{
* URoutineCreditsParser.pas
*
* Provides an implementation of IActiveTextParser that can parse the markup
* used in Credits elements of data files and convert the markup into an active
* text object.
*
* $Rev$
* $Date$
*
* ***** BEGIN LICENSE BLOCK *****
*
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The Original Code is URoutineCreditsParser.pas
*
* The Initial Developer of the Original Code is Peter Johnson
* (http://www.delphidabbler.com/).
*
* Portions created by the Initial Developer are Copyright (C) 2008-2009 Peter
* Johnson. All Rights Reserved.
*
* Contributor(s)
* NONE
*
* ***** END LICENSE BLOCK *****
}
unit URoutineCreditsParser;
interface
uses
// Project
UActiveText;
type
{
TRoutineCreditsParser:
Class that parses markup used in Credits element read from snippets data
files. Markup is translated into active text. The Credits element may occur
in main database files and v1 of the user database and export files.
}
TRoutineCreditsParser = class(TInterfacedObject, IActiveTextParser)
strict private
fURL: string;
{URL to use in any link contained in markup}
protected // do not make strict
{ IActiveTextParser method }
procedure Parse(const Markup: string; const ActiveText: IActiveText);
{Parses markup and updates active text object with details.
@param Markup [in] Markup containing definition of active text. Must be
in format understood by parser.
@param ActiveText [in] Active text object updated by parser.
}
public
constructor Create(const URL: string);
{Class constructor. Sets up object.
@param URL [in] URL to be used in any hyperlinks.
}
end;
implementation
{
About the "Credits" Markup
--------------------------
The markup is simple. It is just plain text with at most one group of text
delimited by '[' and ']' characters. The text enclosed in brackets represents
a hyperlink. The destination URL of the hyperlink is given by the URL
parameter passed to the constructor.
Examples:
"Some markup without a link."
"Some markup with a [link]."
}
uses
// Delphi
SysUtils, StrUtils,
// Project
UUtils;
{ TRoutineCreditsParser }
constructor TRoutineCreditsParser.Create(const URL: string);
{Class constructor. Sets up object.
@param URL [in] URL to be used in any hyperlinks.
}
begin
inherited Create;
fURL := URL;
end;
procedure TRoutineCreditsParser.Parse(const Markup: string;
const ActiveText: IActiveText);
{Parses markup and updates active text object with details.
@param Markup [in] Markup containing definition of active text. Must be in
format understood by parser.
@param ActiveText [in] Active text object updated by parser.
}
const
cOpenBracket = '['; // open bracket character that starts a link
cCloseBracket = ']'; // close bracket character that ends a link
resourcestring
// Error messages
sUnexpectedCloser = 'Unexpected closing bracket found';
sUnterminatedLink = 'Unterminated link';
sEmptyLink = 'Empty link definition';
sWrongBracketOrder = 'Close bracket preceeds link open bracket';
sMultipleOpeners = 'More than one open bracket is present';
sMultipleClosers = 'More than one close bracket is present';
sNoURL = 'No URL specified';
var
OpenBracketPos: Integer; // position of opening bracket in markup
CloseBracketPos: Integer; // position of closing bracket in markup
Prefix, Postfix: string; // text before and after link (can be empty)
LinkText: string; // link text
begin
// Find open and closing brackets that delimit link text
OpenBracketPos := AnsiPos(cOpenBracket, Markup);
CloseBracketPos := AnsiPos(cCloseBracket, Markup);
if OpenBracketPos = 0 then
begin
// No links: plain text only
// check for errors
if CloseBracketPos > 0 then
raise EActiveTextParserError.Create(sUnexpectedCloser);
// record text element
ActiveText.AddElem(TActiveTextFactory.CreateTextElem(Markup));
end
else
begin
// We have a potential link
// check for errors
if CloseBracketPos = 0 then
raise EActiveTextParserError.Create(sUnterminatedLink);
if CloseBracketPos = OpenBracketPos + 1 then
raise EActiveTextParserError.Create(sEmptyLink);
if CloseBracketPos < OpenBracketPos then
raise EActiveTextParserError.Create(sWrongBracketOrder);
if CountDelims(Markup, cOpenBracket) > 1 then
raise EActiveTextParserError.Create(sMultipleOpeners);
if CountDelims(Markup, cCloseBracket) > 1 then
raise EActiveTextParserError.Create(sMultipleClosers);
// must have a URL
if fURL = '' then
raise EActiveTextParserError.Create(sNoURL);
// get the various components
LinkText := MidStr(
Markup, OpenBracketPos + 1, CloseBracketPos - OpenBracketPos - 1
);
Assert(LinkText <> '', // ** do not localise
ClassName + '.Parse: Link text is '' but has passed check');
Prefix := LeftStr(Markup, OpenBracketPos - 1);
Postfix := RightStr(Markup, Length(Markup) - CloseBracketPos);
// record the elements
if Prefix <> '' then
ActiveText.AddElem(TActiveTextFactory.CreateTextElem(Prefix));
ActiveText.AddElem(TActiveTextFactory.CreateActionElem(
ekLink, fURL, fsOpen)
);
ActiveText.AddElem(TActiveTextFactory.CreateTextElem(LinkText));
ActiveText.AddElem(TActiveTextFactory.CreateActionElem(
ekLink, fURL, fsClose)
);
if Postfix <> '' then
ActiveText.AddElem(TActiveTextFactory.CreateTextElem(Postfix));
end;
end;
end.
