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#![deny(missing_docs)] //! This template crate uses and defines a [DisplayAs] trait, which //! allows a type to be displayed in a particular format. //! //! # Overview //! //! This crate defines three things that you need be aware of in order //! to use it: the [Format] trait, which defines a markup language or //! other format, the [DisplayAs] trait which is implemented for any //! type that can be converted into some [Format], and finally the //! template language and macros which allow you to conveniently //! implement [DisplayAs] for your own types. I will describe each of //! these concepts in order. (**FIXME** I should also have a //! quick-start...) //! //! ## [Format] //! //! There are a number of predefined Formats (and I can easily add //! more if there are user requests), so the focus here will be on //! using these Formats, rather than on defining your own (which also //! isn't too hard). A format is a zero-size type that has a rule for //! escaping strings and an associated MIME type. The builtin formats //! include [HTML], [LaTeX], and [Math] (which is math-mode LaTeX). //! //! ## [DisplayAs]`<F>` //! //! The `[DisplayAs]<F: Format>` trait is entirely analogous to the [Display](std::fmt::Display) trait //! in the standard library, except that it is parametrized by a //! [Format] so you can have different representations for the same //! type in different formats. This also makes it harder to //! accidentally include the wrong representation in your output. //! //! Most of the primitive types already have [DisplayAs] implemented //! for the included Formats. If you encounter a type that you wish //! had [DisplayAs] implemented for a given format, just let me know. //! You can manually implement [DisplayAs] for any of your own types //! (it's not worse than implementing [Display](std::fmt::Display)) but that isn't how //! you are intended to do things (except perhaps in very simple //! cases, like a wrapper around an integer). Instead you will want //! to use a template to implement [DisplayAs] for your own types. //! //! ## Templates! //! //! There are two template macros that you can use. If you just want //! to get a string out of one or more [DisplayAs] objects, you will //! use something like `format_as!(HTML, "hello world" value)`. If //! you want to implement [DisplayAs], you will use the attribute //! [with_template!]. In these examples I will use //! [format_as!] because that makes it easy to write testable //! documentation. But in practice you will most likely primarily use //! the [with_template] attribute. //! //! ### String literals //! //! The first thing you can include in a template is a string literal, //! which is treated literally. //! //! ``` //! use display_as::{HTML, format_as}; //! assert_eq!(&format_as!(HTML, "Treat this literally <" ), //! "Treat this literally <"); //! ``` //! //! ### Expressions //! //! String literals are essential to representing some other [Format]. //! To include your data in the output, you can include any expression //! that yields a type with [DisplayAs]`<F>` where `F` is your [Format]. //! Each expression is delimited by string literals (or the other //! options below). Note that since an expression is //! //! ``` //! use display_as::{HTML, format_as}; //! let s = "This is not a literal: <"; //! assert_eq!(&format_as!(HTML, s ), //! "This is not a literal: <"); //! ``` //! //! ### Blocks and conditionals //! //! You can use braces to enclose any template expression. Any rust //! code before the braces is treated as literal rust. This enables //! you to write conditionals, match expressions, and loops. //! //! ``` //! use display_as::{HTML, format_as}; //! assert_eq!(&format_as!(HTML, //! for i in 1..4 { //! "Counting " i "...\n" //! } //! "Blast off!"), //! "Counting 1...\nCounting 2...\nCounting 3...\nBlast off!"); //! ``` //! //! ### Semicolons //! //! You may also play any rust statements you wish, if you end them //! with a semicolon. This enables you to define local variables. //! //! ``` //! use display_as::{HTML, format_as}; //! assert_eq!(&format_as!(HTML, "I am counting " let count = 5; //! count " and again " count ), //! "I am counting 5 and again 5"); //! ``` //! //! ### Embedding a different format //! //! You can also embed in one format a representation from another //! type. This can be helpful, for instance, if you want to use //! MathJax to handle LaTeX math embedded in an HTML file. //! //! ``` //! use display_as::{HTML, Math, format_as}; //! assert_eq!(&format_as!