Add support for 'optional' parameters

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Optional parameters are now supported in routes.
+
 ### Changed
 
 - Successful matches now return a flattened representation of node data.

README.md

@@ -104,6 +104,55 @@ fn main() -> Result<(), Box<dyn Error>> {
 }
 ```
 
+### Optional Parameters
+
+`wayfind` supports optional parameters for both dynamic and wildcard routes.
+
+TODO
+
+#### Example
+
+```rust
+use std::error::Error;
+use wayfind::{Path, Router};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut router = Router::new();
+    router.insert("/users/{id?}", 1)?;
+    router.insert("/files/{*files}/{file}.{extension?}", 2)?;
+
+    let path = Path::new("/users")?;
+    let search = router.search(&path)?.unwrap();
+    assert_eq!(*search.data, 1);
+
+    let path = Path::new("/users/123")?;
+    let search = router.search(&path)?.unwrap();
+    assert_eq!(*search.data, 1);
+    assert_eq!(search.parameters[0].key, "id");
+    assert_eq!(search.parameters[0].value, "123");
+
+    let path = Path::new("/files/documents/folder/report.pdf")?;
+    let search = router.search(&path)?.unwrap();
+    assert_eq!(*search.data, 2);
+    assert_eq!(search.parameters[0].key, "files");
+    assert_eq!(search.parameters[0].value, "documents/folder");
+    assert_eq!(search.parameters[1].key, "file");
+    assert_eq!(search.parameters[1].value, "report");
+    assert_eq!(search.parameters[2].key, "extension");
+    assert_eq!(search.parameters[2].value, "pdf");
+
+    let path = Path::new("/files/documents/folder/readme")?;
+    let search = router.search(&path)?.unwrap();
+    assert_eq!(*search.data, 2);
+    assert_eq!(search.parameters[0].key, "files");
+    assert_eq!(search.parameters[0].value, "documents/folder");
+    assert_eq!(search.parameters[1].key, "file");
+    assert_eq!(search.parameters[1].value, "readme");
+
+    Ok(())
+}
+```
+
 ### Constraints
 
 Constraints allow for custom logic to be injected into the routing process.

src/expander.rs

@@ -0,0 +1,298 @@
+use crate::parser::{ParsedRoute, RoutePart, RouteParts};
+use std::collections::VecDeque;
+
+/// Represents a collection of expanded, simplified routes, derived from an original route.
+#[derive(Debug, PartialEq, Eq)]
+pub struct ExpandedRoutes {
+    pub raw: ParsedRoute,
+    pub routes: Vec<ParsedRoute>,
+}
+
+impl ExpandedRoutes {
+    pub fn new(route: ParsedRoute) -> Self {
+        let mut routes = VecDeque::new();
+        Self::recursive_expand(route.parts.0.clone(), VecDeque::new(), &mut routes);
+
+        let routes =
+            routes
+                .into_iter()
+                .map(|parts| {
+                    // Handle special case, where optional is at the start of a route.
+                    // Replace with a single "/" part.
+                    if parts.0.iter().all(
+                        |part| matches!(part, RoutePart::Static { prefix } if prefix.is_empty()),
+                    ) {
+                        RouteParts(VecDeque::from(vec![RoutePart::Static {
+                            prefix: b"/".to_vec(),
+                        }]))
+                    } else {
+                        parts
+                    }
+                })
+                .map(ParsedRoute::from)
+                .collect();
+
+        Self { raw: route, routes }
+    }
+
+    fn recursive_expand(
+        mut remaining: VecDeque<RoutePart>,
+        mut current: VecDeque<RoutePart>,
+        expanded: &mut VecDeque<RouteParts>,
+    ) {
+        let Some(part) = remaining.pop_front() else {
+            expanded.push_back(RouteParts(current));
+            return;
+        };
+
+        match part {
+            RoutePart::Static { .. }
+            | RoutePart::Dynamic {
+                optional: false, ..
+            }
+            | RoutePart::Wildcard {
+                optional: false, ..
+            } => {
+                current.push_back(part);
+                Self::recursive_expand(remaining, current, expanded);
+            }
+            RoutePart::Dynamic { .. } | RoutePart::Wildcard { .. } => {
+                // Handle optional present case
+                let mut new_part = part.clone();
+                new_part.disable_optional();
+                let mut new_route = current.clone();
+                new_route.push_back(new_part);
+                Self::recursive_expand(remaining.clone(), new_route, expanded);
+
+                // Handle optional absent case
+                // TODO: Consider calculating this at insert time.
+                // Then we could handle this at the match level?
+                let is_segment = matches!(&part, RoutePart::Static { .. })
+                    || current.back().map_or(true, RoutePart::ends_with_slash)
+                    || remaining.front().map_or(true, RoutePart::starts_with_slash);
+
+                if is_segment {
