1 files changed, 111 insertions, 0 deletions
diff --git a/src/google/protobuf/compiler/scc.cc b/src/google/protobuf/compiler/scc.cc
new file mode 100644
index 00000000..bbdabbfc
--- /dev/null
+++ b/src/google/protobuf/compiler/scc.cc
@@ -0,0 +1,111 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <google/protobuf/compiler/scc.h>
+
+#include <google/protobuf/stubs/logging.h>
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/descriptor.h>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+
+SCCAnalyzer::NodeData SCCAnalyzer::DFS(const Descriptor* descriptor) {
+  // Must not have visited already.
+  GOOGLE_DCHECK_EQ(cache_.count(descriptor), 0);
+
+  // Mark visited by inserting in map.
+  NodeData& result = cache_[descriptor];
+  // Initialize data structures.
+  result.index = result.lowlink = index_++;
+  stack_.push_back(descriptor);
+
+  // Recurse the fields / nodes in graph
+  for (int i = 0; i < descriptor->field_count(); i++) {
+    const Descriptor* child = descriptor->field(i)->message_type();
+    if (child) {
+      if (cache_.count(child) == 0) {
+        // unexplored node
+        NodeData child_data = DFS(child);
+        result.lowlink = std::min(result.lowlink, child_data.lowlink);
+      } else {
+        NodeData child_data = cache_[child];
+        if (child_data.scc == nullptr) {
+          // Still in the stack_ so we found a back edge
+          result.lowlink = std::min(result.lowlink, child_data.index);
+        }
+      }
+    }
+  }
+  if (result.index == result.lowlink) {
+    // This is the root of a strongly connected component
+    SCC* scc = CreateSCC();
+    while (true) {
+      const Descriptor* scc_desc = stack_.back();
+      scc->descriptors.push_back(scc_desc);
+      // Remove from stack
+      stack_.pop_back();
+      cache_[scc_desc].scc = scc;
+
+      if (scc_desc == descriptor) break;
+    }
+
+    // The order of descriptors is random and depends how this SCC was
+    // discovered. In-order to ensure maximum stability we sort it by name.
+    std::sort(scc->descriptors.begin(), scc->descriptors.end(),
+              [](const Descriptor* a, const Descriptor* b) {
+                return a->full_name() < b->full_name();
+              });
+    AddChildren(scc);
+  }
+  return result;
+}
+
+void SCCAnalyzer::AddChildren(SCC* scc) {
+  std::set<const SCC*> seen;
+  for (int i = 0; i < scc->descriptors.size(); i++) {
+    const Descriptor* descriptor = scc->descriptors[i];
+    for (int j = 0; j < descriptor->field_count(); j++) {
+      const Descriptor* child_msg = descriptor->field(j)->message_type();
+      if (child_msg) {
+        const SCC* child = GetSCC(child_msg);
+        if (child == scc) continue;
+        if (seen.insert(child).second) {
+          scc->children.push_back(child);
+        }
+      }
+    }
+  }
+}
+
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google