From 9dcca0c616d2a5ccc21420ea1a84732935872915 Mon Sep 17 00:00:00 2001
From: Brian Cardarella <bcardarella@gmail.com>
Date: Fri, 25 Oct 2024 09:01:52 -0400
Subject: [PATCH] Documentation and exception testing

---
 CHANGELOG.md                                  |   2 +
 lib/live_view_native/template/parse_error.ex  |  44 +++++++
 lib/live_view_native/template/parser.ex       |  84 ++++++++++++-
 .../live_view_native/template/parser_test.exs | 110 +++++++++++-------
 4 files changed, 199 insertions(+), 41 deletions(-)
 create mode 100644 lib/live_view_native/template/parse_error.ex

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 46de98f..d24e8ea 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* LiveViewNative.Template.Parser - a new Elixir parser for the LVN template syntax
+
 ### Changed
 
 * `LiveViewNative.Component` no longer imports `Phoenix.Component.to_form/2`
diff --git a/lib/live_view_native/template/parse_error.ex b/lib/live_view_native/template/parse_error.ex
new file mode 100644
index 0000000..2b6ea61
--- /dev/null
+++ b/lib/live_view_native/template/parse_error.ex
@@ -0,0 +1,44 @@
+defmodule LiveViewNative.Template.ParseError do
+  @moduledoc """
+
+
+  """
+
+  defexception [:message]
+
+  @impl true
+  def exception({document, message, [start: cursor, end: cursor]}) do
+    msg = """
+    #{message}
+
+    #{document_line(document, cursor)}
+    """
+
+    %__MODULE__{message: msg}
+  end
+
+  def exception({document, message, [start: start_cursor, end: end_cursor]}) do
+    msg = """
+    #{message}
+
+    Start:
+    #{document_line(document, start_cursor)}
+
+    End:
+    #{document_line(document, end_cursor)}
+    """
+
+    %__MODULE__{message: msg}
+  end
+
+  defp document_line(document, [line: line, column: column]) do
+    doc_line =
+      document
+      |> String.split("\n")
+      |> Enum.at(line - 1)
+
+    loc = "#{line}: "
+
+    ~s|#{loc}#{doc_line}\n#{String.duplicate(" ", String.length(loc))}#{String.pad_leading("^", column, "-")}|
+  end
+end
diff --git a/lib/live_view_native/template/parser.ex b/lib/live_view_native/template/parser.ex
index 1e74968..7baa5bd 100644
--- a/lib/live_view_native/template/parser.ex
+++ b/lib/live_view_native/template/parser.ex
@@ -1,8 +1,76 @@
 defmodule LiveViewNative.Template.Parser do
+  @moduledoc ~S'''
+  Floki-compliant parser for LiveView Native template syntax
+
+      iex> """
+      ...> <Group>
+      ...>   <Text class="bold">Hello</Text>
+      ...>   <Text>world!</Text>
+      ...> </Group>
+      ...> """
+      ...> |> LiveViewNative.Template.Parser.parse_document()
+      {:ok, [{"Group", [], [{"Text", [{"class", "bold"}], ["Hello"]}, {"Text", [], ["world!"]}]}]}
+
+  You can pass this AST into Floki for querying:
+
+      iex> """
+      ...> <Group>
+      ...>   <Text class="bold">Hello</Text>"
+      ...>   <Text>world!</Text>
+      ...> </Group>
+      ...> """
+      ...> |> LiveViewNative.Template.Parser.parse_document!()
+      ...> |> Floki.find("Text.bold")
+      [{"Text", [{"class", "bold"}], ["Hello"]}]
+
+  ## Floki Integration
+
+  Floki support passing parser in by option, this parser is compliant with that API:
+
+      iex> """
+      ...> <Group>
+      ...>   <Text class="bold">Hello</Text>"
+      ...>   <Text>world!</Text>
+      ...> </Group>
+      ...> """
+      ...> |> Floki.parse_document!(html_parser: LiveViewNative.Template.Parser)
+      ...> |> Floki.find("Text.bold")
+      [{"Text", [{"class", "bold"}], ["Hello"]}]
+
+  Or you can configure as the default:
+
+  ```elixir
+  config :floki, :html_parser, LiveViewNative.Tempalte.Parser
+  ```
+  '''
+
+  alias LiveViewNative.Template.ParseError
+
   @first_chars ~c"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
   @chars ~c"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-"
   @whitespace ~c"\s\t\n\r"
 
+  @doc """
+  Parses an LVN document from a string.
+
+  This is the main function to get a tree from a LVN string.
+
+  ## Options
+
+    * `:attributes_as_maps` - Change the behaviour of the parser to return the attributes
+      as maps, instead of a list of `{"key", "value"}`. Default to `false`.
+
+  ## Examples
+
+      iex> LiveViewNative.Template.Parser.parse_document("<Group><Text></Text><Text>hello</Text></Group>")
+      {:ok, [{"Group", [], [{"Text", [], []}, {"Text", [], ["hello"]}]}]}
+
+      iex> LiveViewNative.Template.Parser.parse_document(
+      ...>   ~S(<Group><Text></Text><Text class="main">hello</Text></Group>),
+      ...>   attributes_as_maps: true
+      ...>)
+      {:ok, [{"Group", %{}, [{"Text", %{}, []}, {"Text", %{"class" => "main"}, ["hello"]}]}]}
+  """
   def parse_document(document, args \\ []) do
     parse(document, [line: 1, column: 1], [], args)
     |> case do
@@ -11,10 +79,22 @@ defmodule LiveViewNative.Template.Parser do
     end
   end
 
