azalea_block_macros/

lib.rs

//! An internal crate used by `azalea_block`.

mod utils;

use std::{collections::HashMap, fmt::Write};

use proc_macro::TokenStream;
use proc_macro2::TokenTree;
use quote::quote;
use syn::{
    Expr, Ident, LitStr, Token, braced,
    ext::IdentExt,
    parenthesized,
    parse::{Parse, ParseStream, Result},
    parse_macro_input,
    punctuated::Punctuated,
    token,
};
use utils::{combinations_of, to_pascal_case};

// must be the same as the type in `azalea-block/src/lib.rs`
type BlockStateIntegerRepr = u16;
enum PropertyType {
    /// `Axis { X, Y, Z }`
    Enum {
        enum_name: Ident,
        variants: Punctuated<Ident, Token![,]>,
    },
    /// `Snowy(bool)`
    Boolean { struct_name: Ident },
}

/// `"snowy" => Snowy(bool)`
struct PropertyDefinition {
    name: LitStr,
    property_type: PropertyType,
}

/// Comma separated PropertyDefinitions (`"snowy" => Snowy(bool),`)
struct PropertyDefinitions {
    properties: Vec<PropertyDefinition>,
}

/// `"snowy": Snowy(false)` or `"axis": properties::Axis::Y`
#[derive(Debug)]
struct PropertyWithNameAndDefault {
    // "snowy" "axis"
    name: String,
    /// The property name, potentially modified so it works better as a struct
    /// field.
    name_ident: Ident,
    // Snowy / Axis
    property_type: Ident,
    property_value_type: Ident,
    is_enum: bool,
    // false / properties::Axis::Y
    default: proc_macro2::TokenStream,
}

/// ```ignore
/// grass_block => BlockBehavior::default(), {
///   "snowy": false,
/// },
/// ```
struct BlockDefinition {
    name: Ident,
    behavior: Expr,
    properties_and_defaults: Vec<PropertyWithNameAndDefault>,
}
impl Parse for PropertyWithNameAndDefault {
    fn parse(input: ParseStream) -> 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 is_enum = false;

        if input.parse::<Token![::]>().is_ok() {
            // enum
            is_enum = true;
            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,
            is_enum,
            default: property_default,
        })
    }
}

struct BlockDefinitions {
    blocks: Vec<BlockDefinition>,
}
struct MakeBlockStates {
    property_definitions: PropertyDefinitions,
    block_definitions: BlockDefinitions,
}

impl Parse for PropertyType {
    fn parse(input: ParseStream) -> Result<Self> {
        // like `Axis { X, Y, Z }` or `Waterlogged(bool)`

        let keyword = Ident::parse(input)?;

        fn parse_braced(input: ParseStream) -> Result<Punctuated<Ident, Token![,]>> {
            let content;
            braced!(content in input);
            let variants = content.parse_terminated(Ident::parse, Token![,])?;
            Ok(variants)
        }

        fn parse_paren(input: ParseStream) -> 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,
            })
        } else if let Ok(inner) = parse_paren(input) {
            assert_eq!(
                inner.to_string(),
                "bool",
                "Currently only bool unit structs are supported"
            );
            Ok(Self::Boolean {
                struct_name: keyword,
            })
        } else {
            Err(input.error("Expected a unit struct or an enum"))
        }
    }
}

impl Parse for PropertyDefinition {
    fn parse(input: ParseStream) -> 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,
            property_type,
        })
    }
}

impl Parse for PropertyDefinitions {
    fn parse(input: ParseStream) -> Result<Self> {
        let mut property_definitions = Vec::new();
        while !input.is_empty() {
            property_definitions.push(input.parse()?);
        }

        Ok(PropertyDefinitions {
            properties: property_definitions,
        })
    }
}

impl Parse for BlockDefinition {
    fn parse(input: ParseStream) -> Result<Self> {
        // acacia_button => BlockBehavior::new().strength(0.5, 0.5), {
        //     "face": Face::Wall,
        //     "facing": FacingCardinal::North,
        //     "powered": Powered(false),
        // },
        let name = input.parse()?;
        input.parse::<Token![=>]>()?;
        let behavior = input.parse()?;

        input.parse::<Token![,]>()?;
        let content;
        braced!(content in input);

        let mut properties_and_defaults = Vec::new();

