ref!: major refactor

.editorconfig

@@ -0,0 +1,3 @@
+[*.lua]
+indent_style = space
+indent_size = 2

.github/workflows/ci.yml

@@ -14,7 +14,6 @@ jobs:
           version: latest
           args: --check .
 
-
   docs:
     runs-on: ubuntu-latest
     name: pandoc to vimdoc
@@ -28,7 +27,7 @@ jobs:
           treesitter: true
       - uses: stefanzweifel/git-auto-commit-action@v4
         with:
-          commit_message: 'chore(doc): auto generate docs'
+          commit_message: "chore(doc): auto generate docs"
           commit_user_name: "github-actions[bot]"
           commit_user_email: "github-actions[bot]@users.noreply.github.com"
           commit_author: "github-actions[bot] <github-actions[bot]@users.noreply.github.com>"

ADVANCED.md

@@ -1,5 +1,187 @@
 # Advanced tips
 
+## Special case formatting logic
+
+With the introduction of `vim.system` in neovim 0.10, it is now easy to write custom formatting logic. Let's work through an example of how you could do so.
+
+`prettierd` does not work well with guard because of it's error mechanism. Guard follows a reasonable unix standard when it comes to determining exit status, that is, assuming the program would exit with non-zero exit code and print some reasonable error message in stderr:
+
+```lua
+if exit_code ~= 0 and num_stderr_chunks ~= 0 then
+    -- failed
+else
+    -- success
+end
+```
+
+However, `prettierd` prints error messages to stdout, so guard will fail to detect an error and proceed to replace your code with its error message :cry:
+
+But fear not! You can create your custom logic by passing a function in the config table, let's do this step by step:
+
+```lua
+local function prettierd_fmt(buf, range, acc)
+    local co = assert(coroutine.running())
+end
+```
+
+Guard runs the format function in a coroutine so as not to block the UI, to achieve what we want we have to interact with the current coroutine.
+
+We can now go on to mimic how we would call `prettierd` on the cmdline:
+
+```
+cat test.js | prettierd test.js
+```
+
+```lua
+-- previous code omitted
+local handle = vim.system({ "prettierd", vim.api.nvim_buf_get_name(buf) }, {
+	stdin = true,
+}, function(result)
+	if result.code ~= 0 then
+		-- "returns" the error
+		coroutine.resume(co, result)
+	else
+		-- "returns" the result
+		coroutine.resume(co, result.stdout)
+	end
+end)
+```
+
+We get the unformatted code, then call `vim.system` with 3 arguments
+
+- the cmd, which is of the form `prettierd <file>`
+- the option table, here we only specified that we wish to write to its stdin, but you can refer to `:h vim.system` for more options
+- the `at_exit` function, which takes in a result table (again, check out `:h vim.system` for more details)
+
+Now we can do our custom error handling, here we simply return if `prettierd` failed. But if it succeeded we replace the range with the formatted code and save the file.
+
+Finally we write the unformatted code to stdin
+
+```lua
+-- previous code omitted
+handle:write(acc)
+handle:write(nil)           -- closes stdin
+return coroutine.yield()    -- this returns either the error or the formatted code we returned earlier
+```
+
+Whoa la! Now we can tell guard to register our formatting function
+
+```lua
+ft("javascript"):fmt({
+    fn = prettierd_fmt
+})
+```
+
+[demo](https://github.com/xiaoshihou514/guard.nvim/assets/108414369/56dd35d4-8bf6-445a-adfd-8786fb461021)
+
+You can always refer to [spawn.lua](https://github.com/nvimdev/guard.nvim/blob/main/lua/guard/spawn.lua).
+
+## Custom logic with linters
+
+`clippy-driver` is a linter for rust, because it prints diagnostics to stderr, you cannot just specify it the usual way. But guard allows you to pass a custom function, which would make it work :)
+
+Let's start by doing some imports:
+
+```lua
+local ft = require("guard.filetype")
+local lint = require("guard.lint")
+```
+
+The lint function is a simple modification of the one in [spawn.lua](https://github.com/nvimdev/guard.nvim/blob/main/lua/guard/spawn.lua).
+
+```lua
+local function clippy_driver_lint(acc)
+    local co = assert(coroutine.running())
+    local handle = vim.system({ "clippy-driver", "-", "--error-format=json", "--edition=2021" }, {
+    stdin = true,
+    }, function(result)
+        -- wake coroutine on exit, omit error checking
+        coroutine.resume(co, result.stderr)
+    end)
+    -- write contents to stdin and close it
+    handle:write(acc)
+    handle:write(nil)
+    -- sleep until awakened after process finished
+    return coroutine.yield()
+end
+```
+
+We register it via guard:
+
+```lua
+ft("rust"):lint({
+    fn = clippy_driver_lint,
+    stdin = true,
+    parse = clippy_diagnostic_parse, -- TODO!
+})
+```
+
+To write the lint function, we inspect the output of `clippy-driver` when called with the arguments above:
