feat: range formatting

Should work the same as vim.lsp.buf.format(). Additionally, range
formatting is supported for *any* formatter. If the formatter doesn't
have native support for ranges, conform will do its best to only apply the
diffs that affect that range.

1 files changed, 57 insertions, 25 deletions

diff --git a/lua/conform/runner.lua b/lua/conform/runner.lua
index 7ccaec6..843dae1 100644
--- a/lua/conform/runner.lua
+++ b/lua/conform/runner.lua
@@ -5,35 +5,51 @@ local uv = vim.uv or vim.loop
 local M = {}
 
 ---@param ctx conform.Context
----@param config conform.StaticFormatterConfig
+---@param config conform.FormatterConfig
 M.build_cmd = function(ctx, config)
   local command = config.command
   if type(command) == "function" then
     command = command(ctx)
   end
   local cmd = { command }
-  if config.args then
-    local args = config.args
+  local args = {}
+  if ctx.range and config.range_args then
+    ---@cast ctx conform.RangeContext
+    args = config.range_args(ctx)
+  elseif config.args then
     if type(config.args) == "function" then
       args = config.args(ctx)
+    else
+      ---@diagnostic disable-next-line: cast-local-type
+      args = config.args
     end
-    ---@cast args string[]
-    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
+
+  ---@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
   return cmd
 end
 
+---@param range? conform.Range
+---@param start_a integer
+---@param end_a integer
+local function indices_in_range(range, start_a, end_a)
+  return not range or (start_a <= range["end"][1] and range["start"][1] <= end_a)
+end
+
 ---@param bufnr integer
 ---@param original_lines string[]
 ---@param new_lines string[]
-local function apply_format(bufnr, original_lines, new_lines)
+---@param range? conform.Range
+---@param only_apply_range boolean
+local function apply_format(bufnr, original_lines, new_lines, range, only_apply_range)
   local original_text = table.concat(original_lines, "\n")
   -- Trim off the final newline from the formatted text because that is baked in to
   -- the vim lines representation
@@ -68,18 +84,21 @@ local function apply_format(bufnr, original_lines, new_lines)
       count_b = count_b + 1
     end
     local replacement = util.tbl_slice(new_lines, start_b, start_b + count_b - 1)
-    vim.api.nvim_buf_set_lines(bufnr, start_a - 1, start_a - 1 + count_a, true, replacement)
+    local end_a = start_a + count_a
+    if not only_apply_range or indices_in_range(range, start_a, end_a) then
+      vim.api.nvim_buf_set_lines(bufnr, start_a - 1, end_a - 1, true, replacement)
+    end
   end
 end
 
 ---@param bufnr integer
 ---@param formatter conform.FormatterInfo
+---@param config conform.FormatterConfig
+---@param ctx conform.Context
 ---@param input_lines string[]
 ---@param callback fun(err?: string, output?: string[])
----@return integer
-local function run_formatter(bufnr, formatter, input_lines, callback)
-  local config = assert(require("conform").get_formatter_config(formatter.name))
-  local ctx = M.build_context(bufnr, config)
+---@return integer job_id
+local function run_formatter(bufnr, formatter, config, ctx, input_lines, callback)
   local cmd = M.build_cmd(ctx, config)
   local cwd = nil
   if config.cwd then
@@ -159,9 +178,10 @@ local function run_formatter(bufnr, formatter, input_lines, callback)
 end
 
 ---@param bufnr integer
----@param config conform.StaticFormatterConfig
+---@param config conform.FormatterConfig
+---@param range? conform.Range
 ---@return conform.Context
-M.build_context = function(bufnr, config)
+M.build_context = function(bufnr, config, range)
   if bufnr == 0 then
     bufnr = vim.api.nvim_get_current_buf()
   end
@@ -193,13 +213,15 @@ M.build_context = function(bufnr, config)
     buf = bufnr,
     filename = filename,
     dirname = dirname,
+    range = range,
   }
 end
 
