make syntax highlighting colors configurable by mvanhorn · Pull Request #37 · elixir-dbvisor/sql

mvanhorn · 2026-10-04T06:56:11Z

SQL.Format.syntax_color/1 reads :syntax_colors from the :sql application environment and turns a color name, or a list of them, into an ANSI fragment with IO.ANSI.format_fragment. Formatted SQL and the compile-time warnings that quote it always highlight keywords, literals, enclosed quotes, and errors with the same ANSI colors.

Tests for this live in test/syntax_colors_test.exs.

Closes #26

Schultzer · 2026-10-04T13:35:35Z

@mvanhorn thanks for this PR, I think we can simplify this by using Application.get_compile_env in the module attributes instead of introduce new public functions.

Are you currently using this library?

mvanhorn · 2026-10-05T04:26:06Z

Updated in 5fc9f84: syntax colors are now read with Application.compile_env in module attributes, and the public helper is gone. Defaults are unchanged, and the tests and README now describe the compile-time configuration. The full test suite passes locally.

To answer your question: no, I'm not using the library myself. I picked up #26 to contribute. If compile-time configuration isn't the direction you want, I'm happy to close this.

Schultzer

Thanks, we're almost there. I imagine this feature to be around 13 lines of additions.

Also @mvanhorn can you tell me how you work now a days, obvisouly there is an agent behind this, but I'm not sure if there is a human in this loop.

Schultzer · 2026-10-05T15:12:55Z

-  @error IO.ANSI.red()
-  @reset IO.ANSI.reset()
-  @keyword IO.ANSI.magenta()
-  @literal IO.ANSI.yellow()
-  @enclosed IO.ANSI.green()


No need to move the code around just change these to:

Suggested change

@error IO.ANSI.red()

@reset IO.ANSI.reset()

@keyword IO.ANSI.magenta()

@literal IO.ANSI.yellow()

@enclosed IO.ANSI.green()

@error Application.compile_env(:sql, [:syntax_colors, :error], IO.ANSI.red()))

@reset IO.ANSI.reset()

@keyword Application.compile_env(:sql, [:syntax_colors, :keyword], IO.ANSI.magenta()))

@literal Application.compile_env(:sql, [:syntax_colors, :literal], IO.ANSI.yellow()))

@enclosed Application.compile_env(:sql, [:syntax_colors, :enclosed], IO.ANSI.green()))

reset should not be configured.

Schultzer · 2026-10-05T15:13:20Z

+        newline(color(color, [keyword(case, unquote(atom)),?\s,keyword(case, atom)], [?\n|to_iodata(values, color, case, errors, indent+1, acc)]), indent)
      else
-        newline([@keyword, keyword(case, unquote(atom)),?\s,keyword(case, atom),@reset|to_iodata(values, color, case, errors, indent, acc)], indent)
+        newline(color(color, [keyword(case, unquote(atom)),?\s,keyword(case, atom)], to_iodata(values, color, case, errors, indent, acc)), indent)


You don't need to change this.

Schultzer · 2026-10-05T15:14:18Z

 defmodule SQL.Inspect do
  @moduledoc false

-  @error IO.ANSI.red()


Suggested change

@error IO.ANSI.red()

@error Application.compile_env(:sql, [:syntax_colors, :error], IO.ANSI.red()))

@reset IO.ANSI.reset()

reset should not be configured.

Schultzer · 2026-10-05T15:16:12Z

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2025 DBVisor
+
+defmodule SQL.SyntaxColorsTest do
+  use ExUnit.Case, async: false
+
+  setup do
+    original = Application.fetch_env(:sql, :syntax_colors)
+
+    on_exit(fn ->
+      case original do
+        {:ok, colors} -> Application.put_env(:sql, :syntax_colors, colors)
+        :error -> Application.delete_env(:sql, :syntax_colors)
+      end
+
+      recompile()
+    end)
+
+    Application.delete_env(:sql, :syntax_colors)
+    recompile()
+    :ok
+  end
+
+  test "default palette" do
+    formatted = formatted("select +1000", true)
+    assert formatted =~ "\e[35mselect\e[0m"
+    assert formatted =~ "\e[33m1000\e[0m"
+  end
+
+  test "partial override keeps unspecified roles" do
+    configure(keyword: :cyan)
+    formatted = formatted("select +1000", true)
+    assert formatted =~ "\e[36mselect\e[0m"
+    assert formatted =~ "\e[33m1000\e[0m"
+  end
+
+  test "runtime changes do not affect compiled colors" do
+    configure(keyword: [:bright, :cyan])
+    Application.put_env(:sql, :syntax_colors, keyword: :blue)
+    assert formatted("select +1000", true) =~ "\e[1m\e[36mselect\e[0m"
+  end
+
+  test "enclosed quotes" do
+    assert formatted("select 'abc'", true) =~ "\e[32mabc\e[0m"
+
+    configure(enclosed: :cyan)
+    assert formatted("select 'abc'", true) =~ "\e[36mabc\e[0m"
+  end
+
+  test "color false emits no ansi" do
+    configure(keyword: :cyan, literal: :blue)
+    formatted = formatted("select +1000", false)
+    refute formatted =~ "\e["
+  end
+
+  test "error nodes" do
+    {context, tokens} = parse("select users")
+    [{:select, _, [ident]}] = tokens
+    context = %{context | errors: [ident]}
+    formatted = IO.iodata_to_binary(SQL.Format.to_iodata(tokens, context, 0, true))
+    assert formatted =~ "\e[31musers\e[0m"
+
+    configure(error: :blue)
+    formatted = IO.iodata_to_binary(SQL.Format.to_iodata(tokens, context, 0, true))
+    assert formatted =~ "\e[34musers\e[0m"
+
+    warning = IO.iodata_to_binary(SQL.Inspect.format_error([{:ident, [], "users"}]))
+    assert warning =~ "the relation \e[34musers\e[0m does not exist"
+  end
+
+  test "unknown color raises" do
+    assert_raise ArgumentError, fn ->
+      configure(keyword: :not_a_color)
+    end
+  end
+
+  defp configure(colors) do
+    Application.put_env(:sql, :syntax_colors, colors)
+    recompile()
+  end
+
+  defp recompile do
+    options = Code.compiler_options(ignore_module_conflict: true)
+
+    try do
+      Code.compile_file("lib/format.ex")
+      Code.compile_file("lib/inspect.ex")
+    after
+      Code.compiler_options(options)
+    end
+  end
+
+  defp parse(sql) do
+    {:ok, context, tokens} = SQL.Lexer.lex(sql)
+    {:ok, context, tokens} = SQL.Parser.parse(tokens, context)
+    {context, tokens}
+  end
+
+  defp formatted(sql, color) do
+    {context, tokens} = parse(sql)
+    IO.iodata_to_binary(SQL.Format.to_iodata(tokens, context, 0, color))
+  end
+end


