[pitboss] phase 12: Track L.10 — Flask / Django / FastAPI / Starlette adapters

src/dynamic/framework/adapters/python_starlette.rs

@@ -0,0 +1,265 @@
+//! Python Starlette [`super::super::FrameworkAdapter`] (Phase 12 — Track L.10).
+//!
+//! Recognises `Route("/path", endpoint=handler)` and
+//! `Route("/path", handler)` registrations inside a Starlette
+//! application file (`from starlette.routing import Route` /
+//! `from starlette.applications import Starlette`).  Detection walks
+//! every `call` node in the AST so the order of declaration relative
+//! to the handler does not matter.  Methods are picked up from the
+//! `methods=[...]` kwarg when present and default to `GET`.
+
+use crate::dynamic::framework::{
+    FrameworkAdapter, FrameworkBinding, HttpMethod, RouteShape,
+};
+use crate::evidence::EntryKind;
+use crate::summary::FuncSummary;
+use crate::symbol::Lang;
+use tree_sitter::Node;
+
+use super::python_routes::{
+    bind_path_params, find_python_function, function_formal_names, source_imports_starlette,
+};
+
+pub struct PythonStarletteAdapter;
+
+const ADAPTER_NAME: &str = "python-starlette";
+
+/// Find a `Route("/path", endpoint=target)` or
+/// `Route("/path", target)` call and return its `(method, path)`.
+/// Returns `None` when no matching call is present.
+fn route_registration_for(
+    root: Node<'_>,
+    bytes: &[u8],
+    target: &str,
+) -> Option<(HttpMethod, String)> {
+    let mut hit: Option<(HttpMethod, String)> = None;
+    walk_routes(root, bytes, target, &mut hit);
+    hit
+}
+
+fn walk_routes(node: Node<'_>, bytes: &[u8], target: &str, out: &mut Option<(HttpMethod, String)>) {
+    if out.is_some() {
+        return;
+    }
+    if node.kind() == "call"
+        && let Some(callee) = node
+            .child_by_field_name("function")
+            .and_then(|n| n.utf8_text(bytes).ok())
+    {
+        let last = callee.rsplit_once('.').map(|(_, s)| s).unwrap_or(callee);
+        if matches!(last, "Route" | "WebSocketRoute") {
+            if let Some(args) = node.child_by_field_name("arguments") {
+                if let Some(path) = first_string_arg(args, bytes) {
+                    if endpoint_references(args, bytes, target) {
+                        let method = methods_kwarg(args, bytes).unwrap_or(HttpMethod::GET);
+                        *out = Some((method, path));
+                        return;
+                    }
+                }
+            }
+        }
+    }
+    let mut cur = node.walk();
+    for child in node.children(&mut cur) {
+        walk_routes(child, bytes, target, out);
+    }
+}
+
+fn first_string_arg(args: Node<'_>, bytes: &[u8]) -> Option<String> {
+    let mut cur = args.walk();
+    for c in args.named_children(&mut cur) {
+        if c.kind() == "string" {
+            let raw = c.utf8_text(bytes).ok()?;
+            return Some(strip_quotes(raw).to_owned());
+        }
+    }
+    None
+}
+
+fn strip_quotes(raw: &str) -> &str {
+    let t = raw.trim();
+    let t = t.strip_prefix("b").unwrap_or(t);
+    let t = t.strip_prefix("r").unwrap_or(t);
+    let t = t.strip_prefix("u").unwrap_or(t);
+    t.trim_matches(['\'', '"'])
+}
+
+fn endpoint_references(args: Node<'_>, bytes: &[u8], target: &str) -> bool {
+    let mut cur = args.walk();
+    let mut seen_positional = 0usize;
+    for arg in args.named_children(&mut cur) {
+        if arg.kind() == "keyword_argument" {
+            let Some(name) = arg.child_by_field_name("name") else {
+                continue;
+            };
+            let Ok(name_text) = name.utf8_text(bytes) else {
+                continue;
+            };
+            if name_text == "endpoint" {
+                if let Some(value) = arg.child_by_field_name("value") {
+                    if identifier_matches(value, bytes, target) {
+                        return true;
+                    }
+                }
+            }
+        } else {
+            seen_positional += 1;
+            // Second positional argument is the endpoint when no
+            // keyword form is used.
