Import existing sourcemaps from libraries

src/assets/JSAsset.js

@@ -13,13 +13,18 @@ const generate = require('babel-generator').default;
 const terser = require('../transforms/terser');
 const SourceMap = require('../SourceMap');
 const hoist = require('../scope-hoisting/hoist');
+const path = require('path');
+const fs = require('../utils/fs');
+const logger = require('../Logger');
 
 const IMPORT_RE = /\b(?:import\b|export\b|require\s*\()/;
 const ENV_RE = /\b(?:process\.env)\b/;
 const GLOBAL_RE = /\b(?:process|__dirname|__filename|global|Buffer|define)\b/;
 const FS_RE = /\breadFileSync\b/;
 const SW_RE = /\bnavigator\s*\.\s*serviceWorker\s*\.\s*register\s*\(/;
 const WORKER_RE = /\bnew\s*Worker\s*\(/;
+const SOURCEMAP_RE = /\/\/\s*[@#]\s*sourceMappingURL\s*=\s*([^\s]+)/;
+const DATA_URL_RE = /^data:[^;]+(?:;charset=[^;]+)?;base64,(.*)/;
 
 class JSAsset extends Asset {
   constructor(name, options) {
@@ -104,7 +109,74 @@ class JSAsset extends Asset {
     walk.ancestor(this.ast, collectDependencies, this);
   }
 
+  async loadSourceMap() {
+    // Get original sourcemap if there is any
+    let match = this.contents.match(SOURCEMAP_RE);
+    if (match) {
+      this.contents = this.contents.replace(SOURCEMAP_RE, '');
+
+      let url = match[1];
+      let dataURLMatch = url.match(DATA_URL_RE);
+
+      try {
+        let json, filename;
+        if (dataURLMatch) {
+          filename = this.name;
+          json = new Buffer(dataURLMatch[1], 'base64').toString();
+        } else {
+          filename = path.join(path.dirname(this.name), url);
+          json = await fs.readFile(filename, 'utf8');
+
+          // Add as a dep so we watch the source map for changes.
+          this.addDependency(filename, {includedInParent: true});
+        }
+
+        this.sourceMap = JSON.parse(json);
+
+        // Attempt to read missing source contents
+        if (!this.sourceMap.sourcesContent) {
+          this.sourceMap.sourcesContent = [];
+        }
+
+        let missingSources = this.sourceMap.sources.slice(
+          this.sourceMap.sourcesContent.length
+        );
+        if (missingSources.length) {
+          let contents = await Promise.all(
+            missingSources.map(async source => {
+              try {
+                let sourceFile = path.join(
+                  path.dirname(filename),
+                  this.sourceMap.sourceRoot || '',
+                  source
+                );
+                let result = await fs.readFile(sourceFile, 'utf8');
+                this.addDependency(sourceFile, {includedInParent: true});
+                return result;
+              } catch (err) {
+                logger.warn(
+                  `Could not load source file "${source}" in source map of "${
+                    this.relativeName
+                  }".`
+                );
+              }
+            })
+          );
+
+          this.sourceMap.sourcesContent = this.sourceMap.sourcesContent.concat(
+            contents
+          );
+        }
+      } catch (e) {
+        logger.warn(
+          `Could not load existing sourcemap of "${this.relativeName}".`
+        );
+      }
+    }
+  }
+
   async pretransform() {
+    await this.loadSourceMap();
     await babel(this);
 
     // Inline environment variables

test/graphql.js

@@ -31,6 +31,7 @@ describe('graphql', function() {
           firstName
           lastName
         }
+
       `.definitions
     );
   });

test/integration/sourcemap-existing/index.js

@@ -0,0 +1,5 @@
+const sum = require('./sum');
+
+module.exports = function() {
+  return sum(1, 2);
+}

test/integration/sourcemap-existing/sum.map

@@ -0,0 +1,11 @@
+{
+  "version": 3,
+  "file": "sum.js",
+  "sourceRoot": "",
+  "sources": [
+    "sum.coffee"
+  ],
+  "names": [],
+  "mappings": ";AAAA;EAAA,MAAM,CAAC,OAAP,GAAiB,CAAA,SAAA,KAAA;WAAA,SAAC,CAAD,EAAI,CAAJ;aAAU,CAAA,GAAI;IAAd;EAAA,CAAA,CAAA,CAAA,IAAA;AAAjB",
+  "sourcesContent": ["module.exports = (a, b) => a + b"]
+}

