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// This module is only a chapter of the documentation. //! This module describes the template syntax used by ructe. //! //! The syntax is inspired by //! [Twirl](https://github.com/playframework/twirl), the Scala-based //! template engine in //! [Play framework](https://www.playframework.com/), //! but of course with rust types expressions instead of scala. //! //! A template consists of three basic parts: //! First a preamble of `use` statements, each prepended by an @ sign. //! Secondly a declaration of the parameters the template takes. //! And third, the template body. //! //! ```html //! @(name: &str, value: &u32) //! //! <html> //! <head><title>@name</title></head> //! <body> //! <p>The value of @name is @value.</p> //! <body> //! </html> //! ``` //! //! As seen above, string slices and integers can easily be outputed //! in the template body, using `@name` where `name` is a parameter of //! the template. //! Actually, more complex expressions can be outputed in the same //! way, as long as the resulting value implements [`ToHtml`]. //! Rust types that implements [`Display`] automatically implements //! [`ToHtml`] in such a way that contents are safely escaped for //! html. //! //! ```html //! @use any::rust::Type; //! //! @(name: &str, items: &[Type]) //! //! <html> //! <head><title>@name</title></head> //! <body> //! @if items.is_empty() { //! <p>There are no items.</p> //! } else { //! <p>There are @items.len() items.</p> //! <ul> //! @for item in items { //! <li>@item</li> //! } //! </ul> //! <body> //! </html> //! ``` //! //! The curly brackets, `{` and `}`, is used for blocks (see Loops, //! Conditionals, and Calling other templates below). //! To use verbatim curly brackets in the template body, they must be //! escaped as `@{` and `@}`, the same goes for the `@` sign, that //! precedes expressions and special blocks; verbtim `@` signs must be //! escaped as `@@`. //! //! [`ToHtml`]: ../templates/trait.ToHtml.html //! [`Display`]: https://doc.rust-lang.org/std/fmt/trait.Display.html #![allow(non_snake_case)] pub mod a_Value_expressions { //! A value expression can be as simple as `@name` to get the value of //! a parameter, but more complicated expressions, including function //! calls, are also allowed. //! //! # Value expressions //! //! A parameter can be used in an expression preceded by an @ sign. //! //! ```text //! <h1>@name</h1> //! ``` //! //! If a parameter is a struct or a trait object, its fields or methods can //! be used, and if it is a callable, it can be called. //! //! ```text //! <p>The user @user.name has email @user.get_email().</p> //! <p>A function result is @function(with, three, arguments).</p> //! ``` //! //! Standard function and macros can also be used, e.g. for specific //! formatting needs: //! //! ```text //! <p>The value is @format!("{:.1}", float_value).</p> //! ``` //! //! If more complex expressions are needed, they can be put in //! parenthesis. //! //! ```text //! <p>The sum @a+3 is @(a+3).</p> //! ``` //! If `a` is 2, this exapands to: //! ```text //! <p>The sum 2+3 is 5.</p> //! ``` //! //! Anything is allowed in parenthesis, as long as parenthesis, //! brackets and string quotes are balanced. //! Note that this also applies to the parenthesis of a function //! call or the brackets of an index, so complex things like the //! following are allowed: //! //! ```text //! <p>Index: @myvec[t.map(|s| s.length()).unwrap_or(0)].</p> //! <p>Argument: @call(a + 3, |t| t.something()).</p> //! ``` //! //! An expression ends when parenthesis and brackets are matched //! and it is followed by something not allowed in an expression. //! This includes whitespace and e.g. the `<` and `@` characters. //! If an expression starts with an open parenthesis, the //! expression ends when that parentheis is closed. //! That is usefull if an expression is to be emmediatley followed //! by something that would be allowed in an expression. //! //! ```text //! <p>@arg</p> //! <p>@arg.</p> //! <p>@arg.