use quote::quote;
use syn;
use syn::parse::Error;
use syn::spanned::Spanned;
use proc_macro2::TokenStream;
use crate::util::ident_to_type;
use crate::util::{expr_to_single_string, path_to_single_string};
#[derive(Debug)]
pub struct FieldInfo<'a> {
pub ordinal: usize,
pub name: &'a syn::Ident,
pub generic_ident: syn::Ident,
pub ty: &'a syn::Type,
pub builder_attr: FieldBuilderAttr,
}
impl<'a> FieldInfo<'a> {
pub fn new(ordinal: usize, field: &syn::Field, field_defaults: FieldBuilderAttr) -> Result<FieldInfo, Error> {
if let Some(ref name) = field.ident {
Ok(FieldInfo {
ordinal,
name: &name,
generic_ident: syn::Ident::new(
&format!("__{}", name),
proc_macro2::Span::call_site(),
),
ty: &field.ty,
builder_attr: field_defaults.with(&field.attrs)?,
})
} else {
Err(Error::new(field.span(), "Nameless field in struct"))
}
}
pub fn generic_ty_param(&self) -> syn::GenericParam {
syn::GenericParam::Type(self.generic_ident.clone().into())
}
pub fn type_ident(&self) -> syn::Type {
ident_to_type(self.generic_ident.clone())
}
pub fn tuplized_type_ty_param(&self) -> syn::Type {
let mut types = syn::punctuated::Punctuated::default();
types.push(self.ty.clone());
types.push_punct(Default::default());
syn::TypeTuple {
paren_token: Default::default(),
elems: types,
}
.into()
}
pub fn type_from_inside_option(&self) -> Option<&syn::Type> {
let path = if let syn::Type::Path(type_path) = self.ty {
if type_path.qself.is_some() {
return None
} else {
&type_path.path
}
} else {
return None
};
let segment = path.segments.last()?;
if segment.ident != "Option" {
return None;
}
let generic_params = if let syn::PathArguments::AngleBracketed(generic_params) = &segment.arguments {
generic_params
} else {
return None;
};
if let syn::GenericArgument::Type(ty) = generic_params.args.first()? {
Some(ty)
} else {
return None;
}
}
}
#[derive(Debug, Default, Clone)]
pub struct FieldBuilderAttr {
pub default: Option<syn::Expr>,
pub setter: SetterSettings,
}
#[derive(Debug, Default, Clone)]
pub struct SetterSettings {
pub doc: Option<syn::Expr>,
pub skip: bool,
pub auto_into: bool,
pub strip_option: bool,
}
impl FieldBuilderAttr {
pub fn with(mut self, attrs: &[syn::Attribute]) -> Result<Self, Error> {
let mut skip_tokens = None;
for attr in attrs {
if path_to_single_string(&attr.path).as_ref().map(|s| &**s) != Some("builder") {
continue;
}
if attr.tokens.is_empty() {
continue;
}
let as_expr: syn::Expr = syn::parse2(attr.tokens.clone())?;
match as_expr {
syn::Expr::Paren(body) => {
self.apply_meta(*body.expr)?;
}
syn::Expr::Tuple(body) => {
for expr in body.elems.into_iter() {
self.apply_meta(expr)?;
}
}
_ => {
return Err(Error::new_spanned(attr.tokens.clone(), "Expected (<...>)"));
}
}
if self.setter.skip && skip_tokens.is_none() {
skip_tokens = Some(attr.tokens.clone());
}
}
if self.setter.skip && self.default.is_none() {
return Err(Error::new_spanned(
skip_tokens.unwrap(),
"#[builder(skip)] must be accompanied by default or default_code",
));
}
Ok(self)
}
pub fn apply_meta(&mut self, expr: syn::Expr) -> Result<(), Error> {
match expr {
syn::Expr::Assign(assign) => {
let name = expr_to_single_string(&assign.left)
.ok_or_else(|| Error::new_spanned(&assign.left, "Expected identifier"))?;
match name.as_str() {
"default" => {
self.default = Some(*assign.right);
Ok(())
}
"default_code" => {
if let syn::Expr::Lit(syn::ExprLit {
lit: syn::Lit::Str(code),
..