+  @doc """
+  Parses a LVN Document from a string.
+
+  Similar to `parse_document/1`, but raises `LiveViewNative.Template.ParseError` if there was an
+  error parsing the document.
+
+  ## Example
+
+      iex> LiveViewNative.Template.Parser.parse_document!("<Group><Text></Text><Text>hello</Text></Group>")
+      [{"Group", [], [{"Text", [], []}, {"Text", [], ["hello"]}]}]
+
+  """
   def parse_document!(document, args \\ []) do
     case parse_document(document, args) do
-      {:ok, {nodes, _cursor}} -> nodes
-      {:error, message, _range} -> raise message
+      {:ok, nodes} -> nodes
+      {:error, message, range} -> raise ParseError, {document, message, range}
     end
   end
 
diff --git a/test/live_view_native/template/parser_test.exs b/test/live_view_native/template/parser_test.exs
index 7b9ae3e..05df169 100644
--- a/test/live_view_native/template/parser_test.exs
+++ b/test/live_view_native/template/parser_test.exs
@@ -2,6 +2,10 @@ defmodule LiveViewNative.Template.ParserTest do
   use ExUnit.Case, async: false
   import LiveViewNative.Template.Parser
 
+  alias LiveViewNative.Template.ParseError
+
+  doctest LiveViewNative.Template.Parser
+
   test "will parse a tag" do
     {:ok, nodes} = """
     <FooBar></FooBar>
@@ -119,98 +123,126 @@ defmodule LiveViewNative.Template.ParserTest do
 
   describe "parsing errors" do
     test "eof within a comment" do
-      {:error, _message, [start: start_pos, end: end_pos]} = "<!--"
-      |> parse_document()
+      doc = "<!--"
+      {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
       assert start_pos == end_pos
       assert start_pos == [line: 1, column: 5]
+
+      assert_raise ParseError, fn ->
+        parse_document!(doc)
+      end
     end
 
     test "invalid tag name character" do
-      {:error, _message, [start: start_pos, end: end_pos]} = """
-      <FooBar!></FooBar!>
-      """
-      |> parse_document()
+      doc = "<FooBar!></FooBar!>"
+      {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
       assert start_pos == end_pos
       assert start_pos == [line: 1, column: 8]
+
+      assert_raise ParseError, fn ->
+        parse_document!(doc)
+      end
     end
 
     test "eof during tag name parsing" do
-      {:error, _message, [start: start_pos, end: end_pos]} = "<FooBar"
-      |> parse_document()
+      doc = "<FooBar"
+      {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
       assert start_pos == end_pos
       assert start_pos == [line: 1, column: 8]
+
+      assert_raise ParseError, fn ->
+        parse_document!(doc)
+      end
     end
 
     test "invalid attribute key name" do
-      {:error, _message, [start: start_pos, end: end_pos]} = """
-      <FooBar
-        a-*b="123"></FooBar>
-      """
-      |> parse_document()
+      doc = """
+        <FooBar
+          a-*b="123"></FooBar>
+        """
+      {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
       assert start_pos == end_pos
       assert start_pos == [line: 2, column: 5]
+
+      assert_raise ParseError, fn ->
+        parse_document!(doc)
+      end
     end
 
     test "eof during attribute key parsing" do
-      {:error, _message, [start: start_pos, end: end_pos]} = """
-      <FooBar a
-      """
-      |> parse_document()
+      doc = "<FooBar a"
+      {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
       assert start_pos == end_pos
-      assert start_pos == [line: 2, column: 1]
+      assert start_pos == [line: 1, column: 10]
+
+      assert_raise ParseError, fn ->
+        parse_document!(doc)
+      end
     end
 
      test "eof during attribute value parsing" do
-       {:error, _message, [start: start_pos, end: end_pos]} = """
-       <FooBar a="
-       """
-       |> parse_document()
+       doc = "<FooBar a="
+       {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
        assert start_pos == end_pos
-       assert start_pos == [line: 2, column: 1]
+       assert start_pos == [line: 1, column: 11]
+
+       assert_raise ParseError, fn ->
+         parse_document!(doc)
+       end
      end
 
      test "catches parsing errors with invalid value format for attribute" do
-       {:error, _message, [start: start_pos, end: end_pos]} = """
-       <FooBar a=
-       """
-       |> parse_document()
+       doc = "<FooBar a=></FooBar>"
+       {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
        assert start_pos == end_pos
-       assert start_pos == [line: 2, column: 1]
+       assert start_pos == [line: 1, column: 11]
+
+       assert_raise ParseError, fn ->
+         parse_document!(doc)
+       end
      end
 
      test "catches errors with not closing tag entity propery" do
-       {:error, _message, [start: start_pos, end: end_pos]} = """
-       <FooBar <Baz/>
-       """
-       |> parse_document()
+       doc = "<FooBar <Baz/>"
+       {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
        assert start_pos == end_pos
        assert start_pos == [line: 1, column: 9]
+
+       assert_raise ParseError, fn ->
+         parse_document!(doc)
+       end
      end
 
      test "eof while parsing tag entity" do
-       {:error, _message, [start: start_pos, end: end_pos]} = "<FooBar a=\"123\""
-       |> parse_document()
+       doc = ~s(<FooBar a="123")
+       {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
        assert start_pos == end_pos
        assert start_pos == [line: 1, column: 16]
+
+       assert_raise ParseError, fn ->
+         parse_document!(doc)
+       end
      end
 
      test "eof while parsing children" do
-       {:error, _message, [start: start_pos, end: end_pos]} = """
-       <FooBar>
-       """
-       |> parse_document()
+       doc = "<FooBar>"
+       {:error, _message, [start: start_pos, end: end_pos]} = parse_document(doc)
 
        assert start_pos == end_pos
-       assert start_pos == [line: 2, column: 1]
+       assert start_pos == [line: 1, column: 9]
+
+       assert_raise ParseError, fn ->
+         parse_document!(doc)
+       end
      end
   end
 end