        // read the things comma-separated
        let property_and_default_punctuated =
            content.parse_terminated(PropertyWithNameAndDefault::parse, Token![,])?;

        for property_and_default in property_and_default_punctuated {
            properties_and_defaults.push(property_and_default);
        }

        Ok(BlockDefinition {
            name,
            behavior,
            properties_and_defaults,
        })
    }
}

impl Parse for BlockDefinitions {
    fn parse(input: ParseStream) -> Result<Self> {
        let mut blocks = Vec::new();

        let block_definitions_punctuated =
            input.parse_terminated(BlockDefinition::parse, Token![,])?;
        for block_definition in block_definitions_punctuated {
            blocks.push(block_definition);
        }

        Ok(BlockDefinitions { blocks })
    }
}

impl Parse for MakeBlockStates {
    fn parse(input: ParseStream) -> Result<Self> {
        // Properties => { ... } Blocks => { ... }
        let properties_ident = input.parse::<Ident>()?;
        assert_eq!(properties_ident.to_string(), "Properties");
        input.parse::<Token![=>]>()?;
        let content;
        braced!(content in input);
        let properties = content.parse()?;

        input.parse::<Token![,]>()?;

        let blocks_ident = input.parse::<Ident>()?;
        assert_eq!(blocks_ident.to_string(), "Blocks");
        input.parse::<Token![=>]>()?;
        let content;
        braced!(content in input);
        let blocks = content.parse()?;

        Ok(MakeBlockStates {
            property_definitions: properties,
            block_definitions: blocks,
        })
    }
}

struct PropertyVariantData {
    pub block_state_ids: Vec<BlockStateIntegerRepr>,
    pub ident: Ident,
    pub is_enum: bool,
}

#[proc_macro]
pub fn make_block_states(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as MakeBlockStates);

    let mut property_enums = quote! {};
    let mut properties_map = HashMap::new();
    let mut property_struct_names_to_names = HashMap::new();

    let mut state_id: BlockStateIntegerRepr = 0;

    for property in &input.property_definitions.properties {
        let property_struct_name: Ident;
        // this is usually the same as property_struct_name except for bool
        let property_value_name: Ident;
        let mut property_variant_types = Vec::new();

        match &property.property_type {
            PropertyType::Enum {
                enum_name,
                variants,
            } => {
                let mut property_enum_variants = quote! {};
                let mut property_from_number_variants = quote! {};

                property_value_name = enum_name.clone();
                property_struct_name = enum_name.clone();

                property_struct_names_to_names.insert(
                    property_struct_name.to_string(),
                    property.name.clone().value(),
                );

                for i in 0..variants.len() {
                    let variant = &variants[i];

                    let i_lit = syn::Lit::Int(syn::LitInt::new(
                        &i.to_string(),
                        proc_macro2::Span::call_site(),
                    ));

                    property_enum_variants.extend(quote! {
                        #variant = #i_lit,
                    });

                    // i_lit is used here instead of i because otherwise it says 0size
                    // in the expansion and that looks uglier
                    property_from_number_variants.extend(quote! {
                        #i_lit => #property_struct_name::#variant,
                    });

                    property_variant_types.push(variant.to_string());
                }

                property_enums.extend(quote! {
                    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
                    pub enum #property_struct_name {
                        #property_enum_variants
                    }

                    impl From<crate::block_state::BlockStateIntegerRepr> for #property_struct_name {
                        fn from(value: crate::block_state::BlockStateIntegerRepr) -> Self {
                            match value {
                                #property_from_number_variants
                                _ => panic!("Invalid property value: {}", value),
                            }
                        }
                    }
                });
            }
            PropertyType::Boolean { struct_name } => {
                property_value_name = Ident::new("bool", proc_macro2::Span::call_site());
                property_struct_name = struct_name.clone();
                property_variant_types = vec!["true".to_string(), "false".to_string()];

