Handle complex Qt types to read or write widget properties

Program example:

Dim s As size
s.setSize( 140,50)
button1.size = s

Steps to handle assignment statements

1) Prepare left side
        findIdentifierDescription + createVariableAddress (if variable)
2) Prepare right side
3) Read right side
         moveVariableValue( READMODE)
4) Write left side

Write complex component property


Line button1.size = s

1) Compute address of component button1
2) Compute address of component (memory) s
3) none
4) Call method to change component value to variant (getVariant)
          and set Property with QObject::setProperty( variant )

Runtime information needed for 4:

Pointer to getVariant method in s component
Pointer to button1 description (actually the pointer to the widget which is in the runtime description)
type of property
name of property

Read complex component property


s = button1.size

1) Compute address of component address s
2) Compute address of button component (runtime gui)
3) Call QObject::property( ) and call setVariant to change to comp property
4) Write new pointer to component memory

Initializer method  s = Size( 140, 50)


1) Compute address of component s
2) none
3) Call init method which creates and returns pointer to new component
4) Write pointer to new component.


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Structure for component access

COMP_ACCESS_DESC -> comp_type  Dim component or GUI component
read access or write access
COMP_ACCESS_DESC -> access_type
   Call method, access comp property, call QT method, access QT property
        read/ write complex property, call init method


implement for Interpreter / Compiler

-Dim component
   property
      read
      write
   method
   event

- Gui component
   property
      user defined
         read
         write
      QT
         read
         write
   method
   qt method
   event
   qt event

parse varname.propname    (read or write)
or      varname.methodname( par1expr, par2expr...)
or      comp_var_name
or      comp_gui_name
or      guiname.propname
or      guiname.methodname( par1expr1, par2expr2 ...)
or      comp_var( initpar1, initpar2...)

Syntax Examples:

var = variable of simple type like integer
compvar = variable with component type
-> Dim compvar As comptype   or component created with Formdesigner


compvar = comp( 3 )
comp.method1( 2, 4)
var = comp.method( 2 )
var = Date.static_method( )
comp.prop1 = 5
var = comp.prop3

Information for code generation will be created in three steps.

1) find description for Identifier found in parser (function findIdentifierDescription)
2) create code to put address of variable on address stack (interpreter) or ebx stack (compiler) (function createVariableAddress)
3) create code to move variable value (function moveVariableValue)

For an assignment statement idf1 = idf2 the order will be

read idf1
The problem is that writing the value of var1 must be suspended until the right side of the = has completly been parsed and the matching code has been generated. Therefore a description of every detail that is needed to create the code to write the left side will be stored in memory. The starting structure is FACT_DESC with it's access type and the sub_desc_ptr. The access_type describes the type of the substructure and sub_desc_ptr is normally a pointer to the substructure.

Parser structure description

FACT_DESC
  access_type = TYPE_COMPONENT
  sub_desc_ptr = COMP_ACCESS_DESC



Contents of COMP_ACCESS_DESC structure in parser

static methods / init method ??

   access_type
       TYPE_COMPMETH   for method calls
       TYPE_COMPPROP   for property access
       TYPE_QTCOMPMETH   for qt methods
       TYPE_QTCOMPPROP    for qt properties
       TYPE_COMPONENT    for access to whole component (without .)

   comp_type
       TYPE_GUICOMP for GUI components
       TYPE_DIMCOMP  for components created with "Dim varname As compname"
       TYPE_SCOMPONENT  for static component access

   gui_desc_ptr = pointer to GUI_HEADER of component for Gui components
   class_desc_ptr = pointer to COMP_HEADER for Dim components

   sub_desc_ptr
       COMP_PROPERTY if access to property
       COMP_METHOD  if access-type = TYPE_COMPMETH

Call to Qt method willl immediatly create code and set TFLAG_CODE_READY
    interpreter-code
   CODE_GUIMCALL
        + (long) pointer to runtime-gui structure of GUI component
        + (short) function number



Dim component
  Get address of variable
  read component address from variable memory (indaccess)

Gui component
   Get address of GUI runtime description (static place or label)