add a binary module

3 files changed, 77 insertions, 0 deletions

diff --git a/src/gleam/binary.gleam b/src/gleam/binary.gleam
new file mode 100644
index 0000000..1fa54a8
--- /dev/null
+++ b/src/gleam/binary.gleam
@@ -0,0 +1,23 @@
+//// Working with raw binary data.
+//// The Binary type should be used instead of a String type when not utf8 encoded.
+
+pub external type Binary
+
+/// Convert a utf8 String type into a raw Binary type.
+pub external fn from_string(String) -> Binary =
+  "gleam_stdlib" "identity"
+
+/// Extracts the part of a binary.
+///
+/// Binary part will start at given position and continue up to specified length.
+/// A negative length can be used to extract bytes at the end of a binary:
+pub external fn part(string: Binary, position: Int, length: Int) -> Binary = "binary" "part"
+
+
+/// Returns an integer which is the number of bytes in the binary.
+pub external fn byte_size(Binary) -> Int =
+  "erlang" "byte_size"
+
+// Not sure these will be necessary with bit syntax for for now I think they are
+pub external fn int_to_u32(Int) -> Result(Binary, Nil) = "binary_native" "int_to_u32"
+pub external fn int_from_u32(Binary) -> Result(Int, Nil) = "binary_native" "int_from_u32"
diff --git a/src/gleam/binary_native.erl b/src/gleam/binary_native.erl
new file mode 100644
index 0000000..d7e774c
--- /dev/null
+++ b/src/gleam/binary_native.erl
@@ -0,0 +1,12 @@
+-module (binary_native).
+-export ([int_to_u32/1, int_from_u32/1]).
+
+int_to_u32(I) when 0 =< I, I < 4294967296 ->
+  {ok, <<I:32>>};
+int_to_u32(_) ->
+  {error, nil}.
+
+int_from_u32(<<I:32>>) ->
+  {ok, I};
+int_from_u32(_) ->
+  {error, nil}.
diff --git a/test/gleam/binary_test.gleam b/test/gleam/binary_test.gleam
new file mode 100644
index 0000000..580aff7
--- /dev/null
+++ b/test/gleam/binary_test.gleam
@@ -0,0 +1,42 @@
+import gleam/binary
+import gleam/should
+
+pub fn length_test() {
+    binary.byte_size(binary.from_string("hello"))
+    |> should.equal(5)
+
+    binary.byte_size(binary.from_string(""))
+    |> should.equal(0)
+
+}
+
+pub fn part_test() {
+    binary.from_string("hello")
+    |> binary.part(0, 5)
+    |> should.equal(binary.from_string("hello"))
+
+    binary.from_string("hello")
+    |> binary.part(0, 0)
+    |> should.equal(binary.from_string(""))
+
+    binary.from_string("hello")
+    |> binary.part(2, 2)
+    |> should.equal(binary.from_string("ll"))
+
+    binary.from_string("hello")
+    |> binary.part(5, -2)
+    |> should.equal(binary.from_string("lo"))
+}
+
+pub fn u32_test() {
+    let Ok(bin) = binary.int_to_u32(0)
+    should.equal(4, binary.byte_size(bin))
+    should.equal(Ok(0), binary.int_from_u32(bin))
+
+    let Ok(bin) = binary.int_to_u32(4294967295)
+    should.equal(4, binary.byte_size(bin))
+    should.equal(Ok(4294967295), binary.int_from_u32(bin))
+
+    should.equal(Error(Nil), binary.int_from_u32(binary.from_string("")))
+    should.equal(Error(Nil), binary.int_from_u32(binary.from_string("12345")))
+}