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//! Tree comparison operations.
use crate::tree::Tree;
/// Represents a difference between two trees.
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum TreeDiff {
/// A node/leaf exists in the first tree but not in the second
OnlyInFirst { path: Vec<usize>, content: String },
/// A node/leaf exists in the second tree but not in the first
OnlyInSecond { path: Vec<usize>, content: String },
/// A node/leaf exists in both but has different content
DifferentContent {
path: Vec<usize>,
first: String,
second: String,
},
}
impl Tree {
/// Compares the structure of two trees, ignoring labels and content.
///
/// Returns `true` if the trees have the same structure (same number of
/// children at each level, same node/leaf types), `false` otherwise.
///
/// # Examples
///
/// ```
/// use treelog::Tree;
///
/// let tree1 = Tree::Node("root1".to_string(), vec![
/// Tree::Leaf(vec!["a".to_string()])
/// ]);
/// let tree2 = Tree::Node("root2".to_string(), vec![
/// Tree::Leaf(vec!["b".to_string()])
/// ]);
/// assert!(tree1.eq_structure(&tree2));
/// ```
pub fn eq_structure(&self, other: &Tree) -> bool {
match (self, other) {
(Tree::Node(_, children1), Tree::Node(_, children2)) => {
if children1.len() != children2.len() {
return false;
}
children1
.iter()
.zip(children2.iter())
.all(|(c1, c2)| c1.eq_structure(c2))
}
(Tree::Leaf(_), Tree::Leaf(_)) => true,
_ => false,
}
}
/// Computes the differences between two trees.
///
/// Returns a vector of `TreeDiff` entries describing all differences.
///
/// # Examples
///
/// ```
/// use treelog::Tree;
///
/// let tree1 = Tree::Node("root".to_string(), vec![
/// Tree::Leaf(vec!["a".to_string()])
/// ]);
/// let tree2 = Tree::Node("root".to_string(), vec![
/// Tree::Leaf(vec!["b".to_string()])
/// ]);
/// let diffs = tree1.diff(&tree2);
/// ```
pub fn diff(&self, other: &Tree) -> Vec<TreeDiff> {
let mut diffs = Vec::new();
self.diff_recursive(other, &mut diffs, &mut Vec::new());
diffs
}
fn diff_recursive(&self, other: &Tree, diffs: &mut Vec<TreeDiff>, path: &mut Vec<usize>) {
match (self, other) {
(Tree::Node(label1, children1), Tree::Node(label2, children2)) => {
if label1 != label2 {
diffs.push(TreeDiff::DifferentContent {
path: path.clone(),
first: label1.clone(),
second: label2.clone(),
});
}
// Compare children
let max_len = children1.len().max(children2.len());
for i in 0..max_len {
path.push(i);
match (children1.get(i), children2.get(i)) {
(Some(c1), Some(c2)) => {
c1.diff_recursive(c2, diffs, path);
}
(Some(c1), None) => {
let content = match c1 {
Tree::Node(label, _) => label.clone(),
Tree::Leaf(lines) => lines.first().cloned().unwrap_or_default(),
};
diffs.push(TreeDiff::OnlyInFirst {
path: path.clone(),
content,
});
}
(None, Some(c2)) => {
let content = match c2 {
Tree::Node(label, _) => label.clone(),
Tree::Leaf(lines) => lines.first().cloned().unwrap_or_default(),
};
diffs.push(TreeDiff::OnlyInSecond {
path: path.clone(),
content,
});
}
(None, None) => {}
}
path.pop();
}
}
(Tree::Leaf(lines1), Tree::Leaf(lines2)) => {
if lines1 != lines2 {
let first = lines1.first().cloned().unwrap_or_default();
let second = lines2.first().cloned().unwrap_or_default();
diffs.push(TreeDiff::DifferentContent {
path: path.clone(),
first,
second,
});
}
}
(Tree::Node(label, _), Tree::Leaf(lines)) => {
let second = lines.first().cloned().unwrap_or_default();
diffs.push(TreeDiff::DifferentContent {
path: path.clone(),
first: label.clone(),
second,
});
}
(Tree::Leaf(lines), Tree::Node(label, _)) => {
let first = lines.first().cloned().unwrap_or_default();
diffs.push(TreeDiff::DifferentContent {
path: path.clone(),
first,
second: label.clone(),
});
}
}
}
/// Checks if this tree is a subtree of another tree.
///
/// Returns `true` if this tree structure and content appears as a
/// subtree within the other tree, `false` otherwise.
///
/// # Examples
///
/// ```
/// use treelog::Tree;
///
/// let subtree = Tree::Node("child".to_string(), vec![
/// Tree::Leaf(vec!["item".to_string()])
/// ]);
/// let tree = Tree::Node("root".to_string(), vec![
/// subtree.clone(),
/// Tree::Leaf(vec!["other".to_string()])
/// ]);
/// assert!(subtree.is_subtree_of(&tree));
/// ```
pub fn is_subtree_of(&self, other: &Tree) -> bool {
// Check if this tree matches the other tree
if self == other {
return true;
}
// Check if this tree is a subtree of any child
if let Tree::Node(_, children) = other {
for child in children {
if self.is_subtree_of(child) {
return true;
}
}
}
false
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_eq_structure() {
let tree1 = Tree::Node("root1".to_string(), vec![Tree::Leaf(vec!["a".to_string()])]);
let tree2 = Tree::Node("root2".to_string(), vec![Tree::Leaf(vec!["b".to_string()])]);
assert!(tree1.eq_structure(&tree2));
let tree3 = Tree::Node(
"root".to_string(),
vec![
Tree::Leaf(vec!["a".to_string()]),
Tree::Leaf(vec!["b".to_string()]),
],
);
assert!(!tree1.eq_structure(&tree3));
}
#[test]
fn test_diff() {
let tree1 = Tree::Node("root".to_string(), vec![Tree::Leaf(vec!["a".to_string()])]);
let tree2 = Tree::Node("root".to_string(), vec![Tree::Leaf(vec!["b".to_string()])]);
let diffs = tree1.diff(&tree2);
assert!(!diffs.is_empty());
}
#[test]
fn test_is_subtree_of() {
let subtree = Tree::Node(
"child".to_string(),
vec![Tree::Leaf(vec!["item".to_string()])],
);
let tree = Tree::Node(
"root".to_string(),
vec![subtree.clone(), Tree::Leaf(vec!["other".to_string()])],
);
assert!(subtree.is_subtree_of(&tree));
let not_subtree = Tree::Node(
"nonexistent".to_string(),
vec![Tree::Leaf(vec!["item".to_string()])],
);
assert!(!not_subtree.is_subtree_of(&tree));
}
}