Merge pull request #2910 from rtfeldman/i/2880

Ability codegen for Encode/Decode

compiler/test_gen/src/gen_abilities.rs

@@ -10,6 +10,9 @@ use crate::helpers::wasm::assert_evals_to;
 #[cfg(test)]
 use indoc::indoc;
 
+#[cfg(test)]
+use roc_std::RocList;
+
 #[test]
 #[cfg(any(feature = "gen-llvm", feature = "gen-wasm"))]
 fn hash_specialization() {
@@ -216,3 +219,107 @@ fn ability_used_as_type_still_compiles() {
         u64
     )
 }
+
+#[test]
+#[cfg(any(feature = "gen-llvm"))]
+fn encode() {
+    assert_evals_to!(
+        indoc!(
+            r#"
+            app "test" provides [ myU8Bytes ] to "./platform"
+
+            Encoder fmt := List U8, fmt -> List U8 | fmt has Format
+
+            Encoding has
+              toEncoder : val -> Encoder fmt | val has Encoding, fmt has Format
+
+            Format has
+              u8 : U8 -> Encoder fmt | fmt has Format
+
+            appendWith : List U8, Encoder fmt, fmt -> List U8 | fmt has Format
+            appendWith = \lst, (@Encoder doFormat), fmt -> doFormat lst fmt
+
+            toBytes : val, fmt -> List U8 | val has Encoding, fmt has Format
+            toBytes = \val, fmt -> appendWith [] (toEncoder val) fmt
+
+
+            Linear := {} 
+
+            # impl Format for Linear
+            u8 = \n -> @Encoder (\lst, @Linear {} -> List.append lst n)
+
+            Rgba := { r : U8, g : U8, b : U8, a : U8 }
+
+            # impl Encoding for Rgba
+            toEncoder = \@Rgba {r, g, b, a} ->
+                @Encoder \lst, fmt -> lst
+                    |> appendWith (u8 r) fmt
+                    |> appendWith (u8 g) fmt
+                    |> appendWith (u8 b) fmt
+                    |> appendWith (u8 a) fmt
+
+            myU8Bytes = toBytes (@Rgba { r: 106, g: 90, b: 205, a: 255 }) (@Linear {})
+            "#
+        ),
+        RocList::from_slice(&[106, 90, 205, 255]),
+        RocList<u8>
+    )
+}
+
+#[test]
+#[cfg(any(feature = "gen-llvm"))]
+fn decode() {
+    assert_evals_to!(
+        indoc!(
+            r#"
+            app "test" provides [ myU8 ] to "./platform"
+
+            DecodeError : [ TooShort, Leftover (List U8) ]
+
+            Decoder val fmt := List U8, fmt -> { result: Result val DecodeError, rest: List U8 } | fmt has DecoderFormatting
+
+            Decoding has
+                decoder : Decoder val fmt | val has Decoding, fmt has DecoderFormatting
+
+            DecoderFormatting has
+                u8 : Decoder U8 fmt | fmt has DecoderFormatting
+
+            decodeWith : List U8, Decoder val fmt, fmt -> { result: Result val DecodeError, rest: List U8 } | fmt has DecoderFormatting
+            decodeWith = \lst, (@Decoder doDecode), fmt -> doDecode lst fmt
+
+            fromBytes : List U8, fmt -> Result val DecodeError
+                        | fmt has DecoderFormatting, val has Decoding
+            fromBytes = \lst, fmt ->
+                when decodeWith lst decoder fmt is
+                    { result, rest } ->
+                        Result.after result \val ->
+                            if List.isEmpty rest
+                            then Ok val
+                            else Err (Leftover rest)
+
+
+            Linear := {}
+
+            # impl DecoderFormatting for Linear
+            u8 = @Decoder \lst, @Linear {} ->
+                    when List.first lst is
+                        Ok n -> { result: Ok n, rest: List.dropFirst lst }
+                        Err _ -> { result: Err TooShort, rest: [] }
+
+            MyU8 := U8
+
+            # impl Decoding for MyU8
+            decoder = @Decoder \lst, fmt ->
+                { result, rest } = decodeWith lst u8 fmt
+                { result: Result.map result (\n -> @MyU8 n), rest }
+
+            myU8 =
+                when fromBytes [ 15 ] (@Linear {}) is
+                    Ok (@MyU8 n) -> n
+                    _ -> 27u8
+            "#
+        ),
+        15,
+        u8
+    );
+}