askama_derive/
lib.rs

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1#![deny(elided_lifetimes_in_paths)]
2#![deny(unreachable_pub)]
3
4use std::fmt;
5use std::{borrow::Cow, collections::HashMap};
6
7use proc_macro::TokenStream;
8use proc_macro2::Span;
9
10use parser::ParseError;
11
12mod config;
13use config::Config;
14mod generator;
15use generator::{Generator, MapChain};
16mod heritage;
17use heritage::{Context, Heritage};
18mod input;
19use input::{Print, TemplateArgs, TemplateInput};
20
21#[proc_macro_derive(Template, attributes(template))]
22pub fn derive_template(input: TokenStream) -> TokenStream {
23    let ast = syn::parse::<syn::DeriveInput>(input).unwrap();
24    match build_template(&ast) {
25        Ok(source) => source.parse().unwrap(),
26        Err(e) => e.into_compile_error(),
27    }
28}
29
30/// Takes a `syn::DeriveInput` and generates source code for it
31///
32/// Reads the metadata from the `template()` attribute to get the template
33/// metadata, then fetches the source from the filesystem. The source is
34/// parsed, and the parse tree is fed to the code generator. Will print
35/// the parse tree and/or generated source according to the `print` key's
36/// value as passed to the `template()` attribute.
37pub(crate) fn build_template(ast: &syn::DeriveInput) -> Result<String, CompileError> {
38    let template_args = TemplateArgs::new(ast)?;
39    let toml = template_args.config()?;
40    let config = Config::new(&toml, template_args.whitespace.as_deref())?;
41    let input = TemplateInput::new(ast, &config, &template_args)?;
42
43    let mut templates = HashMap::new();
44    input.find_used_templates(&mut templates)?;
45
46    let mut contexts = HashMap::new();
47    for (path, parsed) in &templates {
48        contexts.insert(
49            path.as_path(),
50            Context::new(input.config, path, parsed.nodes())?,
51        );
52    }
53
54    let ctx = &contexts[input.path.as_path()];
55    let heritage = if !ctx.blocks.is_empty() || ctx.extends.is_some() {
56        Some(Heritage::new(ctx, &contexts))
57    } else {
58        None
59    };
60
61    if input.print == Print::Ast || input.print == Print::All {
62        eprintln!("{:?}", templates[input.path.as_path()].nodes());
63    }
64
65    let code = Generator::new(&input, &contexts, heritage.as_ref(), MapChain::default())
66        .build(&contexts[input.path.as_path()])?;
67    if input.print == Print::Code || input.print == Print::All {
68        eprintln!("{code}");
69    }
70    Ok(code)
71}
72
73#[derive(Debug, Clone)]
74struct CompileError {
75    msg: Cow<'static, str>,
76    span: Span,
77}
78
79impl CompileError {
80    fn new<S: Into<Cow<'static, str>>>(s: S, span: Span) -> Self {
81        Self {
82            msg: s.into(),
83            span,
84        }
85    }
86
87    fn into_compile_error(self) -> TokenStream {
88        syn::Error::new(self.span, self.msg)
89            .to_compile_error()
90            .into()
91    }
92}
93
94impl std::error::Error for CompileError {}
95
96impl fmt::Display for CompileError {
97    #[inline]
98    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
99        fmt.write_str(&self.msg)
100    }
101}
102
103impl From<ParseError> for CompileError {
104    #[inline]
105    fn from(e: ParseError) -> Self {
106        Self::new(e.to_string(), Span::call_site())
107    }
108}
109
110impl From<&'static str> for CompileError {
111    #[inline]
112    fn from(s: &'static str) -> Self {
113        Self::new(s, Span::call_site())
114    }
115}
116
117impl From<String> for CompileError {
118    #[inline]
119    fn from(s: String) -> Self {
120        Self::new(s, Span::call_site())
121    }
122}
123
124// This is used by the code generator to decide whether a named filter is part of
125// Askama or should refer to a local `filters` module. It should contain all the
126// filters shipped with Askama, even the optional ones (since optional inclusion
127// in the const vector based on features seems impossible right now).
128const BUILT_IN_FILTERS: &[&str] = &[
129    "abs",
130    "capitalize",
131    "center",
132    "e",
133    "escape",
134    "filesizeformat",
135    "fmt",
136    "format",
137    "indent",
138    "into_f64",
139    "into_isize",
140    "join",
141    "linebreaks",
142    "linebreaksbr",
143    "paragraphbreaks",
144    "lower",
145    "lowercase",
146    "safe",
147    "trim",
148    "truncate",
149    "upper",
150    "uppercase",
151    "urlencode",
152    "urlencode_strict",
153    "wordcount",
154    // optional features, reserve the names anyway:
155    "json",
156    "markdown",
157    "yaml",
158];
askama_derive/lib.rs

askama_derive/
lib.rs
