Transpilation Optimization

eo2js/src/commands/transpile.js

@@ -56,43 +56,57 @@ const hasMeta = function(xmir, name) {
   return res
 }
 
+/**
+ * Check if source needs to be retranspiled by comparing modification times.
+ * @param {String} source - Source file path
+ * @param {String} transpiled - Transpiled file path
+ * @return {boolean} - True if source needs to be retranspiled
+ */
+const needsRetranspile = function(source, transpiled) {
+  return !fs.existsSync(transpiled) || fs.statSync(source).mtime > fs.statSync(transpiled).mtime
+}
+
 /**
  * Transform XMIR from given tojo and save.
  * @param {Object} tojo - Tojo.
- * @param {{target: String, project: String}} options - Program options
+ * @param {{target: String, project: String, verbose: boolean}} options - Program options
  * @param {Array.<String>} transformations - List of transformations to apply to XMIR
  * @param {any} parser - XML parser
  */
 const transform = function(tojo, options, transformations, parser) {
   const text = fs.readFileSync(tojo[verified]).toString()
   let xml = parser.parse(text)
   const pth = pathFromName(xml['program']['@_name'])
-  const transpiled = path.resolve(options.target, dir, `${pth}.xmir`)
-  makeDirIfNotExist(transpiled.substring(0, transpiled.lastIndexOf(path.sep)))
-  fs.writeFileSync(transpiled, text)
-  xml = text
-  transformations.forEach((transformation) => {
-    xml = saxon.transform({
-      stylesheetFileName: transformation,
-      sourceText: xml,
-      destination: 'serialized'
-    }).principalResult
-  })
-  fs.writeFileSync(transpiled, xml)
-  xml = parser.parse(xml)
-  let objects = xml.program.objects.object
-  if (!Array.isArray(objects)) {
-    objects = [objects]
-  }
-  const filtered = objects.filter((obj) => !!obj && obj.hasOwnProperty('javascript') && !obj.hasOwnProperty('@_atom'))
   const isTest = hasMeta(xml, 'tests')
-  const count = isTest ? 0 : 1
-  if (filtered.length > count) {
-    const first = filtered[0]
-    const dest = path.resolve(options.project, `${pth}${isTest ? '.test' : ''}.js`)
-    makeDirIfNotExist(dest.substring(0, dest.lastIndexOf(path.sep)))
-    fs.writeFileSync(dest, first['javascript'])
-    filtered.slice(1).forEach((obj) => fs.appendFileSync(dest, `\n${obj['javascript']}`))
+  const transpiled = path.resolve(options.target, dir, `${pth}.xmir`)
+  const dest = path.resolve(options.project, `${pth}${isTest ? '.test' : ''}.js`)
+  if (needsRetranspile(tojo[verified], transpiled)) {
+    makeDirIfNotExist(transpiled.substring(0, transpiled.lastIndexOf(path.sep)))
+    fs.writeFileSync(transpiled, text)
+    xml = text
+    transformations.forEach((transformation) => {
+      xml = saxon.transform({
+        stylesheetFileName: transformation,
+        sourceText: xml,
+        destination: 'serialized'
+      }).principalResult
+    })
+    fs.writeFileSync(transpiled, xml)
+    xml = parser.parse(xml)
+    let objects = xml.program.objects.object
+    if (!Array.isArray(objects)) {
+      objects = [objects]
+    }
+    const filtered = objects.filter((obj) => !!obj && obj.hasOwnProperty('javascript') && !obj.hasOwnProperty('@_atom'))
+    const count = isTest ? 0 : 1
+    if (filtered.length > count) {
+      const first = filtered[0]
+      makeDirIfNotExist(dest.substring(0, dest.lastIndexOf(path.sep)))
+      fs.writeFileSync(dest, first['javascript'])
+      filtered.slice(1).forEach((obj) => fs.appendFileSync(dest, `\n${obj['javascript']}`))
+    }
+  } else if (options.verbose) {
+    console.log(`Skipping ${pth} - already transpiled`)
   }
 }
 
@@ -119,7 +133,7 @@ const transpile = function(options) {
     .filter((tojo) => tojo.hasOwnProperty(verified))
     .forEach((tojo) => transform(
       tojo,
-      {target: options['target'], project},
+      {target: options['target'], project, verbose: options.verbose},
       transformations,
       parser
     ))

eo2js/test/commands/transpile.test.js

@@ -26,6 +26,7 @@ describe('transpile', function() {
     beforeEach(function() {
       fs.rmSync(target, {recursive: true, force: true})
       fs.mkdirSync(target)
+      prepare()
     })
     it('should fail if eo-foreign is not found', function() {
       assert.throws(() => runSync(['transpile', '-t', target], false))
@@ -36,11 +37,11 @@ describe('transpile', function() {
       assert.throws(() => runSync(['transpile', '-t', target, '-f', foreign], false))
     })
     /**
-     * Call transpile command.
-     * @param {String} name - Name of the object to transpile
-     * @return {String} - Stdout
+     * Prepare files for transpilation.
+     * Creates eo-foreign.json file and copies XMIR file from test resources.
+     * @param {String} name - Name of the object to transpile, defaults to 'simple'
      */
-    const transpile = function(name = 'simple') {
+    const prepare = function(name = 'simple') {
       const verified = path.resolve(target, `6-verify/com/eo2js/${name}.xmir`)
       const foreign = [{
         id: `com.eo2js.${name}`,
@@ -49,6 +50,13 @@ describe('transpile', function() {
       fs.writeFileSync(path.resolve(target, 'eo-foreign.json'), JSON.stringify(foreign))
       fs.mkdirSync(path.resolve(target, '6-verify/com/eo2js'), {recursive: true})
       fs.copyFileSync(path.resolve(`test/resources/transpile/${name}.xmir`), verified)
+    }
+    /**
+     * Run transpile command with verbose output.
+     * @param {String} name - Name of the object to transpile
+     * @return {String} - Command stdout
+     */
+    const transpile = function() {
       return runSync([
         'transpile',
         '--verbose',
@@ -65,9 +73,28 @@ describe('transpile', function() {
     });
     ['simple-test', 'alone-test'].forEach((name) => {
       it(`should generate test JS file for ${name}`, function() {
-        assertFilesExist(transpile(name), target, [`project/com/eo2js/${name}.test.js`])
+        prepare(name)
+        assertFilesExist(transpile(), target, [`project/com/eo2js/${name}.test.js`])
       })
     })
+    it('should skip transpilation if source was not modified', function() {
+      transpile()
+      const transpiled = path.resolve(target, '8-transpile/com/eo2js/simple.xmir')
+      const first = fs.statSync(transpiled).mtime
+      transpile()
+      const second = fs.statSync(transpiled).mtime
+      assert.equal(first.getTime(), second.getTime())
+    })
+    it('should retranspile if source was modified', async function() {
+      const transpiled = path.resolve(target, '8-transpile/com/eo2js/simple.xmir')
+      const source = path.resolve(target, '6-verify/com/eo2js/simple.xmir')
+      transpile()
+      const first = fs.statSync(transpiled).mtime
+      fs.writeFileSync(source, fs.readFileSync(source))
+      transpile()
+      const second = fs.statSync(transpiled).mtime
+      assert.notEqual(first.getTime(), second.getTime())
+    })
   })
   describe('transformation packs', function() {
     this.timeout(0)