1 files changed, 109 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/haskell/private/ls_modules.py b/third_party/bazel/rules_haskell/haskell/private/ls_modules.py
new file mode 100755
index 000000000000..8e281366cca9
--- /dev/null
+++ b/third_party/bazel/rules_haskell/haskell/private/ls_modules.py
@@ -0,0 +1,109 @@
+#!/usr/bin/env python
+#
+# Create a list of exposed modules (including reexported modules)
+# given a directory full of interface files and the content of the
+# global package database (to mine the versions of all prebuilt
+# dependencies). The exposed modules are filtered using a provided
+# list of hidden modules, and augmented with reexport declarations.
+
+from __future__ import unicode_literals, print_function
+
+import collections
+import fnmatch
+import itertools
+import os
+import re
+import sys
+import io
+
+if len(sys.argv) != 6:
+    sys.exit("Usage: %s <DIRECTORY> <GLOBAL_PKG_DB> <HIDDEN_MODS_FILE> <REEXPORTED_MODS_FILE> <RESULT_FILE>" % sys.argv[0])
+
+root = sys.argv[1]
+global_pkg_db_dump = sys.argv[2]
+hidden_modules_file = sys.argv[3]
+reexported_modules_file = sys.argv[4]
+results_file = sys.argv[5]
+
+with io.open(global_pkg_db_dump, "r", encoding='utf8') as f:
+    names = [line.split()[1] for line in f if line.startswith("name:")]
+    f.seek(0)
+    ids = [line.split()[1] for line in f if line.startswith("id:")]
+
+    # A few sanity checks.
+    assert len(names) == len(ids)
+
+    # compute duplicate, i.e. package name associated with multiples ids
+    duplicates = set()
+    if len(names) != len(set(names)):
+        duplicates = set([
+            name for name, count in collections.Counter(names).items()
+            if count > 1
+        ])
+
+    # This associate pkg name to pkg id
+    pkg_ids_map = dict(zip(names, ids))
+
+with io.open(hidden_modules_file, "r", encoding='utf8') as f:
+    hidden_modules = [mod.strip() for mod in f.read().split(",")]
+
+with io.open(reexported_modules_file, "r", encoding='utf8') as f:
+    raw_reexported_modules = (
+        mod.strip() for mod in f.read().split(",") if mod.strip()
+    )
+    # Substitute package ids for package names in reexports, because
+    # GHC really wants package ids.
+    regexp = re.compile("from (%s):" % "|".join(map(re.escape, pkg_ids_map)))
+
+    def replace_pkg_by_pkgid(match):
+        pkgname = match.group(1)
+
+        if pkgname in duplicates:
+            sys.exit(
+                "\n".join([
+                    "Multiple versions of the following packages installed: ",
+                    ", ".join(duplicates),
+                    "\nThe following was explictly used: " + pkgname,
+                    "\nThis is not currently supported.",
+                ])
+            )
+
+        return "from %s:" % pkg_ids_map[pkgname]
+
+    reexported_modules = (
+        regexp.sub(replace_pkg_by_pkgid, mod)
+        for mod in raw_reexported_modules
+    )
+
+def handle_walk_error(e):
+    print("""
+Failed to list interface files:
+    {}
+On Windows you may need to enable long file path support:
+    Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' -Name 'LongPathsEnabled' -Value 1
+    """.strip().format(e), file=sys.stderr)
+    exit(1)
+
+interface_files = (
+    os.path.join(path, f)
+    for path, dirs, files in os.walk(root, onerror=handle_walk_error)
+    for f in fnmatch.filter(files, '*.hi')
+)
+
+modules = (
+    # replace directory separators by . to generate module names
+    # / and \ are respectively the separators for unix (linux / darwin) and windows systems
+    os.path.splitext(os.path.relpath(f, start=root))[0]
+        .replace("/",".")
+        .replace("\\",".")
+    for f in interface_files
+)
+
+exposed_modules = (
+    m
+    for m in modules
+    if m not in hidden_modules
+)
+
+with io.open(results_file, "w", encoding='utf8') as f:
+    f.write(", ".join(itertools.chain(exposed_modules, reexported_modules)))