+                    // Trim the prior `/`, if exists.
+                    if let Some(RoutePart::Static { prefix }) = current.back_mut() {
+                        prefix.pop();
+                    }
+
+                    Self::recursive_expand(remaining, current, expanded);
+                } else {
+                    // Trim any prior static characters.
+                    let mut current = current.clone();
+                    while let Some(last) = current.back() {
+                        if matches!(last, RoutePart::Static { prefix } if !prefix.is_empty() && !last.ends_with_slash())
+                        {
+                            current.pop_back();
+                        } else {
+                            break;
+                        }
+                    }
+
+                    expanded.push_back(RouteParts(current));
+                }
+            }
+        };
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use similar_asserts::assert_eq;
+    use std::error::Error;
+
+    #[test]
+    fn test_expander_segment_simple() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/users/{id?}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/users/{id}")?,
+                    ParsedRoute::new(b"/users")?
+                ],
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_segment_simple_suffix() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/users/{id?}/info")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/users/{id}/info")?,
+                    ParsedRoute::new(b"/users/info")?
+                ],
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_segment_multiple() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/users/{id?}/{name?}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/users/{id}/{name}")?,
+                    ParsedRoute::new(b"/users/{id}")?,
+                    ParsedRoute::new(b"/users/{name}")?,
+                    ParsedRoute::new(b"/users")?,
+                ]
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_segment_constraint() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/users/{id?:int}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/users/{id:int}")?,
+                    ParsedRoute::new(b"/users")?,
+                ]
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_segment_all_optional() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/{category?}/{subcategory?}/{id?}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/{category}/{subcategory}/{id}")?,
+                    ParsedRoute::new(b"/{category}/{subcategory}")?,
+                    ParsedRoute::new(b"/{category}/{id}")?,
+                    ParsedRoute::new(b"/{category}")?,
+                    ParsedRoute::new(b"/{subcategory}/{id}")?,
+                    ParsedRoute::new(b"/{subcategory}")?,
+                    ParsedRoute::new(b"/{id}")?,
+                    ParsedRoute::new(b"/")?,
+                ]
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_segment_mixed() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/api/{version}/{resource}/{id?}/details")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/api/{version}/{resource}/{id}/details")?,
+                    ParsedRoute::new(b"/api/{version}/{resource}/details")?,
+                ]
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_inline_simple() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/files/{name}.{extension?}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/files/{name}.{extension}")?,
+                    ParsedRoute::new(b"/files/{name}")?,
+                ],
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_inline_multiple() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/release/v{major}.{minor?}.{patch?}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![
+                    ParsedRoute::new(b"/release/v{major}.{minor}.{patch}")?,
+                    ParsedRoute::new(b"/release/v{major}.{minor}")?,
+                    ParsedRoute::new(b"/release/v{major}")?,
+                ],
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_start() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"{id?}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![ParsedRoute::new(b"{id}")?, ParsedRoute::new(b"/")?,],
+            }
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_expander_start_slash() -> Result<(), Box<dyn Error>> {
+        let route = ParsedRoute::new(b"/{id?}")?;
+        let expanded = ExpandedRoutes::new(route.clone());
+
+        assert_eq!(
+            expanded,
+            ExpandedRoutes {
+                raw: route,
+                routes: vec![ParsedRoute::new(b"/{id}")?, ParsedRoute::new(b"/")?,],
+            }
+        );
+
+        Ok(())
+    }
+}

src/lib.rs

@@ -7,6 +7,8 @@ pub(crate) mod decode;
 
 pub mod errors;
 
+pub(crate) mod expander;
+
 pub(crate) mod node;
 pub use node::search::{Match, Parameter};