Bitcoin ABC
0.26.3
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src
script
conditionstack.h
Go to the documentation of this file.
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// Copyright (c) 2024 The Bitcoin developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_SCRIPT_CONDITIONSTACK_H
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#define BITCOIN_SCRIPT_CONDITIONSTACK_H
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#include <cassert>
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#include <cstdint>
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#include <limits>
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class
ConditionStack
{
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private
:
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static
constexpr
uint32_t
NO_FALSE
= std::numeric_limits<uint32_t>::max();
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uint32_t
m_stack_size
= 0;
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uint32_t
m_first_false_pos
=
NO_FALSE
;
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public
:
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bool
empty
()
const
{
return
m_stack_size
== 0; }
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bool
all_true
()
const
{
return
m_first_false_pos
==
NO_FALSE
; }
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void
push_back
(
bool
f
) {
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if
(
m_first_false_pos
==
NO_FALSE
&& !
f
) {
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// The stack consists of all true values, and a false is added.
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// The first false value will appear at the current size.
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m_first_false_pos
=
m_stack_size
;
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}
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++
m_stack_size
;
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}
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void
pop_back
() {
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assert
(
m_stack_size
> 0);
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--
m_stack_size
;
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if
(
m_first_false_pos
==
m_stack_size
) {
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// When popping off the first false value, everything becomes true.
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m_first_false_pos
=
NO_FALSE
;
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}
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}
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void
toggle_top
() {
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assert
(
m_stack_size
> 0);
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if
(
m_first_false_pos
==
NO_FALSE
) {
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// The current stack is all true values; the first false will be the
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// top.
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m_first_false_pos
=
m_stack_size
- 1;
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}
else
if
(
m_first_false_pos
==
m_stack_size
- 1) {
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// The top is the first false value; toggling it will make
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// everything true.
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m_first_false_pos
=
NO_FALSE
;
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}
else
{
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// There is a false value, but not on top. No action is needed as
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// toggling anything but the first false value is unobservable.
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}
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}
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};
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#endif
// BITCOIN_SCRIPT_CONDITIONSTACK_H
ConditionStack
A data type to abstract out the condition stack during script execution.
Definition
conditionstack.h:28
ConditionStack::push_back
void push_back(bool f)
Definition
conditionstack.h:42
ConditionStack::empty
bool empty() const
Definition
conditionstack.h:40
ConditionStack::m_first_false_pos
uint32_t m_first_false_pos
The position of the first false value on the implied stack, or NO_FALSE if all true.
Definition
conditionstack.h:37
ConditionStack::m_stack_size
uint32_t m_stack_size
The size of the implied stack.
Definition
conditionstack.h:34
ConditionStack::NO_FALSE
static constexpr uint32_t NO_FALSE
A constant for m_first_false_pos to indicate there are no falses.
Definition
conditionstack.h:31
ConditionStack::toggle_top
void toggle_top()
Definition
conditionstack.h:58
ConditionStack::pop_back
void pop_back()
Definition
conditionstack.h:50
ConditionStack::all_true
bool all_true() const
Definition
conditionstack.h:41
GetRand
T GetRand(T nMax=std::numeric_limits< T >::max()) noexcept
Generate a uniform random integer of type T in the range [0..nMax) nMax defaults to std::numeric_limi...
Definition
random.h:85
assert
assert(!tx.IsCoinBase())
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