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//! High-level builder API for constructing trees.
use crate::tree::Tree;
/// A builder for constructing trees using a fluent API.
///
/// This provides a convenient way to build trees without manually
/// constructing nested `Tree::Node` and `Tree::Leaf` variants.
///
/// # Examples
///
/// ```
/// use treelog::builder::TreeBuilder;
///
/// let mut builder = TreeBuilder::new();
/// builder.node("root").leaf("item1");
/// let tree = builder.build();
/// ```
pub struct TreeBuilder {
stack: Vec<Tree>,
}
impl TreeBuilder {
/// Creates a new tree builder.
///
/// # Examples
///
/// ```
/// use treelog::builder::TreeBuilder;
///
/// let builder = TreeBuilder::new();
/// ```
pub fn new() -> Self {
TreeBuilder { stack: Vec::new() }
}
/// Adds a node with the given label and makes it the current context.
///
/// # Examples
///
/// ```
/// use treelog::builder::TreeBuilder;
///
/// let mut builder = TreeBuilder::new();
/// builder.node("root");
/// ```
pub fn node(&mut self, label: impl Into<String>) -> &mut Self {
let node = Tree::new_node(label);
self.stack.push(node);
self
}
/// Adds a leaf with a single line of text.
///
/// # Examples
///
/// ```
/// use treelog::builder::TreeBuilder;
///
/// let mut builder = TreeBuilder::new();
/// builder.node("root").leaf("item");
/// ```
pub fn leaf(&mut self, line: impl Into<String>) -> &mut Self {
if let Some(Tree::Node(_, children)) = self.stack.last_mut() {
children.push(Tree::new_leaf(line));
}
self
}
/// Adds a leaf with multiple lines of text.
///
/// # Examples
///
/// ```
/// use treelog::builder::TreeBuilder;
///
/// let mut builder = TreeBuilder::new();
/// builder.node("root").leaf_lines(vec!["line1", "line2"]);
/// ```
pub fn leaf_lines(&mut self, lines: Vec<impl Into<String>>) -> &mut Self {
if let Some(Tree::Node(_, children)) = self.stack.last_mut() {
children.push(Tree::new_leaf_lines(lines));
}
self
}
/// Ends the current node context and returns to the parent.
///
/// This should be called after adding children to a node to return
/// to the parent context.
///
/// # Examples
///
/// ```
/// use treelog::builder::TreeBuilder;
///
/// let mut builder = TreeBuilder::new();
/// builder.node("root")
/// .node("child")
/// .leaf("item")
/// .end() // Returns to "root" context
/// .leaf("another");
/// ```
pub fn end(&mut self) -> &mut Self {
if self.stack.len() > 1 {
let child = self.stack.pop().unwrap();
if let Some(Tree::Node(_, children)) = self.stack.last_mut() {
children.push(child);
}
}
self
}
/// Builds and returns the final tree.
///
/// # Panics
///
/// Panics if no nodes have been added or if the builder is in an invalid state.
///
/// # Examples
///
/// ```
/// use treelog::builder::TreeBuilder;
///
/// let mut builder = TreeBuilder::new();
/// builder.node("root").leaf("item");
/// let tree = builder.build();
/// ```
pub fn build(mut self) -> Tree {
if self.stack.is_empty() {
panic!("TreeBuilder: cannot build empty tree");
}
if self.stack.len() > 1 {
// Close all remaining nodes
while self.stack.len() > 1 {
self.end();
}
}
self.stack.pop().unwrap()
}
}
impl Default for TreeBuilder {
fn default() -> Self {
Self::new()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_simple_tree() {
let mut builder = TreeBuilder::new();
builder.node("root").leaf("item");
let tree = builder.build();
assert!(tree.is_node());
assert_eq!(tree.label(), Some("root"));
}
#[test]
fn test_nested_tree() {
let mut builder = TreeBuilder::new();
builder.node("root").node("child").leaf("item").end();
let tree = builder.build();
assert!(tree.is_node());
if let Tree::Node(_, children) = &tree {
assert_eq!(children.len(), 1);
assert!(children[0].is_node());
}
}
#[test]
fn test_multiple_children() {
let mut builder = TreeBuilder::new();
builder
.node("root")
.leaf("item1")
.leaf("item2")
.node("child")
.leaf("subitem")
.end();
let tree = builder.build();
if let Tree::Node(_, children) = &tree {
assert_eq!(children.len(), 3);
}
}
}