(HTML, "The number $" 1.2e12 as Math "$"), //! r"The number $1.2\times10^{12}$"); //! ``` //! //! ### Saving a portion of a template for reuse //! //! You can also save a template expression using a let statement, //! provided the template expression is enclosed in braces. This //! allows you to achieve goals similar to the base templates in //! Jinja2. (Once we have an include feature... Example to come in //! the future.) //! //! ``` //! use display_as::{HTML, format_as}; //! assert_eq!(&format_as!(HTML, //! let x = 1; //! let announce = { "number " x }; //! "The " announce " is silly " announce), //! "The number 1 is silly number 1"); //! ``` //! //! ## Differences when putting a template in a file //! //! You will most likely always put largish templates in a separate //! file. This makes editing your template simpler and keeps things //! in general easier. The template language for templates held in a //! distinct file has one difference from those shown above: the file //! always begins and ends with string literals, but their initial and //! final quotes respectively are omitted. Furthermore, the first and //! last string literals must be "raw" literals with a number of # //! signs equal to the maximum used in the template. I suggest using //! an equal number of # signs for all string literals in a given //! template. Thus a template might look like: //! //! ```ignore //! <html> //! <body> //! "## self.title r##" //! </body> //! </html> //! ``` //! You can see that the quotes appear "inside out." This is //! intentional, so that for most formats the quotes will appear to //! enclose the rust code rather than everything else, and as a result //! editors will hopefully be able to do the "right thing" for the //! template format (e.g. HTML in this case). #![cfg_attr(feature = "docinclude", feature(external_doc))] //! ## Using `include!("...")` within a template //! //! Now I will demonstrate how you can include template files within //! other template files by using the `include!` macro within a //! template. To demonstrate this, we will need a few template files. //! //! We will begin with a "base" template that describes how a page is //! laid out. //! #### `base.html`: //! ```ignore #![cfg_attr(feature = "docinclude", doc(include = "base.html"))] //! ``` //! We can have a template for how we will display students... //! #### `student.html`: //! ```ignore #![cfg_attr(feature = "docinclude", doc(include = "student.html"))] //!``` //! Finally, an actual web page describing a class! //! #### `class.html`: //! ```ignore #![cfg_attr(feature = "docinclude", doc(include = "class.html"))] //! ``` //! Now to put all this together, we'll need some rust code. //! //! ``` //! use display_as::{DisplayAs, HTML, format_as, with_template}; //! struct Student { name: &'static str }; //! #[with_template("student.html")] //! impl DisplayAs<HTML> for Student {} //! //! struct Class { coursename: &'static str, coursenumber: usize, students: Vec<Student> }; //! #[with_template("class.html")] //! impl DisplayAs<HTML> for Class {} //! //! let myclass = Class { //! coursename: "Templates", //! coursenumber: 365, //! students: vec![Student {name: "David"}, Student {name: "Joel"}], //! }; //! assert_eq!(&format_as!(HTML, myclass), r#"<title>PH365: Templates</title> //! <html> //! <ul> //! //! // This is buggy: I want to iterate, but it fails! //! for s in self.students.iter() { //! "<li>" s "</li>" //! } //! //! </ul> //! </html> //! //! //!"#); //! ``` extern crate display_as_proc_macro; extern crate mime; extern crate proc_macro_hack; #[proc_macro_hack] pub use display_as_proc_macro::format_as; #[proc_macro_hack] pub use display_as_proc_macro::write_as; use proc_macro_hack::proc_macro_hack; /// Can I write doc here? pub use display_as_proc_macro::with_template; use std::fmt::{Display, Error, Formatter}; #[macro_use] mod html; mod latex; mod mathlatex; mod rust; mod url; mod utf8; pub mod float; pub use crate::html::HTML; pub use crate::url::URL; pub use crate::latex::LaTeX; pub use crate::mathlatex::Math; pub use crate::rust::Rust; pub use crate::utf8::UTF8; /// Format is a format that we can use for displaying data. pub trait Format { /// "Escape" the given string so it can be safely displayed in /// this format. The precise meaning of this may vary from format /// to format, but the general sense is that this string does not /// have any internal formatting, and must be displayed /// appropriately. fn escape(f: &mut Formatter, s: &str) -> Result<(), Error>; /// The mime type of this format. fn mime() -> mime::Mime; /// Return an actual [Format] for use in [As] below. fn this_format() -> Self; } /// This trait is analogous to [Display](std::fmt::Display), but will display the