moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

cranelift/codegen/meta/src/unique_table.rs

@@ -0,0 +1,68 @@
+use std::slice;
+
+/// A table of sequences which tries to avoid common subsequences.
+pub struct UniqueTable<T: PartialEq + Clone> {
+    table: Vec<T>,
+}
+
+impl<T: PartialEq + Clone> UniqueTable<T> {
+    pub fn new() -> Self {
+        Self { table: Vec::new() }
+    }
+    pub fn add(&mut self, values: &Vec<T>) -> usize {
+        if let Some(offset) = find_subsequence(values, &self.table) {
+            offset
+        } else {
+            let offset = self.table.len();
+            self.table.extend((*values).clone());
+            offset
+        }
+    }
+    pub fn len(&self) -> usize {
+        self.table.len()
+    }
+    pub fn iter(&self) -> slice::Iter<T> {
+        self.table.iter()
+    }
+}
+
+/// Try to find the subsequence `sub` in the `whole` sequence. Returns None if
+/// it's not been found, or Some(index) if it has been. Naive implementation
+/// until proven we need something better.
+fn find_subsequence<T: PartialEq>(sub: &Vec<T>, whole: &Vec<T>) -> Option<usize> {
+    assert!(sub.len() > 0);
+    // We want i + sub.len() <= whole.len(), i.e. i < whole.len() + 1 - sub.len().
+    if whole.len() < sub.len() {
+        return None;
+    }
+    let max = whole.len() + 1 - sub.len();
+    for i in 0..max {
+        let mut found: Option<usize> = Some(i);
+        for j in 0..sub.len() {
+            if sub[j] != whole[i + j] {
+                found = None;
+                break;
+            }
+        }
+        if found.is_some() {
+            return found;
+        }
+    }
+    return None;
+}
+
+#[test]
+fn test_find_subsequence() {
+    assert_eq!(find_subsequence(&vec![1], &vec![4]), None);
+    assert_eq!(find_subsequence(&vec![1], &vec![1]), Some(0));
+    assert_eq!(find_subsequence(&vec![1, 2], &vec![1]), None);
+    assert_eq!(find_subsequence(&vec![1, 2], &vec![1, 2]), Some(0));
+    assert_eq!(find_subsequence(&vec![1, 2], &vec![1, 3]), None);
+    assert_eq!(find_subsequence(&vec![1, 2], &vec![0, 1, 2]), Some(1));
+    assert_eq!(find_subsequence(&vec![1, 2], &vec![0, 1, 3, 1]), None);
+    assert_eq!(find_subsequence(&vec![1, 2], &vec![0, 1, 3, 1, 2]), Some(3));
+    assert_eq!(
+        find_subsequence(&vec![1, 1, 3], &vec![1, 1, 1, 3, 3]),
+        Some(1)
+    );
+}