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https://github.com/ethereum/go-ethereum.git
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7b7be249cb
This adds a new type wrapper that decodes as a list, but does not actually decode the contents of the list. The type parameter exists as a marker, and enables decoding the elements lazily. RawList can also be used for building a list incrementally.
89 lines
2.6 KiB
Go
89 lines
2.6 KiB
Go
// Copyright 2020 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it 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
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// GNU Lesser 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 <http://www.gnu.org/licenses/>.
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package rlp
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// Iterator is an iterator over the elements of an encoded container.
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type Iterator struct {
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data []byte
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next []byte
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offset int
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err error
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}
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// NewListIterator creates an iterator for the (list) represented by data.
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func NewListIterator(data RawValue) (*Iterator, error) {
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k, t, c, err := readKind(data)
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if err != nil {
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return nil, err
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}
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if k != List {
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return nil, ErrExpectedList
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}
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it := &Iterator{data: data[t : t+c], offset: int(t)}
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return it, nil
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}
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func newIterator(data []byte) *Iterator {
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return &Iterator{data: data}
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}
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// Next forwards the iterator one step.
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// Returns true if there is a next item or an error occurred on this step (check Err()).
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// On parse error, the iterator is marked finished and subsequent calls return false.
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func (it *Iterator) Next() bool {
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if len(it.data) == 0 {
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return false
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}
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_, t, c, err := readKind(it.data)
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if err != nil {
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it.next = nil
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it.err = err
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// Mark iteration as finished to avoid potential infinite loops on subsequent Next calls.
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it.data = nil
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return true
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}
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length := t + c
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it.next = it.data[:length]
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it.data = it.data[length:]
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it.offset += int(length)
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it.err = nil
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return true
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}
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// Count returns the remaining number of items.
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// Note this is O(n) and the result may be incorrect if the list data is invalid.
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// The returned count is always an upper bound on the remaining items
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// that will be visited by the iterator.
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func (it *Iterator) Count() int {
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count, _ := CountValues(it.data)
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return count
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}
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// Value returns the current value.
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func (it *Iterator) Value() []byte {
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return it.next
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}
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// Offset returns the offset of the current value into the list data.
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func (it *Iterator) Offset() int {
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return it.offset - len(it.next)
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}
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// Err returns the error that caused Next to return false, if any.
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func (it *Iterator) Err() error {
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return it.err
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}
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