feat: callback on file (#48)

Co-authored-by: XhmikosR <xhmikosr@gmail.com>

Author: AndersDJohnson

README.md

@@ -28,6 +28,8 @@ const dependencies = detective(mySourceCode);
 - `mixedImports`: (default: `false`) Include CJS imports in dependency list
 - `skipAsyncImports`: (default: `false`) Whether or not to omit async imports (import('foo'))
 - `jsx`: (default: `false`) Enable parsing of JSX
+- `onFile`: A callback that will be called before the file is processed. Intended for use with [`dependency-tree`](https://github.com/dependents/node-dependency-tree). Passed an object argument with properties `options` (echoing any options passed in, e.g., by [`precinct`](https://github.com/dependents/node-precinct)), `src` (source code for file as string), `ast` (parsed AST object for the file source), and `walker` (a `Walker` instance from [`source-walk`](https://github.com/dependents/node-source-walk) configured for TypeScript to which you can pass the `ast` or `src`).
+- `onAfterFile`: Similar to `onFile`, but the callback is also passed an object property `dependencies`, a string array with the extracted dependencies.
 
 ## License
 

index.js

@@ -29,6 +29,14 @@ module.exports = (src, options = {}) => {
   const walker = new Walker(walkerOptions);
   const dependencies = [];
 
+  // Pre-parse the source to get the AST to pass to `onFile`,
+  // then reuse that AST below in our walker walk.
+  const ast = typeof src === 'string' ? walker.parse(src) : src;
+
+  if (options.onFile) {
+    options.onFile({ options, src, ast, walker });
+  }
+
   walker.walk(src, node => {
     switch (node.type) {
       case 'ImportExpression': {
@@ -100,6 +108,10 @@ module.exports = (src, options = {}) => {
     }
   });
 
+  if (options.onAfterFile) {
+    options.onAfterFile({ options, src, ast, walker, dependencies });
+  }
+
   return dependencies;
 };
 

test/test.js

@@ -37,6 +37,47 @@ describe('detective-typescript', () => {
     assert.equal(deps[0], 'mylib');
   });
 
+  it('calls onFile callback', () => {
+    let onFileCalledArgs;
+    const onFile = (...args) => {
+      onFileCalledArgs = args;
+    };
+
+    const src = 'import {foo, bar} from "mylib";';
+
+    detective(src, { onFile });
+
+    assert.ok(onFileCalledArgs);
+    assert.ok(onFileCalledArgs[0]);
+    assert.equal(onFileCalledArgs[0].src, src);
+    assert.ok(typeof onFileCalledArgs[0].ast === 'object');
+    assert.ok(typeof onFileCalledArgs[0].walker === 'object');
+
+    assert.ok(typeof onFileCalledArgs[0].options === 'object');
+    assert.equal(onFileCalledArgs[0].options.onFile, onFile);
+  });
+
+  it('calls onAfterFile callback', () => {
+    let onAfterFileCalledArgs;
+    const onAfterFile = (...args) => {
+      onAfterFileCalledArgs = args;
+    };
+
+    const src = 'import {foo, bar} from "mylib";';
+
+    detective(src, { onAfterFile });
+
+    assert.ok(onAfterFileCalledArgs);
+    assert.ok(onAfterFileCalledArgs[0]);
+    assert.equal(onAfterFileCalledArgs[0].src, src);
+    assert.ok(typeof onAfterFileCalledArgs[0].ast === 'object');
+    assert.ok(typeof onAfterFileCalledArgs[0].walker === 'object');
+    assert.ok(Array.isArray(onAfterFileCalledArgs[0].dependencies));
+
+    assert.ok(typeof onAfterFileCalledArgs[0].options === 'object');
+    assert.equal(onAfterFileCalledArgs[0].options.onAfterFile, onAfterFile);
+  });
+
   it('retrieves the re-export dependencies of modules', () => {
     const deps = detective('export {foo, bar} from "mylib";');
     assert.equal(deps.length, 1);