int Expression(t_result *result,wchar_t *expression,uchar *data,ulong base,ulong size,ulong threadid,ulong a,ulong b,ulong mode);

Evaluates expression to numerical and/or text value in one step. In fact, this is a shortcut that calls first Cexpression() (expression parser) then Eexpression() (expression estimator). Does not support multi-expression strings. If value of expression must be calculated several times, split this call in two or consider use of Fastexpression().


(out) Structure of type t_result that receives results of the evaluation
(in) Pointer to the expression, zero-terminated UNICODE string. The syntax of  expressions is described here. Note that Expression() is unable to process multi-expression strings in form "<expression1>,<expression2>, ..."
(in) Pointer to the optional copy of memory contents. If data is NULL, flag EMOD_NOMEMORY is not set and expression includes contents of memory, Expression() reads memory of debugged process. If data is not NULL and expression accesses memory in the range [base..base+size-1], contents of memory is taken from the data. In all other cases attempt to access memory will result in the failure
(in) Base address of the supplied data block, ignored if data is NULL
(in) Size of the supplied data block, ignored if data is NULL
(in) Identifier of the thread containing CPU registers used in the evaluation of the expression. If expression specifies register and threadid is 0, Expression() will fail
(in) First parameter, determines value of the pseudovariable %A in expression
(in) Second parameter, determines value of the pseudovariable %B in expression
(in) Evaluation mode, combination of zero or more of the following flags:
EMOD_CHKEXTRA - reports error "Extra characters on line" if the first non-blank symbol
after syntactically complete expression of maximal length is neither '\0' nor semicolon (starts comment)
EMOD_NOVALUE - requests not to convert the binary value of the expression (result->data) to text (result->value)
EMOD_NOMEMORY - forbids reading of the Debuggee's memory. If expression includes contents of memory and data is not supplied, evaluation will fail
EMOD_MULTI - not allowed in calls to Expression()

Return values:

Number of processed UNICODE characters in expression. If expression is syntactically invalid, this is roughly the location of the syntax error. The inability to estimate the value of the syntaxically correct expression is indicated by the type EXPR_INVALID in result->datatype


This is the drawing function of the Watches window:

typedef struct t_watch {               // Watch descriptor
  ulong          addr;                 // 0-based watch index
  ulong          size;                 // Reserved, always 1
  ulong          type;                 // Service information, TY_xxx
  wchar_t        expr[TEXTLEN];        // Watch expression
} t_watch;

// Drawing function of watch window.
int Watchdraw(wchar_t *s,uchar *mask,int *select,
  t_table *pt,t_drawheader *ph,int column,void *cache) {
  int n=0;
  t_watch *pwatch=(t_watch *)ph;
  t_result result;
  switch (column) {
    case DF_CACHESIZE:                 // Request for draw cache size
      return 0;
    case DF_FILLCACHE:                 // Request to fill draw cache
      return 0;
    case DF_FREECACHE:                 // Request to free cached resources
      return 0;
    case DF_NEWROW:                    // Request to start new row in window
      return 0;
    case 0:                            // Expression
    case 1:                            // Value of expression
      if (pwatch->addr==(ulong)watch.sorted.n-1)
        break;                         // Last expression is always empty
      if (result.datatype==EXPR_INVALID)
    default: break; };
  return n;

See also:
Expressions, t_result, t_watch, Cexpression(), Eexpression(), Exprcount(), Fastexpression()