1 files changed, 184 insertions, 0 deletions
diff --git a/include/mbgl/util/pbf.hpp b/include/mbgl/util/pbf.hpp
new file mode 100644
index 0000000000..1f78a0072f
--- /dev/null
+++ b/include/mbgl/util/pbf.hpp
@@ -0,0 +1,184 @@
+#ifndef MBGL_UTIL_PBF
+#define MBGL_UTIL_PBF
+
+/*
+ * Some parts are from upb - a minimalist implementation of protocol buffers.
+ *
+ * Copyright (c) 2008-2011 Google Inc.  See LICENSE for details.
+ * Author: Josh Haberman <jhaberman@gmail.com>
+ */
+
+#include <string>
+#include <cstring>
+
+namespace mbgl {
+
+struct pbf {
+    struct exception : std::exception { const char *what() const noexcept { return "pbf exception"; } };
+    struct unterminated_varint_exception : exception { const char *what() const noexcept { return "pbf unterminated varint exception"; } };
+    struct varint_too_long_exception : exception { const char *what() const noexcept { return "pbf varint too long exception"; } };
+    struct unknown_field_type_exception : exception { const char *what() const noexcept { return "pbf unknown field type exception"; } };
+    struct end_of_buffer_exception : exception { const char *what() const noexcept { return "pbf end of buffer exception"; } };
+
+    inline pbf(const unsigned char *data, size_t length);
+    inline pbf();
+
+    inline operator bool() const;
+
+    inline bool next();
+    inline bool next(uint32_t tag);
+    template <typename T = uint32_t> inline T varint();
+    template <typename T = uint32_t> inline T svarint();
+
+    template <typename T = uint32_t, int bytes = 4> inline T fixed();
+    inline float float32();
+    inline double float64();
+
+    inline std::string string();
+    inline bool boolean();
+
+    inline pbf message();
+
+    inline void skip();
+    inline void skipValue(uint32_t val);
+    inline void skipBytes(uint32_t bytes);
+
+    const uint8_t *data = nullptr;
+    const uint8_t *end = nullptr;
+    uint32_t value = 0;
+    uint32_t tag = 0;
+};
+
+pbf::pbf(const unsigned char *data, size_t length)
+    : data(data),
+      end(data + length),
+      value(0),
+      tag(0) {
+}
+
+pbf::pbf()
+    : data(nullptr),
+      end(nullptr),
+      value(0),
+      tag(0) {
+}
+
+
+pbf::operator bool() const {
+    return data < end;
+}
+
+bool pbf::next() {
+    if (data < end) {
+        value = static_cast<uint32_t>(varint());
+        tag = value >> 3;
+        return true;
+    }
+    return false;
+}
+
+bool pbf::next(uint32_t requested_tag) {
+    while (next()) {
+        if (tag == requested_tag) {
+            return true;
+        } else {
+            skip();
+        }
+    }
+    return false;
+}
+
+template <typename T>
+T pbf::varint() {
+    uint8_t byte = 0x80;
+    T result = 0;
+    int bitpos;
+    for (bitpos = 0; bitpos < 70 && (byte & 0x80); bitpos += 7) {
+        if (data >= end) {
+            throw unterminated_varint_exception();
+        }
+        result |= ((T)(byte = *data) & 0x7F) << bitpos;
+
+        data++;
+    }
+    if (bitpos == 70 && (byte & 0x80)) {
+        throw varint_too_long_exception();
+    }
+
+    return result;
+}
+
+template <typename T>
+T pbf::svarint() {
+    T n = varint<T>();
+    return (n >> 1) ^ -(T)(n & 1);
+}
+
+template <typename T, int bytes>
+T pbf::fixed() {
+    skipBytes(bytes);
+    T result;
+    memcpy(&result, data - bytes, bytes);
+    return result;
+}
+
+float pbf::float32() {
+    return fixed<float, 4>();
+}
+
+double pbf::float64() {
+    return fixed<double, 8>();
+}
+
+std::string pbf::string() {
+    uint32_t bytes = static_cast<uint32_t>(varint());
+    const char *string = reinterpret_cast<const char*>(data);
+    skipBytes(bytes);
+    return std::string(string, bytes);
+}
+
+bool pbf::boolean() {
+    skipBytes(1);
+    return *(bool *)(data - 1);
+}
+
+pbf pbf::message() {
+    uint32_t bytes = static_cast<uint32_t>(varint());
+    const uint8_t *pos = data;
+    skipBytes(bytes);
+    return pbf(pos, bytes);
+}
+
+void pbf::skip() {
+    skipValue(value);
+}
+
+void pbf::skipValue(uint32_t val) {
+    switch (val & 0x7) {
+        case 0: // varint
+            varint();
+            break;
+        case 1: // 64 bit
+            skipBytes(8);
+            break;
+        case 2: // string/message
+            skipBytes(static_cast<uint32_t>(varint()));
+            break;
+        case 5: // 32 bit
+            skipBytes(4);
+            break;
+        default:
+            throw unknown_field_type_exception();
+    }
+}
+
+void pbf::skipBytes(uint32_t bytes) {
+    if (data + bytes > end) {
+        throw end_of_buffer_exception();
+    }
+    data += bytes;
+}
+
+} // end namespace mbgl
+
+#endif