Build liblouis_nacl using gyp.

third_party/liblouis/nacl_wrapper/liblouis_instance.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_instance.h"
+
+#include <cstring>
+#include <sys/mount.h>
+#include <vector>
+
+#include "nacl_io/nacl_io.h"
+#include "ppapi/c/pp_errors.h"
+#include "ppapi/cpp/module.h"
+
+#include "translation_result.h"
+
+namespace {
+
+static const char kHexadecimalChars[] = "0123456789abcdef";
+
+// Converts a vector of bytes into a (lowercase) hexadecimal string.
+static void BytesToHexString(const std::vector<unsigned char>& bytes,
+    std::string* out) {
+  std::string hex;
+  hex.reserve(bytes.size() * 2);
+  for (size_t i = 0; i < bytes.size(); ++i) {
+    unsigned char byte = bytes[i];
+    hex.push_back(kHexadecimalChars[byte >> 4]);
+    hex.push_back(kHexadecimalChars[byte & 0x0f]);
+  }
+  out->swap(hex);
+}
+
+// Converts a hexadecimal string to a vector of bytes.
+// Returns false on failure.
+static bool HexStringToBytes(const std::string& hex,
+    std::vector<unsigned char>* out) {
+  if (hex.size() % 2 != 0) {
+    return false;
+  }
+
+  std::vector<unsigned char> bytes;
+  bytes.reserve(hex.size() / 2);
+  for (size_t i = 0; i < hex.size(); i += 2) {
+    unsigned char byte;
+    char ch = hex[i];
+    if ('0' <= ch && ch <= '9') {
+      byte = (ch - '0') << 4;
+    } else if ('a' <= ch && ch <= 'f') {
+      byte = (ch - 'a' + 10) << 4;
+    } else if ('A' <= ch && ch <= 'F') {
+      byte = (ch - 'A' + 10) << 4;
+    } else {
+      return false;
+    }
+    ch = hex[i+1];
+    if ('0' <= ch && ch <= '9') {
+      byte |= ch - '0';
+    } else if ('a' <= ch && ch <= 'f') {
+      byte |= ch - 'a' + 10;
+    } else if ('A' <= ch && ch <= 'F') {
+      byte |= ch - 'A' + 10;
+    } else {
+      return false;
+    }
+    bytes.push_back(byte);
+  }
+  out->swap(bytes);
+  return true;
+}
+
+template <typename T>
+static void CopyVectorToJson(const std::vector<T>& vec, Json::Value* out) {
+  Json::Value result(Json::arrayValue);
+  result.resize(vec.size());
+  for (size_t i = 0; i < vec.size(); ++i) {
+    result[i] = vec[i];
+  }
+  out->swap(result);
+}
+
+}  // namespace
+
+
+namespace liblouis_nacl {
+
+// Well-known strings used for configuration.
+static const char kTablesDirKey[] = "tablesdir";
+static const char kTablesDirDefault[] = "tables";
+
+// Well-known strings used in JSON messages.
+static const char kCommandKey[] = "command";
+static const char kMessageIdKey[] = "message_id";
+static const char kInReplyToKey[] = "in_reply_to";
+static const char kErrorKey[] = "error";
+static const char kTableNameKey[] = "table_name";
+static const char kSuccessKey[] = "success";
+static const char kTextKey[] = "text";
+static const char kCellsKey[] = "cells";
+static const char kCursorPositionKey[] = "cursor_position";
+static const char kTextToBrailleKey[] = "text_to_braille";
+static const char kBrailleToTextKey[] = "braille_to_text";
+static const char kCheckTableCommand[] = "CheckTable";
+static const char kTranslateCommand[] = "Translate";
+static const char kBackTranslateCommand[] = "BackTranslate";
+
+LibLouisInstance::LibLouisInstance(PP_Instance instance)
+    : pp::Instance(instance), liblouis_thread_(this), cc_factory_(this) {}
+
+LibLouisInstance::~LibLouisInstance() {}
+
+bool LibLouisInstance::Init(uint32_t argc, const char* argn[],
+    const char* argv[]) {
+  const char* tables_dir = kTablesDirDefault;
+  for (size_t i = 0; i < argc; ++i) {
+    if (strcmp(argn[i], kTablesDirKey) == 0) {
+      tables_dir = argv[i];
+    }
+  }
+
+  nacl_io_init_ppapi(pp_instance(),
+      pp::Module::Get()->get_browser_interface());
+  if (mount(tables_dir, liblouis_.tables_dir(), "httpfs", 0, "") != 0) {
+    // TODO(jbroman): report this error.
