Integrate from internal code base.

1 files changed, 44 insertions, 16 deletions

diff --git a/src/google/protobuf/compiler/python/python_generator.cc b/src/google/protobuf/compiler/python/python_generator.cc
index cc54a8ab..d5468a0c 100644
--- a/src/google/protobuf/compiler/python/python_generator.cc
+++ b/src/google/protobuf/compiler/python/python_generator.cc
@@ -44,6 +44,7 @@
 // performance-minded Python code leverage the fast C++ implementation
 // directly.
 
+#include <algorithm>
 #include <google/protobuf/stubs/hash.h>
 #include <limits>
 #include <map>
@@ -107,20 +108,25 @@ string ModuleAlias(const string& filename) {
   return module_name;
 }
 
-
-// Returns an import statement of form "from X.Y.Z import T" for the given
-// .proto filename.
-string ModuleImportStatement(const string& filename) {
-  string module_name = ModuleName(filename);
-  int last_dot_pos = module_name.rfind('.');
-  if (last_dot_pos == string::npos) {
-    // NOTE(petya): this is not tested as it would require a protocol buffer
-    // outside of any package, and I don't think that is easily achievable.
-    return "import " + module_name;
-  } else {
-    return "from " + module_name.substr(0, last_dot_pos) + " import " +
-        module_name.substr(last_dot_pos + 1);
+// Keywords reserved by the Python language.
+const char* const kKeywords[] = {
+    "False",   "None",     "True",     "and",    "as",    "assert", "break",
+    "class",   "continue", "def",      "del",    "elif",  "else",   "except",
+    "finally", "for",      "from",     "global", "if",    "import", "in",
+    "is",      "lambda",   "nonlocal", "not",    "or",    "pass",   "raise",
+    "return",  "try",      "while",    "with",   "yield",
+};
+const char* const* kKeywordsEnd =
+    kKeywords + (sizeof(kKeywords) / sizeof(kKeywords[0]));
+
+bool ContainsPythonKeyword(const string& module_name) {
+  vector<string> tokens = Split(module_name, ".");
+  for (int i = 0; i < tokens.size(); ++i) {
+    if (std::find(kKeywords, kKeywordsEnd, tokens[i]) != kKeywordsEnd) {
+      return true;
+    }
   }
+  return false;
 }
 
 
@@ -359,10 +365,32 @@ bool Generator::Generate(const FileDescriptor* file,
 void Generator::PrintImports() const {
   for (int i = 0; i < file_->dependency_count(); ++i) {
     const string& filename = file_->dependency(i)->name();
-    string import_statement = ModuleImportStatement(filename);
+
+    string module_name = ModuleName(filename);
     string module_alias = ModuleAlias(filename);
-    printer_->Print("$statement$ as $alias$\n", "statement",
-                    import_statement, "alias", module_alias);
+    if (ContainsPythonKeyword(module_name)) {
+      // If the module path contains a Python keyword, we have to quote the
+      // module name and import it using importlib. Otherwise the usual kind of
+      // import statement would result in a syntax error from the presence of
+      // the keyword.
+      printer_->Print("import importlib\n");
+      printer_->Print("$alias$ = importlib.import_module('$name$')\n", "alias",
+                      module_alias, "name", module_name);
+    } else {
+      int last_dot_pos = module_name.rfind('.');
+      string import_statement;
+      if (last_dot_pos == string::npos) {
+        // NOTE(petya): this is not tested as it would require a protocol buffer
+        // outside of any package, and I don't think that is easily achievable.
+        import_statement = "import " + module_name;
+      } else {
+        import_statement = "from " + module_name.substr(0, last_dot_pos) +
+                           " import " + module_name.substr(last_dot_pos + 1);
+      }
+      printer_->Print("$statement$ as $alias$\n", "statement", import_statement,
+                      "alias", module_alias);
+    }
+
     CopyPublicDependenciesAliases(module_alias, file_->dependency(i));
   }
   printer_->Print("\n");