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use anyhow::{Ok, Result};
use petgraph::{
algo::is_cyclic_directed,
graph::{DiGraph, NodeIndex},
visit::{IntoNodeReferences, NodeIndexable},
Direction,
};
use std::collections::{HashMap, HashSet};
pub struct DependenciesBuilder<'a> {
all_elements: Vec<&'a str>,
all_dependencies: Vec<&'a str>,
graph: DiGraph<&'a str, ()>,
dependency_map: HashMap<&'a str, (NodeIndex, &'a [&'a str])>,
}
impl<'a> DependenciesBuilder<'a> {
pub fn add_element(mut self, name: &'a str, dependecies: &'a [&str]) -> Self {
self.all_elements.push(name);
self.all_dependencies.extend(dependecies);
let node = self.graph.add_node(name);
self.dependency_map.insert(name, (node, dependecies));
self
}
fn add_edges(&mut self) {
for (node, dependencies) in self.dependency_map.values() {
for dependency in *dependencies {
let dependency_node = self.dependency_map[dependency].0;
self.graph.add_edge(*node, dependency_node, ());
}
}
}
fn dependencies_are_met(&self) -> bool {
let elements_set: HashSet<_> = self.all_elements.iter().collect();
self.all_dependencies
.iter()
.all(|dependency| elements_set.contains(dependency))
}
fn no_cyclic_dependencies(&self) -> bool {
!is_cyclic_directed(&self.graph)
}
fn validate(&mut self) -> Result<()> {
if !self.dependencies_are_met() {
return Err(anyhow::anyhow!(
"Some dependencies do not exist as elements"
));
}
self.add_edges();
if !self.no_cyclic_dependencies() {
return Err(anyhow::anyhow!("Cyclic dependency detected"));
}
self.graph.clear_edges();
Ok(())
}
pub fn build(&mut self) -> Result<Dependencies> {
self.validate()?;
self.add_edges();
Ok(Dependencies {
graph: self.graph.clone(),
})
}
}
#[derive(Debug)]
pub struct Dependencies<'a> {
graph: DiGraph<&'a str, ()>,
}
impl<'a> Dependencies<'a> {
pub fn generate_tranches(&self) -> Result<Vec<Vec<String>>> {
let mut tranches: Vec<Vec<String>> = vec![];
let mut traverse_graph = self.graph.clone();
while traverse_graph.node_count() > 0 {
let mut node_to_remove: Vec<(NodeIndex, String)> = vec![];
let mut new_layer: Vec<String> = Vec::new();
for (node_index, node_name) in traverse_graph.node_references() {
if traverse_graph
.neighbors_directed(node_index, Direction::Outgoing)
.count()
== 0
{
node_to_remove.push((node_index, node_name.to_string()));
}
}
for (node_index, node_name) in node_to_remove {
let adjusted_index = traverse_graph.to_index(node_index) - new_layer.len();
traverse_graph.remove_node(traverse_graph.from_index(adjusted_index));
new_layer.push(node_name.to_string())
}
tranches.push(new_layer);
}
Ok(tranches)
}
pub fn builder() -> DependenciesBuilder<'a> {
DependenciesBuilder {
all_elements: Vec::new(),
all_dependencies: Vec::new(),
graph: DiGraph::new(),
dependency_map: HashMap::new(),
}
}
}
#[cfg(test)]
mod tests {
use super::Dependencies;
#[test]
fn can_validate_simple_tree() {
let mut dependencies_builder = Dependencies::builder()
.add_element("a", &["b", "c"])
.add_element("b", &["c"])
.add_element("c", &[]);
assert!(dependencies_builder.build().is_ok());
}
#[test]
fn can_validate_complex_tree() {
let mut dependencies_builder = Dependencies::builder()
.add_element("a", &["b", "c"])
.add_element("b", &["c"])
.add_element("c", &["d", "e"])
.add_element("d", &["e"])
.add_element("e", &[]);
assert!(dependencies_builder.build().is_ok());
}
#[test]
fn detects_missing_dependencies() {
let mut dependencies_builder = Dependencies::builder()
.add_element("a", &["b", "c"])
.add_element("b", &["c"]);
assert_eq!(
dependencies_builder.build().unwrap_err().to_string(),
"Some dependencies do not exist as elements"
);
}
#[test]
fn detects_cyclic_dependencies() {
let mut dependencies_builder = Dependencies::builder()
.add_element("a", &["b", "c"])
.add_element("b", &["c"])
.add_element("c", &["a", "b"]);
assert_eq!(
dependencies_builder.build().unwrap_err().to_string(),
"Cyclic dependency detected"
);
}
#[test]
fn can_divide_into_tranches() {
let mut dependencies_builder = Dependencies::builder()
.add_element("b", &["d"])
.add_element("c", &["d"])
.add_element("a", &["d", "e", "y"])
.add_element("d", &["e"])
.add_element("e", &[])
.add_element("y", &[]);
let dependencies = dependencies_builder.build().unwrap();
assert!(dependencies.generate_tranches().is_ok());
}
}
