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use proc_macro2::TokenStream;
use quote::ToTokens;
use shared::Config;
use std::path::PathBuf;
use syn;
pub struct TemplateInput<'a> {
pub ast: &'a syn::DeriveInput,
pub config: Config,
pub source: Source,
pub print: Print,
pub escaping: EscapeMode,
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(ast: &'a syn::DeriveInput) -> TemplateInput<'a> {
// Check that an attribute called `template()` exists and that it is
// the proper type (list).
let mut meta = None;
for attr in &ast.attrs {
match attr.interpret_meta() {
Some(m) => if m.name() == "template" {
meta = Some(m)
},
None => {
let mut tokens = TokenStream::new();
attr.to_tokens(&mut tokens);
panic!("unable to interpret attribute: {}", tokens)
}
}
}
let meta_list = match meta.expect("no attribute 'template' found") {
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;
for nm_item in meta_list.nested {
if let syn::NestedMeta::Meta(ref item) = nm_item {
if let syn::Meta::NameValue(ref pair) = item {
match pair.ident.to_string().as_ref() {
"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");
},
"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");
},
"print" => if let syn::Lit::Str(ref s) = pair.lit {
print = s.value().into();
} else {
panic!("print value must be string literal");
},
"escape" => if let syn::Lit::Str(ref s) = pair.lit {
escaping = Some(s.value().into());
} else {
panic!("escape value must be string literal");
},
"ext" => if let syn::Lit::Str(ref s) = pair.lit {
ext = Some(s.value());
} else {
panic!("ext value must be string literal");
},
attr => panic!("unsupported annotation key '{}' found", attr),
}
}
}
}
// 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 config = Config::new();
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,
};
TemplateInput {
ast,
config,
source,
print,
escaping: escaping.unwrap_or_else(|| EscapeMode::from_path(&path)),
ext,
parent,
path,
}
}
}
pub enum Source {
Path(String),
Source(String),
}
#[derive(PartialEq)]
pub enum EscapeMode {
Html,
None,
}
impl From<String> for EscapeMode {
fn from(s: String) -> EscapeMode {
use self::EscapeMode::*;
match s.as_ref() {
"html" => Html,
"none" => None,
v => panic!("invalid value for escape option: {}", v),
}
}
}
impl EscapeMode {
fn from_path(path: &PathBuf) -> EscapeMode {
let extension = path.extension().map(|s| s.to_str().unwrap()).unwrap_or("");
if HTML_EXTENSIONS.contains(&extension) {
EscapeMode::Html
} else {
EscapeMode::None
}
}
}
#[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),
}
}
}
const HTML_EXTENSIONS: [&str; 3] = ["html", "htm", "xml"];
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