device/bluetooth: Implemented UriBeacon decoder.

device/bluetooth/uribeacon/uri_encoder.cc

Index: device/bluetooth/uribeacon/uri_encoder.cc
diff --git a/device/bluetooth/uribeacon/uri_encoder.cc b/device/bluetooth/uribeacon/uri_encoder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2c3fe4dfff14b85ca95f05d6209b93991416ea10
--- /dev/null
+++ b/device/bluetooth/uribeacon/uri_encoder.cc
@@ -0,0 +1,135 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "uri_encoder.h"
+
+using base::StringPiece;
+
+namespace {
+
+struct expansion {
+  uint8_t code;
+  const char* value;
+};
+
+// The two following data structures are the expansions code tables for URI
+// encoding described in the following specification:
+// https://github.com/google/uribeacon/blob/master/specification/AdvertisingMode.md
+
+// For the prefix of the URI.
+struct expansion prefix_expansions_list[] = {
+    {0, "http://www."},
+    {1, "https://www."},
+    {2, "http://"},
+    {3, "https://"},
+    {4, "urn:uuid:"},
+};
+
+// For the remaining part of the URI.
+struct expansion expansions_list[] = {
+    {0, ".com/"},
+    {1, ".org/"},
+    {2, ".edu/"},
+    {3, ".net/"},
+    {4, ".info/"},
+    {5, ".biz/"},
+    {6, ".gov/"},
+    {7, ".com"},
+    {8, ".org"},
+    {9, ".edu"},
+    {10, ".net"},
+    {11, ".info"},
+    {12, ".biz"},
+    {13, ".gov"},
+};
+
+struct expansion* CommonLookupExpansionByValue(struct expansion* table,
+                                               int table_length,
+                                               const std::string& input,
+                                               int input_index) {
+  int found = -1;
+  int found_length = -1;
+
+  for (int k = 0; k < table_length; k++) {
+    const char* value = table[k].value;
+    int len = strlen(table[k].value);
+    if (input_index + len <= static_cast<int>(input.size())) {
+      if (len > found_length && strncmp(&input[input_index], value, len) == 0) {
+        found = k;
+        found_length = len;
+      }
+    }
+  }
+  if (found == -1) {
+    return NULL;
+  }

[armansito, 2015/03/06 22:00:30]

nit: no need for curly braces in single-line if body. Here and elsewhere.

[dvh, 2015/03/09 20:52:00]

Done.

+  return &table[found];
+}
+
+struct expansion* LookupExpansionByValue(const std::string& input,
+                                         int input_index) {
+  return CommonLookupExpansionByValue(
+      expansions_list, arraysize(expansions_list), input, input_index);
+}
+
+struct expansion* LookupPrefixExpansionByValue(const std::string& input,
+                                               int input_index) {
+  return CommonLookupExpansionByValue(prefix_expansions_list,
+                                      arraysize(prefix_expansions_list), input,
+                                      input_index);
+}
+
+struct expansion* LookupExpansionByCode(const std::vector<uint8_t>& input,
+                                        int input_index) {
+  if (input[input_index] >= arraysize(expansions_list))
+    return NULL;
+  return &expansions_list[input[input_index]];
+}
+
+struct expansion* LookupPrefixExpansionByCode(const std::vector<uint8_t>& input,
+                                              int input_index) {
+  if (input[input_index] >= arraysize(prefix_expansions_list))
+    return NULL;
+  return &prefix_expansions_list[input[input_index]];
+}
+
+}  // namespace
+
+void device::EncodeUriBeaconUri(const std::string& input,
+                                std::vector<uint8_t>& output) {
+  int i = 0;
+  while (i < static_cast<int>(input.size())) {
+    struct expansion* exp;
+    if (i == 0) {
+      exp = LookupPrefixExpansionByValue(input, i);

[armansito, 2015/03/06 22:00:30]

nit: ditto

[dvh, 2015/03/09 20:52:00]

Done.

+    } else {

[armansito, 2015/03/06 22:00:30]

nit: ditto

[dvh, 2015/03/09 20:52:00]

Done.

+      exp = LookupExpansionByValue(input, i);
+    }
+    if (exp == NULL) {
+      output.push_back(static_cast<uint8_t>(input[i]));
+      i++;
+    } else {
+      output.push_back(exp->code);
+      i += strlen(exp->value);
+    }
+  }
+}
+
+void device::DecodeUriBeaconUri(const std::vector<uint8_t>& input,
+                                std::string& output) {
+  int length = input.size();
+  for (int i = 0; i < length; i++) {
+    struct expansion* exp;
+    if (i == 0) {

[armansito, 2015/03/06 22:00:30]

nit: ditto

[dvh, 2015/03/09 20:52:00]

Done.

+      exp = LookupPrefixExpansionByCode(input, i);
+    } else {
+      exp = LookupExpansionByCode(input, i);
+    }
+    if (exp == NULL) {

[armansito, 2015/03/06 22:00:30]

nit: ditto

[dvh, 2015/03/09 20:52:00]

Done.

+      output.push_back(static_cast<char>(input[i]));
+    } else {
+      output.append(exp->value);
+    }
+  }
+}