@arg</p> //! <p>@arg.len()</p> //! <p>@(arg).len()</p> //! <p>@((2_i8 - 3).abs())</p>@* Note extra parens needed here *@ //! ``` //! With `arg = "name"`, the above renders as: //! ```text //! <p>name</p> //! <p>name.</p> //! <p>name.name</p> //! <p>4</p> //! <p>name.len()</p> //! <p>1</p> //! ``` } pub mod b_Loops { //! A ructe `@for` loop works just as a rust `for` loop, //! iterating over anything that implements `std::iter::IntoIterator`, //! such as a `Vec` or a slice. //! //! # Loops //! //! Rust-like loops are supported like this: //! //! ```text //! <ul>@for item in items { //! <li>@item</li> //! }</ul> //! ``` //! //! Note that the thing to loop over (items, in the example) is a rust //! expression, while the contents of the block is template code. //! //! If items is a slice of tuples (or really, anything that is //! iterable yielding tuples), it is possible to deconstruct the //! tuples into separate values directly: //! //! ```text //! @for (n, item) in items.iter().enumerate() { //! <p>@n: @item</p> //! } //! ``` //! //! It is also possible to loop over a literal array (which may be //! an array of tuples), as long as you do it by reference: //! //! ```text //! @for &(name, age) in &[("Rasmus", 44), ("Mike", 36)] { //! <p>@name is @age years old.</p> //! } //! ``` } pub mod c_Conditionals { //! Both `@if` statements with boolean expressions, `@if let` guard //! statements, and `@match` statements are supported. //! //! # Conditionals //! //! Rust-like conditionals are supported in a style similar to the loops: //! //! ```text //! @if items.is_empty() { //! <p>There are no items.</p> //! } //! ``` //! //! Pattern matching let expressions are also supported, as well as an //! optional else part. //! //! ```text //! @if let Some(foo) = foo { //! <p>Foo is @foo.</p> //! } else { //! <p>There is no foo.</p> //! } //! ``` //! //! The condition or let expression should allow anything that would be //! allowed in the same place in plain rust. //! As with loops, the things in the curly brackets are ructe template //! code. //! //! ## match //! //! Pattern matching using `match` statements are also supported. //! //! ```text //! @match answer { //! Ok(value) => { //! <p>The answer is @value.</p> //! } //! Err(_) => { //! <p>I don't know the answer.</p> //! } //! } //! ``` //! //! The let expression and patterns should allow anything that would be //! allowed in the same place in plain rust. //! As above, the things in the curly brackets are ructe template code. } pub mod d_Calling_other_templates { //! The ability to call other templates for from a template makes //! both "tag libraries" and "base templates" possible with the //! same syntax. //! //! # Calling other templates //! //! While rust methods can be called as a simple expression, there is a //! special syntax for calling other templates: //! `@:template_name(template_arguments)`. //! Also, before calling a template, it has to be imported by a `use` //! statement. //! Templates are declared in a `templates` module. //! //! So, given something like this in `header.rs.html`: //! //! ```text //! @(title: &str) //! //! <head> //! <title>@title</title> //! <link rel="stylesheet" href="/my/style.css" type="text/css"> //! </head> //! ``` //! //! It can be used like this: //! //! ```text //! @use super::header_html; //! //! @() //! //! <html> //! @:header_html("Example") //! <body> //! <h1>Example</h1> //! <p>page content ...</p> //! </body> //! </html> //! ``` //! //! It is also possible to send template blocks as parameters to templates. //! A structure similar to the above can be created by having something like //! this in `base_page.rs.html`: //! //! ```text //! @(title: &str, body: Content) //! //! <html> //! <head> //! <title>@title</title> //! <link rel="stylesheet" href="/my/style.css" type="text/css"> //! </head> //! <body> //! <h1>@title</h1> //! @:body() //! </body> //! </html> //! ``` //! //! And use it like this: //! //! ```text //! @use super::base_page_html; //! //! @() //! //! @:base_page_html("Example", { //! <p>page content ...</p> //! }) //! ``` }