add support for serializing and deserializing records

src/dpq2/conv/from_d_types.d

@@ -317,8 +317,35 @@ if (is(Unqual!T == Json))
     return r;
 }
 
+Value toRecordValue(Value[] elements)
+{
+    import std.array : appender;
+    auto buffer = appender!(ubyte[])();
+    buffer ~= nativeToBigEndian!int(cast(int)elements.length)[];
+    foreach (element; elements)
+    {
+        buffer ~= nativeToBigEndian!int(element.oidType)[];
+        if (element.isNull) {
+            buffer ~= nativeToBigEndian!int(-1)[];
+        } else {
+            buffer ~= nativeToBigEndian!int(cast(int)element.data.length)[];
+            buffer ~= element.data;
+        }
+    }
+
+    return Value(buffer.data.idup, OidType.Record);
+}
+
 version(unittest)
-import dpq2.conv.to_d_types : as;
+import dpq2.conv.to_d_types : as, deserializeRecord;
+
+unittest
+{
+    import std.stdio;
+    Value[] vals = [toValue(17.34), toValue(Nullable!long(17)), toValue(Nullable!long.init)];
+    Value v = vals.toRecordValue;
+    assert(deserializeRecord(v) == vals);
+}
 
 unittest
 {

src/dpq2/conv/to_d_types.d

@@ -117,6 +117,47 @@ if(!is(T : const(char)[]) && !is(T == Bson) && !is(T == Nullable!R,R))
     assertThrown!AE(v.as!int);
 }
 
+Value[] deserializeRecord(in Value v)
+{
+    if(!(v.oidType == OidType.Record))
+        throwTypeComplaint(v.oidType, "record", __FILE__, __LINE__);
+
+    if(!(v.data.length >= uint.sizeof))
+        throw new AE(ET.SIZE_MISMATCH,
+            "Value length isn't enough to hold a size", __FILE__, __LINE__);
+
+    immutable(ubyte)[] data = v.data;
+    uint entries = bigEndianToNative!uint(v.data[0 .. uint.sizeof]);
+    data = data[uint.sizeof .. $];
+
+    Value[] ret = new Value[entries];
+
+    foreach (ref res; ret) {
+        if (!(data.length >= 2*int.sizeof))
+            throw new AE(ET.SIZE_MISMATCH,
+                "Value length isn't enough to hold an oid and a size", __FILE__, __LINE__);
+        OidType oidType = cast(OidType)bigEndianToNative!int(data[0 .. int.sizeof]);
+        data = data[int.sizeof .. $];
+        int size = bigEndianToNative!int(data[0 .. int.sizeof]);
+        data = data[int.sizeof .. $];
+
+        if (size == -1)
+        {
+            res = Value(null, oidType, true);
+            continue;
+        }
+        assert(size >= 0);
+        if (!(data.length >= size))
+            throw new AE(ET.SIZE_MISMATCH,
+                "Value length isn't enough to hold object body", __FILE__, __LINE__);
+        immutable(ubyte)[] resData = data[0 .. size];
+        data = data[size .. $];
+        res = Value(resData, oidType);
+    }
+
+    return ret;
+}
+
 package:
 
 /*