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use proc_macro2::Ident;
use quote::quote;
use syn::{
LitStr, Token, braced,
ext::IdentExt,
parenthesized,
parse::{self, Parse, ParseStream},
punctuated::Punctuated,
token,
};
use crate::{PropertyKind, name_to_ident};
/// `"snowy": Snowy(false)` or `"axis": properties::Axis::Y`
#[derive(Debug)]
pub struct PropertyWithNameAndDefault {
// "snowy" "axis"
pub name: String,
/// The property name, potentially modified so it works better as a struct
/// field.
pub name_ident: Ident,
// Snowy / Axis
pub property_type: Ident,
pub property_value_type: Ident,
/// Whether it's an enum or a boolean.
pub kind: PropertyKind,
// false / properties::Axis::Y
pub default: proc_macro2::TokenStream,
}
impl Parse for PropertyWithNameAndDefault {
fn parse(input: ParseStream) -> parse::Result<Self> {
// `"snowy": Snowy(false)` or `"axis": properties::Axis::Y`
let property_name = input.parse::<LitStr>()?.value();
input.parse::<Token![:]>()?;
let first_ident = input.call(Ident::parse_any)?;
let mut property_default = quote! { #first_ident };
let property_type: Ident;
let property_value_type: Ident;
let mut kind = PropertyKind::Bool;
if input.parse::<Token![::]>().is_ok() {
// enum
kind = PropertyKind::Enum;
property_type = first_ident.clone();
property_value_type = first_ident;
let variant = input.parse::<Ident>()?;
property_default = quote! { properties::#property_default::#variant };
} else {
// must be a unit struct if it's not an enum
let content;
let _paren_token: token::Paren = parenthesized!(content in input);
// we use this instead of .parse so it works with rust keywords like true and
// false
let unit_struct_inner = content.call(Ident::parse_any)?;
let unit_struct_inner_string = unit_struct_inner.to_string();
if matches!(unit_struct_inner_string.as_str(), "true" | "false") {
property_value_type = Ident::new("bool", first_ident.span());
property_type = first_ident;
property_default = quote! { #unit_struct_inner };
} else {
return Err(input.error("Expected a boolean or an enum variant"));
}
};
let property_name_ident = name_to_ident(&property_name);
Ok(PropertyWithNameAndDefault {
name: property_name,
name_ident: property_name_ident,
property_type,
property_value_type,
kind,
default: property_default,
})
}
}
/// `"snowy" => Snowy(bool)`
pub struct PropertyDefinition {
pub name: LitStr,
pub data: PropertyData,
}
impl Parse for PropertyDefinition {
fn parse(input: ParseStream) -> parse::Result<Self> {
// "face" => Face {
// Floor,
// Wall,
// Ceiling
// },
// if you're wondering, the reason it's in quotes is because `type` is
// a keyword in rust so if we don't put it in quotes it results in a
// syntax error
let name = input.parse()?;
input.parse::<Token![=>]>()?;
let property_type = input.parse()?;
input.parse::<Token![,]>()?;
Ok(PropertyDefinition {
name,
data: property_type,
})
}
}
pub enum PropertyData {
/// `Axis { X = "x", Y = "y", Z = "z" }`
Enum {
enum_name: Ident,
variants: Vec<PropertyVariant>,
},
/// `Snowy(bool)`
Bool { struct_name: Ident },
}
impl Parse for PropertyData {
// like `Axis { X = "x", Y = "y", Z = "z" }` or `Waterlogged(bool)`
fn parse(input: ParseStream) -> parse::Result<Self> {
let keyword = Ident::parse(input)?;
fn parse_braced(
input: ParseStream,
) -> parse::Result<Punctuated<PropertyVariant, Token![,]>> {
let content;
braced!(content in input);
let variants = content.parse_terminated(parse_variant, Token![,])?;
Ok(variants)
}
/// Parses something like `X = "x"`
fn parse_variant(input: ParseStream) -> parse::Result<PropertyVariant> {
let ident = Ident::parse(input)?;
input.parse::<Token![=]>()?;
let name = input.parse::<syn::LitStr>()?;
Ok(PropertyVariant { ident, name })
}
fn parse_paren(input: ParseStream) -> parse::Result<Ident> {
let content;
parenthesized!(content in input);
let inner = content.parse::<Ident>()?;
Ok(inner)
}
if let Ok(variants) = parse_braced(input) {
Ok(Self::Enum {
enum_name: keyword,
variants: variants.into_iter().collect(),
})
} else if let Ok(inner) = parse_paren(input) {
assert_eq!(
inner.to_string(),
"bool",
"Currently only bool unit structs are supported"
);
Ok(Self::Bool {
struct_name: keyword,
})
} else {
Err(input.error("Expected a unit struct or an enum"))
}
}
}
pub struct PropertyVariant {
/// The Rust identifier for the property variant, like `X` or `_1`.
pub ident: Ident,
/// The Minecraft name for the property variant, like `"x"` or `"1"`.
pub name: LitStr,
}
/// Parses comma separated `PropertyDefinition`s like `"snowy" => Snowy(bool),`
pub fn parse_property_definitions(input: ParseStream) -> parse::Result<Vec<PropertyDefinition>> {
let mut property_definitions = Vec::new();
while !input.is_empty() {
property_definitions.push(input.parse()?);
}
Ok(property_definitions)
}
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