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use syn::{
braced, bracketed,
parse::{Parse, ParseStream},
Expr, Ident, LitStr, Result, Token,
};
pub enum RouteDecl {
Method {
method: String,
path: LitStr,
handler: Expr,
/// Optional route name for a generated `{name}_path()` helper (`as: name`).
name: Option<Ident>,
/// Optional `constraints: { param: validator }` — each param must satisfy
/// its validator (`fn(&str) -> bool`) or the route 404s.
constraints: Vec<(Ident, Expr)>,
},
Root {
handler: Expr,
},
Redirect {
from: LitStr,
to: LitStr,
},
Mount {
path: LitStr,
router: Expr,
},
Resources {
resource_name: Ident,
controller: Ident,
filter: ResourceFilter,
/// Extra GET routes under `/{id}/<action>` (Rails `member do … end`).
member: Vec<String>,
/// Extra GET routes under `/<action>` (Rails `collection do … end`).
collection: Vec<String>,
},
Resource {
name: Ident,
controller: Ident,
},
ShallowResources {
parent: Ident,
child: Ident,
controller: Ident,
},
Namespace {
name: Ident,
body: RoutesInput,
},
Scope {
path_prefix: LitStr,
body: RoutesInput,
},
}
pub enum ResourceFilter {
All,
Only(Vec<String>),
Except(Vec<String>),
}
pub struct RoutesInput {
pub decls: Vec<RouteDecl>,
}
fn parse_action_list(input: ParseStream) -> Result<Vec<String>> {
let content;
bracketed!(content in input);
let mut actions = Vec::new();
while !content.is_empty() {
let ident: Ident = content.parse()?;
actions.push(ident.to_string());
let _comma: Option<Token![,]> = content.parse().ok();
}
Ok(actions)
}
impl Parse for RoutesInput {
fn parse(input: ParseStream) -> Result<Self> {
let mut decls = Vec::new();
while !input.is_empty() {
let macro_ident: Ident = input.parse()?;
let _bang: Token![!] = input.parse()?;
let content;
syn::parenthesized!(content in input);
let _semi: Option<Token![;]> = input.parse().ok();
match macro_ident.to_string().as_str() {
"namespace" => {
let name: Ident = content.parse()?;
let _comma: Token![,] = content.parse()?;
let inner;
braced!(inner in content);
let body: RoutesInput = inner.parse()?;
decls.push(RouteDecl::Namespace { name, body });
}
"scope" => {
let path_prefix: LitStr = content.parse()?;
let _comma: Token![,] = content.parse()?;
let inner;
braced!(inner in content);
let body: RoutesInput = inner.parse()?;
decls.push(RouteDecl::Scope { path_prefix, body });
}
"resource" => {
let name: Ident = content.parse()?;
let _comma: Token![,] = content.parse()?;
let controller: Ident = content.parse()?;
decls.push(RouteDecl::Resource { name, controller });
}
"shallow_resources" => {
let parent: Ident = content.parse()?;
let _comma: Token![,] = content.parse()?;
let child: Ident = content.parse()?;
let _comma: Token![,] = content.parse()?;
let controller: Ident = content.parse()?;
decls.push(RouteDecl::ShallowResources {
parent,
child,
controller,
});
}
"resources" => {
let resource_name: Ident = content.parse()?;
let _comma: Token![,] = content.parse()?;
let controller: Ident = content.parse()?;
// Zero or more `, key: [actions]` options (only/except/member/collection).
let mut filter = ResourceFilter::All;
let mut member = Vec::new();
let mut collection = Vec::new();
while !content.is_empty() {
let _comma: Token![,] = content.parse()?;
let key: Ident = content.parse()?;
let _colon: Token![:] = content.parse()?;
let actions = parse_action_list(&content)?;
match key.to_string().as_str() {
"only" => filter = ResourceFilter::Only(actions),
"except" => filter = ResourceFilter::Except(actions),
"member" => member = actions,
"collection" => collection = actions,
other => {
return Err(syn::Error::new(
key.span(),
format!("unknown option: {other}"),
))
}
}
}
decls.push(RouteDecl::Resources {
resource_name,
controller,
filter,
member,
collection,
});
}
"root" => {
let handler: Expr = content.parse()?;
decls.push(RouteDecl::Root { handler });
}
"redirect" => {
let from: LitStr = content.parse()?;
let _comma: Token![,] = content.parse()?;
let to: LitStr = content.parse()?;
decls.push(RouteDecl::Redirect { from, to });
}
"mount" => {
let path: LitStr = content.parse()?;
let _comma: Token![,] = content.parse()?;
let router: Expr = content.parse()?;
decls.push(RouteDecl::Mount { path, router });
}
method @ ("get" | "post" | "put" | "patch" | "delete" | "head" | "options") => {
let path: LitStr = content.parse()?;
let _comma: Token![,] = content.parse()?;
let handler: Expr = content.parse()?;
// Optional trailing `, as: name` and/or `, constraints: { … }`,
// in any order. `as` is a keyword, so peek it as a token.
let mut name = None;
let mut constraints = Vec::new();
while content.peek(Token![,]) {
let _comma: Token![,] = content.parse()?;
if content.peek(Token![as]) {
let _as: Token![as] = content.parse()?;
let _colon: Token![:] = content.parse()?;
name = Some(content.parse()?);
} else {
let key: Ident = content.parse()?;
let _colon: Token![:] = content.parse()?;
match key.to_string().as_str() {
"constraints" => {
let inner;
braced!(inner in content);
while !inner.is_empty() {
let param: Ident = inner.parse()?;
let _colon: Token![:] = inner.parse()?;
let validator: Expr = inner.parse()?;
constraints.push((param, validator));
let _comma: Option<Token![,]> = inner.parse().ok();
}
}
other => {
return Err(syn::Error::new(
key.span(),
format!("unknown route option: {other}"),
))
}
}
}
}
decls.push(RouteDecl::Method {
method: method.to_string(),
path,
handler,
name,
constraints,
});
}
other => {
return Err(syn::Error::new(
macro_ident.span(),
format!("unknown macro: {other}!"),
))
}
}
}
Ok(RoutesInput { decls })
}
}