add map support

README.md

@@ -6,7 +6,8 @@ Based on Noah Pederson's [gleemor] module, licensed under MIT
 
 ## License
 
-This library is licensed under the GNU Affero General Public License version 3, see `LICENSE`.
+This library is licensed under the GNU Affero General Public License version 3,
+see `LICENSE`.
 
 [Pdor]:https://www.youtube.com/watch?v=k3aehC2SSPw
 [gleemor]:https://github.com/chiefnoah/gleebor

src/kmer.gleam

@@ -12,6 +12,7 @@ pub type DecodedValue {
   Bytes(value: BitArray)
   String(value: String)
   Array(List(DecodedValue))
+  Map(List(#(DecodedValue, DecodedValue)))
   Null
   Undefined
 }
@@ -47,6 +48,9 @@ pub fn decode(bits: BitArray) -> DecodeResult {
     <<4:3, rest:bits>> ->
       decode_array(rest)
       |> map_decoded(Array)
+    <<5:3, rest:bits>> ->
+      decode_map(rest)
+      |> map_decoded(Map)
     <<7:3, x:5, rest:bits>> if x < 25 -> decode_simple(<<x:5, rest:bits>>)
     <<7:3, x:5, rest:bits>> if x >= 25 ->
       decode_float(<<x:5, rest:bits>>)
@@ -93,6 +97,15 @@ fn decode_array(bits: BitArray) -> DecoderResult(List(DecodedValue)) {
   decode_next_n([], rest, length)
 }
 
+fn decode_map(
+  bits: BitArray,
+) -> DecoderResult(List(#(DecodedValue, DecodedValue))) {
+  use #(length, rest) <- try(decode_int(bits))
+  use #(entries, remainder) <- try(decode_next_n([], rest, length * 2))
+  use pairs <- try(into_pairs(entries))
+  Ok(#(pairs, remainder))
+}
+
 fn decode_float(bits: BitArray) -> DecoderResult(IEEEFloat) {
   case bits {
     <<25:5, float16:bytes-size(2), rest:bits>> ->
@@ -115,6 +128,21 @@ fn decode_simple(bits: BitArray) -> DecodeResult {
   }
 }
 
+fn into_pairs(list: List(a)) -> Result(List(#(a, a)), DecodeError) {
+  into_pairs_aggr([], list)
+}
+
+fn into_pairs_aggr(
+  accum: List(#(a, a)),
+  remaining: List(a),
+) -> Result(List(#(a, a)), DecodeError) {
+  case remaining {
+    [] -> Ok(reverse(accum))
+    [_] -> Error(Malformed)
+    [key, value, ..rest] -> into_pairs_aggr([#(key, value), ..accum], rest)
+  }
+}
+
 fn decode_next_n(
   retrieved: List(DecodedValue),
   rest: BitArray,

test/kmer_test.gleam

@@ -4,7 +4,7 @@ import gleeunit/should
 import ieee_float.{finite, nan, positive_infinity}
 import kmer.{
   type DecodeResult, type DecodedValue, Array, Boolean, Bytes, Float, Integer,
-  Null, String, Undefined,
+  Map, Null, String, Undefined,
 }
 
 pub fn main() {
@@ -136,6 +136,25 @@ pub fn decode_list_test() {
   |> table_fn(table_test_decode)
 }
 
+pub fn decode_map_test() {
+  [
+    #(
+      <<5:3, 2:5, 3:3, 8:5, "test-key", 5, 3:3, 5:5, "other", 10>>,
+      Map([#(String("test-key"), Integer(5)), #(String("other"), Integer(10))]),
+    ),
+    #(
+      <<5:3, 24:5, 4:8, 1, 2, 3, 4, 5, 6, 7, 8>>,
+      Map([
+        #(Integer(1), Integer(2)),
+        #(Integer(3), Integer(4)),
+        #(Integer(5), Integer(6)),
+        #(Integer(7), Integer(8)),
+      ]),
+    ),
+  ]
+  |> table_fn(table_test_decode)
+}
+
 fn table_fn(tests: List(#(a, b)), test_fn: fn(a, b) -> Nil) {
   list.map(tests, fn(t) {
     let #(test_case, expected) = t