Added enhancement for watch mode callbacks

README.md

@@ -16,6 +16,11 @@ anything similar to this making hard knowing what happens under the hood. In
 this package you will be able to understand what is happening on the
 enhancements just by reading their source files.
 
+> The earliest version of Typescript supported by this package is actually v2.8.0 because
+Typescript Enhaced uses the internal mechanism of `tsc` watch mode. Maybe, if demanded,
+in a future release this could be upgraded.
+
+
 ### Usage
 ```bash
 npm i --save-dev typescript typescript-enhanced
@@ -73,3 +78,30 @@ To enable this enhacement just add to your `tsconfig.json` the following line.
 
 This is applied as the last before transformation of the chain so you can
 modify its behaviour by using any before transformer if you want.
+
+#### On Fail/Success Commands for watch mode
+Sometimes do you want to do anything on watch mode states like starting a
+server or execute a post-process. This is actually imposible with the `tsc`
+command but `tsce` is able to manage this situation.
+
+To enable this enhacement just add to your `tsconfig.json` the following line.
+```json5
+{
+  // ...
+  "compilerOptions": {
+      // ...
+      "onWatchFail": "<My command>",
+      "onWatchSuccess": "<My command>"
+      // ...
+  }
+  // ...
+}
+```
+
+or just by adding the following parameters to the `tsce` command call
+
+```bash
+tsce --watch --onWatchFail <My command> --onWatchSuccess <My command>
+```
+### Contribution
+Any contribution to upgrade this package is actually welcome :)

package.json

@@ -13,6 +13,6 @@
     "typescript": "^3.4.1"
   },
   "peerDependencies": {
-    "typescript": ">= 2.3.0"
+    "typescript": ">= 2.8.0"
   }
 }

samples/call-program-on-watch-success/src/main.ts

@@ -0,0 +1 @@
+console.log('This will be printed on build');

samples/call-program-on-watch-success/tsconfig.json

@@ -0,0 +1,22 @@
+{
+    "extends": "../_common_/tsconfig",
+
+    "compilerOptions": {
+        "outDir": "./dist",                       /* Redirect output structure to the directory. */
+        "rootDirs": [
+            "./src"
+        ],
+
+        /* Module Resolution Options */
+        "baseUrl": "./src",                       /* Base directory to resolve non-absolute module names. */
+        "paths": {                                /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+            "@module/*": ["./module/*"]
+        },
+
+        /* Enhanced Options */
+        "onWatchSuccess": "node ./dist/main"
+    },
+    "include": [
+        "./src"
+    ]
+}

src/enhancements/enable-custom-transformers.js

@@ -83,8 +83,7 @@ module.exports = function (ts) {
         return Array.isArray(transformerModules)
             ? transformerModules
                 .map(({module, options}) => {
-                    // TODO: Handle error
-                    // TODO: Put an actual transformer
+                    // TODO: Handle errors
                     return require(module.startsWith('./') || module.startsWith('../') || module.startsWith('/')
                         ? configPath + '/' + module
                         : module)(options);

src/enhancements/enable-watch-mode-callbacks.js

@@ -0,0 +1,93 @@
+/**
+ * This file is part of the typescript-enhanced package.
+ *
+ * (c) Pedro Pérez Furio <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE.md
+ * file that was distributed with this source code.
+ */
+const { spawnSync } = require('child_process');
+const { dirname, resolve } = require('path');
+
+/**
+ * Enables the "onWatchSuccess" and "onWatchFail" properties on the tsconfig.json. It requires the version 2.8.0 of
+ * typescript package because before that version, the "createWatchProgram" don't exists.
+ *
+ * @param ts
+ */
+module.exports = function (ts) {
+    // Creates a message for the tsce --init command
+    ts.Diagnostics.On_Watch_Success_Description = ts.diag(100004,
+        ts.DiagnosticCategory.Message, "On_Watch_Success_Description_100004",
+        "Command that will be called on watch when the compilation process ends succesfully.");
+
+    ts.Diagnostics.On_Watch_Fail_Description = ts.diag(100006,
+        ts.DiagnosticCategory.Message, "On_Watch_Fail_Description_100006",
+        "Command that will be called on watch when the compilation process fails.");
+
+    // Adds an option to tsconfig.json to enable this enhacement
+    ts.optionDeclarations = ts.optionDeclarations.concat([
+        {
+            name: "onWatchSuccess",
+            type: "string",
+            category: ts.Diagnostics.Enhancement_Options,
+            description: ts.Diagnostics.On_Watch_Success_Description
+        },
+        {
+            name: "onWatchFail",
+            type: "string",
+            category: ts.Diagnostics.Enhancement_Options,
+            description: ts.Diagnostics.On_Watch_Fail_Description
+        }
+    ]);
+
+    // Config path
+    const { options: { project } } = ts.parseCommandLine(ts.sys.args);
+    const configPath = dirname(resolve(ts.normalizePath(project || ts.sys.getCurrentDirectory())));
+
+    // Hook on createProgram
+    const createWatchProgram = ts.createWatchProgram;
+    ts.createWatchProgram = function (...args) {
+        let hadProgram = false, hadErrors = false, watchProcessed = false, compilerOptions = false;
+
+        const [host] = args;
+        const afterProgramCreate = host.afterProgramCreate;
+        const onWatchStatusChange = host.onWatchStatusChange;
+
+        host.afterProgramCreate = function (...args) {
+            const [builderProgram] = args;
+            const program = builderProgram.getProgramOrUndefined();
+
+            hadProgram = !!program;
+            hadErrors = program && !ts.getPreEmitDiagnostics(program).length;
+            watchProcessed = false;
+            compilerOptions = program.getCompilerOptions();
+
+            return afterProgramCreate(...args);
+        };
+
+        host.onWatchStatusChange = function (...args) {
+            const result = onWatchStatusChange(...args);
+
+            if (!watchProcessed && hadProgram) {
+                watchProcessed = true;
+
+                const { onWatchSuccess, onWatchFail } = compilerOptions;
+
+                if (onWatchSuccess && hadErrors) {
+                    const [ onWatchSuccessCommand, ...onWatchSuccessArgs] = onWatchSuccess.split(' ');
+                    spawnSync(onWatchSuccessCommand, onWatchSuccessArgs, { cwd: configPath, stdio: 'inherit' });
+                }
+
+                if (onWatchFail && !hadErrors) {
+                    const [ onWatchFailCommand, ...onWatchFailArgs] = onWatchFail.split(' ');
+                    spawnSync(onWatchFailCommand, onWatchFailArgs, { cwd: configPath, stdio: 'inherit' });
+                }
+            }
+
+            return result;
+        };
+
+        return createWatchProgram(...args);
+    };
+};

src/tsce.js

@@ -15,5 +15,6 @@ const ts = require('typescript/lib/tsc');
 require('./enhancements/enable-enhancements-diagnostic-messages')(ts);
 require('./enhancements/enable-resolve-aliased-modules')(ts);
 require('./enhancements/enable-custom-transformers')(ts);
+require('./enhancements/enable-watch-mode-callbacks')(ts);
 
 module.exports = ts;