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|
use askama_shared::{Config, Syntax};
use std::path::PathBuf;
use quote::ToTokens;
use syn;
pub struct TemplateInput<'a> {
pub ast: &'a syn::DeriveInput,
pub config: &'a Config<'a>,
pub syntax: &'a Syntax<'a>,
pub source: Source,
pub print: Print,
pub escaper: &'a str,
pub ext: Option<String>,
pub parent: Option<&'a syn::Type>,
pub path: PathBuf,
}
impl<'a> TemplateInput<'a> {
/// Extract the template metadata from the `DeriveInput` structure. This
/// mostly recovers the data for the `TemplateInput` fields from the
/// `template()` attribute list fields; it also finds the of the `_parent`
/// field, if any.
pub fn new<'n>(ast: &'n syn::DeriveInput, config: &'n Config) -> TemplateInput<'n> {
// Check that an attribute called `template()` exists and that it is
// the proper type (list).
let meta = ast
.attrs
.iter()
.find_map(|attr| match attr.parse_meta() {
Ok(m) => {
if m.path().is_ident("template") {
Some(m)
} else {
None
}
}
Err(e) => panic!("unable to parse attribute: {}", e),
})
.expect("no attribute 'template' found");
let meta_list = match meta {
syn::Meta::List(inner) => inner,
_ => panic!("attribute 'template' has incorrect type"),
};
// Loop over the meta attributes and find everything that we
// understand. Raise panics if something is not right.
// `source` contains an enum that can represent `path` or `source`.
let mut source = None;
let mut print = Print::None;
let mut escaping = None;
let mut ext = None;
let mut syntax = None;
for item in meta_list.nested {
let pair = match item {
syn::NestedMeta::Meta(syn::Meta::NameValue(ref pair)) => pair,
_ => panic!(
"unsupported attribute argument {:?}",
item.to_token_stream()
),
};
if pair.path.is_ident("path") {
if let syn::Lit::Str(ref s) = pair.lit {
if source.is_some() {
panic!("must specify 'source' or 'path', not both");
}
source = Some(Source::Path(s.value()));
} else {
panic!("template path must be string literal");
}
} else if pair.path.is_ident("source") {
if let syn::Lit::Str(ref s) = pair.lit {
if source.is_some() {
panic!("must specify 'source' or 'path', not both");
}
source = Some(Source::Source(s.value()));
} else {
panic!("template source must be string literal");
}
} else if pair.path.is_ident("print") {
if let syn::Lit::Str(ref s) = pair.lit {
print = s.value().into();
} else {
panic!("print value must be string literal");
}
} else if pair.path.is_ident("escape") {
if let syn::Lit::Str(ref s) = pair.lit {
escaping = Some(s.value());
} else {
panic!("escape value must be string literal");
}
} else if pair.path.is_ident("ext") {
if let syn::Lit::Str(ref s) = pair.lit {
ext = Some(s.value());
} else {
panic!("ext value must be string literal");
}
} else if pair.path.is_ident("syntax") {
if let syn::Lit::Str(ref s) = pair.lit {
syntax = Some(s.value())
} else {
panic!("syntax value must be string literal");
}
} else {
panic!(
"unsupported attribute key '{}' found",
pair.path.to_token_stream()
)
}
}
// Validate the `source` and `ext` value together, since they are
// related. In case `source` was used instead of `path`, the value
// of `ext` is merged into a synthetic `path` value here.
let source = source.expect("template path or source not found in attributes");
let path = match (&source, &ext) {
(&Source::Path(ref path), None) => config.find_template(path, None),
(&Source::Source(_), Some(ext)) => PathBuf::from(format!("{}.{}", ast.ident, ext)),
(&Source::Path(_), Some(_)) => {
panic!("'ext' attribute cannot be used with 'path' attribute")
}
(&Source::Source(_), None) => {
panic!("must include 'ext' attribute when using 'source' attribute")
}
};
// Check to see if a `_parent` field was defined on the context
// struct, and store the type for it for use in the code generator.
let parent = match ast.data {
syn::Data::Struct(syn::DataStruct {
fields: syn::Fields::Named(ref fields),
..
}) => fields
.named
.iter()
.find(|f| f.ident.as_ref().filter(|name| *name == "_parent").is_some())
.map(|f| &f.ty),
_ => None,
};
if parent.is_some() {
eprint!(
" --> in struct {}\n = use of deprecated field '_parent'\n",
ast.ident
);
}
// Validate syntax
let syntax = syntax.map_or_else(
|| config.syntaxes.get(config.default_syntax).unwrap(),
|s| {
config
.syntaxes
.get(&s)
.expect(&format!("attribute syntax {} not exist", s))
},
);
// Match extension against defined output formats
let extension = escaping.unwrap_or_else(|| {
path.extension()
.map(|s| s.to_str().unwrap())
.unwrap_or("")
.to_string()
});
let mut escaper = None;
for (extensions, path) in &config.escapers {
if extensions.contains(&extension) {
escaper = Some(path);
break;
}
}
let escaper = escaper.unwrap_or_else(|| {
panic!("no escaper defined for extension '{}'", extension);
});
TemplateInput {
ast,
config,
source,
print,
escaper,
ext,
parent,
path,
syntax,
}
}
}
pub enum Source {
Path(String),
Source(String),
}
#[derive(PartialEq)]
pub enum Print {
All,
Ast,
Code,
None,
}
impl From<String> for Print {
fn from(s: String) -> Print {
use self::Print::*;
match s.as_ref() {
"all" => All,
"ast" => Ast,
"code" => Code,
"none" => None,
v => panic!("invalid value for print option: {}", v),
}
}
}
|