 ---@param bufnr integer
 ---@param formatters conform.FormatterInfo[]
+---@param range? conform.Range
 ---@param callback? fun(err?: string)
-M.format_async = function(bufnr, formatters, callback)
+M.format_async = function(bufnr, formatters, range, callback)
   if bufnr == 0 then
     bufnr = vim.api.nvim_get_current_buf()
   end
@@ -207,6 +229,7 @@ M.format_async = function(bufnr, formatters, callback)
   local changedtick = vim.b[bufnr].changedtick
   local original_lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
   local input_lines = original_lines
+  local all_support_range_formatting = true
 
   -- kill previous jobs for buffer
   local prev_jid = vim.b[bufnr].conform_jid
@@ -221,7 +244,7 @@ M.format_async = function(bufnr, formatters, callback)
     if not formatter then
       -- discard formatting if buffer has changed
       if vim.b[bufnr].changedtick == changedtick then
-        apply_format(bufnr, original_lines, input_lines)
+        apply_format(bufnr, original_lines, input_lines, range, not all_support_range_formatting)
       else
         log.info(
           "Async formatter discarding changes for %s: concurrent modification",
@@ -235,8 +258,10 @@ M.format_async = function(bufnr, formatters, callback)
     end
     idx = idx + 1
 
+    local config = assert(require("conform").get_formatter_config(formatter.name))
+    local ctx = M.build_context(bufnr, config, range)
     local jid
-    jid = run_formatter(bufnr, formatter, input_lines, function(err, output)
+    jid = run_formatter(bufnr, formatter, config, ctx, input_lines, function(err, output)
       if err then
         -- Only log the error if the job wasn't canceled
         if vim.api.nvim_buf_is_valid(bufnr) and jid == vim.b[bufnr].conform_jid then
@@ -250,6 +275,7 @@ M.format_async = function(bufnr, formatters, callback)
       input_lines = output
       run_next_formatter()
     end)
+    all_support_range_formatting = all_support_range_formatting and config.range_args ~= nil
   end
   run_next_formatter()
 end
@@ -258,7 +284,8 @@ end
 ---@param formatters conform.FormatterInfo[]
 ---@param timeout_ms integer
 ---@param quiet boolean
-M.format_sync = function(bufnr, formatters, timeout_ms, quiet)
+---@param range? conform.Range
+M.format_sync = function(bufnr, formatters, timeout_ms, quiet, range)
   if bufnr == 0 then
     bufnr = vim.api.nvim_get_current_buf()
   end
@@ -274,6 +301,7 @@ M.format_sync = function(bufnr, formatters, timeout_ms, quiet)
     end
   end
 
+  local all_support_range_formatting = true
   for _, formatter in ipairs(formatters) do
     local remaining = timeout_ms - (uv.hrtime() / 1e6 - start)
     if remaining <= 0 then
@@ -286,13 +314,16 @@ M.format_sync = function(bufnr, formatters, timeout_ms, quiet)
     end
     local done = false
     local result = nil
-    run_formatter(bufnr, formatter, input_lines, function(err, output)
+    local config = assert(require("conform").get_formatter_config(formatter.name))
+    local ctx = M.build_context(bufnr, config, range)
+    local jid = run_formatter(bufnr, formatter, config, ctx, input_lines, function(err, output)
       if err then
         log.error(err)
       end
       done = true
       result = output
     end)
+    all_support_range_formatting = all_support_range_formatting and config.range_args ~= nil
 
     local wait_result, wait_reason = vim.wait(remaining, function()
       return done
@@ -306,6 +337,7 @@ M.format_sync = function(bufnr, formatters, timeout_ms, quiet)
           vim.notify(string.format("Formatter '%s' timed out", formatter.name), vim.log.levels.WARN)
         end
       end
+      vim.fn.jobstop(jid)
       return
     end
 
@@ -317,7 +349,7 @@ M.format_sync = function(bufnr, formatters, timeout_ms, quiet)
   end
 
   local final_result = input_lines
-  apply_format(bufnr, original_lines, final_result)
+  apply_format(bufnr, original_lines, final_result, range, not all_support_range_formatting)
 end
 
 return M