Add Packer/Unpacker, add serialization to LuaSnap

luprex/core/cpp/packer.cpp

@@ -0,0 +1,115 @@
+#include <packer.hpp>
+#include <cassert>
+
+void Packer::write_int8(int8_t v) {
+    oss_->write((const char *)&v, sizeof(v));
+}
+
+void Packer::write_int16(int16_t v) {
+    oss_->write((const char *)&v, sizeof(v));
+}
+
+void Packer::write_int32(int32_t v) {
+    oss_->write((const char *)&v, sizeof(v));
+}
+
+void Packer::write_int64(int64_t v) {
+    oss_->write((const char *)&v, sizeof(v));
+}
+
+void Packer::overwrite_int8(size_t tell_after, int8_t v) {
+    oss_->seekp(tell_after - 1);
+    write_int8(v);
+    oss_->seekp(0, std::ios_base::end);
+}
+
+void Packer::overwrite_int16(size_t tell_after, int16_t v) {
+    oss_->seekp(tell_after - 2);
+    write_int16(v);
+    oss_->seekp(0, std::ios_base::end);
+}
+
+void Packer::overwrite_int32(size_t tell_after, int32_t v) {
+    oss_->seekp(tell_after - 4);
+    write_int32(v);
+    oss_->seekp(0, std::ios_base::end);
+}
+
+void Packer::overwrite_int64(size_t tell_after, int64_t v) {
+    oss_->seekp(tell_after - 8);
+    write_int64(v);
+    oss_->seekp(0, std::ios_base::end);
+}
+
+int Packer::lua_writer(lua_State *L, const void *p, size_t sz, void *ud) {
+    Packer *pkr = (Packer *)ud;
+    pkr->oss_->write((const char *)p, sz);
+    return 0;
+}
+
+Unpacker::Unpacker(const char *d, size_t s) {
+    assert(d != nullptr);
+    assert(s >= 0);
+    data_ = d;
+    size_ = s;
+}
+
+int8_t Unpacker::read_int8() {
+    assert(size_ >= 1);
+    int8_t result;
+    memcpy(&result, data_, 1);
+    data_ += 1;
+    size_ -= 1;
+    return result;
+}
+
+int16_t Unpacker::read_int16() {
+    assert(size_ >= 2);
+    int16_t result;
+    memcpy(&result, data_, 2);
+    data_ += 2;
+    size_ -= 2;
+    return result;
+}
+
+int32_t Unpacker::read_int32() {
+    assert(size_ >= 4);
+    int32_t result;
+    memcpy(&result, data_, 4);
+    data_ += 4;
+    size_ -= 4;
+    return result;
+}
+
+int64_t Unpacker::read_int64() {
+    assert(size_ >= 8);
+    int64_t result;
+    memcpy(&result, data_, 8);
+    data_ += 8;
+    size_ -= 8;
+    return result;
+}
+
+void Unpacker::skip(size_t n) {
+    assert(size_ >= n);
+    data_ += n;
+    size_ -= n;
+}
+
+Unpacker Unpacker::read_section(size_t n) {
+    assert(size_ >= n);
+    const char *d = data_;
+    data_ += n;
+    size_ -= n;
+    return Unpacker(d, n);
+}
+
+const char *Unpacker::lua_reader(lua_State *L, void *ud, size_t *size) {
+    Unpacker *unpk = (Unpacker *)ud;
+    const char *retval = unpk->data_;
+    *size = unpk->size_;
+    if (unpk->size_ == 0) retval = nullptr;
+    unpk->data_ += unpk->size_;
+    unpk->size_ = 0;
+    return retval;
+}