Eval library. Arithmetic,String,Date & Boolean Expression Evaluator You can evaluate expressions at run-time, run-time database filters, enduser friendly inteface.
Download trial version, Demo Exe	Eval library in details	Functions list

                    EVAL Library is library of components for run-time scoring expressions and conditions ordered by user. Basic component is replenished about some of graphic components used for users enjoyable inputting expressions and conditions, so, that final user doesn't have to know syntax of individual functions. There is a component to disposition too, which enables simple registry created expressions and conditions and their again exploitation without necessary again putting information's.

Component TEVAL is base of the library EVAL LIB. Enables to score expressions inputted in the form of string .Library supports almost 180 functions, that some of them are normal using in Delphi, but to many is over standard.

Package of components Eval help serving for alleviation of work in a data base applications written in Delphi. These components have to alleviate respectively to enable following reality .

Problems:

• Filters in the component TDataSet. Standard filters Delphi have several disadvantages
• • they have a very weak collection of supporting functions
  • the work with them in the big database is small
  • they don´t have any user interface
• Calculated fields we can hardly use them, as long we don´t know the formula for their calculation. Sometimes occures a situation, that the   program doesn't know this formula, so we know him at working respectively it can change. Else The work with many calculated fields Delphi program is very decelerated, because these fields are calculated relatively often.
• Delphi doesn't have any users editor of terms and filters like e.g. Excel has.

The solutions :

Our offered package of components Eval in a big section is solving these small Delphi defolts. The basic is the component Eval, which serves for run-time for scoring of expressions ordered in string variables. This component has powerful basic, which string after calculates it analyses and than repeating scores. Besides it's supporting prevailingly section of standard functions Delphi and over has a few very strong functions, which are built into the component TEVAL.

• Filtering tables we can solve by two ways
• 1. To expand a collection of functions by assistance of Teval component with using change on filter record for TDataSet.
  2. These lines of table which are suitable for the filter, put them an a different colour. E.g. in DBGrid we using an event OnDrawDataCell, (OnCellParams) for evaluation of condition through TEval, and if condition = true, we put BackgroundColor = clYellow. Otherwice we can see here all lines of the table but we have expressed that, what we supposed to see with using of point 1. Over and above we received on speed, because it's evaluating whole collection, but always not just that, what is to be seen on the screen. Using the component TEvalDBNavigator we can support an advance just down these lines, which conform a condition.
• Calculated fields we can define directly during a running of a program,  also add new fields. Interfacing event the OnGetText for TField and component Teval we can support transformation of result. See demo.
• For editing of expressions and filters serves a component TEvalPanel or TEvalSimple which allows to select from collection of functions and their parameters and this way to assembly an expression or filter. During setting the result can be controlled directly in this panel for forgetful or comfortable people it contains also history combo box, where you can to selsct from the older conditions and filters,resp. that is to save new expressions and filters.
• The packet of components Eval contains also components, which with their assistance help to assembly own user's dividing line in this way, that it will realize your concept.
• Library EVAL expanding Delphi about quantity of functions, which are necessary for user, e.g. comparison of a text with mistakes, test of chains according to sound equality, operations with dates, transfer of course on text and the like.
• If you buy a version with a source code, you can very easy add your own functions.

Example of user interface:

Example of using component TEvalSimpleDesigner and linked grid with filtered records.

Disadvantages of components EVAL:

As there is evaluated a term, which is defined when the program is working, its evaluation takes a longer time as a classic one. According to measuring installed in demo program to EVAL library, there is a direct compile code and times faster as the evaluation through EVAL library.