+    return false;
+  }
+
+  return liblouis_thread_.Start();
+}
+
+void LibLouisInstance::HandleMessage(const pp::Var& var_message) {
+  if (!var_message.is_string()) {
+    PostError("expected message to be a JSON string");
+    return;
+  }
+
+  Json::Value message;
+  Json::Reader reader;
+  bool parsed = reader.parse(var_message.AsString(),
+      message, false /* collectComments */);
+  if (!parsed) {
+    PostError("expected message to be a JSON string");
+    return;
+  }
+
+  Json::Value message_id = message[kMessageIdKey];
+  if (!message_id.isString()) {
+    PostError("expected message_id string");
+    return;
+  }
+  std::string message_id_str = message_id.asString();
+
+  Json::Value command = message[kCommandKey];
+  if (!command.isString()) {
+    PostError("expected command string", message_id_str);
+    return;
+  }
+
+  std::string command_str = command.asString();
+  if (command_str == kCheckTableCommand) {
+    HandleCheckTable(message, message_id_str);
+  } else if (command_str == kTranslateCommand) {
+    HandleTranslate(message, message_id_str);
+  } else if (command_str == kBackTranslateCommand) {
+    HandleBackTranslate(message, message_id_str);
+  } else {
+    PostError("unknown command", message_id_str);
+  }
+}
+
+void LibLouisInstance::PostReply(Json::Value reply,
+    const std::string& in_reply_to) {
+  Json::FastWriter writer;
+  reply[kInReplyToKey] = in_reply_to;
+  pp::Var var_reply(writer.write(reply));
+  PostMessage(var_reply);
+}
+
+void LibLouisInstance::PostError(const std::string& error_message) {
+  Json::FastWriter writer;
+  Json::Value reply(Json::objectValue);
+  reply[kErrorKey] = error_message;
+  pp::Var var_reply(writer.write(reply));
+  PostMessage(var_reply);
+}
+
+void LibLouisInstance::PostError(const std::string& error_message,
+    const std::string& in_reply_to) {
+  Json::FastWriter writer;
+  Json::Value reply(Json::objectValue);
+  reply[kErrorKey] = error_message;
+  reply[kInReplyToKey] = in_reply_to;
+  reply[kSuccessKey] = false;
+  pp::Var var_reply(writer.write(reply));
+  PostMessage(var_reply);
+}
+
+void LibLouisInstance::HandleCheckTable(const Json::Value& message,
+    const std::string& message_id) {
+  Json::Value table_name = message[kTableNameKey];
+  if (!table_name.isString()) {
+    PostError("expected table_name to be a string", message_id);
+    return;
+  }
+  PostWorkToBackground(cc_factory_.NewCallback(
+      &LibLouisInstance::CheckTableInBackground,
+      table_name.asString(), message_id));
+}
+
+void LibLouisInstance::CheckTableInBackground(int32_t result,
+    const std::string& table_name, const std::string& message_id) {
+  if (result != PP_OK) {
+    PostError("failed to transfer call to background thread", message_id);
+    return;
+  }
+  bool success = liblouis_.CheckTable(table_name);
+  Json::Value reply(Json::objectValue);
+  reply[kSuccessKey] = success;
+  PostReply(reply, message_id);
+}
+
+void LibLouisInstance::HandleTranslate(const Json::Value& message,
+    const std::string& message_id) {
+  Json::Value table_name = message[kTableNameKey];
+  Json::Value text = message[kTextKey];
+  Json::Value cursor_position = message[kCursorPositionKey];
+  if (!table_name.isString()) {
+    PostError("expected table_name to be a string", message_id);
+    return;
+  } else if (!text.isString()) {
+    PostError("expected text to be a string", message_id);
+    return;
+  } else if (!cursor_position.isNull() && !cursor_position.isIntegral()) {
+    PostError("expected cursor_position to be null or integral", message_id);
+    return;
+  }
+  TranslationParams params;
+  params.table_name = table_name.asString();
+  params.text = text.asString();
+  params.cursor_position = cursor_position.isIntegral() ?
+      cursor_position.asInt() : -1;
+  PostWorkToBackground(cc_factory_.NewCallback(
+      &LibLouisInstance::TranslateInBackground,
+      params, message_id));
+}
+
+void LibLouisInstance::TranslateInBackground(int32_t result,
+    const TranslationParams& params, const std::string& message_id) {
+  if (result != PP_OK) {
+    PostError("failed to transfer call to background thread", message_id);
+    return;
+  }
+  TranslationResult translation_result;
+  bool success = liblouis_.Translate(params, &translation_result);
+  Json::Value reply(Json::objectValue);
+  reply[kSuccessKey] = success;
+  if (success) {
+    std::string hex_cells;
+    Json::Value text_to_braille;
+    Json::Value braille_to_text;
+    BytesToHexString(translation_result.cells, &hex_cells);
+    CopyVectorToJson(translation_result.text_to_braille, &text_to_braille);
+    CopyVectorToJson(translation_result.braille_to_text, &braille_to_text);
+    reply[kCellsKey] = hex_cells;
+    reply[kTextToBrailleKey] = text_to_braille;
+    reply[kBrailleToTextKey] = braille_to_text;
+    if (translation_result.cursor_position >= 0) {
+      reply[kCursorPositionKey] = translation_result.cursor_position;
+    }
+  }
+  PostReply(reply, message_id);
+}
+
+void LibLouisInstance::HandleBackTranslate(const Json::Value& message,
+    const std::string& message_id) {
+  Json::Value table_name = message[kTableNameKey];
+  Json::Value cells = message[kCellsKey];
+  if (!table_name.isString()) {
+    PostError("expected table_name to be a string", message_id);
+    return;
+  } else if (!cells.isString()) {
+    PostError("expected cells to be a string", message_id);
+    return;
+  }
+  std::vector<unsigned char> cells_vector;
+  if (!HexStringToBytes(cells.asString(), &cells_vector)) {
+    PostError("expected cells to be a valid hexadecimal string", message_id);
+    return;
+  }
+  PostWorkToBackground(cc_factory_.NewCallback(
+      &LibLouisInstance::BackTranslateInBackground,
+      table_name.asString(), cells_vector, message_id));
+}
+
+void LibLouisInstance::BackTranslateInBackground(int32_t result,
+    const std::string& table_name, const std::vector<unsigned char>& cells,
+    const std::string& message_id) {
+  if (result != PP_OK) {
+    PostError("failed to transfer call to background thread", message_id);
+    return;
+  }
+  std::string text;
+  bool success = liblouis_.BackTranslate(table_name, cells, &text);
+  Json::Value reply(Json::objectValue);
+  reply[kSuccessKey] = success;
+  if (success) {
+    reply[kTextKey] = text;
+  }
+  PostReply(reply, message_id);
+}
+
+}  // namespace liblouis_nacl