support check formatting

Author: tsnobip

scripts/rescript_format.js

@@ -5,8 +5,11 @@ var format_usage = `Usage: rescript format <options> [files]
 \`rescript format\` formats the current directory
 `;
 var child_process = require("child_process");
+var util = require("node:util");
+var asyncExecFile = util.promisify(child_process.execFile);
 var path = require("path");
 var fs = require("fs");
+var asyncFs = fs.promises;
 /**
  * @type {arg.stringref}
  */
@@ -17,6 +20,11 @@ var stdin = { val: undefined };
  */
 var format = { val: undefined };
 
+/**
+ * @type {arg.boolref}
+ */
+ var check = { val: undefined };
+
 /**
  * @type{arg.specs}
  */
@@ -27,12 +35,16 @@ var specs = [
     `[.res|.resi|.ml|.mli] Read the code from stdin and print
 the formatted code to stdout in ReScript syntax`,
   ],
-  //  ml|mli
   [
     "-all",
     { kind: "Unit", data: { kind: "Unit_set", data: format } },
     "Format the whole project ",
   ],
+  [
+    "-check",
+    { kind: "Unit", data: { kind: "Unit_set", data: check } },
+    "Check formatting only",
+  ],
 ];
 var formattedStdExtensions = [".res", ".resi", ".ml", ".mli"];
 var formattedFileExtensions = [".res", ".resi"];
@@ -55,12 +67,33 @@ async function readStdin() {
   return Buffer.concat(chunks).toString("utf8");
 }
 
+/**
+ * 
+ * @param {string} file 
+ * @returns void
+ */
+function printIncorrectlyFormattedFile(file) {
+  console.error("[format check]", file);
+}
+
+/**
+* 
+* @param {number} incorrectlyFormattedFiles 
+* @returns void
+*/
+function printFormatCheckResult(incorrectlyFormattedFiles) {
+  if (incorrectlyFormattedFiles > 0){
+    console.error(`${incorrectlyFormattedFiles} file${incorrectlyFormattedFiles > 1 ? "s":""} listed above need${incorrectlyFormattedFiles > 1 ? "": "s"} formatting.`);
+    process.exit(3);
+  }
+  }
+
 /**
  * @param {string[]} argv
  * @param {string} rescript_exe
  * @param {string} bsc_exe
  */
-function main(argv, rescript_exe, bsc_exe) {
+async function main(argv, rescript_exe, bsc_exe) {
   var isSupportedFile = hasExtension(formattedFileExtensions);
   var isSupportedStd = hasExtension(formattedStdExtensions);
 
@@ -95,26 +128,33 @@ function main(argv, rescript_exe, bsc_exe) {
         process.exit(2);
       }
       files = output.stdout.split("\n").map(x => x.trim());
-      var hasError = false;
-      for (let arg of files) {
-        if (isSupportedFile(arg)) {
-          // console.log(`processing ${arg}`);
-          child_process.execFile(
-            bsc_exe,
-            ["-o", arg, "-format", arg],
-            (error, _stdout, stderr) => {
-              if (error !== null) {
-                console.error(stderr);
-                hasError = true;
+      var incorrectlyFormattedFiles = 0;
+      try {
+        const _promises = await Promise.all(files.map(async (file) => {
+          if (isSupportedFile(file)) {
+            // console.log(`processing ${arg}`);
+            const flags = check.val ? ["-format", file] : ["-o", file, "-format", file];
+            const {stdout} = await asyncExecFile(bsc_exe,flags);
+            if (check.val){
+              const original = await asyncFs.readFile(file, 'utf-8');
+              if (original != stdout){
+                printIncorrectlyFormattedFile(file);
+                incorrectlyFormattedFiles++;
               }
             }
-          );
-        }
-      }
-      if (hasError) {
+          }
+          return null;
+        }));
+      } catch (err) {
+        console.error(err);
         process.exit(2);
       }
+      printFormatCheckResult(incorrectlyFormattedFiles);
     } else if (use_stdin) {
+      if (check.val){
+        console.error("format -stdin cannot be used with -check flag");
+        process.exit(2);
+      }
       if (isSupportedStd(use_stdin)) {
         var crypto = require("crypto");
         var os = require("os");
@@ -144,7 +184,7 @@ function main(argv, rescript_exe, bsc_exe) {
           );
         })();
       } else {
-        console.error(`Unsupported exetnsion ${use_stdin}`);
+        console.error(`Unsupported extension ${use_stdin}`);
         console.error(`Supported extensions: ${formattedStdExtensions} `);
         process.exit(2);
       }
@@ -164,20 +204,34 @@ function main(argv, rescript_exe, bsc_exe) {
         }
       }
       var hasError = false;
+      var incorrectlyFormattedFiles = 0;
       files.forEach(file => {
-        var write = isSupportedFile(file);
+        var write = isSupportedFile(file) && !check.val;
         var flags = write ? ["-o", file, "-format", file] : ["-format", file];
-        child_process.execFile(bsc_exe, flags, (error, stdout, stderr) => {
-          if (error === null) {
-            if (!write) {
-              process.stdout.write(stdout);
+        try {
+          const formatted = child_process.execFileSync(bsc_exe, flags);
+          if (!write) {
+            if (check.val) {
+              try {
+                const original = fs.readFileSync(file, 'utf-8');
+                if (original != formatted){
+                  printIncorrectlyFormattedFile(file);
+                  incorrectlyFormattedFiles++;
+                }
+              } catch (err){
+                console.error(err);
+                hasError = true;
+              }
+            } else {
+              process.stdout.write(formatted);
             }
-          } else {
-            console.error(stderr);
-            hasError = true;
           }
-        });
+        } catch (err) {
+          console.error(err);
+          hasError = true;
+        }
       });
+      printFormatCheckResult(incorrectlyFormattedFiles);
       if (hasError) {
         process.exit(2);
       }