apple-swift-format: linter and fixer with config swiftpm support (#3671)

autoload/ale/fix/registry.vim

@@ -191,6 +191,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['swift'],
 \       'description': 'Apply SwiftFormat to a file.',
 \   },
+\   'apple-swift-format': {
+\       'function': 'ale#fixers#appleswiftformat#Fix',
+\       'suggested_filetypes': ['swift'],
+\       'description': 'Apply apple/swift-format to a file.',
+\   },
 \   'phpcbf': {
 \       'function': 'ale#fixers#phpcbf#Fix',
 \       'suggested_filetypes': ['php'],

autoload/ale/fixers/appleswiftformat.vim

@@ -0,0 +1,16 @@
+" Author: (bosr) <bosr@bosr.cc>
+" Description: Integration of apple/swift-format formatter with ALE.
+
+function! ale#fixers#appleswiftformat#Fix(buffer) abort
+    let l:command_args = ale#swift#GetAppleSwiftFormatCommand(a:buffer) . ' format --in-place %t'
+    let l:config_args = ale#swift#GetAppleSwiftFormatConfigArgs(a:buffer)
+
+    if l:config_args isnot# ''
+        let l:command_args = l:command_args . ' ' . l:config_args
+    endif
+
+    return {
+    \   'read_temporary_file': 1,
+    \   'command': l:command_args,
+    \}
+endfunction

autoload/ale/swift.vim

@@ -11,3 +11,60 @@ function! ale#swift#FindProjectRoot(buffer) abort
 
     return ''
 endfunction
+
+" Support Apple Swift Format {{{1
+
+call ale#Set('swift_appleswiftformat_executable', 'swift-format')
+call ale#Set('swift_appleswiftformat_use_swiftpm', 0)
+
+" Return the executable depending on whether or not to use Swift Package Manager.
+"
+" If not asked to use Swift Package Manager (use_swiftpm = 0), the returned
+" value is the global executable, else the returned value is 'swift' because
+" the final command line will be `swift run swift-format ...`.
+"
+" Failure is expected if use_swiftpm is `1` but no Package.swift can be located.
+function! ale#swift#GetAppleSwiftFormatExecutable(buffer) abort
+    if !ale#Var(a:buffer, 'swift_appleswiftformat_use_swiftpm')
+        return ale#Var(a:buffer, 'swift_appleswiftformat_executable')
+    endif
+
+    if ale#path#FindNearestFile(a:buffer, 'Package.swift') is# ''
+        " If there is no Package.swift file, we don't use swift-format even if it exists,
+        " so we return '' to indicate failure.
+        return ''
+    endif
+
+    return 'swift'
+endfunction
+
+" Return the command depending on whether or not to use Swift Package Manager.
+"
+" If asked to use Swift Package Manager (use_swiftpm = 1), the command
+" arguments are prefixed with 'swift run'.
+"
+" In either case, the configuration file is located and added to the command.
+function! ale#swift#GetAppleSwiftFormatCommand(buffer) abort
+    let l:executable = ale#swift#GetAppleSwiftFormatExecutable(a:buffer)
+    let l:command_args = ''
+
+    if ale#Var(a:buffer, 'swift_appleswiftformat_use_swiftpm')
+        let l:command_args = ' ' . 'run swift-format'
+    endif
+
+    return ale#Escape(l:executable) . l:command_args
+endfunction
+
+" Locate the nearest '.swift-format' configuration file, and return the
+" arguments, else return an empty string.
+function! ale#swift#GetAppleSwiftFormatConfigArgs(buffer) abort
+    let l:config_filepath = ale#path#FindNearestFile(a:buffer, '.swift-format')
+
+    if l:config_filepath isnot# ''
+        return '--configuration' . ' ' . l:config_filepath
+    endif
+
+    return ''
+endfunction
+
+" }}}