Build liblouis_nacl using gyp.

third_party/liblouis/nacl_wrapper/liblouis_wrapper.cc

+// Copyright 2013 Google Inc.
+//
+// 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.
+
+#include "liblouis_wrapper.h"
+
+#include <cstddef>
+
+#include "liblouis/liblouis.h"
+
+namespace {
+
+// Decodes UTF-8 into 16-bit wide characters.
+// This implementation is very permissive and may miss encoding errors.
+// It ignores charaters which are not in the Unicode Basic Multilingual Plane.
+// TODO(jbroman): Handle more than BMP if liblouis changes to accept UTF-16.
+static bool DecodeUtf8(const std::string& in, std::vector<widechar>* out) {
+  int len = in.length();
+  std::vector<widechar> result;
+  result.reserve(len);
+  int i = 0;
+  while (i < len) {
+    int ch = static_cast<unsigned char>(in[i++]);
+    widechar cp;
+    if ((ch & 0x80) == 0x00) {                      // U+0000 - U+007F
+      cp = ch;
+    } else if ((ch & 0xe0) == 0xc0 && i < len) {    // U+0080 - U+07FF
+      cp = (ch & 0x1f) << 6;
+      ch = static_cast<unsigned char>(in[i++]);
+      cp |= (ch & 0x3f);
+    } else if ((ch & 0xf0) == 0xe0 && i+1 < len) {  // U+0800 - U+FFFF
+      cp = (ch & 0x0f) << 12;
+      ch = static_cast<unsigned char>(in[i++]);
+      cp |= (ch & 0x3f) << 6;
+      ch = static_cast<unsigned char>(in[i++]);
+      cp |= (ch & 0x3f);
+    } else if ((ch & 0xf8) == 0xf0 && i+2 < len) {  // U+10000 - U+1FFFFF
+      i += 3;
+      continue;
+    } else if ((ch & 0xfc) == 0xf8 && i+3 < len) {  // U+200000 - U+3FFFFFF
+      i += 4;
+      continue;
+    } else if ((ch & 0xfe) == 0xfc && i+4 < len) {  // U+4000000 - U+7FFFFFFF
+      i += 5;
+      continue;
+    } else {
+      // Invalid first code point.
+      return false;
+    }
+    result.push_back(cp);
+  }
+  out->swap(result);
+  return true;
+}
+
+// Encodes 16-bit wide characters into UTF-8.
+// This implementation is very permissive and may miss invalid code points in
+// its input.
+// TODO(jbroman): Handle more than BMP if widechar ever becomes larger.
+static bool EncodeUtf8(const std::vector<widechar>& in, std::string* out) {
+  std::string result;
+  result.reserve(in.size() * 2);
+  for (std::vector<widechar>::const_iterator it = in.begin(); it != in.end();
+      ++it) {
+    unsigned int cp = *it;
+    if (cp <= 0x007f) {         // U+0000 - U+007F
+      result.push_back(static_cast<char>(cp));
+    } else if (cp <= 0x07ff) {  // U+0080 - U+07FF
+      result.push_back(static_cast<char>(0xc0 | ((cp >> 6) & 0x1f)));
+      result.push_back(static_cast<char>(0x80 | (cp & 0x3f)));
+    } else if (cp <= 0xffff) {  // U+0800 - U+FFFF
+      result.push_back(static_cast<char>(0xe0 | ((cp >> 12) & 0x0f)));
+      result.push_back(static_cast<char>(0x80 | ((cp >> 6) & 0x3f)));
+      result.push_back(static_cast<char>(0x80 | (cp & 0x3f)));
+    } else {
+      // This can't happen if widechar is 16 bits wide.
+      // TODO(jbroman): assert this
+    }
+  }
+  out->swap(result);
+  return true;
+}
+
+}  // namespace
+
+
+namespace liblouis_nacl {
+
+LibLouisWrapper::LibLouisWrapper() {
+  char data_path[] = "/";  // Needed because lou_setDataPath takes a char*.
+  lou_setDataPath(data_path);
+}
+
+LibLouisWrapper::~LibLouisWrapper() {
+  lou_free();
+}
+
+const char* LibLouisWrapper::tables_dir() const {
+  return "/liblouis/tables";
+}
+
+bool LibLouisWrapper::CheckTable(const std::string& table_name) {
+  return lou_getTable(table_name.c_str()) != NULL;
+}
+
+bool LibLouisWrapper::Translate(const TranslationParams& params,
+    TranslationResult* out) {
+  // Convert the character set of the input text.
+  std::vector<widechar> inbuf;
+  if (!DecodeUtf8(params.text, &inbuf)) {
+    // TODO(jbroman): log this
+    return false;
+  }
+
+  int inlen = inbuf.size();
+  int outlen = inlen * 2;  // TODO(jbroman): choose this size more accurately.
+  std::vector<widechar> outbuf(outlen);
+  std::vector<int> text_to_braille(inlen);
+  std::vector<int> braille_to_text(outlen);
+
+  // Compute the cursor position pointer to pass to liblouis.
+  int out_cursor_position;
+  int* out_cursor_position_ptr;
+  if (params.cursor_position < 0) {
+    out_cursor_position = -1;
+    out_cursor_position_ptr = NULL;
+  } else {
+    out_cursor_position = params.cursor_position;
+    out_cursor_position_ptr = &out_cursor_position;
+  }
+
+  // Invoke liblouis.
+  int result = lou_translate(params.table_name.c_str(),
+      &inbuf[0], &inlen, &outbuf[0], &outlen,
+      NULL /* typeform */, NULL /* spacing */,
+      &text_to_braille[0], &braille_to_text[0],
+      out_cursor_position_ptr, dotsIO /* mode */);
+  if (result == 0) {
+    // TODO(jbroman): log this
+    return false;
+  }
+
+  // Massage the result.
+  std::vector<unsigned char> cells;
+  cells.reserve(outlen);
+  for (int i = 0; i < outlen; i++) {
+    cells.push_back(outbuf[i]);
+  }
+  braille_to_text.resize(outlen);
+
+  // Return the translation result.
+  out->cells.swap(cells);
+  out->text_to_braille.swap(text_to_braille);
+  out->braille_to_text.swap(braille_to_text);
+  out->cursor_position = out_cursor_position;
+  return true;
+}
+
+bool LibLouisWrapper::BackTranslate(const std::string& table_name,
+    const std::vector<unsigned char>& cells, std::string* out) {
+  std::vector<widechar> inbuf;
+  inbuf.reserve(cells.size());
+  for (std::vector<unsigned char>::const_iterator it = cells.begin();
+      it != cells.end(); ++it) {
+    // Set the high-order bit to prevent liblouis from dropping empty cells.
+    inbuf.push_back(*it | 0x8000);
+  }
+  int inlen = inbuf.size();
+  int outlen = inlen * 2;  // TODO(jbroman): choose this size more accurately.
+  std::vector<widechar> outbuf(outlen);
+
+  // Invoke liblouis.
+  int result = lou_backTranslateString(table_name.c_str(),
+      &inbuf[0], &inlen, &outbuf[0], &outlen,
+      NULL /* typeform */, NULL /* spacing */, dotsIO /* mode */);
+  if (result == 0) {
+    // TODO(njbroman): log this
+    return false;
+  }
+
+  // Massage the result.
+  outbuf.resize(outlen);
+  std::string text;
+  if (!EncodeUtf8(outbuf, &text)) {
+    // TODO(jbroman): log this
+    return false;
+  }
+
+  // Return the back translation result.
+  out->swap(text);
+  return true;
+}
+
+}  // namespace liblouis_nacl