cfx_vm_interpreter/interpreter/
stack.rs

1// Copyright 2015-2018 Parity Technologies (UK) Ltd.
2// This file is part of Parity.
3
4// Parity is free software: you can redistribute it and/or modify
5// it under the terms of the GNU General Public License as published by
6// the Free Software Foundation, either version 3 of the License, or
7// (at your option) any later version.
8
9// Parity is distributed in the hope that it will be useful,
10// but WITHOUT ANY WARRANTY; without even the implied warranty of
11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12// GNU General Public License for more details.
13
14// You should have received a copy of the GNU General Public License
15// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
16
17// Copyright 2019 Conflux Foundation. All rights reserved.
18// Conflux is free software and distributed under GNU General Public License.
19// See http://www.gnu.org/licenses/
20
21use super::instructions;
22use std::fmt;
23
24/// Stack trait with VM-friendly API
25pub trait Stack<T> {
26    /// Returns `Stack[len(Stack) - no_from_top]`
27    fn peek(&self, no_from_top: usize) -> &T;
28    /// Swaps Stack[len(Stack)] and Stack[len(Stack) - no_from_top]
29    fn swap_with_top(&mut self, no_from_top: usize);
30    /// Returns true if Stack has at least `no_of_elems` elements
31    fn has(&self, no_of_elems: usize) -> bool;
32    /// Get element from top and remove it from Stack. Panics if stack is empty.
33    fn pop_back(&mut self) -> T;
34    /// Get (up to `instructions::MAX_NO_OF_TOPICS`) elements from top and
35    /// remove them from Stack. Panics if stack is empty.
36    fn pop_n(&mut self, no_of_elems: usize) -> &[T];
37    /// Add element on top of the Stack
38    fn push(&mut self, elem: T);
39    /// Get number of elements on Stack
40    fn size(&self) -> usize;
41    /// Returns all data on stack.
42    #[allow(dead_code)]
43    fn peek_top(&self, no_of_elems: usize) -> &[T];
44}
45
46pub struct VecStack<S> {
47    stack: Vec<S>,
48    logs: [S; instructions::MAX_NO_OF_TOPICS],
49}
50
51impl<S: Copy> VecStack<S> {
52    pub fn with_capacity(capacity: usize, zero: S) -> Self {
53        VecStack {
54            stack: Vec::with_capacity(capacity),
55            logs: [zero; instructions::MAX_NO_OF_TOPICS],
56        }
57    }
58
59    pub fn content(&self) -> &Vec<S> { &self.stack }
60}
61
62impl<S: fmt::Display> Stack<S> for VecStack<S> {
63    fn peek(&self, no_from_top: usize) -> &S {
64        &self.stack[self.stack.len() - no_from_top - 1]
65    }
66
67    fn swap_with_top(&mut self, no_from_top: usize) {
68        let len = self.stack.len();
69        self.stack.swap(len - no_from_top - 1, len - 1);
70    }
71
72    fn has(&self, no_of_elems: usize) -> bool {
73        self.stack.len() >= no_of_elems
74    }
75
76    fn pop_back(&mut self) -> S {
77        self.stack.pop().expect(
78            "instruction validation prevents from popping too many items; qed",
79        )
80    }
81
82    fn pop_n(&mut self, no_of_elems: usize) -> &[S] {
83        assert!(no_of_elems <= instructions::MAX_NO_OF_TOPICS);
84
85        for i in 0..no_of_elems {
86            self.logs[i] = self.pop_back();
87        }
88        &self.logs[0..no_of_elems]
89    }
90
91    fn push(&mut self, elem: S) { self.stack.push(elem); }
92
93    fn size(&self) -> usize { self.stack.len() }
94
95    fn peek_top(&self, no_from_top: usize) -> &[S] {
96        assert!(
97            self.stack.len() >= no_from_top,
98            "peek_top asked for more items than exist."
99        );
100        &self.stack[self.stack.len() - no_from_top..self.stack.len()]
101    }
102}
cfx_vm_interpreter/interpreter/stack.rs

cfx_vm_interpreter/interpreter/
stack.rs