+            if seen_positional == 2 && identifier_matches(arg, bytes, target) {
+                return true;
+            }
+        }
+    }
+    false
+}
+
+fn identifier_matches(node: Node<'_>, bytes: &[u8], target: &str) -> bool {
+    let Ok(text) = node.utf8_text(bytes) else {
+        return false;
+    };
+    let trimmed = text.trim().trim_end_matches("()");
+    let last = trimmed.rsplit_once('.').map(|(_, s)| s).unwrap_or(trimmed);
+    last == target || trimmed == target
+}
+
+fn methods_kwarg(args: Node<'_>, bytes: &[u8]) -> Option<HttpMethod> {
+    let mut cur = args.walk();
+    for arg in args.children(&mut cur) {
+        if arg.kind() != "keyword_argument" {
+            continue;
+        }
+        let Some(name) = arg
+            .child_by_field_name("name")
+            .and_then(|n| n.utf8_text(bytes).ok())
+        else {
+            continue;
+        };
+        if name != "methods" {
+            continue;
+        }
+        let Some(value) = arg.child_by_field_name("value") else {
+            continue;
+        };
+        let mut vc = value.walk();
+        for child in value.named_children(&mut vc) {
+            if child.kind() == "string"
+                && let Some(raw) = child.utf8_text(bytes).ok()
+                && let Some(m) = HttpMethod::from_ident(strip_quotes(raw))
+            {
+                return Some(m);
+            }
+        }
+    }
+    None
+}
+
+impl FrameworkAdapter for PythonStarletteAdapter {
+    fn name(&self) -> &'static str {
+        ADAPTER_NAME
+    }
+
+    fn lang(&self) -> Lang {
+        Lang::Python
+    }
+
+    fn detect(
+        &self,
+        summary: &FuncSummary,
+        ast: Node<'_>,
+        file_bytes: &[u8],
+    ) -> Option<FrameworkBinding> {
+        if !source_imports_starlette(file_bytes) {
+            return None;
+        }
+        let (func_node, _) = find_python_function(ast, file_bytes, &summary.name)?;
+        let (method, path) = route_registration_for(ast, file_bytes, &summary.name)?;
+        let formals = function_formal_names(func_node, file_bytes);
+        let request_params = bind_path_params(&formals, &path);
+        Some(FrameworkBinding {
+            adapter: ADAPTER_NAME.to_owned(),
+            kind: EntryKind::HttpRoute,
+            route: Some(RouteShape { method, path }),
+            request_params,
+            response_writer: None,
+            middleware: Vec::new(),
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::dynamic::framework::ParamSource;
+
+    fn parse(src: &[u8]) -> tree_sitter::Tree {
+        let mut parser = tree_sitter::Parser::new();
+        let lang = tree_sitter::Language::from(tree_sitter_python::LANGUAGE);
+        parser.set_language(&lang).unwrap();
+        parser.parse(src, None).unwrap()
+    }
+
+    fn summary(name: &str) -> FuncSummary {
+        FuncSummary {
+            name: name.into(),
+            lang: "python".into(),
+            ..Default::default()
+        }
+    }
+
+    #[test]
+    fn fires_on_route_with_keyword_endpoint() {
+        let src: &[u8] = b"from starlette.applications import Starlette\nfrom starlette.routing import Route\nasync def homepage(request):\n    return None\napp = Starlette(routes=[Route(\"/\", endpoint=homepage)])\n";
+        let tree = parse(src);
+        let binding = PythonStarletteAdapter
+            .detect(&summary("homepage"), tree.root_node(), src)
+            .unwrap();
+        let route = binding.route.unwrap();
+        assert_eq!(route.path, "/");
+        assert_eq!(route.method, HttpMethod::GET);
+    }
+
+    #[test]
+    fn fires_on_route_with_positional_endpoint() {
+        let src: &[u8] = b"from starlette.routing import Route\nasync def homepage(request):\n    return None\nroutes = [Route(\"/items/{id}\", homepage)]\n";
+        let tree = parse(src);
+        let binding = PythonStarletteAdapter
+            .detect(&summary("homepage"), tree.root_node(), src)
+            .unwrap();
+        assert_eq!(binding.route.unwrap().path, "/items/{id}");
+    }
+
+    #[test]
+    fn picks_up_post_methods_kwarg() {
+        let src: &[u8] = b"from starlette.routing import Route\nasync def create(request):\n    return None\nroutes = [Route(\"/items\", endpoint=create, methods=[\"POST\"])]\n";
+        let tree = parse(src);
+        let binding = PythonStarletteAdapter
+            .detect(&summary("create"), tree.root_node(), src)
+            .unwrap();
+        assert_eq!(binding.route.unwrap().method, HttpMethod::POST);
+    }
+
+    #[test]
+    fn binds_request_as_implicit() {
+        let src: &[u8] = b"from starlette.routing import Route\nasync def homepage(request):\n    return None\nroutes = [Route(\"/\", endpoint=homepage)]\n";
+        let tree = parse(src);
+        let binding = PythonStarletteAdapter
+            .detect(&summary("homepage"), tree.root_node(), src)
+            .unwrap();
+        let req = binding
+            .request_params
+            .iter()
+            .find(|p| p.name == "request")
+            .unwrap();
+        assert!(matches!(req.source, ParamSource::Implicit));
+    }
+
+    #[test]
+    fn skips_when_starlette_not_imported() {
+        let src: &[u8] = b"def homepage(request):\n    return None\n";
+        let tree = parse(src);
+        assert!(PythonStarletteAdapter
+            .detect(&summary("homepage"), tree.root_node(), src)
+            .is_none());
+    }
+}