Mega Code Archive
A Class to Get Tokens, Parse Strings, Count Words, Search Tokens
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Title: A Class to Get Tokens, Parse Strings, Count Words, Search Tokens.
Question: A general way for get tokens, parse strings, count words and search for a specific token on a string.
Answer:
There are many functions and ways for get a token on a string. I have written a general class for handle tokens and parse strings.
The class is named as TToken. I want to describe it with some examples.
var xTk: TToken;
i: Integer;
s: String;
b: Boolean;
begin
xTk:=TToken.Create;
{//////////
the class has some variables:
TEXT contains the string to handle
SEPS contains the set of characters that separate tokens
}
xTk.Text:='Here is my example. Contains commas, dots and spaces.';
xTk.Seps:=[' ',',','.'];
{//////////
with the method COUNT I can count the number of tokens.
I can use it on two ways, I can call the method and the variable NUMTOKENS save the number of tokens or I can assign the method to a memory variable. Here is the example of the two ways.
}
i:=xTk.Count;
ShowMessage(IntToStr(i));
ShowMessage(IntToStr(xTk.NumTokens));
{//////////
When I want to search all tokens on a sequential way Im going to use the methods FIRT and NEXT. Im going to use two Variables: MORETOKENS and LASTTOKEN. MORETOKENS is a boolean variabale that indicates that after I execute the First or Next method I have a token that is saved on the LASTTOKEN variable
}
xTk.First;
while xTk.MoreTokens do begin
ShowMessage(xTk.LastToken);
xTk.Next;
end;
{//////////
I can assign the Firt and Next method to a memory variable and I can use the variable NOTOKEN that contains the negative value of MORETOKENS
}
s:=xTk.First;
while not xTk.NoToken do begin
ShowMessage(s);
s:=xTk.Next;
end;
{//////////
I can search for a specific token with the SEARCH method
}
b:=xTk.Search('IS');
if b then
ShowMessage('Found it')
else
ShowMessage('Not found it');
b:=xTk.Search('YOUR');
if b then
ShowMessage('Found it')
else
ShowMessage('Not found it');
xTk.Free;
end;
///////////////////////////////////////////////////////////////
The class is:
unit UToken;
{
Class for handle Tokens
Author: Alejandro Castro
}
interface
uses SysUtils;
type
TToken = Class(Tobject)
private
xCharText: String;
function xGetToken(xText: String): String;
public
Seps: set of char; // Separators
Text: String; // string to handle
LastToken: String; // token readed with first or next method
NoToken: Boolean; // flag that indicate that there ARENT more tokens
MoreTokens: Boolean;// flag that indicate that there ARE more tokens
NumTokens: Integer; // no of tokens on Text
constructor Create;
function Count: Integer; // count the number of tokens
function First: String; // Find the First Token
function Next: String; // Find the Next Token
function Search(TokSearch: String): Boolean;// Search for a specific token
end;
implementation
constructor TToken.Create;
begin
Seps:=[];
Text:='';
xCharText:='';
NoToken:=True;
MoreTokens:=False;
LastToken:='';
end;
function TToken.Count: Integer;
var i,xLen: Integer;
xFlag: Boolean;
begin
NumTokens:=0;
xLen:=length(Text);
i:=1;
xFlag:=False;
while (i0) do begin
if (Text[i] in Seps) then
xFlag:=False
else begin
if (not xFlag) then begin
xFlag:=True;
inc(NumTokens);
end;
end;
inc(i);
end;
Result:=NumTokens;
end;
function TToken.Next: String;
begin
Result:=xGetToken(xCharText);
LastToken:=Result;
if Result='' then
NoToken:=True
else
NoToken:=False;
MoreTokens:=not NoToken;
end;
function TToken.First: String;
begin
Result:=xGetToken(Text);
LastToken:=Result;
if Result='' then
NoToken:=True
else
NoToken:=False;
MoreTokens:=not NoToken;
end;
function TToken.xGetToken(xText: String): String;
var i,xLen: Integer;
xFlag,xAgain: Boolean;
begin
Result:='';
xLen:=length(xText);
i:=1;
xFlag:=False;
xAgain:=True;
while (i0) and (xAgain) do begin
if (xText[i] in Seps) then begin
xAgain:=(xAgain and (not xFlag));
xFlag:=False
end
else begin
if (not xFlag) then begin
xFlag:=True;
xAgain:=true;
end;
Result:=Result+xText[i];
end;
inc(i);
end;
xCharText:=copy(xText,i,xLen);
end;
function TToken.Search(TokSearch: String): Boolean;
var xAgain: Boolean;
begin
Result:=False;
xAgain:=True;
First;
while (not noToken) and (xAgain) do begin
if UpperCase(LastToken)=UpperCase(TokSearch) then begin
Result:=true;
xAgain:=False;
end;
Next;
end;
end;
end.
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