50 lines
1.4 KiB
Elixir
50 lines
1.4 KiB
Elixir
defmodule Home73k.Highlighter do
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@moduledoc """
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Performs code highlighting.
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"""
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alias Home73k.Temp
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@chroma_bin Home73k.app_chroma_bin() |> Path.expand()
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@doc """
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Highlights all code block in an already generated HTML document.
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"""
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def highlight_code_blocks(html) do
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~r/<pre><code(?:\s+class="(\w*)")?>([^<]*)<\/code><\/pre>/
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|> Regex.replace(html, &highlight_code_block(&1, &2, &3))
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end
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defp highlight_code_block(_full_block, lang, code) do
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# unescape the code
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unescaped_code = unescape_html(code) |> IO.iodata_to_binary()
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# write code to temp file
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tmp_file = Temp.file()
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File.write!(tmp_file, unescaped_code)
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# use chroma to highlight the code via temp file
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bin_args = ["-l", lang, "-f", "html", "--html-only", "--html-prevent-surrounding-pre", tmp_file]
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{highlighted, _} = System.cmd(@chroma_bin, bin_args)
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# return properly wrapped highlighted code
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~s(<pre class="chroma"><code class="language-#{lang}">#{highlighted}</code></pre>)
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end
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entities = [{"&", ?&}, {"<", ?<}, {">", ?>}, {""", ?"}, {"'", ?'}]
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for {encoded, decoded} <- entities do
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defp unescape_html(unquote(encoded) <> rest) do
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[unquote(decoded) | unescape_html(rest)]
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end
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end
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defp unescape_html(<<c, rest::binary>>) do
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[c | unescape_html(rest)]
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end
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defp unescape_html(<<>>) do
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[]
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end
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end
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