test/integration/sourcemap-external-contents/index.js

@@ -0,0 +1,5 @@
+const sum = require('./sum');
+
+module.exports = function() {
+  return sum(1, 2);
+}

test/integration/sourcemap-external-contents/sum.coffee

@@ -0,0 +1 @@
+module.exports = (a, b) => a + b

test/integration/sourcemap-external-contents/sum.map

@@ -0,0 +1,10 @@
+{
+  "version": 3,
+  "file": "sum.js",
+  "sourceRoot": "",
+  "sources": [
+    "sum.coffee"
+  ],
+  "names": [],
+  "mappings": ";AAAA;EAAA,MAAM,CAAC,OAAP,GAAiB,CAAA,SAAA,KAAA;WAAA,SAAC,CAAD,EAAI,CAAJ;aAAU,CAAA,GAAI;IAAd;EAAA,CAAA,CAAA,CAAA,IAAA;AAAjB"
+}

test/integration/sourcemap-inline/index.js

@@ -0,0 +1,5 @@
+const sum = require('./sum');
+
+module.exports = function() {
+  return sum(1, 2);
+}

test/sourcemaps.js

@@ -204,4 +204,110 @@ describe('sourcemaps', function() {
     let map = (await fs.readFile(path.join(sourcemapReference))).toString();
     mapValidator(jsOutput, map);
   });
+
+  it('should load existing sourcemaps of libraries', async function() {
+    let b = await bundle(
+      __dirname + '/integration/sourcemap-existing/index.js'
+    );
+
+    assertBundleTree(b, {
+      name: 'index.js',
+      assets: ['index.js', 'sum.js'],
+      childBundles: [
+        {
+          type: 'map'
+        }
+      ]
+    });
+
+    let jsOutput = await fs.readFile(b.name, 'utf8');
+
+    let sourcemapReference = path.join(
+      __dirname,
+      '/dist/',
+      jsOutput.substring(jsOutput.lastIndexOf('//# sourceMappingURL') + 22)
+    );
+
+    assert(
+      await fs.exists(path.join(sourcemapReference)),
+      'referenced sourcemap should exist'
+    );
+
+    let map = await fs.readFile(path.join(sourcemapReference), 'utf8');
+    assert(
+      map.indexOf('module.exports = (a, b) => a + b') > -1,
+      'Sourcemap should contain the existing sourcemap'
+    );
+    mapValidator(jsOutput, map);
+  });
+
+  it('should load inline sourcemaps of libraries', async function() {
+    let b = await bundle(__dirname + '/integration/sourcemap-inline/index.js');
+
+    assertBundleTree(b, {
+      name: 'index.js',
+      assets: ['index.js', 'sum.js'],
+      childBundles: [
+        {
+          type: 'map'
+        }
+      ]
+    });
+
+    let jsOutput = await fs.readFile(b.name, 'utf8');
+
+    let sourcemapReference = path.join(
+      __dirname,
+      '/dist/',
+      jsOutput.substring(jsOutput.lastIndexOf('//# sourceMappingURL') + 22)
+    );
+
+    assert(
+      await fs.exists(path.join(sourcemapReference)),
+      'referenced sourcemap should exist'
+    );
+
+    let map = await fs.readFile(path.join(sourcemapReference), 'utf8');
+    assert(
+      map.indexOf('module.exports = (a, b) => a + b') > -1,
+      'Sourcemap should contain the existing sourcemap'
+    );
+    mapValidator(jsOutput, map);
+  });
+
+  it('should load referenced contents of sourcemaps', async function() {
+    let b = await bundle(
+      __dirname + '/integration/sourcemap-external-contents/index.js'
+    );
+
+    assertBundleTree(b, {
+      name: 'index.js',
+      assets: ['index.js', 'sum.js'],
+      childBundles: [
+        {
+          type: 'map'
+        }
+      ]
+    });
+
+    let jsOutput = await fs.readFile(b.name, 'utf8');
+
+    let sourcemapReference = path.join(
+      __dirname,
+      '/dist/',
+      jsOutput.substring(jsOutput.lastIndexOf('//# sourceMappingURL') + 22)
+    );
+
+    assert(
+      await fs.exists(path.join(sourcemapReference)),
+      'referenced sourcemap should exist'
+    );
+
+    let map = await fs.readFile(path.join(sourcemapReference), 'utf8');
+    assert(
+      map.indexOf('module.exports = (a, b) => a + b') > -1,
+      'Sourcemap should contain the existing sourcemap'
+    );
+    mapValidator(jsOutput, map);
+  });
 });