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pyeKVS
Binary key value storage
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README
pyeKVS for Delphi
PyeKVS is a Key-Value-Storage format for data serialization. The format corresponds to the JSON format, but the values are binary encoded.
pyeKVS format specification
see pyeKVS_Spec.md
Version: 1.0
Date: 01.03.2021
License: MIT
Home: pyeKVS specification
Features
- Storage of an object as a set of key and value
- Key representation as AnsiString
- Value representation as value data type + optional value header [e.g. size] + optional value data
- Value data are stored in binary representation
- Specification for a header of the entire document including format version and size
- Low effort for coding and decoding
- Reduction to necessary data types
Project
This pyeKVS project is a pascal implementation for Delphi. It's stores the data into a stream.
Version
Version: 3
Date: 02.08.2021
Author: Michael Koch
Home: pyeKVS for Delphi
History
Version: 1 from 01.03.2021 for pyeKVS V 1.0
-
initial release Version: 2 from 14.03.2021 for pyeKVS V 1.0
-
update pyeList to use external interfaces
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update pyeDocument
- New constructor to define custom container classes for pyeKVSList, pyeKVSArray and pyeKVSArrayMap User can overwrite these classes to e.g. define own interfaces.
- New constructor to define custom stream classes. Useful to write values direct in userdef stream class
Version: 3 from 02.08.2021 for pyeKVS V 1.0
- Interface TPYEKVSCSVOutput to create CSV output format (external unit)
License
License: MIT
Usage
Limitations All values are saved directly in one bytestream. Because of that:
- the function named 'PutXX' will be saved the values in the order of the function call
- a list value must be completed; late write of list values is not possible
- the stream holds a complete copy of the source data plus keys (memory usage)
The stream is a complete copy of all source data (memory consumption).
procedure TMain.PyeKVS_Save();
var cData:array [0..127] of Byte;
FPYEKVS : TPYEKVSDocument;
L1: TPYEKVSList;
A1,A2: TPYEKVSArray;
begin
//create a document (pyeKVS-stream)
FPYEKVS:=TPYEKVSDocument.Create();
//start with storing values
FPYEKVS.PutBegin;
//simple data types
FPYEKVS.PutInt('Key1', 1);
FPYEKVS.PutInt('Key2', 2);
FPYEKVS.PutInt64('Key3', 3);
FPYEKVS.PutString('Key4', 'Hallo pyeKVS. Make UTF8: �������@��|�');
//array type of vtInt32
A1:=FPYEKVS.PutArray('KeyA1', vtInt32);
A1.PutInt(10);
A1.PutInt(20);
A1.PutInt(30);
//array type of vtStringUTF8 (dynamic item length!)
A2:=FPYEKVS.PutArray('KeyA2', vtStringUTF8);
A2.PutString('String-1');
A2.PutString('String-2');
//list type
L1:=FPYEKVS.PutList('KeyL1');
L1.PutSingle('Key1', Random*10000);
L1.PutDouble('Key2', Random*1000000);
//memory type
FPYEKVS.PutMemory('Mem1', cData, sizeof(cData));
//finish the collection (this call close the stram)
FPYEKVS.PutEnd;
//save the stream to file
FPYEKVS.SaveToFile(ExtractFilePath(Application.ExeName)+'pyeKVS_01.data');
//free the document
FPYEKVS.Free();
end;procedure TMain.PyeKVS_Load();
var cData:array [0..127] of Byte;
FPYEKVS : TPYEKVSDocument;
L1: TPYEKVSList;
A1: TPYEKVSArray;
i:Integer;
s:string;
f:Double;
begin
//create a document (pyeKVS-stream)
FPYEKVS:=TPYEKVSDocument.Create();
//load stream from file
FPYEKVS.LoadFromFile(ExtractFilePath(Application.ExeName)+'pyeKVS_01.data');
//Get some values ...
i:=FPYEKVS.GetInt('Key1');
i:=FPYEKVS.GetInt('Key1');
s:=FPYEKVS.GetString('Key4');
A1:=FPYEKVS.GetArray('KeyA1');
if (A1<>nil) then begin
//Values by index
i:=A1.GetInt(0);
i:=A1.GetInt(1);
i:=A1.GetInt(2);
end;
L1:=FPYEKVS.GetList('KeyL1');
if (L1<>nil) then begin
f:=L1.GetSingle('Key1');
f:=L1.GetDouble('Key2');
end;
FPYEKVS.GetMemory('Mem1', cData, sizeof(cData));
//free the document
FPYEKVS.Free();
end;