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// ----------------------------------------------------------------------------

//! Macros for graph creation.

// ----------------------------------------------------------------------------
// Macros
// ----------------------------------------------------------------------------

/// Creates a graph builder from the given pairs.
///
/// This macro creates a [`Builder`][] and adds nodes and edges based on the
/// provided source-target pairs. It's primarily intended for use in tests and
/// examples to quickly set up graphs, and is not optimized for performance.
/// Additionally, the node type must implement [`Copy`].
///
/// [`Builder`]: crate::graph::Builder
///
/// # Examples
///
/// ```
/// use zrx_graph::graph_builder;
///
/// // Create graph builder from pairs
/// let builder = graph_builder! {
///     "a" => "b", "a" => "c",
///     "b" => "c",
/// };
/// ```
#[macro_export]
macro_rules! graph_builder {
    ($($source:expr => $target:expr),+ $(,)?) => {{
        let mut builder = $crate::Graph::builder();
        let mut nodes = std::collections::BTreeMap::new();
        $(
            nodes.entry($source).or_insert_with(|| builder.add_node($source));
            nodes.entry($target).or_insert_with(|| builder.add_node($target));
        )*
        // We can just swallow the result here, since nodes are guaranteed to
        // exist and point to valid indices, so errors can't possibly occur
        $(
            let _ = builder.add_edge(nodes[$source], nodes[$target]);
        )*
        builder
    }};
}

/// Creates a graph from the given pairs.
///
/// This macro creates a [`Graph`][] and adds nodes and edges based on the
/// provided source-target pairs. It's primarily intended for use in tests and
/// examples to quickly set up graphs, and is not optimized for performance.
/// Additionally, the node type must implement [`Copy`].
///
/// In case you need a [`Builder`][], e.g. to inspect the graph before building
/// or to print it to DOT format, use the [`graph_builder!`][] macro.
///
/// [`Builder`]: crate::graph::Builder
/// [`Graph`]: crate::graph::Graph
///
/// # Examples
///
/// ```
/// use zrx_graph::graph;
///
/// // Create graph from pairs
/// let graph = graph! {
///     "a" => "b", "a" => "c",
///     "b" => "c",
/// };
/// ```
#[macro_export]
macro_rules! graph {
    ($($source:expr => $target:expr),+ $(,)?) => {{
        $crate::graph_builder!($($source => $target),+).build()
    }};
}
