doc: add some recipes to the documentation

2 files changed, 144 insertions, 18 deletions

diff --git a/doc/conform.txt b/doc/conform.txt
index 0052326..bcae22f 100644
--- a/doc/conform.txt
+++ b/doc/conform.txt
@@ -27,6 +27,7 @@ OPTIONS                                                          *conform-option
       },
       -- If this is set, Conform will run the formatter on save.
       -- It will pass the table to conform.format().
+      -- This can also be a function that returns the table.
       format_on_save = {
         -- I recommend these options. See :help conform.format for details.
         lsp_fallback = true,
@@ -34,6 +35,7 @@ OPTIONS                                                          *conform-option
       },
       -- If this is set, Conform will run the formatter asynchronously after save.
       -- It will pass the table to conform.format().
+      -- This can also be a function that returns the table.
       format_after_save = {
         lsp_fallback = true,
       },
@@ -222,35 +224,23 @@ AUTOFORMAT                                                    *conform-autoforma
 If you want more complex logic than the `format_on_save` option allows, you can
 write it yourself using your own autocmd. For example:
 >lua
-    -- Format synchronously on save
-    vim.api.nvim_create_autocmd("BufWritePre", {
-      pattern = "*",
-      callback = function(args)
+    -- if format_on_save is a function, it will be called during BufWritePre
+    require("conform").setup({
+      format_on_save = function(bufnr)
         -- Disable autoformat on certain filetypes
         local ignore_filetypes = { "sql", "java" }
-        if vim.tbl_contains(ignore_filetypes, vim.bo[args.buf].filetype) then
+        if vim.tbl_contains(ignore_filetypes, vim.bo[bufnr].filetype) then
           return
         end
         -- Disable with a global or buffer-local variable
-        if vim.g.disable_autoformat or vim.b[args.buf].disable_autoformat then
+        if vim.g.disable_autoformat or vim.b[bufnr].disable_autoformat then
           return
         end
         -- Disable autoformat for files in a certain path
-        local bufname = vim.api.nvim_buf_get_name(args.buf)
+        local bufname = vim.api.nvim_buf_get_name(bufnr)
         if bufname:match("/node_modules/") then
           return
         end
-        require("conform").format({ timeout_ms = 500, lsp_fallback = true, bufnr = args.buf })
-      end,
-    })
-
-    -- To eliminate the boilerplate, you can pass a function to format_on_save
-    -- and it will be called during the BufWritePre callback.
-    require("conform").setup({
-      format_on_save = function(bufnr)
-        if vim.g.disable_autoformat or vim.b[bufnr].disable_autoformat then
-          return
-        end
         -- ...additional logic...
         return { timeout_ms = 500, lsp_fallback = true }
       end,
diff --git a/doc/recipes.md b/doc/recipes.md
new file mode 100644
index 0000000..9fed51d
--- /dev/null
+++ b/doc/recipes.md
@@ -0,0 +1,136 @@
+# Recipes
+
+<!-- TOC -->
+
+- [Format command](#format-command)
+- [Customizing formatters](#customizing-formatters)
+- [Autoformat with extra features](#autoformat-with-extra-features)
+- [Command to toggle format-on-save](#command-to-toggle-format-on-save)
+
+<!-- /TOC -->
+
+## Format command
+
+Define a command to run async formatting
+
+```lua
+vim.api.nvim_create_user_command("Format", function(args)
+  local range = nil
+  if args.count ~= -1 then
+    local end_line = vim.api.nvim_buf_get_lines(0, args.line2 - 1, args.line2, true)[1]
+    range = {
+      start = { args.line1, 0 },
+      ["end"] = { args.line2, end_line:len() },
+    }
+  end
+  require("conform").format({ async = true, lsp_fallback = true, range = range })
+end, { range = true })
+```
+
+## Customizing formatters
+
+If you want to customize how a formatter runs (for example, to pass in environment variables or
+change the command arguments), you can either edit the formatter directly or create one yourself.
+
+```lua
+-- Directly change the values on the built-in configuration
+require("conform.formatters.yamlfix").env = {
+  YAMLFIX_SEQUENCE_STYLE = "block_style",
+}
+
+-- Or create your own formatter that overrides certain values
+require("conform").formatters.yamlfix = vim.tbl_deep_extend("force", require("conform.formatters.yamlfix"), {
+  env = {
+    YAMLFIX_SEQUENCE_STYLE = "block_style",
+  },
+})
+
+-- Here is an example that modifies the command arguments for prettier to add
+-- a custom config file, if it is present
+require("conform.formatters.prettier").args = function(ctx)
+  local args = { "--stdin-filepath", "$FILENAME" }
+  local found = vim.fs.find(".custom-config.json", { upward = true, path = ctx.dirname })[1]
+  if found then
+    vim.list_extend(args, { "--config", found })
+  end
+  return args
+end
+```
+
+## Autoformat with extra features
+
+If you want more complex logic than the basic `format_on_save` option allows, you can use a function instead.
+
+<!-- AUTOFORMAT -->
+
+```lua
+-- if format_on_save is a function, it will be called during BufWritePre
+require("conform").setup({
+  format_on_save = function(bufnr)
+    -- Disable autoformat on certain filetypes
+    local ignore_filetypes = { "sql", "java" }
+    if vim.tbl_contains(ignore_filetypes, vim.bo[bufnr].filetype) then
+      return
+    end
+    -- Disable with a global or buffer-local variable
+    if vim.g.disable_autoformat or vim.b[bufnr].disable_autoformat then
+      return
+    end
+    -- Disable autoformat for files in a certain path
+    local bufname = vim.api.nvim_buf_get_name(bufnr)
+    if bufname:match("/node_modules/") then
+      return
+    end
+    -- ...additional logic...
+    return { timeout_ms = 500, lsp_fallback = true }
+  end,
+})
+
+-- There is a similar affordance for format_after_save, which uses BufWritePost.
+-- This is good for formatters that are too slow to run synchronously.
+require("conform").setup({
+  format_after_save = function(bufnr)
+    if vim.g.disable_autoformat or vim.b[bufnr].disable_autoformat then
+      return
+    end
+    -- ...additional logic...
+    return { lsp_fallback = true }
+  end,
+})
+```
+
+<!-- /AUTOFORMAT -->
+
+## Command to toggle format-on-save
+
+Create user commands to quickly enable/disable autoformatting
+
+```lua
+require("conform").setup({
+  format_on_save = function(bufnr)
+    -- Disable with a global or buffer-local variable
+    if vim.g.disable_autoformat or vim.b[bufnr].disable_autoformat then
+      return
+    end
+    return { timeout_ms = 500, lsp_fallback = true }
+  end,
+})
+
+vim.api.nvim_create_user_command("FormatDisable", function(args)
+  if args.bang then
+    -- FormatDisable! will disable formatting just for this buffer
+    vim.b.disable_autoformat = true
+  else
+    vim.g.disable_autoformat = true
+  end
+end, {
+  desc = "Disable autoformat-on-save",
+  bang = true,
+})
+vim.api.nvim_create_user_command("FormatEnable", function()
+  vim.b.disable_autoformat = false
+  vim.g.disable_autoformat = false
+end, {
+  desc = "Re-enable autoformat-on-save",
+})
+```