feat(prettier): use npx for project-local prettier

If npx is available, use it in preference to calling prettier directly.
This enables project-local prettier, which is important for teams to use
matching versions.

This doesn't change anything for non-project prettier installs, because
npx will fall back to global prettier.

Since the existence of npx doesn't actually imply the existence of
prettier, we have to call it once to find out if it's usable. Since this
is expensive (compared to not calling it, anyway), cache the result as
s:prettier_is_available and invalidate if prettier_executable changes.

Author: agriffis

autoload/codefmt/prettier.vim

@@ -20,6 +20,14 @@ let s:supported_filetypes = ['javascript', 'markdown', 'html', 'css', 'yaml',
       \ 'jsx', 'less', 'scss', 'mdx', 'vue']
 
 
+""
+" @private
+" Invalidates the cached prettier availability detection.
+function! codefmt#prettier#InvalidateIsAvailable() abort
+  unlet! s:prettier_is_available
+endfunction
+
+
 ""
 " @private
 " Formatter: prettier
@@ -30,9 +38,21 @@ function! codefmt#prettier#GetFormatter() abort
           \ 'and configure the prettier_executable flag'}
 
   function l:formatter.IsAvailable() abort
-    let l:cmd = codefmt#formatterhelpers#ResolveFlagToArray(
-          \ 'prettier_executable')
-    return !empty(l:cmd) && executable(l:cmd[0])
+    if !exists('s:prettier_is_available')
+      let s:prettier_is_available = 0
+      let l:cmd = codefmt#formatterhelpers#ResolveFlagToArray(
+            \ 'prettier_executable')
+      if !empty(l:cmd) && executable(l:cmd[0])
+        " Unfortunately the availability of npx isn't enough to tell whether
+        " prettier is available, and npx doesn't have a way of telling us.
+        " Fetching the prettier version should suffice.
+        let l:result = maktaba#syscall#Create(l:cmd + ['--version']).Call(0)
+        if v:shell_error == 0
+          let s:prettier_is_available = 1
+        endif
+      endif
+    endif
+    return s:prettier_is_available
   endfunction
 
   function l:formatter.AppliesToBuffer() abort
@@ -52,7 +72,7 @@ function! codefmt#prettier#GetFormatter() abort
     if @% == ""
       call extend(l:cmd, ['--parser', 'babylon'])
     else
-      call extend(l:cmd, ['--stdin-filepath', @%])
+      call extend(l:cmd, ['--stdin-filepath', expand('%:p')])
     endif
 
     call maktaba#ensure#IsNumber(a:startline)
@@ -71,7 +91,13 @@ function! codefmt#prettier#GetFormatter() abort
           \ 'prettier_options'))
 
     try
-      let l:result = maktaba#syscall#Create(l:cmd).WithStdin(l:input).Call()
+      let l:syscall = maktaba#syscall#Create(l:cmd).WithStdin(l:input)
+      if isdirectory(expand('%:p:h'))
+        " Change to the containing directory so that npx will find
+        " a project-local prettier in node_modules
+        let l:syscall = l:syscall.WithCwd(expand('%:p:h'))
+      endif
+      let l:result = l:syscall.Call()
       let l:formatted = split(l:result.stdout, "\n")
       call maktaba#buffer#Overwrite(1, line('$'), l:formatted)
     catch /ERROR(ShellError):/

instant/flags.vim

@@ -114,8 +114,21 @@ call s:plugin.Flag('shfmt_executable', 'shfmt')
 call s:plugin.Flag('prettier_options', [])
 
 ""
-" The path to the prettier executable.
-call s:plugin.Flag('prettier_executable', 'prettier')
+" @private
+function s:PrettierExecutable() abort
+  return executable('npx') ? ['npx', '--no-install', 'prettier'] : 'prettier'
+endfunction
+
+""
+" The path to the prettier executable. String, list, or callable that
+" takes no args and returns a string or a list. The default uses npx if
+" available, so that the repository-local prettier will have priority.
+call s:plugin.Flag('prettier_executable', function('s:PrettierExecutable'))
+
+" Invalidate cache of detected prettier availability whenever
+" prettier_executable changes.
+call s:plugin.flags.prettier_executable.AddCallback(
+    \ maktaba#function#FromExpr('codefmt#prettier#InvalidateIsAvailable()'), 0)
 
 ""
 " Command line arguments to feed rustfmt. Either a list or callable that

vroom/prettier.vroom

@@ -14,12 +14,17 @@ examples.
 
   :call codefmt#SetWhetherToPerformIsAvailableChecksForTesting(0)
 
+The default value of prettier_executable is a function that checks if npx is
+available. We need a deterministic result for these tests, so we'll replace that
+with a simple string.
+
+  :Glaive codefmt prettier_executable='prettier'
 
 The prettier formatter expects the prettier executable to be installed on your system.
 
   % function HelloWorld(){if(!greeting){return null};}
   :FormatCode prettier
-  ! prettier .*
+  ! cd .* prettier .*
   $ function HelloWorld() {
   $   if (!greeting) {
   $     return null;
@@ -31,7 +36,7 @@ prettier_executable flag if the default of "prettier" doesn't work.
 
   :Glaive codefmt prettier_executable='myprettier'
   :FormatCode prettier
-  ! myprettier .*
+  ! cd .* myprettier .*
   $ function HelloWorld() {
   $   if (!greeting) {
   $     return null;
@@ -46,7 +51,7 @@ You can format any buffer with prettier specifying the formatter explicitly.
   % function HelloWorld(){if(!greeting){return null};}
 
   :FormatCode prettier
-  ! prettier .*2>.*
+  ! cd .* prettier .*2>.*
   $ function HelloWorld() {
   $   if (!greeting) {
   $     return null;
@@ -65,7 +70,7 @@ Errors are reported using the quickfix list.
   % function foo() {
 
   :FormatCode prettier
-  ! prettier .*2> (.*)
+  ! cd .* prettier .*2> (.*)
   $ 2 (status)
   $ echo >\1 ' (command)
   |[error] stdin: SyntaxError: Unexpected token (2:1)\n
@@ -87,7 +92,7 @@ It can format specific line ranges of code using :FormatLines.
   |function Greet(){if(!greeting){return null};}
 
   :1,1FormatLines prettier
-  ! prettier .*--parser babylon --range-end 50.*2>.*
+  ! cd .* prettier .*--parser babylon --range-end 50.*2>.*
   $ function HelloWorld() {
   $   if (!greeting) {
   $     return null;