+
+<details>
+<summary>full output</summary>
+
+```
+❯ cat test.rs
+fn main() {
+    let _ = 'a' .. 'z';
+    if 42 > i32::MAX {}
+}
+❯ cat test.rs | clippy-driver - --error-format=json --edition=2021
+{"$message_type":"diagnostic","message":"almost complete ascii range","code":{"code":"clippy::almost_complete_range","explanation":null},"level":"warning","spans":[{"file_name":"<anon>","byte_start":24,"byte_end":34,"line_start":2,"line_end":2,"column_start":13,"column_end":23,"is_primary":true,"text":[{"text":"    let _ = 'a' .. 'z';","highlight_start":13,"highlight_end":23}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#almost_complete_range","code":null,"level":"help","spans":[],"children":[],"rendered":null},{"message":"`#[warn(clippy::almost_complete_range)]` on by default","code":null,"level":"note","spans":[],"children":[],"rendered":null},{"message":"use an inclusive range","code":null,"level":"help","spans":[{"file_name":"<anon>","byte_start":28,"byte_end":30,"line_start":2,"line_end":2,"column_start":17,"column_end":19,"is_primary":true,"text":[{"text":"    let _ = 'a' .. 'z';","highlight_start":17,"highlight_end":19}],"label":null,"suggested_replacement":"..=","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"warning: almost complete ascii range\n --> <anon>:2:13\n  |\n2 |     let _ = 'a' .. 'z';\n  |             ^^^^--^^^^\n  |                 |\n  |                 help: use an inclusive range: `..=`\n  |\n  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#almost_complete_range\n  = note: `#[warn(clippy::almost_complete_range)]` on by default\n\n"}
+{"$message_type":"diagnostic","message":"this comparison involving the minimum or maximum element for this type contains a case that is always true or always false","code":{"code":"clippy::absurd_extreme_comparisons","explanation":null},"level":"error","spans":[{"file_name":"<anon>","byte_start":43,"byte_end":56,"line_start":3,"line_end":3,"column_start":8,"column_end":21,"is_primary":true,"text":[{"text":"    if 42 > i32::MAX {}","highlight_start":8,"highlight_end":21}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"because `i32::MAX` is the maximum value for this type, this comparison is always false","code":null,"level":"help","spans":[],"children":[],"rendered":null},{"message":"for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#absurd_extreme_comparisons","code":null,"level":"help","spans":[],"children":[],"rendered":null},{"message":"`#[deny(clippy::absurd_extreme_comparisons)]` on by default","code":null,"level":"note","spans":[],"children":[],"rendered":null}],"rendered":"error: this comparison involving the minimum or maximum element for this type contains a case that is always true or always false\n --> <anon>:3:8\n  |\n3 |     if 42 > i32::MAX {}\n  |        ^^^^^^^^^^^^^\n  |\n  = help: because `i32::MAX` is the maximum value for this type, this comparison is always false\n  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#absurd_extreme_comparisons\n  = note: `#[deny(clippy::absurd_extreme_comparisons)]` on by default\n\n"}
+{"$message_type":"diagnostic","message":"aborting due to 1 previous error; 1 warning emitted","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 1 previous error; 1 warning emitted\n\n"}
+```
+
+</details>
+
+That's a lot of output! But we can see three main blocks: the first two diagnostics and the last one an overview. We only need the first two:
+
+```lua
+local clippy_diagnostic_parse =
+	parse = lint.from_json({
+		get_diagnostics = function(line)
+			local json = vim.json.decode(line)
+            -- ignore overview json which does not have position info
+			if not vim.tbl_isempty(json.spans) then
+				return json
+			end
+		end,
+        lines = true,
+		attributes = { ... } -- TODO
+    })
+```
+
+Now our diagnostics are transformed into a list of json, we just need to get the attributes we need: the positions, the message and the error level. That's what the attributes field does, it extracts them from the json table:
+
+```lua
+attributes = {
+    -- it is json turned into a lua table
+    lnum = function(it)
+        -- clippy has really weird indexes
+        return math.ceil(tonumber(it.spans[1].line_start) / 2)
+    end,
+    lnum_end = function(it)
+        return math.ceil(tonumber(it.spans[1].line_end) / 2)
+    end,
+    code = function(it)
+        return it.code.code
+    end,
+    col = function(it)
+        return it.spans[1].column_start
+    end,
+    col_end = function(it)
+        return it.spans[1].column_end
+    end,
+    severity = "level",     -- "it.level"
+    message = "message",    -- "it.message"
+},
+```
+
+Et voilà!
+
+![image](https://github.com/xiaoshihou514/guard.nvim/assets/108414369/f9137b5a-ae69-494f-9f5b-b6044ae63c86)
+
 ## Take advantage of autocmd events
 
