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Diffstat (limited to 'src/google/protobuf/compiler/scc.cc')
-rw-r--r-- | src/google/protobuf/compiler/scc.cc | 111 |
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 |