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some tests for RangeMap
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RalfJung committed Aug 9, 2017
1 parent 65a3131 commit de80bcb
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Showing 3 changed files with 59 additions and 10 deletions.
2 changes: 1 addition & 1 deletion .travis.yml
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ script:
- |
# Test plain miri
cargo build --release --features "cargo_miri" &&
cargo test --release &&
cargo test --release --all &&
cargo install --features "cargo_miri"
- |
# Test cargo miri
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1 change: 0 additions & 1 deletion src/librustc_mir/Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@ version = "0.1.0"
workspace = "../.."

[lib]
test = false
path = "lib.rs"

[dependencies]
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66 changes: 58 additions & 8 deletions src/librustc_mir/interpret/range_map.rs
Original file line number Diff line number Diff line change
@@ -1,4 +1,9 @@
//! Implements a map from disjoint non-empty integer ranges to data associated with those ranges
//! Implements a map from integer indices to data.
//! Rather than storing data for every index, internally, this maps entire ranges to the data.
//! To this end, the APIs all work on ranges, not on individual integers. Ranges are split as
//! necessary (e.g. when [0,5) is first associated with X, and then [1,2) is mutated).
//! Users must not depend on whether a range is coalesced or not, even though this is observable
//! via the iteration APIs.
use std::collections::{BTreeMap};
use std::ops;

Expand All @@ -21,6 +26,7 @@ struct Range {

impl Range {
fn range(offset: u64, len: u64) -> ops::Range<Range> {
assert!(len > 0);
// We select all elements that are within
// the range given by the offset into the allocation and the length.
// This is sound if all ranges that intersect with the argument range, are in the
Expand All @@ -36,6 +42,7 @@ impl Range {
left..right
}

/// Tests if all of [offset, offset+len) are contained in this range.
fn overlaps(&self, offset: u64, len: u64) -> bool {
assert!(len > 0);
offset < self.end && offset+len >= self.start
Expand All @@ -48,6 +55,7 @@ impl<T> RangeMap<T> {
}

fn iter_with_range<'a>(&'a self, offset: u64, len: u64) -> impl Iterator<Item=(&'a Range, &'a T)> + 'a {
assert!(len > 0);
self.map.range(Range::range(offset, len))
.filter_map(move |(range, data)| {
if range.overlaps(offset, len) {
Expand All @@ -63,7 +71,7 @@ impl<T> RangeMap<T> {
}

fn split_entry_at(&mut self, offset: u64) where T: Clone {
let range = match self.iter_with_range(offset, 0).next() {
let range = match self.iter_with_range(offset, 1).next() {
Some((&range, _)) => range,
None => return,
};
Expand All @@ -88,6 +96,7 @@ impl<T> RangeMap<T> {
pub fn iter_mut_with_gaps<'a>(&'a mut self, offset: u64, len: u64) -> impl Iterator<Item=&'a mut T> + 'a
where T: Clone
{
assert!(len > 0);
// Preparation: Split first and last entry as needed.
self.split_entry_at(offset);
self.split_entry_at(offset+len);
Expand All @@ -112,14 +121,15 @@ impl<T> RangeMap<T> {
{
// Do a first iteration to collect the gaps
let mut gaps = Vec::new();
let mut last_end = None;
let mut last_end = offset;
for (range, _) in self.iter_with_range(offset, len) {
if let Some(last_end) = last_end {
if last_end < range.start {
gaps.push(Range { start: last_end, end: range.start });
}
if last_end < range.start {
gaps.push(Range { start: last_end, end: range.start });
}
last_end = Some(range.end);
last_end = range.end;
}
if last_end < offset+len {
gaps.push(Range { start: last_end, end: offset+len });
}

// Add default for all gaps
Expand Down Expand Up @@ -147,3 +157,43 @@ impl<T> RangeMap<T> {
}
}
}

#[cfg(test)]
mod tests {
use super::*;

/// Query the map at every offset in the range and collect the results.
fn to_vec<T: Copy>(map: &RangeMap<T>, offset: u64, len: u64) -> Vec<T> {
(offset..offset+len).into_iter().map(|i| *map.iter(i, 1).next().unwrap()).collect()
}

#[test]
fn basic_insert() {
let mut map = RangeMap::<i32>::new();
// Insert
for x in map.iter_mut(10, 1) {
*x = 42;
}
// Check
assert_eq!(to_vec(&map, 10, 1), vec![42]);
}

#[test]
fn gaps() {
let mut map = RangeMap::<i32>::new();
for x in map.iter_mut(11, 1) {
*x = 42;
}
for x in map.iter_mut(15, 1) {
*x = 42;
}

// Now request a range that needs three gaps filled
for x in map.iter_mut(10, 10) {
if *x != 42 { *x = 23; }
}

assert_eq!(to_vec(&map, 10, 10), vec![23, 42, 23, 23, 23, 42, 23, 23, 23, 23]);
assert_eq!(to_vec(&map, 13, 5), vec![23, 23, 42, 23, 23]);
}
}

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