Split tuples, arrays and the C API off from the records file and refactored them

README.md

@@ -1,7 +1,7 @@
 [![License: MIT](https://img.shields.io/badge/License-MIT-green.svg)](https://opensource.org/licenses/MIT)
 [![Build Status](https://travis-ci.com/vmware/differential-datalog.svg?branch=master)](https://travis-ci.com/vmware/differential-datalog)
 [![pipeline status](https://gitlab.com/ddlog/differential-datalog/badges/master/pipeline.svg)](https://gitlab.com/ddlog/differential-datalog/commits/master)
-[![rustc](https://img.shields.io/badge/rustc-1.41+-blue.svg)](https://blog.rust-lang.org/2020/03/12/Rust-1.42.html)
+[![rustc](https://img.shields.io/badge/rustc-1.47+-blue.svg)](https://blog.rust-lang.org/2020/10/08/Rust-1.47.html)
 [![Gitter chat](https://badges.gitter.im/vmware/differential-datalog.png)](https://gitter.im/vmware/differential-datalog)
 
 # Differential Datalog (DDlog)
@@ -96,7 +96,7 @@ You are now ready to [start coding in DDlog](doc/tutorial/tutorial.md).
   ```
   wget -qO- https://get.haskellstack.org/ | sh
   ```
-- Rust toolchain v1.41 or later:
+- Rust toolchain v1.47 or later:
   ```
   curl https://sh.rustup.rs -sSf | sh
   . $HOME/.cargo/env

rust/template/differential_datalog/src/lib.rs

@@ -1,13 +1,8 @@
 #![allow(
-    clippy::unknown_clippy_lints,
     clippy::get_unwrap,
     clippy::missing_safety_doc,
     clippy::type_complexity,
-    clippy::match_like_matches_macro,
-    // match_like_matches_macro not supported in older versions of clippy
-    clippy::unknown_clippy_lints,
-    // required because of a bug in older clippy (1.41).
-    clippy::useless_let_if_seq
+    clippy::match_like_matches_macro
 )]
 
 mod callback;

rust/template/differential_datalog/src/record/arrays.rs

@@ -0,0 +1,61 @@
+//! Implementing `Record`-related traits for Rust arrays
+
+use crate::record::{CollectionKind, FromRecord, IntoRecord, Mutator, Record};
+use std::result::Result;
+
+/// Implements `FromRecord`, `IntoRecord` and `Mutator` for arrays
+// FIXME: Replace this with `min_const_generics` after Rust v1.50
+//        https://github.com/rust-lang/rust/issues/74878
+macro_rules! ddlog_array_traits {
+    ($($length:literal),* $(,)?) => {
+        $(
+            impl<T: FromRecord + Default> FromRecord for [T; $length] {
+                fn from_record(val: &Record) -> Result<Self, String> {
+                    let vec = Vec::from_record(val)?;
+                    let mut arr = <[T; $length]>::default();
+
+                    if vec.len() != $length {
+                        return Err(format!(
+                            "cannot convert {:?} to array of length {}",
+                            *val, $length
+                        ));
+                    };
+                    let mut idx = 0;
+                    for v in vec.into_iter() {
+                        arr[idx] = v;
+                        idx += 1;
+                    }
+                    Ok(arr)
+
+                    // Simpler implementation that requires Rust 1.48:
+                    // Vec::from_record(val)?.try_into().map_err(|_| {
+                    //     format!("cannot convert {:?} to array of length {}", *val, $length)
+                    // })
+                }
+            }
+
+            impl<T: IntoRecord + Clone> IntoRecord for [T; $length] {
+                fn into_record(self) -> Record {
+                    Record::Array(
+                        CollectionKind::Vector,
+                        self.iter().cloned().map(IntoRecord::into_record).collect(),
+                    )
+                }
+            }
+
+            impl<T: FromRecord + Default> Mutator<[T; $length]> for Record {
+                fn mutate(&self, array: &mut [T; $length]) -> Result<(), String> {
+                    *array = <[T; $length]>::from_record(self)?;
+                    Ok(())
+                }
+            }
+        )*
+    };
+}
+
+ddlog_array_traits! {
+    0,  1,  2,  3,  4,  5,  6,  7,  8,  9,
+    10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+    20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
+    30, 31, 32,
+}