{
* USnippetCreditsParser.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 USnippetCreditsParser.pas, formerly
* 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) 2008-2011 Peter
* Johnson. All Rights Reserved.
*
* Contributor(s)
* NONE
*
* ***** END LICENSE BLOCK *****
}
unit USnippetCreditsParser;
interface
uses
// Project
UActiveText;
type
/// <summary>
/// Class that parses markup used in Credits element read from snippets data
/// files. Markup is translated into active text.
/// </summary>
/// <remarks>
/// The Credits element may occur in main database files and v1 of the user
/// database and export files.
/// </remarks>
TSnippetCreditsParser = class(TInterfacedObject, IActiveTextParser)
strict private
var
/// <summary>URL to be used in any link contained in markup.</summary>
fURL: string;
protected // do not make strict
/// <summary>Parses markup and updates active text object.
/// </summary>
/// <param name="Markup">string [in] Markup containing definition of active
/// text. Must be valid Credits element markup.</param>
/// <param name="ActiveText">IActiveText [in] Active text object updated by
/// parser.</param>
/// <remarks>Implements IActiveTextParser.Parse.</remarks>
procedure Parse(const Markup: string; const ActiveText: IActiveText);
public
/// <summary>Object constructor. Sets up object.</summary>
/// <param name="URL">string [in] URL to be used in any hyperlinks defined
/// by Credit markup.</param>
constructor Create(const URL: string);
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
// Project
UStrUtils;
{ TSnippetCreditsParser }
constructor TSnippetCreditsParser.Create(const URL: string);
begin
inherited Create;
fURL := URL;
end;
procedure TSnippetCreditsParser.Parse(const Markup: string;
const ActiveText: IActiveText);
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 := StrPos(cOpenBracket, Markup);
CloseBracketPos := StrPos(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 StrCountDelims(cOpenBracket, Markup) > 1 then
raise EActiveTextParserError.Create(sMultipleOpeners);
if StrCountDelims(cCloseBracket, Markup) > 1 then
raise EActiveTextParserError.Create(sMultipleClosers);
// must have a URL
if fURL = '' then
raise EActiveTextParserError.Create(sNoURL);
// get the various components
LinkText := StrSlice(
Markup, OpenBracketPos + 1, CloseBracketPos - OpenBracketPos - 1
);
Assert(LinkText <> '',
ClassName + '.Parse: Link text is '' but has passed check');
Prefix := StrSliceLeft(Markup, OpenBracketPos - 1);
Postfix := StrSliceRight(Markup, Length(Markup) - CloseBracketPos);
// record the elements
if Prefix <> '' then
ActiveText.AddElem(TActiveTextFactory.CreateTextElem(Prefix));
ActiveText.AddElem(
TActiveTextFactory.CreateActionElem(
ekLink,
TActiveTextFactory.CreateAttrs(
TActiveTextAttr.Create(TActiveTextAttrNames.Link_URL, fURL)
),
fsOpen
)
);
ActiveText.AddElem(TActiveTextFactory.CreateTextElem(LinkText));
ActiveText.AddElem(
TActiveTextFactory.CreateActionElem(
ekLink,
TActiveTextFactory.CreateAttrs(
TActiveTextAttr.Create(TActiveTextAttrNames.Link_URL, fURL)
),
fsClose
)
);
if Postfix <> '' then
ActiveText.AddElem(TActiveTextFactory.CreateTextElem(Postfix));
end;
end;
end.
