Merge pull request #1277 from pguyot/w38/add-elixir-list-chars-protocol

Add Elixir List.Chars protocol.

https://github.com/elixir-lang/elixir/blob/v1.17.2/lib/elixir/lib/list/chars.ex

Split into several source files because of how our CMakeLists.txt is built

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

CHANGELOG.md

@@ -22,6 +22,7 @@ also non string parameters (e.g. `Enum.join([1, 2], ",")`
 - Support for `lists:last/1` and `lists:mapfoldl/3`
 - Add support to Elixir for `Process.send/2` `Process.send_after/3/4` and `Process.cancel_timer/1`
 - Add support for `handle_continue` callback in `gen_server`
+- Support for Elixir `List.Chars` protocol
 
 ### Changed
 

libs/exavmlib/lib/CMakeLists.txt

@@ -75,6 +75,13 @@ set(ELIXIR_MODULES
     Collectable.Map
     Collectable.MapSet
 
+    List.Chars
+    List.Chars.Atom
+    List.Chars.BitString
+    List.Chars.Float
+    List.Chars.Integer
+    List.Chars.List
+
     String.Chars
     String.Chars.Atom
     String.Chars.BitString

libs/exavmlib/lib/List.Chars.Atom.ex

@@ -0,0 +1,26 @@
+#
+# This file is part of elixir-lang.
+#
+# Copyright 2013-2023 Elixir Contributors
+# https://github.com/elixir-lang/elixir/commits/v1.17.2/lib/elixir/lib/list/chars.ex
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defimpl List.Chars, for: Atom do
+  def to_charlist(nil), do: ~c""
+
+  def to_charlist(atom), do: Atom.to_charlist(atom)
+end

libs/exavmlib/lib/List.Chars.BitString.ex

@@ -0,0 +1,36 @@
+#
+# This file is part of elixir-lang.
+#
+# Copyright 2013-2023 Elixir Contributors
+# https://github.com/elixir-lang/elixir/commits/v1.17.2/lib/elixir/lib/list/chars.ex
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defimpl List.Chars, for: BitString do
+  @doc """
+  Returns the given binary `term` converted to a charlist.
+  """
+  def to_charlist(term) when is_binary(term) do
+    String.to_charlist(term)
+  end
+
+  def to_charlist(term) do
+    raise Protocol.UndefinedError,
+      protocol: @protocol,
+      value: term,
+      description: "cannot convert a bitstring to a charlist"
+  end
+end

libs/exavmlib/lib/List.Chars.Float.ex

@@ -0,0 +1,27 @@
+#
+# This file is part of elixir-lang.
+#
+# Copyright 2013-2023 Elixir Contributors
+# https://github.com/elixir-lang/elixir/commits/v1.17.2/lib/elixir/lib/list/chars.ex
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defimpl List.Chars, for: Float do
+  def to_charlist(term) do
+    # TODO: :short option not yet supported right now, so :decimals+:compact should be replaced
+    :erlang.float_to_list(term, [{:decimals, 17}, :compact])
+  end
+end

libs/exavmlib/lib/List.Chars.Integer.ex

@@ -0,0 +1,26 @@
+#
+# This file is part of elixir-lang.
+#
+# Copyright 2013-2023 Elixir Contributors
+# https://github.com/elixir-lang/elixir/commits/v1.17.2/lib/elixir/lib/list/chars.ex
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defimpl List.Chars, for: Integer do
+  def to_charlist(term) do
+    Integer.to_charlist(term)
+  end
+end

libs/exavmlib/lib/List.Chars.List.ex

@@ -0,0 +1,25 @@
+#
+# This file is part of elixir-lang.
+#
+# Copyright 2013-2023 Elixir Contributors
+# https://github.com/elixir-lang/elixir/commits/v1.17.2/lib/elixir/lib/list/chars.ex
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defimpl List.Chars, for: List do
+  # Note that same inlining is used for the rewrite rule.
+  def to_charlist(list), do: list
+end

libs/exavmlib/lib/List.Chars.ex

@@ -0,0 +1,39 @@
+#
+# This file is part of elixir-lang.
+#
+# Copyright 2013-2023 Elixir Contributors
+# https://github.com/elixir-lang/elixir/commits/v1.17.2/lib/elixir/lib/list/chars.ex
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defprotocol List.Chars do
+  @moduledoc ~S"""
+  The `List.Chars` protocol is responsible for
+  converting a structure to a charlist (only if applicable).
+
+  The only function that must be implemented is
+  `to_charlist/1` which does the conversion.
+
+  The `to_charlist/1` function automatically imported
+  by `Kernel` invokes this protocol.
+  """
+
+  @doc """
+  Converts `term` to a charlist.
+  """
+  @spec to_charlist(t) :: charlist
+  def to_charlist(term)
+end