From f4c12fce1ee58e670f9c3fce46c40296ba9ee8a2 Mon Sep 17 00:00:00 2001
From: Ian Hodson <idh@google.com>
Date: Wed, 30 May 2012 21:27:06 +0100
Subject: Add openfst to external, as used by GoogleTTS

Moved from GoogleTTS

Change-Id: I6bc6bdadaa53bd0f810b88443339f6d899502cc8
---
 src/include/fst/string.h | 247 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 247 insertions(+)
 create mode 100644 src/include/fst/string.h

(limited to 'src/include/fst/string.h')

diff --git a/src/include/fst/string.h b/src/include/fst/string.h
new file mode 100644
index 0000000..3099b87
--- /dev/null
+++ b/src/include/fst/string.h
@@ -0,0 +1,247 @@
+
+// string.h
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright 2005-2010 Google, Inc.
+// Author: allauzen@google.com (Cyril Allauzen)
+//
+// \file
+// Utilities to convert strings into FSTs.
+//
+
+#ifndef FST_LIB_STRING_H_
+#define FST_LIB_STRING_H_
+
+#include <fst/compact-fst.h>
+#include <fst/mutable-fst.h>
+
+DECLARE_string(fst_field_separator);
+
+namespace fst {
+
+// Functor compiling a string in an FST
+template <class A>
+class StringCompiler {
+ public:
+  typedef A Arc;
+  typedef typename A::Label Label;
+  typedef typename A::Weight Weight;
+
+  enum TokenType { SYMBOL = 1, BYTE = 2, UTF8 = 3 };
+
+  StringCompiler(TokenType type, const SymbolTable *syms = 0,
+                 Label unknown_label = kNoLabel,
+                 bool allow_negative = false)
+      : token_type_(type), syms_(syms), unknown_label_(unknown_label),
+        allow_negative_(allow_negative) {}
+
+  // Compile string 's' into FST 'fst'.
+  template <class F>
+  bool operator()(const string &s, F *fst) {
+    vector<Label> labels;
+    if (!ConvertStringToLabels(s, &labels))
+      return false;
+    Compile(labels, fst);
+    return true;
+  }
+
+ private:
+  bool ConvertStringToLabels(const string &str, vector<Label> *labels) const {
+    labels->clear();
+    if (token_type_ == BYTE) {
+      for (size_t i = 0; i < str.size(); ++i)
+        labels->push_back(static_cast<unsigned char>(str[i]));
+    } else if (token_type_ == UTF8) {
+      return UTF8StringToLabels(str, labels);
+    } else {
+      char *c_str = new char[str.size() + 1];
+      str.copy(c_str, str.size());
+      c_str[str.size()] = 0;
+      vector<char *> vec;
+      string separator = "\n" + FLAGS_fst_field_separator;
+      SplitToVector(c_str, separator.c_str(), &vec, true);
+      for (size_t i = 0; i < vec.size(); ++i) {
+        Label label;
+        if (!ConvertSymbolToLabel(vec[i], &label))
+          return false;
+        labels->push_back(label);
+      }
+      delete[] c_str;
+    }
+    return true;
+  }
+
+  void Compile(const vector<Label> &labels, MutableFst<A> *fst) const {
+    fst->DeleteStates();
+    while (fst->NumStates() <= labels.size())
+      fst->AddState();
+    for (size_t i = 0; i < labels.size(); ++i)
+      fst->AddArc(i, Arc(labels[i], labels[i], Weight::One(), i + 1));
+    fst->SetStart(0);
+    fst->SetFinal(labels.size(), Weight::One());
+  }
+
+  template <class Unsigned>
+  void Compile(const vector<Label> &labels, CompactFst<A, StringCompactor<A>,
+               Unsigned> *fst) const {
+    fst->SetCompactElements(labels.begin(), labels.end());
+  }
+
+  bool ConvertSymbolToLabel(const char *s, Label* output) const {
+    int64 n;
+    if (syms_) {
+      n = syms_->Find(s);
+      if ((n == -1) && (unknown_label_ != kNoLabel))
+        n = unknown_label_;
+      if (n == -1 || (!allow_negative_ && n < 0)) {
+        VLOG(1) << "StringCompiler::ConvertSymbolToLabel: Symbol \"" << s
+                << "\" is not mapped to any integer label, symbol table = "
+                 << syms_->Name();
+        return false;
+      }
+    } else {
+      char *p;
+      n = strtoll(s, &p, 10);
