[Lazarus] [fpc-pascal] Tests results of several pascal based JSON parsers

[Anthony Walter]

I am not sure how under any situation parsing a JSON from a stream source
would be any faster than parsing a string. Also with regards to timing I am
not sure how accurate Now is. For this purpose I've written:

{ Return a time based on system performance counters }
function TimeQuery: Double;

Implemented as:

const
{$ifdef linux}
  libc = 'libc.so';
{$endif}
{$ifdef darwin}
  libc = 'libSystem.dylib';
{$endif}
function gettimeofday(out TimeVal: TTimeVal; TimeZone: PTimeVal): Integer;
apicall; external libc;

var
  TimeSec: SysInt;

function TimeQuery: Double;
var
  TimeVal: TTimeVal;
begin
  gettimeofday(TimeVal, nil);
  if TimeSec = 0 then
    TimeSec := TimeVal.Sec;
  TimeVal.Sec := TimeVal.Sec - TimeSec;
  Result := TimeVal.Sec + TimeVal.MSec / 1000000;
end;
{$endif}

{$ifdef windows}
const
  kernel32  = 'kernel32.dll';

function QueryPerformanceCounter(var Counter: Int64): LongBool; apicall;
external kernel32;
function QueryPerformanceFrequency(var Frequency: Int64): LongBool;
apicall; external kernel32;

function TimeQuery: Double;
var
  C, F: Int64;
begin
  F := 0;
  C := 0;
  if QueryPerformanceFrequency(F) and QueryPerformanceCounter(C) then
    Result := C / F
  else
    Result := 0;
end;
{$endif}
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