83 lines
1.6 KiB
Rust
83 lines
1.6 KiB
Rust
use prolog::ast::*;
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use std::ops::{Index, IndexMut};
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use std::vec::Vec;
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pub struct Frame {
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pub global_index: usize,
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pub e: usize,
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pub cp: CodePtr,
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perms: Vec<Addr>
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}
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impl Frame {
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fn new(global_index: usize, e: usize, cp: CodePtr, n: usize) -> Self {
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Frame {
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global_index: global_index,
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e: e,
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cp: cp,
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perms: vec![Addr::HeapCell(0); n]
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}
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}
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}
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pub struct AndStack(Vec<Frame>);
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impl AndStack {
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pub fn new() -> Self {
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AndStack(Vec::new())
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}
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pub fn push(&mut self, global_index: usize, e: usize, cp: CodePtr, n: usize) {
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self.0.push(Frame::new(global_index, e, cp, n));
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}
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#[allow(dead_code)]
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pub fn top(&self) -> Option<&Frame> {
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self.0.last()
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}
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pub fn len(&self) -> usize {
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self.0.len()
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}
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pub fn clear(&mut self) {
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self.0.clear()
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}
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// drop the last n frames.
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#[allow(dead_code)]
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pub fn drop_frames(&mut self, n: usize) {
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let len = self.0.len();
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self.0.truncate(len - n);
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}
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}
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impl Index<usize> for AndStack {
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type Output = Frame;
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fn index(&self, index: usize) -> &Self::Output {
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self.0.index(index)
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}
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}
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impl IndexMut<usize> for AndStack {
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fn index_mut(&mut self, index: usize) -> &mut Self::Output {
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self.0.index_mut(index)
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}
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}
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impl Index<usize> for Frame {
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type Output = Addr;
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fn index(&self, index: usize) -> &Self::Output {
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self.perms.index(index - 1)
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}
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}
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impl IndexMut<usize> for Frame {
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fn index_mut(&mut self, index: usize) -> &mut Self::Output {
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self.perms.index_mut(index - 1)
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}
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}
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