31n exists because Int31n is inefficient, but Go 1 compatibility
// int31n exists because Int32N is inefficient, but Go 1 compatibility
// requires that the stream of values produced by math/rand/v2 remain unchanged.
// int31n can thus only be used internally, by newly introduced APIs.
//
@ -173,27 +173,27 @@ func (r *Rand) int31n(n int32) int32 {
return int32(prod >> 32)
}
// Intn returns, as an int, a non-negative pseudo-random number in the half-open interval [0,n).
// IntN returns, as an int, a non-negative pseudo-random number in the half-open interval [0,n).
// It panics if n <= 0.
func (r *Rand) Intn(n int) int {
func (r *Rand) IntN(n int) int {
if n <= 0 {
panic("invalid argument to Intn")
panic("invalid argument to IntN")
}
if n <= 1<<31-1 {
return int(r.Int31n(int32(n)))
return int(r.Int32N(int32(n)))
}
return int(r.Int63n(int64(n)))
return int(r.Int64N(int64(n)))
}
// Float64 returns, as a float64, a pseudo-random number in the half-open interval [0.0,1.0).
func (r *Rand) Float64() float64 {
// A clearer, simpler implementation would be:
// return float64(r.Int63n(1<<53)) / (1<<53)
// return float64(r.Int64N(1<<53)) / (1<<53)
// However, Go 1 shipped with
// return float64(r.Int63()) / (1 << 63)
// return float64(r.Int64()) / (1 << 63)
// and we want to preserve that value stream.
//
// There is one bug in the value stream: r.Int63() may be so close
// There is one bug in the value stream: r.Int64() may be so close
// to 1<<63 that the division rounds up to 1.0, and we've guaranteed
// that the result is always less than 1.0.
//
@ -204,7 +204,7 @@ func (r *Rand) Float64() float64 {
// Getting 1 only happens 1/2⁵³ of the time, so most clients
// will not observe it anyway.
again:
f := float64(r.Int63()) / (1 << 63)
f := float64(r.Int64()) / (1 << 63)
if f == 1 {
goto again // resample; this branch is taken O(never)
}
@ -234,7 +234,7 @@ func (r *Rand) Perm(n int) []int {
// the final state of r. So this change can't be made for compatibility
// reasons for Go 1.
for i := 0; i < n; i++ {
j := r.Intn(i + 1)
j := r.IntN(i + 1)
m[i] = m[j]
m[j] = i
}
@ -257,7 +257,7 @@ func (r *Rand) Shuffle(n int, swap func(i, j int)) {
// Nevertheless, the right API signature accepts an int n, so handle it as best we can.
i := n - 1
for ; i > 1<<31-1-1; i-- {
j := int(r.Int63n(int64(i + 1)))
j := int(r.Int64N(int64(i + 1)))
swap(i, j)
}
for ; i > 0; i-- {
@ -286,9 +286,9 @@ func read(p []byte, src Source, readVal *int64, readPos *int8) (n int, err error
for n = 0; n < len(p); n++ {
if pos == 0 {
if rng != nil {
val = rng.Int63()
val = rng.Int64()
} else {
val = src.Int63()
val = src.Int64()
}
pos = 7
}
@ -356,7 +356,7 @@ type fastSource struct {
mu sync.Mutex
}
func (*fastSource) Int63() int64 {
func (*fastSource) Int64() int64 {
return int64(fastrand64() & rngMask)
}
@ -418,9 +418,9 @@ func Seed(seed int64) {
}
}
// Int63 returns a non-negative pseudo-random 63-bit integer as an int64
// Int64 returns a non-negative pseudo-random 63-bit integer as an int64
// from the default Source.
func Int63() int64 { return globalRand().Int63() }
func Int64() int64 { return globalRand().Int64() }
// Uint32 returns a pseudo-random 32-bit value as a uint32
// from the default Source.
@ -430,27 +430,27 @@ func Uint32() uint32 { return globalRand().Uint32() }
// from the default Source.
func Uint64() uint64 { return globalRand().Uint64() }
// Int31 returns a non-negative pseudo-random 31-bit integer as an int32
// Int32 returns a non-negative pseudo-random 31-bit integer as an int32
// from the default Source.
func Int31() int32 { return globalRand().Int31() }
func Int32() int32 { return globalRand().Int32() }
// Int returns a non-negative pseudo-random int from the default Source.
func Int() int { return globalRand().Int() }
// Int63n returns, as an int64, a non-negative pseudo-random number in the half-open interval [0,n)
// Int64N returns, as an int64, a non-negative pseudo-random number in the half-open interval [0,n)
// from the default Source.
// It panics if n <= 0.
func Int63n(n int64) int64 { return globalRand().Int63n(n) }
func Int64N(n int64) int64 { return globalRand().Int64N(n) }
// Int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n)
// Int32N returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n)
// from the default Source.
// It panics if n <= 0.
func Int31n(n int32) int32 { return globalRand().Int31n(n) }
func Int32N(n int32) int32 { return globalRand().Int32N(n) }
// Intn returns, as an int, a non-negative pseudo-random number in the half-open interval [0,n)
// IntN returns, as an int, a non-negative pseudo-random number in the half-open interval [0,n)
// from the default Source.
// It panics if n <= 0.
func Intn(n int) int { return globalRand().Intn(n) }
func IntN(n int) int { return globalRand().IntN(n) }
// Float64 returns, as a float64, a pseudo-random number in the half-open interval [0.0,1.0)
// from the default Source.
@ -500,9 +500,9 @@ type lockedSource struct {
s *rngSource
}
func (r *lockedSource) Int63() (n int64) {
func (r *lockedSource) Int64() (n int64) {
r.lk.Lock()
n = r.s.Int63()
n = r.s.Int64()
r.lk.Unlock()
return
}