 Guard exposes a `GuardFmt` user event that you can use. It is called both before formatting starts and after it is completely done. To differentiate between pre-format and post-format calls, a `data` table is passed.
@@ -8,17 +190,16 @@ Guard exposes a `GuardFmt` user event that you can use. It is called both before
 -- for pre-format calls
 data = {
     status = "pending", -- type: string, called whenever a format is requested
-    using = {...}       -- type: table, whatever formatters you are using for this format action
+    using = {...}       -- type: table, formatters that are going to run
 }
 -- for post-format calls
 data = {
     status = "done",    -- type: string, only called on success
-    results = {...}     -- type: table, formatted buffer text as a list of lines
 }
 -- or
 data = {
     status = "failed"   -- type: string, buffer remain unchanged
-    msg = "..."         -- type: string, currently only if buffer became invalid or changed during formatting
+    msg = "..."         -- type: string, reason for failure
 }
 ```
 
@@ -50,4 +231,6 @@ vim.api.nvim_create_autocmd("User", {
 })
 ```
 
+[demo](https://github.com/xiaoshihou514/guard.nvim/assets/108414369/339ff4ff-288c-49e4-8ab1-789a6175d201)
+
 You can do the similar for your statusline plugin of choice as long as you "refresh" it on `GuardFmt`.

README.md

@@ -1,6 +1,6 @@
 # guard.nvim
 
-Async formatting and linting utility for neovim.
+Async formatting and linting utility for neovim `0.10+`.
 
 ## Features
 
@@ -88,19 +88,26 @@ Easily setup your custom tool if not in the defaults or you do not want guard-co
 
 ```
 {
+    -- specify an executable
     cmd              -- string: tool command
     args             -- table: command arguments
     fname            -- boolean: insert filename to args tail
     stdin            -- boolean: pass buffer contents into stdin
-    timeout          -- integer
+
+    -- or provide your own logic
+    fn               -- function: write your own logic for formatting / linting, more in ADVANCED.md
+
+    -- running condition
     ignore_patterns  -- table: don't run formatter when pattern match against file name
     ignore_error     -- boolean: when has lsp error ignore format
     find             -- string: format if the file is found in the lsp root dir
+
+    -- misc
     env              -- table: environment variables passed to cmd (key value pair)
+    timeout          -- integer
 
     -- special
-    parse            -- function: used to parse linter output to neovim diagnostic
-    fn               -- function: if fn is set other fields will not take effect
+    parse            -- function: linter only, parses linter output to neovim diagnostic
 }
 ```
 
@@ -115,6 +122,14 @@ ft('asm'):fmt({
 
 Consult the [builtin tools](https://github.com/nvimdev/guard-collection/tree/main/lua/guard-collection) if needed.
 
+### Advanced configuration
+
+[ADVANCED.md](https://github.com/nvimdev/guard.nvim/blob/main/ADVANCED.md) contains tiny tutorials to:
+
+- Write your own formatting logic using the fn field
+- Write your own linting logic using the fn field
+- leverage guard's autocmds, say showing formatting status?
+
 ### Supported Tools
 
 See [here](https://github.com/nvimdev/guard-collection) for an exhaustive list.

doc/guard.nvim.txt

@@ -1,4 +1,4 @@
-*guard.nvim.txt*           For NVIM v0.8.0           Last change: 2024 June 05
+*guard.nvim.txt*           For NVIM v0.8.0           Last change: 2024 June 06
 
 ==============================================================================
 Table of Contents                               *guard.nvim-table-of-contents*