99 lines
2.9 KiB
Rust
99 lines
2.9 KiB
Rust
// Copyright 2015, 2016 Ethcore (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU 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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// Parity 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 General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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use std::fmt;
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use evm::instructions;
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/// Stack trait with VM-friendly API
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pub trait Stack<T> {
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/// Returns `Stack[len(Stack) - no_from_top]`
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fn peek(&self, no_from_top: usize) -> &T;
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/// Swaps Stack[len(Stack)] and Stack[len(Stack) - no_from_top]
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fn swap_with_top(&mut self, no_from_top: usize);
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/// Returns true if Stack has at least `no_of_elems` elements
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fn has(&self, no_of_elems: usize) -> bool;
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/// Get element from top and remove it from Stack. Panics if stack is empty.
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fn pop_back(&mut self) -> T;
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/// Get (up to `instructions::MAX_NO_OF_TOPICS`) elements from top and remove them from Stack. Panics if stack is empty.
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fn pop_n(&mut self, no_of_elems: usize) -> &[T];
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/// Add element on top of the Stack
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fn push(&mut self, elem: T);
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/// Get number of elements on Stack
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fn size(&self) -> usize;
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/// Returns all data on stack.
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fn peek_top(&self, no_of_elems: usize) -> &[T];
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}
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pub struct VecStack<S> {
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stack: Vec<S>,
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logs: [S; instructions::MAX_NO_OF_TOPICS]
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}
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impl<S : Copy> VecStack<S> {
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pub fn with_capacity(capacity: usize, zero: S) -> Self {
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VecStack {
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stack: Vec::with_capacity(capacity),
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logs: [zero; instructions::MAX_NO_OF_TOPICS]
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}
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}
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}
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impl<S : fmt::Display> Stack<S> for VecStack<S> {
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fn peek(&self, no_from_top: usize) -> &S {
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&self.stack[self.stack.len() - no_from_top - 1]
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}
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fn swap_with_top(&mut self, no_from_top: usize) {
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let len = self.stack.len();
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self.stack.swap(len - no_from_top - 1, len - 1);
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}
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fn has(&self, no_of_elems: usize) -> bool {
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self.stack.len() >= no_of_elems
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}
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fn pop_back(&mut self) -> S {
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let val = self.stack.pop();
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match val {
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Some(x) => x,
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None => panic!("Tried to pop from empty stack.")
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}
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}
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fn pop_n(&mut self, no_of_elems: usize) -> &[S] {
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assert!(no_of_elems <= instructions::MAX_NO_OF_TOPICS);
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for i in 0..no_of_elems {
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self.logs[i] = self.pop_back();
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}
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&self.logs[0..no_of_elems]
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}
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fn push(&mut self, elem: S) {
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self.stack.push(elem);
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}
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fn size(&self) -> usize {
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self.stack.len()
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}
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fn peek_top(&self, no_from_top: usize) -> &[S] {
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assert!(self.stack.len() >= no_from_top, "peek_top asked for more items than exist.");
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&self.stack[self.stack.len() - no_from_top .. self.stack.len()]
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}
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}
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