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use item::StringItem;
pub struct TreeBuilder {
item: StringItem,
level: u32,
}
impl TreeBuilder {
pub fn new(text: String) -> TreeBuilder {
TreeBuilder {
item: StringItem {
text,
children: Vec::new(),
},
level: 0,
}
}
fn append_child_level(parent: &mut StringItem, level: u32, item: StringItem) {
if level == 0 {
parent.children.push(item);
} else {
TreeBuilder::append_child_level(parent.children.last_mut().unwrap(), level - 1, item);
}
}
pub fn begin_child(&mut self, text: String) -> &mut Self {
TreeBuilder::append_child_level(
&mut self.item,
self.level,
StringItem {
text,
children: Vec::new(),
},
);
self.level += 1;
self
}
pub fn end_child(&mut self) -> &mut Self {
self.level -= 1;
self
}
pub fn add_empty_child(&mut self, text: String) -> &mut Self {
self.begin_child(text).end_child()
}
pub fn build(&mut self) -> StringItem {
self.item.clone()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn empty() {
let tree = TreeBuilder::new("test".to_string()).build();
assert_eq!(&tree.text, "test");
assert_eq!(tree.children.len(), 0);
}
#[test]
fn single_child() {
let tree = TreeBuilder::new("test".to_string())
.add_empty_child("test_two".to_string())
.build();
assert_eq!(&tree.text, "test");
assert_eq!(tree.children.len(), 1);
assert_eq!(&tree.children[0].text, "test_two");
}
#[test]
fn many_children_flat() {
let mut builder = TreeBuilder::new("test".to_string());
let n = 10;
for i in 0..n {
builder.add_empty_child(format!("test {}", i));
}
let tree = builder.build();
assert_eq!(&tree.text, "test");
assert_eq!(tree.children.len(), n);
for i in 0..n {
assert_eq!(tree.children[i].text, format!("test {}", i));
}
}
#[test]
fn many_children_nested() {
let mut builder = TreeBuilder::new("test".to_string());
let n = 10;
for i in 0..n {
builder.begin_child(format!("test {}", i));
}
for _ in 0..n {
builder.end_child();
}
let tree = builder.build();
assert_eq!(&tree.text, "test");
let mut item = tree;
for _ in 0..n {
assert_eq!(item.children.len(), 1);
item = item.children[0].clone();
}
assert_eq!(item.children.len(), 0);
}
}