feat: allow running commands in a shell (#49)

6 files changed, 64 insertions, 11 deletions

diff --git a/README.md b/README.md
index 3d312b8..e20dcc9 100644
--- a/README.md
+++ b/README.md
@@ -261,6 +261,7 @@ require("conform").setup({
       command = "my_cmd",
       -- OPTIONAL - all fields below this are optional
       -- A list of strings, or a function that returns a list of strings
+      -- Return a single string instead to run the command in a shell
       args = { "--stdin-from-filename", "$FILENAME" },
       -- If the formatter supports range formatting, create the range arguments here
       range_args = function(ctx)
diff --git a/doc/conform.txt b/doc/conform.txt
index e0dd9ff..1d29bdd 100644
--- a/doc/conform.txt
+++ b/doc/conform.txt
@@ -50,6 +50,7 @@ OPTIONS                                                          *conform-option
           command = "my_cmd",
           -- OPTIONAL - all fields below this are optional
           -- A list of strings, or a function that returns a list of strings
+          -- Return a single string instead to run the command in a shell
           args = { "--stdin-from-filename", "$FILENAME" },
           -- If the formatter supports range formatting, create the range arguments here
           range_args = function(ctx)
diff --git a/lua/conform/init.lua b/lua/conform/init.lua
index ff30686..a19813e 100644
--- a/lua/conform/init.lua
+++ b/lua/conform/init.lua
@@ -9,8 +9,8 @@ local M = {}
 
 ---@class (exact) conform.FormatterConfig
 ---@field command string|fun(ctx: conform.Context): string
----@field args? string[]|fun(ctx: conform.Context): string[]
----@field range_args? fun(ctx: conform.RangeContext): string[]
+---@field args? string|string[]|fun(ctx: conform.Context): string|string[]
+---@field range_args? fun(ctx: conform.RangeContext): string|string[]
 ---@field cwd? fun(ctx: conform.Context): nil|string
 ---@field require_cwd? boolean When cwd is not found, don't run the formatter (default false)
 ---@field stdin? boolean Send buffer contents to stdin (default true)
diff --git a/lua/conform/runner.lua b/lua/conform/runner.lua
index ff8fbef..fff638b 100644
--- a/lua/conform/runner.lua
+++ b/lua/conform/runner.lua
@@ -48,12 +48,13 @@ end
 
 ---@param ctx conform.Context
 ---@param config conform.FormatterConfig
+---@return string|string[]
 M.build_cmd = function(ctx, config)
   local command = config.command
   if type(command) == "function" then
     command = command(ctx)
   end
-  local cmd = { command }
+  ---@type string|string[]
   local args = {}
   if ctx.range and config.range_args then
     ---@cast ctx conform.RangeContext
@@ -67,16 +68,22 @@ M.build_cmd = function(ctx, config)
     end
   end
 
-  ---@diagnostic disable-next-line: param-type-mismatch
-  for _, v in ipairs(args) do
-    if v == "$FILENAME" then
-      v = ctx.filename
-    elseif v == "$DIRNAME" then
-      v = ctx.dirname
+  if type(args) == "string" then
+    local interpolated = args:gsub("$FILENAME", ctx.filename):gsub("$DIRNAME", ctx.dirname)
+    return command .. " " .. interpolated
+  else
+    local cmd = { command }
+    ---@diagnostic disable-next-line: param-type-mismatch
+    for _, v in ipairs(args) do
+      if v == "$FILENAME" then
+        v = ctx.filename
+      elseif v == "$DIRNAME" then
+        v = ctx.dirname
+      end
+      table.insert(cmd, v)
     end
-    table.insert(cmd, v)
+    return cmd
   end
-  return cmd
 end
 
 ---@param range? conform.Range
diff --git a/scripts/options_doc.lua b/scripts/options_doc.lua
index 9073369..af7b10c 100644
--- a/scripts/options_doc.lua
+++ b/scripts/options_doc.lua
@@ -36,6 +36,7 @@ require("conform").setup({
       command = "my_cmd",
       -- OPTIONAL - all fields below this are optional
       -- A list of strings, or a function that returns a list of strings
+      -- Return a single string instead to run the command in a shell
       args = { "--stdin-from-filename", "$FILENAME" },
       -- If the formatter supports range formatting, create the range arguments here
       range_args = function(ctx)
diff --git a/tests/runner_spec.lua b/tests/runner_spec.lua
index 10ea075..56cf8e2 100644
--- a/tests/runner_spec.lua
+++ b/tests/runner_spec.lua
@@ -102,6 +102,49 @@ describe("runner", function()
       local cmd = runner.build_cmd(ctx, config)
       assert.are.same({ "echo", "--stdin" }, cmd)
     end)
+
+    it("replaces $FILENAME in string args", function()
+      vim.cmd.edit({ args = { "README.md" } })
+      local bufnr = vim.api.nvim_get_current_buf()
+      conform.formatters.test = {
+        meta = { url = "", description = "" },
+        command = "echo",
+        args = "$FILENAME | patch",
+      }
+      local config = assert(conform.get_formatter_config("test"))
+      local ctx = runner.build_context(0, config)
+      local cmd = runner.build_cmd(ctx, config)
+      assert.equal("echo " .. vim.api.nvim_buf_get_name(bufnr) .. " | patch", cmd)
+    end)
+
+    it("replaces $DIRNAME in string args", function()
+      vim.cmd.edit({ args = { "README.md" } })
+      local bufnr = vim.api.nvim_get_current_buf()
+      conform.formatters.test = {
+        meta = { url = "", description = "" },
+        command = "echo",
+        args = "$DIRNAME | patch",
+      }
+      local config = assert(conform.get_formatter_config("test"))
+      local ctx = runner.build_context(0, config)
+      local cmd = runner.build_cmd(ctx, config)
+      assert.equal("echo " .. vim.fs.dirname(vim.api.nvim_buf_get_name(bufnr)) .. " | patch", cmd)
+    end)
+
+    it("resolves arg function with string results", function()
+      vim.cmd.edit({ args = { "README.md" } })
+      conform.formatters.test = {
+        meta = { url = "", description = "" },
+        command = "echo",
+        args = function()
+          return "| patch"
+        end,
+      }
+      local config = assert(conform.get_formatter_config("test"))
+      local ctx = runner.build_context(0, config)
+      local cmd = runner.build_cmd(ctx, config)
+      assert.equal("echo | patch", cmd)
+    end)
   end)
 
   describe("e2e", function()