TROMacroParser

Overview

TROMacroParser is a class for parsing expressions that allows to replace found variables with their values.

TForm23 = class(TForm)
..
  function Now(Sender: TObject;const Parameters: array of string): string;
end;

function TForm23.Now(Sender: TObject;const Parameters: array of string): string;
begin
  Result := DateTimeToStr(SysUtils.Now);
end;

procedure TForm23.Button1Click(Sender: TObject);
const
  g_macro = '{var1} should be equal to {Now()}';
begin
  with TROMacroParser.Create do try
    // register 'Now' function 
    RegisterProc('Now',Now,0);
    // register a variable
    AddVariable('var1').Value := DateTimeToStr(SysUtils.Now);    
    // evaluate macro
    ShowMessage(Eval(g_macro));  
  finally
    Free;
  end;
end;

Output: 26.02.2010 12:23:50 should be equal to 26.02.2010 12:23:50

Location

Unit: uDAMacros.pas
Ancestry: TDAInterfacedObject | TROMacroParser

constructor Create

Creates a new instance.

constructor Create

AddVariable

Adds a variable.

function AddVariable(const Name: string): TROMacroVar

Parameters:

Name: variable name.

AllowComplexIdent protected

Allows complex identificators, like "table"."name"

property AllowComplexIdent: Boolean read write

AllowDoubleQuotedIdent protected

Allows double quoted identificators, like "field"

property AllowDoubleQuotedIdent: Boolean read write

ClearProcs

Clear all procedures.

procedure ClearProcs

ClearVariables

Clear all variables.

procedure ClearVariables

DeleteVariable (TROMacroVar) overload

Deletes variable

procedure DeleteVariable(aVariable: TROMacroVar)

Parameters:

aVariable: variable

DeleteVariable (Integer) overload

Deletes variable by index

procedure DeleteVariable(I: Integer)

Parameters:

I: index

Eval

Evaluates the given text.

function Eval(const Text: string; TextDelimiter: Char = ''''): string

Parameters:

Text: text
TextDelimiter: delimiter

EvalToken

Evaluates a token.

function EvalToken(const Text: string): string

Parameters:

Text: token

IndexOfName

Returns the position of the first name-value pair with the specified name.

function IndexOfName(const aName: string): Integer

Parameters:

aName: specified name

OnUnknownIdentifier

This event is fired when an unknown variable is detected.

property OnUnknownIdentifier: TOnUnknownIdentifier read write
delegate:  function OnUnknownIdentifier(Sender: TObject; const Name: string; const OrgName: string; var Value: string): Boolean

OpenBlockEscape protected

Allow to use square brackets for identificators, i.e. [something]

property OpenBlockEscape: Boolean read write

QueryInterface protected stdcall (declared in TDAInterfacedObject)

Implements the IInterfaceQueryInterface method.

function QueryInterface(const IID: TGUID; out Obj: ): HResult

Parameters:

IID: Identifier of the interface to return
Obj: Variable to store the returned interface reference to

RefCount protected (declared in TDAInterfacedObject)

Returns 0

property RefCount: Integer read

RegisterProc

Registers a procedure.

procedure RegisterProc(const Name: string; ExProc: TExternalProc; aParamCount: Integer)

Parameters:

Name: Name
ExProc: Method
aParamCount: Parameters count

Variable

Returns the registered variable.

property Variable[I: Integer]: TROMacroVar read

VariableCount

Returns the count of variables.

property VariableCount: Integer read

AllowComplexIdent protected

Allows complex identificators, like "table"."name"

property AllowComplexIdent: Boolean read write

AllowDoubleQuotedIdent protected

Allows double quoted identificators, like "field"

property AllowDoubleQuotedIdent: Boolean read write

OpenBlockEscape protected

Allow to use square brackets for identificators, i.e. [something]

property OpenBlockEscape: Boolean read write

RefCount protected (declared in TDAInterfacedObject)

Returns 0

property RefCount: Integer read

Variable

Returns the registered variable.

property Variable[I: Integer]: TROMacroVar read

VariableCount

Returns the count of variables.

property VariableCount: Integer read

constructor Create

Creates a new instance.

constructor Create

AddVariable

Adds a variable.

function AddVariable(const Name: string): TROMacroVar

Parameters:

Name: variable name.

ClearProcs

Clear all procedures.

procedure ClearProcs

ClearVariables

Clear all variables.

procedure ClearVariables

DeleteVariable (TROMacroVar) overload

Deletes variable

procedure DeleteVariable(aVariable: TROMacroVar)

Parameters:

aVariable: variable

DeleteVariable (Integer) overload

Deletes variable by index

procedure DeleteVariable(I: Integer)

Parameters:

I: index

Eval

Evaluates the given text.

function Eval(const Text: string; TextDelimiter: Char = ''''): string

Parameters:

Text: text
TextDelimiter: delimiter

EvalToken

Evaluates a token.

function EvalToken(const Text: string): string

Parameters:

Text: token

IndexOfName

Returns the position of the first name-value pair with the specified name.

function IndexOfName(const aName: string): Integer

Parameters:

aName: specified name

QueryInterface protected stdcall (declared in TDAInterfacedObject)

Implements the IInterfaceQueryInterface method.

function QueryInterface(const IID: TGUID; out Obj: ): HResult

Parameters:

IID: Identifier of the interface to return
Obj: Variable to store the returned interface reference to

RegisterProc

Registers a procedure.

procedure RegisterProc(const Name: string; ExProc: TExternalProc; aParamCount: Integer)

Parameters:

Name: Name
ExProc: Method
aParamCount: Parameters count

OnUnknownIdentifier

This event is fired when an unknown variable is detected.

property OnUnknownIdentifier: TOnUnknownIdentifier read write
delegate:  function OnUnknownIdentifier(Sender: TObject; const Name: string; const OrgName: string; var Value: string): Boolean

TDASQLMacroProcessor

Macro Processor