data in /// `F` [Format]. pub trait DisplayAs<F: Format> { /// Formats the value using the given formatter. fn fmt(&self, f: &mut Formatter) -> Result<(), Error>; /// Creates a display object fn display<'a>(&'a self) -> As<'a, F, Self> { As::from(self) } } /// Create a Display object, which can be used with various web frameworks. pub fn display<'a, F: Format, T: DisplayAs<F>>(_f: F, x: &'a T) -> As<'a, F, T> { x.display() } struct Closure<F: Format, C: Fn(&mut Formatter) -> Result<(), Error>> { f: C, _format: F, } /// Display the given closure as this format. /// /// This is used internally in template handling. pub fn display_closure_as<F: Format>(f: F, c: impl Fn(&mut Formatter) -> Result<(), Error>) -> impl DisplayAs<F> { Closure { f: c, _format: f, } } impl<F: Format, C: Fn(&mut Formatter) -> Result<(), Error>> DisplayAs<F> for Closure<F,C> { fn fmt(&self, f: &mut Formatter) -> Result<(), Error> { (self.f)(f) } } #[test] fn test_closure() { let x = |__f: &mut Formatter| -> Result<(), Error> { __f.write_str("hello world")?; Ok(()) }; assert_eq!("hello world", &format_as!(HTML, display_closure_as(HTML, x))); } /// Choose to [Display](std::fmt::Display) this type using a particular [Format] `F`. pub struct As<'a, F: Format, T: DisplayAs<F> + ?Sized> { inner: &'a T, _format: F, } impl<'a, F: Format, T: DisplayAs<F> + ?Sized> From<&'a T> for As<'a, F, T> { fn from(value: &'a T) -> Self { As { _format: F::this_format(), inner: value, } } } impl<'a, F: Format, T: DisplayAs<F> + ?Sized> Display for As<'a, F, T> { fn fmt(&self, f: &mut Formatter) -> Result<(), Error> { self.inner.fmt(f) } } /// The `rouille` feature flag enables conversion of any `As<F,T>` /// type into a [rouille::Response]. Note that it is necessary to be /// explicit about the format because a given type `T` may be /// displayed in multiple different formats. #[cfg(feature = "rouille")] pub mod rouille { extern crate rouille; use super::{As, DisplayAs, Format}; impl<'a, F: Format, T: DisplayAs<F>> Into<rouille::Response> for As<'a, F, T> { fn into(self) -> rouille::Response { let s = format!("{}", &self); rouille::Response::from_data(F::mime().as_ref().to_string(), s) } } } /// The `actix-web` feature flag makes any [As] type a /// [actix_web::Responder]. #[cfg(feature = "actix-web")] pub mod actix { extern crate actix_web; use self::actix_web::{HttpRequest, HttpResponse, Responder}; use super::{As, DisplayAs, Format}; impl<'a, F: Format, T: 'a + DisplayAs<F>> Responder for As<'a, F, T> { type Item = HttpResponse; type Error = ::std::io::Error; fn respond_to<S: 'static>( self, _req: &HttpRequest<S>, ) -> Result<HttpResponse, Self::Error> { Ok(HttpResponse::Ok() .content_type(F::mime().as_ref().to_string()) .body(format!("{}", &self))) } } } /// The `gotham-web` feature flag makes any [As] type a /// [gotham::IntoResponse]. #[cfg(feature = "gotham-web")] pub mod gotham { use crate::{As, DisplayAs, Format}; impl<'a, F: Format, T: 'a + DisplayAs<F>> gotham::handler::IntoResponse for As<'a, F, T> { fn into_response(self, state: &gotham::state::State) -> http::Response<hyper::Body> { let s = format!("{}", &self); (http::StatusCode::OK, F::mime(), s).into_response(state) } } } /// The `warp` feature flag makes any [DisplayAs] type Into<[http::Response]>. #[cfg(feature = "warp")] pub mod warp { use crate::{DisplayAs, Format, As}; impl<'a, F: Format, T: DisplayAs<F>> As<'a, F, T> { /// Convert into a [warp::Reply]. pub fn http_response(&self) -> http::Response<String> { let s = format!("{}", self); let m = F::mime().as_ref().to_string(); let mut response = http::Response::builder(); response .header("Content-type", m.as_bytes()) .status(http::StatusCode::OK); response.body(s).unwrap() } } #[test] fn test_warp() { use crate::{HTML, display}; // This sloppy test just verify that the code runs. display(HTML, &"hello world".to_string()).http_response(); } } impl<F: Format> DisplayAs<F> for String { fn fmt(&self, f: &mut Formatter) -> Result<(), Error> { F::escape(f, self) } } impl<'a, F: Format> DisplayAs<F> for &'a String { fn fmt(&self, f: &mut Formatter) -> Result<(), Error> { F::escape(f, self) } } impl<F: Format> DisplayAs<F> for str { fn fmt(&self, f: &mut Formatter) -> Result<(), Error> { F::escape(f, self) } } impl<'a, F: Format> DisplayAs<F> for &'a str { fn fmt(&self, f: &mut Formatter) -> Result<(), Error> { F::escape(f, self) } } #[cfg(test)] mod tests { use super::{HTML}; #[test] fn html_escaping() { assert_eq!(&format_as!(HTML, ("&")), "&"); assert_eq!( &format_as!(HTML, ("hello &>this is cool")), "hello &>this is cool" ); assert_eq!( &format_as!(HTML, ("hello &>this is 'cool")), "hello &>this is 'cool" ); } }