Add source maps support for CoffeeScript

Author: Andrey Fedoseev

CHANGES.rst

@@ -7,6 +7,7 @@ Dev
 
 - Add source maps support for SASS/SCSS
 - Add source maps support for LESS
+- Add source maps support for CoffeeScript
 
 
 1.0.1

README.rst

@@ -174,10 +174,13 @@ CoffeeScript
 ``executable``
   Path to CoffeeScript compiler executable. Default: ``"coffee"``.
 
+``sourcemap_enabled``
+  Boolean. Set to ``True`` to enable source maps. Default: ``False``
+
 Example::
 
     STATIC_PRECOMPILER_COMPILERS = (
-        ('static_precompiler.compilers.CoffeeScript', {"executable": "/usr/bin/coffee"}),
+        ('static_precompiler.compilers.CoffeeScript', {"executable": "/usr/bin/coffee", "sourcemap_enabled": True}),
     )
 
 

static_precompiler/compilers/coffeescript.py

@@ -1,4 +1,6 @@
+import json
 import os
+import posixpath
 
 from static_precompiler import exceptions, settings, utils
 
@@ -15,20 +17,44 @@ class CoffeeScript(base.BaseCompiler):
     input_extension = "coffee"
     output_extension = "js"
 
-    def __init__(self, executable=settings.COFFEESCRIPT_EXECUTABLE):
+    def __init__(self, executable=settings.COFFEESCRIPT_EXECUTABLE, sourcemap_enabled=False):
         self.executable = executable
+        self.is_sourcemap_enabled = sourcemap_enabled
         super(CoffeeScript, self).__init__()
 
     def compile_file(self, source_path):
+        full_output_path = self.get_full_output_path(source_path)
         args = [
             self.executable,
             "-c",
-            "-o", os.path.dirname(self.get_full_output_path(source_path)),
-            self.get_full_source_path(source_path),
         ]
+        if self.is_sourcemap_enabled:
+            args.append("-m")
+        args.extend([
+            "-o", os.path.dirname(full_output_path),
+            self.get_full_source_path(source_path),
+        ])
         out, errors = utils.run_command(args)
+
         if errors:
             raise exceptions.StaticCompilationError(errors)
+
+        if self.is_sourcemap_enabled:
+            # Coffeescript writes source maps to compiled.map, not compiled.js.map
+            sourcemap_full_path = os.path.splitext(full_output_path)[0] + ".map"
+
+            with open(sourcemap_full_path) as sourcemap_file:
+                sourcemap = json.loads(sourcemap_file.read())
+
+            # CoffeeScript, unlike SASS, can't add correct relative paths in source map when the compiled file
+            # is not in the same dir as the source file. We fix it here.
+            sourcemap["sourceRoot"] = "../" * len(source_path.split("/")) + posixpath.dirname(source_path)
+            sourcemap["sources"] = [os.path.basename(source) for source in sourcemap["sources"]]
+            sourcemap["file"] = posixpath.basename(os.path.basename(full_output_path))
+
+            with open(sourcemap_full_path, "w") as sourcemap_file:
+                sourcemap_file.write(json.dumps(sourcemap))
+
         return self.get_output_path(source_path)
 
     def compile_source(self, source):

static_precompiler/tests/test_coffeescript.py

@@ -24,6 +24,21 @@ def test_compile_file(monkeypatch, tmpdir):
         assert clean_javascript(compiled.read()) == """(function() {\n  console.log("Hello, World!");\n}).call(this);"""
 
 
+def test_sourcemap(monkeypatch, tmpdir):
+
+    monkeypatch.setattr("static_precompiler.settings.ROOT", tmpdir.strpath)
+
+    compiler = compilers.CoffeeScript(sourcemap_enabled=False)
+    compiler.compile_file("scripts/test.coffee") == "COMPILED/scripts/test.js"
+    full_output_path = compiler.get_full_output_path("scripts/test.coffee")
+    assert not os.path.exists(os.path.splitext(full_output_path)[0] + ".map")
+
+    compiler = compilers.CoffeeScript(sourcemap_enabled=True)
+    compiler.compile_file("scripts/test.coffee") == "COMPILED/scripts/test.js"
+    full_output_path = compiler.get_full_output_path("scripts/test.coffee")
+    assert os.path.exists(os.path.splitext(full_output_path)[0] + ".map")
+
+
 def test_compile_source():
     compiler = compilers.CoffeeScript()