                property_enums.extend(quote! {
                    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
                    pub struct #property_struct_name(pub bool);

                    impl From<crate::block_state::BlockStateIntegerRepr> for #property_struct_name {
                        fn from(value: crate::block_state::BlockStateIntegerRepr) -> Self {
                            match value {
                                0 => Self(false),
                                1 => Self(true),
                                _ => panic!("Invalid property value: {}", value),
                            }
                        }
                    }
                });
            }
        }
        properties_map.insert(property_value_name.to_string(), property_variant_types);
    }

    let mut block_state_enum_variants = quote! {};
    let mut block_structs = quote! {};

    let mut from_state_to_block_match = quote! {};
    let mut from_registry_block_to_block_match = quote! {};
    let mut from_registry_block_to_blockstate_match = quote! {};
    let mut from_registry_block_to_blockstates_match = quote! {};

    // {
    //     Waterlogged: [
    //         [ vec of waterlogged = true state ids ],
    //         [ vec of waterlogged = false state ids ]
    //     }
    // }
    let mut properties_to_state_ids: HashMap<String, Vec<PropertyVariantData>> = HashMap::new();

    for block in &input.block_definitions.blocks {
        let block_property_names = &block
            .properties_and_defaults
            .iter()
            .map(|p| p.property_value_type.to_string())
            .collect::<Vec<_>>();
        let mut block_properties_vec = Vec::new();
        for property_name in block_property_names {
            // if property_name == "stage" {
            //     panic!("{:?}", block.properties_and_defaults);
            // }
            let property_variants = properties_map
                .get(property_name)
                .unwrap_or_else(|| panic!("Property '{property_name}' not found"))
                .clone();
            block_properties_vec.push(property_variants);
        }

        let mut properties_with_name: Vec<PropertyWithNameAndDefault> =
            Vec::with_capacity(block.properties_and_defaults.len());
        // Used to determine the index of the property so we can optionally add a number
        // to it
        let mut previous_names: Vec<String> = Vec::new();
        for property in &block.properties_and_defaults {
            let index: Option<usize> = if block
                .properties_and_defaults
                .iter()
                .filter(|p| p.name == property.name)
                .count()
                > 1
            {
                Some(
                    previous_names
                        .iter()
                        .filter(|&p| p == &property.name)
                        .count(),
                )
            } else {
                None
            };

            let mut property_name = property_struct_names_to_names
                .get(&property.name)
                .cloned()
                .unwrap_or_else(|| property.name.clone());
            previous_names.push(property_name.clone());
            if let Some(index) = index {
                // property_name.push_str(&format!("_{}", &index.to_string()));
                write!(property_name, "_{index}").unwrap();
            }
            properties_with_name.push(PropertyWithNameAndDefault {
                name_ident: name_to_ident(&property_name),
                name: property_name,
                property_type: property.property_type.clone(),
                property_value_type: property.property_value_type.clone(),
                is_enum: property.is_enum,
                default: property.default.clone(),
            });
        }
        drop(previous_names);

        //     pub face: properties::Face,
        //     pub facing: properties::Facing,
        //     pub powered: properties::Powered,
        // or
        //     pub has_bottle_0: HasBottle,
        //     pub has_bottle_1: HasBottle,
        //     pub has_bottle_2: HasBottle,
        let mut block_struct_fields = quote! {};
        for PropertyWithNameAndDefault {
            property_value_type,
            name_ident,
            is_enum,
            ..
        } in &properties_with_name
        {
            block_struct_fields.extend(if *is_enum {
                quote! { pub #name_ident: properties::#property_value_type, }
            } else {
                quote! { pub #name_ident: #property_value_type, }
            });
        }

        let block_name_pascal_case = Ident::new(
            &to_pascal_case(&block.name.to_string()),
            proc_macro2::Span::call_site(),
        );
        let block_struct_name = Ident::new(
            &block_name_pascal_case.to_string(),
            proc_macro2::Span::call_site(),
        );

        let mut from_block_to_state_match_inner = quote! {};

        let first_state_id = state_id;
        let mut default_state_id = None;

