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0001 0002 namespace KTextTemplate 0003 { 0004 0005 /** 0006 @page internals Internals 0007 0008 @note This page is intended only to be informative for new contributors to %KTextTemplate or people who are really interested in this kind of thing. These are implementation details and are likely to change without notice. 0009 0010 @section how_works How KTextTemplate works. 0011 0012 A template string is first tokenized by the Lexer class. The result is a list of tokens with content which can be of type <tt>TextToken</tt>, <tt>CommentToken</tt>, <tt>VariableToken</tt> or <tt>TagToken</tt>. 0013 0014 The tokens are further processed by the Parser class. The Parser generates nodes from the token stream. For a <tt>TextToken</tt> it generates a <tt>TextNode</tt>, for a <tt>CommentToken</tt> it generates nothing, for a <tt>VariableToken</tt> it generates a <tt>VariableNode</tt>, and for a <tt>TagToken</tt> it generates another type of Node determined by available plugins. Some plugins are built in, and others may be loaded by the template itself using the @gr_tag{load} tag, or preloaded by the application developer. 0015 0016 The plugin uses the Abstract Factory Pattern. It returns a list of concrete factories, one for each tag handled by that plugin. The factories have a <tt>getNode</tt> method which accepts the tag content and the active parser as an argument and returns a concrete Node. The <tt>getNode</tt> method may advance the parser in the case of begin/end tags etc. When the parser is finished, it has created a tree of nodes, which is essentially a Template object. 0017 0018 A Template is rendered with a Context object. During rendering, each node in the template has its <tt>render</tt> method called with the Context. The Node may contain different sub-trees, one of which is rendered, as is the case for <tt>IfNode</tt>, or it might contain a single sub-tree which is rendered multiple times, as in the case of <tt>ForNode</tt>, etc. The rendering outputs a string, which is the rendered output of the Template for a particular Context. A single Template may be rendered multiple times with mutliple different Contexts. 0019 0020 Plugins can return Filter and AbstractNodeFactory instances. Filters can manipulate Variable instances in some way before rendering them to the output. 0021 0022 Loading templates to include or extend is accomplished using the <tt>loadByName</tt> methods. The secondary template should use the same state as the initially created/loaded template, so that it uses the same template loaders, has the same plugins available by default and uses the same search directories to find additional plugins. 0023 0024 */ 0025 0026 } 0027