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## Basic Structure of CppCMS template file |
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When we build templates, we put their content in their own `skin`. Thus when we build any template, we specify its skin name as the first level command. Each skin is represented by a separate namespace at the C++ level. So the skin name is actually the C++ namespace name. |
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The second level is view (representing a C++ class). Each view within its skin represents certain pages that should be rendered. Each skin should implement the virtual function `render()`, unless it is already implemented in its parent. Each view is represented by a separate class that is derived from `cppcms::base_view` by the topmost parent. |
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Example: |
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<% skin purple %> |
<% view master uses data::master %> |
<% template render() %> |
... |
<% end template %> |
<% end view %> |
<% end skin %> |
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All views may be organized to inheritance hierarchy. For example, we can have the following hierarchy for a typical blog application: |
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[master] |
/ \ |
[page] [summary] |
/ \ / \ |
[post] [info.] [archive] [recent_posts] |
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Where `master` defines the general appearance of the page --- theme. `page` uses for displaying general page |
in blog that can be `post` or `info` -- information page. On the other hand `summary` represents a list of recent posts or the archive by category. |
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Each inherited view may redefine its parent templates that are actually virtual functions. |
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## Syntax |
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### HTML and Controls separation |
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The template system of CppCMS is based on HTML pages with injected flow control commands between `<% %>` tags. |
Each template command starts with `<%` and should be closed with `%>` in the same line. |
Each template command starts with `<%` and should be closed with `%>` on the same line. |
Each template command should be closed with these "brackets". |
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For example --- correct code: |
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<% if not empty Name %> |
Hello <% Name %> |
<% else %> |
Hello Visitor |
<% end %> |
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It is incorrect to "merge different commands. For example (incorrect): |
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Hello <% if not empty name ; name ; else %>Visitor<% end %> |
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You should not split command on different rows as well. The following is incorrect: |
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<% if not empty |
name %> Not empty <% end %> |
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Symbols inside commands can not include `%` or `>`. You may include them inside double quotes using C++/C escaping |
rules. For example: |
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<% number | intf("<%04x>") %> |
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### Syntax Description Rules |
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The description of the syntax of template commands is done in the following way: |
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- All keywords will be shown in small caps in single quotes. For example 'skin' |
- **NAME** is a sequence of Latin letters, digits and underscore starting with a letter. They represent identifiers and can be defined by regular expression such as: `[a-zA-Z][a-zA-Z0-9_]*`. For example `skin_1`. |
- **VARIABLE** is non-empty sequence of NAMES separated by dot "`.`" or "`->`" that may optionally end with `()` or begin with `*` for identification of function call result. No blanks are allowed. For example: `data->point.x`, `something.else()` `*foo.bar`. |
- **STRING** is standard C++/C string with standard escape characters like `"Hello \"World\""`. _Note:_ No string concatenation is allowed like `"Hello " "World" when `"Hello World" is meant`. |
- **NUMBER** is a number -- sequence of digits that may start with `-` and include `.`. It can be defined by the regular expression: `\-?\d+(\.\d*)?` |
- **IDENTIFIER** is a sequence of NAME separated by the symbol `::`. No blanks are allowed. For example: `data::page` |
- All punctuation symbols are enclosed with single quotes. Like `','`. |
- Non-mandatory elements are displayed within square brackets `[]` and mandatory ones within round brackets `()`. Options are separated by the symbol `|`. |
- There is no limit on blanks between the words. |
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For example: |
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'view' NAME 'uses' IDENTIFIER ['extends' NAME] |
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Means that the following definitions are legal: |
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<% view page uses data::page extends master %> |
<% view test uses data::test %> |
<% view test uses data_test %> |
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And these are not: |
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<% view 1page uses data::page extends master %> |
<% view page %> |
<% view page uses data::page extends other::master %> |
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