[dws-developer] DWSII 2.0.beta.1

[Matthias A. <mat...@gm...>]

Hello=20

I finally commited my modifications to the CVS (description see  =
change-log and
below). Most changes concern dws2Exprs.pas and deal with some well known =
bugs in
DWSII 1.1. I tested my modifications against all test cases in the =
DWSII-TestBed
(dws2tools\TestBed) and all demo programs. But still there my be some =
problems.
I'm quite sure that there is a problem in dws2ComConnector because of =
the dynamic
arrays. And I didn't test all Tdws2Unit features.=20

Please inform me if you find bugs or problems or if you need closer =
information
about my changes.=20

The next thing I intend to do is to create another beta release from =
DWSII
2.0.beta.1. Afterwards I'll finish the tasks (e. g. documentation) that =
remain to
be done before I release DWSII 2.0.

regards,

Matthias

Changes in DWSII 2.0.beta.1
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=3D=3D

Low/High/Length/SizeOf
----------------------
Delphi supports some "special" functions that take a type as parameter. =
E. g.
the function call "Low(TMyArrayType)" returns the lowest index on the =
array type
TMyArrayType. DWSII now also supports these functions. The necessary =
modifications
were:
Tdws2Compiler.ReadName
Tdws2Compiler.ReadSymbol
Tdws2Compiler.ReadSpecialFunction (new)
dws2Compiler.TSpecialKind (new)
TArrayLengthExpr
TStringLengthExpr

Dynamic Arrays
--------------
Because the support for dynamic arrays was in some parts incomplete I =
replaced
the existing code from Andreas Luleich by another implementation. Now =
dynamic
array behave almost like Delphi arrays, you can pass them as function =
results
and the code is simpler and faster now.

Dynamic arrays are stored as global variables on the stack. You create
such a variable by with dynamic array constant (e. g. "['hello', =
'world']").
Variables of type "array of ..." only hold the (absolute) address of the =
first
element of the dynamic array. The size of the array is stored at this =
address
minus one.

The new or modified classes and functions are:
- TDynamicArraySymbol and TStaticArraySymbol inherit from TArraySymbol
  Definition of array types. Dynamic array types are "array of Integer" =
and
  static array types "array[0..7] of Integer". TArraySymbol is an =
abstract
  superclass.

- TDynamicArrayExpr and TStaticArrayExpr inherit from TArrayExpr
  TDynamicArrayExpr is used to read and write dynamic arrays, =
TStaticArrayExpr
  for static arrays. TArrayExpr is the abstract superclass for both.

- TArrayConstantExpr
  Creates a initialises a dynamic array. The compiler creates this =
objects from
  DWSII code like "a :=3D [1, 2, 3, 4]".

- TProgram.GetGlobalAddr
  TProgram maintains a second TAddressGenerator to generate addresses =
for
  dynamic arrays.

TSymbol
-------
The method CopyData() of TSymbol is no longer necessary because of the =
new
array support.

TStack, TDataExpr
-----------------
The class TStack was extended with several methods (WriteData, =
WriteValue,
ReadValue, ReadData, CopyData) to read and write data from the stack.
The unit dws2Stack contains a new function CopyData().

TDataExpr was also extended, too. The new (or partially renamed) methods =
are
AssignData, AssignDataExpr, AssignExpr and AssignValue.

Prior to these changes the code in dws2Exprs was full of very similar =
code that
copied data. Now this code is encapsulated in TDataExpr and TStack.

TRecordExpr
-----------
Access to record members was achieved by simply altering the offset of =
the base
expression and by modifing its type. The modification of the type =
created several
problems. Therefore I introduced TRecordExpr that accesses a single =
member
of the parent expresssion.

Function Results
----------------
To fix fix several bugs I had to introduce temporary variables to store
function results. If a function returns a record or a static array the
result has to be accessible in the stack-frame of the calling function.
Therefore every function has now in the stack-frame of the calling =
function a
temporary variable to store its result. The functions =
TProgram.GetTempAddr and
TFuncExpr.SetResultAddr are used to generate and set these variables.