1 files changed, 85 insertions, 0 deletions
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..f0d2fd5
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,85 @@
+// Copyright (c) 2018 The predicates-rs Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/license/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Render `Case` as a tree.
+
+use std::fmt;
+
+use predicates_core::reflection;
+
+/// Render `Self` as a displayable tree.
+pub trait CaseTreeExt {
+    /// Render `Self` as a displayable tree.
+    fn tree(&self) -> CaseTree;
+}
+
+impl<'a> CaseTreeExt for reflection::Case<'a> {
+    fn tree(&self) -> CaseTree {
+        CaseTree(convert(self))
+    }
+}
+
+type CaseTreeInner = termtree::Tree<Displayable>;
+
+fn convert(case: &reflection::Case<'_>) -> CaseTreeInner {
+    let mut leaves: Vec<CaseTreeInner> = vec![];
+
+    leaves.extend(case.predicate().iter().flat_map(|pred| {
+        pred.parameters().map(|item| {
+            let root = Displayable::new(&item);
+            termtree::Tree::new(root).with_multiline(true)
+        })
+    }));
+
+    leaves.extend(case.products().map(|item| {
+        let root = Displayable::new(item);
+        termtree::Tree::new(root).with_multiline(true)
+    }));
+
+    leaves.extend(case.children().map(convert));
+
+    let root = case
+        .predicate()
+        .map(|p| Displayable::new(&p))
+        .unwrap_or_default();
+    CaseTreeInner::new(root).with_leaves(leaves)
+}
+
+/// A `Case` rendered as a tree for display.
+#[allow(missing_debug_implementations)]
+pub struct CaseTree(CaseTreeInner);
+
+impl fmt::Display for CaseTree {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+#[derive(Default)]
+struct Displayable {
+    primary: String,
+    alternate: String,
+}
+
+impl Displayable {
+    fn new(display: &dyn std::fmt::Display) -> Self {
+        let primary = format!("{}", display);
+        let alternate = format!("{:#}", display);
+        Self { primary, alternate }
+    }
+}
+
+impl fmt::Display for Displayable {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if f.alternate() {
+            self.alternate.fmt(f)
+        } else {
+            self.primary.fmt(f)
+        }
+    }
+}