SCons: Format buildsystem files with psf/black

Configured for a max line length of 120 characters.

psf/black is very opinionated and purposely doesn't leave much room for
configuration. The output is mostly OK so that should be fine for us,
but some things worth noting:

- Manually wrapped strings will be reflowed, so by using a line length
  of 120 for the sake of preserving readability for our long command
  calls, it also means that some manually wrapped strings are back on
  the same line and should be manually merged again.

- Code generators using string concatenation extensively look awful,
  since black puts each operand on a single line. We need to refactor
  these generators to use more pythonic string formatting, for which
  many options are available (`%`, `format` or f-strings).

- CI checks and a pre-commit hook will be added to ensure that future
  buildsystem changes are well-formatted.

1 files changed, 13 insertions, 12 deletions

diff --git a/platform/javascript/emscripten_helpers.py b/platform/javascript/emscripten_helpers.py
index bda5b40a74..a55c9d3f48 100644
--- a/platform/javascript/emscripten_helpers.py
+++ b/platform/javascript/emscripten_helpers.py
@@ -1,7 +1,8 @@
 import os
 
+
 def parse_config():
-    em_config_file = os.getenv('EM_CONFIG') or os.path.expanduser('~/.emscripten')
+    em_config_file = os.getenv("EM_CONFIG") or os.path.expanduser("~/.emscripten")
     if not os.path.exists(em_config_file):
         raise RuntimeError("Emscripten configuration file '%s' does not exist" % em_config_file)
 
@@ -13,25 +14,25 @@ def parse_config():
             exec(f.read(), em_config)
         except StandardError as e:
             raise RuntimeError("Emscripten configuration file '%s' is invalid:\n%s" % (em_config_file, e))
-    normalized['EMCC_ROOT'] = em_config.get('EMSCRIPTEN_ROOT')
-    normalized['NODE_JS'] = em_config.get('NODE_JS')
-    normalized['CLOSURE_BIN'] = os.path.join(normalized['EMCC_ROOT'], 'node_modules', '.bin', 'google-closure-compiler')
+    normalized["EMCC_ROOT"] = em_config.get("EMSCRIPTEN_ROOT")
+    normalized["NODE_JS"] = em_config.get("NODE_JS")
+    normalized["CLOSURE_BIN"] = os.path.join(normalized["EMCC_ROOT"], "node_modules", ".bin", "google-closure-compiler")
     return normalized
 
 
 def run_closure_compiler(target, source, env, for_signature):
     cfg = parse_config()
-    cmd = [cfg['NODE_JS'], cfg['CLOSURE_BIN']]
-    cmd.extend(['--compilation_level', 'ADVANCED_OPTIMIZATIONS'])
-    for f in env['JSEXTERNS']:
-        cmd.extend(['--externs', f.get_abspath()])
+    cmd = [cfg["NODE_JS"], cfg["CLOSURE_BIN"]]
+    cmd.extend(["--compilation_level", "ADVANCED_OPTIMIZATIONS"])
+    for f in env["JSEXTERNS"]:
+        cmd.extend(["--externs", f.get_abspath()])
     for f in source:
-        cmd.extend(['--js', f.get_abspath()])
-    cmd.extend(['--js_output_file', target[0].get_abspath()])
-    return ' '.join(cmd)
+        cmd.extend(["--js", f.get_abspath()])
+    cmd.extend(["--js_output_file", target[0].get_abspath()])
+    return " ".join(cmd)
 
 
 def create_engine_file(env, target, source, externs):
-    if env['use_closure_compiler']:
+    if env["use_closure_compiler"]:
         return env.BuildJS(target, source, JSEXTERNS=externs)
     return env.Textfile(target, [env.File(s) for s in source])