We already have tests for the inspect, so these test are not nedded, also they are testing Elixir more then our implementation.

Schultzer · 2026-10-05T15:18:21Z

+## Syntax highlighting
+
+Inspect output and compile-time warnings color keywords, literals, enclosed quotes, and errors. Override any of those roles from `config.exs`:
+
+```elixir
+config :sql, :syntax_colors, [keyword: :cyan, literal: :yellow, enclosed: :green, error: :red]
+```
+
+Each value is an `IO.ANSI` color name or a list of them. Roles you omit keep the defaults: magenta keywords, yellow literals, green enclosed quotes, and red errors. Colors are read when the SQL library compiles, so this setting belongs in `config.exs`; recompile the library after changing it (for a dependency, run `mix deps.compile sql --force`). Recompile callers with static `~SQL` sigils as well, since they store their inspect text at compilation.
+


We need to adjust these to the suggestions I gave above, we can also make this more consice, no need for the last paragraph.

Schultzer · 2026-10-05T15:27:05Z

@mvanhorn please do me a favor and just amend the first commit in this PR with all the changes, no need for multiple commits for this feature.

mvanhorn · 2026-10-06T17:27:31Z

@Schultzer Updated and squashed into the first commit, so the PR is now a single commit.

lib/format.ex and lib/inspect.ex use your compile_env suggestions in place (balanced parens), and reset is no longer configurable
the hunk at format.ex:78 is back to what it was
removed test/syntax_colors_test.exs
trimmed the README section to the config example and dropped the last paragraph

The code change is 5 lines now; with the README and CHANGELOG it's 22 additions. mix compile --warnings-as-errors and mix test are clean (397 tests).

On how I work: I use AI coding agents to draft the changes and the replies, and I review and approve every commit and comment before it goes out, including this one. If you'd rather work with me differently on this PR, happy to adjust.

Schultzer · 2026-10-06T18:27:19Z

@Schultzer Updated and squashed into the first commit, so the PR is now a single commit.

lib/format.ex and lib/inspect.ex use your compile_env suggestions in place (balanced parens), and reset is no longer configurable

the hunk at format.ex:78 is back to what it was

removed test/syntax_colors_test.exs

trimmed the README section to the config example and dropped the last paragraph

The code change is 5 lines now; with the README and CHANGELOG it's 22 additions. mix compile --warnings-as-errors and mix test are clean (397 tests).

On how I work: I use AI coding agents to draft the changes and the replies, and I review and approve every commit and comment before it goes out, including this one. If you'd rather work with me differently on this PR, happy to adjust.

Thanks, just a rebase and we should be good to merge this.

Read the keyword, literal, enclosed, and error colors from config :sql, :syntax_colors with Application.compile_env, falling back to the current IO.ANSI defaults. The reset sequence stays fixed. Fixes elixir-dbvisor#26 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019wSaUMZrtm6XSzwEcxavkv

mvanhorn · 2026-10-07T23:32:10Z

Rebased on main (3c23785). The only conflict was CHANGELOG.md, so the entry now sits under a new Unreleased section above v0.6.0. mix test passes locally.

Schultzer requested changes Oct 5, 2026

View reviewed changes

mvanhorn force-pushed the fix/26-configurable-syntax-colors branch from e1e54f3 to e260f74 Compare October 6, 2026 17:19

mvanhorn force-pushed the fix/26-configurable-syntax-colors branch from e260f74 to 3c23785 Compare October 7, 2026 23:31

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make syntax highlighting colors configurable - #37

make syntax highlighting colors configurable#37
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mvanhorn:fix/26-configurable-syntax-colors

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	@error IO.ANSI.red()
	@error Application.compile_env(:sql, [:syntax_colors, :error], IO.ANSI.red()))
	@reset IO.ANSI.reset()

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