Support tab-separated inputs in marian-server (#649)

* Enable multi-source input in marian-server
* Add function converting multi-line tab-separated textual input

Co-authored-by: Tomasz Dwojak <t.dwojak@amu.edu.pl>

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 
 ### Added
+- Decoding multi-source models in marian-server with --tsv
 - GitHub workflows on Ubuntu, Windows, and MacOS
 - LSH indexing to replace short list
 - ONNX support for transformer models

src/data/text_input.cpp

@@ -23,8 +23,11 @@ const SentenceTuple& TextIterator::dereference() const {
 TextInput::TextInput(std::vector<std::string> inputs,
                      std::vector<Ptr<Vocab>> vocabs,
                      Ptr<Options> options)
-    : DatasetBase(inputs, options), vocabs_(vocabs) {
-  // note: inputs are automatically stored in the inherited variable named paths_, but these are
+    : DatasetBase(inputs, options),
+      vocabs_(vocabs),
+      maxLength_(options_->get<size_t>("max-length")),
+      maxLengthCrop_(options_->get<bool>("max-length-crop")) {
+  // Note: inputs are automatically stored in the inherited variable named paths_, but these are
   // texts not paths!
   for(const auto& text : paths_)
     files_.emplace_back(new std::istringstream(text));
@@ -42,6 +45,10 @@ SentenceTuple TextInput::next() {
     std::string line;
     if(io::getline(*files_[i], line)) {
       Words words = vocabs_[i]->encode(line, /*addEOS =*/ true, /*inference =*/ inference_);
+      if(this->maxLengthCrop_ && words.size() > this->maxLength_) {
+        words.resize(maxLength_);
+        words.back() = vocabs_.back()->getEosId();  // note: this will not work with class-labels
+      }
       if(words.empty())
         words.push_back(Word::ZERO); // @TODO: What is this for? @BUGBUG: addEOS=true, so this can never happen, right?
       tup.push_back(words);

src/data/text_input.h

@@ -33,6 +33,9 @@ private:
 
   size_t pos_{0};
 
+  size_t maxLength_{0};
+  bool maxLengthCrop_{false};
+
 public:
   typedef SentenceTuple Sample;
 

src/translator/translator.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <string>
+
 #include "data/batch_generator.h"
 #include "data/corpus.h"
 #include "data/shortlist.h"
@@ -245,7 +247,11 @@ public:
   }
 
   std::string run(const std::string& input) override {
-    auto corpus_ = New<data::TextInput>(std::vector<std::string>({input}), srcVocabs_, options_);
+    // split tab-separated input into fields if necessary
+    auto inputs = options_->get<bool>("tsv", false)
+                      ? convertTsvToLists(input, options_->get<size_t>("tsv-fields", 1))
+                      : std::vector<std::string>({input});
+    auto corpus_ = New<data::TextInput>(inputs, srcVocabs_, options_);
     data::BatchGenerator<data::TextInput> batchGenerator(corpus_, options_);
 
     auto collector = New<StringCollector>();
@@ -258,7 +264,6 @@ public:
       ThreadPool threadPool_(numDevices_, numDevices_);
 
       for(auto batch : batchGenerator) {
-
         auto task = [=](size_t id) {
           thread_local Ptr<ExpressionGraph> graph;
           thread_local std::vector<Ptr<Scorer>> scorers;
@@ -287,5 +292,30 @@ public:
     auto translations = collector->collect(options_->get<bool>("n-best"));
     return utils::join(translations, "\n");
   }
+
+private:
+  // Converts a multi-line input with tab-separated source(s) and target sentences into separate lists
+  // of sentences from source(s) and target sides, e.g.
+  // "src1 \t trg1 \n src2 \t trg2" -> ["src1 \n src2", "trg1 \n trg2"]
+  std::vector<std::string> convertTsvToLists(const std::string& inputText, size_t numFields) {
+    std::vector<std::string> outputFields(numFields);
+
+    std::string line;
+    std::vector<std::string> lineFields(numFields);
+    std::istringstream inputStream(inputText);
+    bool first = true;
+    while(std::getline(inputStream, line)) {
+      utils::splitTsv(line, lineFields, numFields);
+      for(size_t i = 0; i < numFields; ++i) {
+        if(!first)
+          outputFields[i] += "\n";  // join sentences with a new line sign
+        outputFields[i] += lineFields[i];
+      }
+      if(first)
+        first = false;
+    }
+
+    return outputFields;
+  }
 };
 }  // namespace marian