+      if (p < s + strlen(s) || (!allow_negative_ && n < 0)) {
+        VLOG(1) << "StringCompiler::ConvertSymbolToLabel: Bad label integer "
+                << "= \"" << s << "\"";
+        return false;
+      }
+    }
+    *output = n;
+    return true;
+  }
+
+  TokenType token_type_;     // Token type: symbol, byte or utf8 encoded
+  const SymbolTable *syms_;  // Symbol table used when token type is symbol
+  Label unknown_label_;      // Label for token missing from symbol table
+  bool allow_negative_;      // Negative labels allowed?
+
+  DISALLOW_COPY_AND_ASSIGN(StringCompiler);
+};
+
+// Functor to print a string FST as a string.
+template <class A>
+class StringPrinter {
+ public:
+  typedef A Arc;
+  typedef typename A::Label Label;
+  typedef typename A::StateId StateId;
+  typedef typename A::Weight Weight;
+
+  enum TokenType { SYMBOL = 1, BYTE = 2, UTF8 = 3 };
+
+  StringPrinter(TokenType token_type,
+                const SymbolTable *syms = 0)
+      : token_type_(token_type), syms_(syms) {}
+
+  // Convert the FST 'fst' into the string 'output'
+  bool operator()(const Fst<A> &fst, string *output) {
+    bool is_a_string = FstToLabels(fst);
+    if (!is_a_string) {
+      VLOG(1) << "StringPrinter::operator(): Fst is not a string.";
+      return false;
+    }
+
+    output->clear();
+
+    if (token_type_ == SYMBOL) {
+      stringstream sstrm;
+      for (size_t i = 0; i < labels_.size(); ++i) {
+        if (i)
+          sstrm << *(FLAGS_fst_field_separator.rbegin());
+        if (!PrintLabel(labels_[i], sstrm))
+          return false;
+      }
+      *output = sstrm.str();
+    } else if (token_type_ == BYTE) {
+      for (size_t i = 0; i < labels_.size(); ++i) {
+        output->push_back(labels_[i]);
+      }
+    } else if (token_type_ == UTF8) {
+      return LabelsToUTF8String(labels_, output);
+    } else {
+      VLOG(1) << "StringPrinter::operator(): Unknown token type: "
+              << token_type_;
+      return false;
+    }
+    return true;
+  }
+
+ private:
+  bool FstToLabels(const Fst<A> &fst) {
+    labels_.clear();
+
+    StateId s = fst.Start();
+    if (s == kNoStateId) {
+      VLOG(2) << "StringPrinter::FstToLabels: Invalid starting state for "
+              << "string fst.";
+      return false;
+    }
+
+    while (fst.Final(s) == Weight::Zero()) {
+      ArcIterator<Fst<A> > aiter(fst, s);
+      if (aiter.Done()) {
+        VLOG(2) << "StringPrinter::FstToLabels: String fst traversal does "
+                << "not reach final state.";
+        return false;
+      }
+
+      const A& arc = aiter.Value();
+      labels_.push_back(arc.olabel);
+
+      s = arc.nextstate;
+      if (s == kNoStateId) {
+        VLOG(2) << "StringPrinter::FstToLabels: Transition to invalid "
+                << "state.";
+        return false;
+      }
+
+      aiter.Next();
+      if (!aiter.Done()) {
+        VLOG(2) << "StringPrinter::FstToLabels: State with multiple "
+                << "outgoing arcs found.";
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  bool PrintLabel(Label lab, ostream& ostrm) {
+    if (syms_) {
+      string symbol = syms_->Find(lab);
+      if (symbol == "") {
+        VLOG(2) << "StringPrinter::PrintLabel: Integer " << lab << " is not "
+                << "mapped to any textual symbol, symbol table = "
+                 << syms_->Name();
+        return false;
+      }
+      ostrm << symbol;
+    } else {
+      ostrm << lab;
+    }
+    return true;
+  }
+
+  TokenType token_type_;     // Token type: symbol, byte or utf8 encoded
+  const SymbolTable *syms_;  // Symbol table used when token type is symbol
+  vector<Label> labels_;     // Input FST labels.
+
+  DISALLOW_COPY_AND_ASSIGN(StringPrinter);
+};
+
+}  // namespace fst
+
+#endif // FST_LIB_STRING_H_
-- 
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