get/nth impl

.github/workflows/check.yml

@@ -35,6 +35,7 @@ jobs:
         run: |
           cargo test --all-features --no-fail-fast --target ${{ matrix.target }}
           cargo test --features std --no-default-features --no-fail-fast --target ${{ matrix.target }}
+          cargo run --example get-nth --target ${{ matrix.target }}
 
   build_linux:
     name: Build Linux
@@ -113,6 +114,7 @@ jobs:
         run: |
           cargo test --all-features --no-fail-fast --target ${{ matrix.target }}
           cargo test --features std --no-default-features --no-fail-fast --target ${{ matrix.target }}
+          cargo run --example get-nth --target ${{ matrix.target }}
 
   build_embedded:
     name: Build Embedded

Cargo.toml

@@ -19,6 +19,7 @@ unsafe_code = "deny"
 nursery = { level = "warn", priority = -1 }
 pedantic = { level = "warn", priority = -1 }
 inline_always = "allow"
+must_use_candidate = "allow"
 
 [features]
 default = ["floats", "std"]
@@ -28,3 +29,5 @@ std = []
 [dependencies]
 ordered-float = { version = "4.1", default-features = false, optional = true }
 
+[[example]]
+name = "get-nth"

bb.edn

@@ -8,14 +8,15 @@
                                 :task (fs/delete-tree "target")}
   test_lib_features            (shell "cargo test --all-features --no-fail-fast")
   test_lib_no_default_features (shell "cargo test --features std --no-default-features --no-fail-fast")
+  test-examples                (do (shell "cargo run --example get-nth"))
   cargo-test                   {:doc     "Runs all cargo tests"
-                                :depends [test_lib_features test_lib_no_default_features]}
+                                :depends [test_lib_features test_lib_no_default_features test-examples]}
   cargo-fmt                    {:doc  "Checks cargo fmt"
                                 :task (shell "cargo fmt --check")}
   cargo-clippy-all-features    {:doc  "Cargo clippy with all features"
-                                :task (shell "cargo clippy --all-features -- -W future-incompatible -W rust_2018_idioms -W clippy::all -W clippy::pedantic -W clippy::nursery --deny warnings")}
+                                :task (shell "cargo clippy --all-features -- --deny warnings")}
   cargo-clippy-no-defaults     {:doc  "Cargo clippy with no default features"
-                                :task (shell "cargo clippy --no-default-features -- -W future-incompatible -W rust_2018_idioms -W clippy::all -W clippy::pedantic -W clippy::nursery --deny warnings")}
+                                :task (shell "cargo clippy --no-default-features -- --deny warnings")}
   clippy                       {:doc     "Runs all variations of cargo clippy"
                                 :depends [cargo-clippy-all-features cargo-clippy-no-defaults]}
   cov-all-features             {:doc  "Coverage, all features"

examples/get-nth.rs

@@ -0,0 +1,18 @@
+use clojure_reader::edn::{self, Edn};
+
+fn maybe_forty_two<'a>() -> Option<i64> {
+    let e = edn::read_string("{:foo {:bar [1 2 42 3]}}").unwrap();
+
+    // This roughly tries to match clojure's
+    // (-> (clojure.edn/read-string "{:foo {:bar [1 2 42 3]}}") (get :foo) (get :bar) (nth 2)) -> 42
+    let idx = e.get(&Edn::Key(":foo"))?.get(&Edn::Key(":bar"))?.nth(2)?;
+
+    if let Edn::Int(i) = idx {
+        return Some(*i);
+    }
+    None
+}
+
+fn main() {
+    println!("{:?}", maybe_forty_two());
+}

src/edn.rs

@@ -31,6 +31,27 @@ pub fn read_string(edn: &str) -> Result<Edn<'_>, crate::error::Error> {
     crate::parse::parse(edn)
 }
 
+impl<'e> Edn<'e> {
+    pub fn get(&self, e: &Edn<'e>) -> Option<&Edn<'e>> {
+        if let Edn::Map(m) = self {
+            let lol = m.get(e);
+            if let Some(l) = lol {
+                return Some(l);
+            };
+        }
+        None
+    }
+    pub fn nth(&self, i: usize) -> Option<&Edn<'e>> {
+        let vec = match self {
+            Edn::Vector(v) => v,
+            Edn::List(l) => l,
+            _ => return None,
+        };
+
+        vec.get(i)
+    }
+}
+
 const fn char_to_edn(c: char) -> Option<&'static str> {
     match c {
         '\n' => Some("newline"),