}) = *assign.right
{
use std::str::FromStr;
let tokenized_code = TokenStream::from_str(&code.value())?;
self.default = Some(
syn::parse(tokenized_code.into())
.map_err(|e| Error::new_spanned(code, format!("{}", e)))?,
);
} else {
return Err(Error::new_spanned(assign.right, "Expected string"));
}
Ok(())
}
_ => Err(Error::new_spanned(
&assign,
format!("Unknown parameter {:?}", name),
)),
}
}
syn::Expr::Path(path) => {
let name = path_to_single_string(&path.path)
.ok_or_else(|| Error::new_spanned(&path, "Expected identifier"))?;
match name.as_str() {
"default" => {
self.default = Some(syn::parse(quote!(Default::default()).into()).unwrap());
Ok(())
}
_ => Err(Error::new_spanned(
&path,
format!("Unknown parameter {:?}", name),
))
}
}
syn::Expr::Call(call) => {
let subsetting_name = if let syn::Expr::Path(path) = &*call.func {
path_to_single_string(&path.path)
} else {
None
}.ok_or_else(|| {
let call_func = &call.func;
let call_func = quote!(#call_func);
Error::new_spanned(&call.func, format!("Illegal builder setting group {}", call_func))
})?;
match subsetting_name.as_ref() {
"setter" => {
for arg in call.args {
self.setter.apply_meta(arg)?;
}
Ok(())
}
_ => {
Err(Error::new_spanned(&call.func, format!("Illegal builder setting group name {}", subsetting_name)))
}
}
},
syn::Expr::Unary(syn::ExprUnary {
op: syn::UnOp::Not(_),
expr,
..
}) => {
if let syn::Expr::Path(path) = *expr {
let name = path_to_single_string(&path.path)
.ok_or_else(|| Error::new_spanned(&path, "Expected identifier"))?;
match name.as_str() {
"default" => {
self.default = None;
Ok(())
}
_ => Err(Error::new_spanned(path, format!("Unknown setting")))
}
} else {
Err(Error::new_spanned(expr, format!("Expected simple identifier")))
}
},
_ => {
Err(Error::new_spanned(expr, "Expected (<...>=<...>)"))
},
}
}
}
impl SetterSettings {
fn apply_meta(&mut self, expr: syn::Expr) -> Result<(), Error> {
match expr {
syn::Expr::Assign(assign) => {
let name = expr_to_single_string(&assign.left)
.ok_or_else(|| Error::new_spanned(&assign.left, "Expected identifier"))?;
match name.as_str() {
"doc" => {
self.doc = Some(*assign.right);
Ok(())
}
_ => Err(Error::new_spanned(
&assign,
format!("Unknown parameter {:?}", name),
)),
}
},
syn::Expr::Path(path) => {
let name = path_to_single_string(&path.path)
.ok_or_else(|| Error::new_spanned(&path, "Expected identifier"))?;
macro_rules! handle_fields {
( $( $flag:expr, $field:ident, $already:expr; )* ) => {
match name.as_str() {
$(
$flag => {
if self.$field {
Err(Error::new(path.span(), concat!("Illegal setting - field is already ", $already)))
} else {
self.$field = true;
Ok(())
}
}
)*
_ => Err(Error::new_spanned(
&path,
format!("Unknown setter parameter {:?}", name),
))
}
}
}
handle_fields!(
"skip", skip, "skipped";
"into", auto_into, "calling into() on the argument";
"strip_option", strip_option, "putting the argument in Some(...)";
)
},
syn::Expr::Unary(syn::ExprUnary {
op: syn::UnOp::Not(_),
expr,
..
}) => {
if let syn::Expr::Path(path) = *expr {
let name = path_to_single_string(&path.path)
.ok_or_else(|| Error::new_spanned(&path, "Expected identifier"))?;
match name.as_str() {
"doc" => {
self.doc = None;
Ok(())
},
"skip" => {
self.skip = false;
Ok(())
},
"auto_into" => {
self.auto_into = false;
Ok(())
},
"strip_option" => {
self.strip_option = false;
Ok(())
},
_ => Err(Error::new_spanned(path, format!("Unknown setting")))
}
} else {
Err(Error::new_spanned(expr, format!("Expected simple identifier")))
}
},
_ => Err(Error::new_spanned(expr, "Expected (<...>=<...>)")),
}
}
}