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d71677f141
## Why this should be merged Consolidates duplicated logic. Similar rationale to #84. ## How this works New `register.AtMostOnce[T]` type is responsible for limiting calls to `Register()`. ## How this was tested Existing unit tests of `params`. Note that the equivalent functionality in `types` wasn't tested but now is.
68 lines
2 KiB
Go
68 lines
2 KiB
Go
// Copyright 2024 the libevm authors.
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//
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// The libevm additions to go-ethereum are free software: you can redistribute
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// them and/or modify them under the terms of the GNU Lesser General Public License
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// as published by the Free Software Foundation, either version 3 of the License,
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// or (at your option) any later version.
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//
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// The libevm additions are distributed in the hope that they will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
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// General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see
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// <http://www.gnu.org/licenses/>.
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// Package register provides functionality for optional registration of types.
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package register
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import (
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"errors"
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"github.com/ava-labs/libevm/libevm/testonly"
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)
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// An AtMostOnce allows zero or one registration of a T.
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type AtMostOnce[T any] struct {
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v *T
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}
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// ErrReRegistration is returned on all but the first of calls to
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// [AtMostOnce.Register].
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var ErrReRegistration = errors.New("re-registration")
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// Register registers `v` or returns [ErrReRegistration] if already called.
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func (o *AtMostOnce[T]) Register(v T) error {
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if o.Registered() {
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return ErrReRegistration
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}
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o.v = &v
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return nil
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}
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// MustRegister is equivalent to [AtMostOnce.Register], panicking on error.
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func (o *AtMostOnce[T]) MustRegister(v T) {
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if err := o.Register(v); err != nil {
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panic(err)
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}
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}
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// Registered reports whether [AtMostOnce.Register] has been called.
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func (o *AtMostOnce[T]) Registered() bool {
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return o.v != nil
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}
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// Get returns the registered value. It MUST NOT be called before
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// [AtMostOnce.Register].
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func (o *AtMostOnce[T]) Get() T {
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return *o.v
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}
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// TestOnlyClear clears any previously registered value, returning `o` to its
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// default state. It panics if called from a non-testing call stack.
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func (o *AtMostOnce[T]) TestOnlyClear() {
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testonly.OrPanic(func() {
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o.v = nil
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})
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}
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