        // if there's no properties, then the block is just a single state
        if block_properties_vec.is_empty() {
            block_state_enum_variants.extend(quote! {
                #block_name_pascal_case,
            });
            default_state_id = Some(state_id);
            state_id += 1;
        }
        for combination in combinations_of(&block_properties_vec) {
            let mut is_default = true;

            // 	face: properties::Face::Floor,
            // 	facing: properties::Facing::North,
            // 	powered: properties::Powered::True,
            let mut from_block_to_state_combination_match_inner = quote! {};
            for i in 0..properties_with_name.len() {
                let property = &properties_with_name[i];
                let property_name_ident = &property.name_ident;
                let property_value_name_ident = &property.property_type;
                let variant =
                    Ident::new(&combination[i].to_string(), proc_macro2::Span::call_site());

                // this terrible code just gets the property default as a string
                let property_default_as_string =
                    match property.default.clone().into_iter().last().unwrap() {
                        TokenTree::Ident(ident) => ident.to_string(),
                        _ => {
                            panic!()
                        }
                    };
                if property_default_as_string != combination[i] {
                    is_default = false;
                }

                let property_variant = if property.is_enum {
                    quote! {properties::#property_value_name_ident::#variant}
                } else {
                    quote! {#variant}
                };

                from_block_to_state_combination_match_inner.extend(quote! {
                    #property_name_ident: #property_variant,
                });

                // add to properties_to_state_ids
                let property_variants = properties_to_state_ids
                    .entry(property_value_name_ident.to_string())
                    .or_default();
                let property_variant_data =
                    property_variants.iter_mut().find(|v| v.ident == variant);
                if let Some(property_variant_data) = property_variant_data {
                    property_variant_data.block_state_ids.push(state_id);
                } else {
                    property_variants.push(PropertyVariantData {
                        block_state_ids: vec![state_id],
                        ident: variant,
                        is_enum: property.is_enum,
                    });
                }
            }

            from_block_to_state_match_inner.extend(quote! {
                #block_struct_name {
                    #from_block_to_state_combination_match_inner
                } => BlockState::new_const(#state_id),
            });

            if is_default {
                default_state_id = Some(state_id);
            }

            state_id += 1;
        }

        let Some(default_state_id) = default_state_id else {
            let defaults = properties_with_name
                .iter()
                .map(|p| match p.default.clone().into_iter().last().unwrap() {
                    TokenTree::Ident(i) => i.to_string(),
                    _ => {
                        panic!()
                    }
                })
                .collect::<Vec<_>>();
            panic!(
                "Couldn't get default state id for {block_name_pascal_case}, combinations={block_properties_vec:?}, defaults={defaults:?}"
            )
        };

        // 7035..=7058 => {
        //     let b = b - 7035;
        //     &AcaciaButtonBlock {
        //         powered: properties::Powered::from((b / 1) % 2),
        //         facing: properties::Facing::from((b / 2) % 4),
        //         face: properties::Face::from((b / 8) % 3),
        //     }
        // }
        let mut from_state_to_block_inner = quote! {};
        let mut division: BlockStateIntegerRepr = 1;
        for i in (0..properties_with_name.len()).rev() {
            let PropertyWithNameAndDefault {
                property_type: property_struct_name_ident,
                name_ident: property_name_ident,
                property_value_type,
                ..
            } = &properties_with_name[i];

            let property_variants = &block_properties_vec[i];
            let property_variants_count = property_variants.len() as crate::BlockStateIntegerRepr;
            let conversion_code = {
                if &property_value_type.to_string() == "bool" {
                    assert_eq!(property_variants_count, 2);
                    // this is not a mistake, it starts with true for some reason
                    quote! {(b / #division) % #property_variants_count == 0}
                } else {
                    quote! {properties::#property_struct_name_ident::from((b / #division) % #property_variants_count)}
                }
            };
            from_state_to_block_inner.extend(quote! {
                #property_name_ident: #conversion_code,
            });

            division *= property_variants_count;
        }

        let last_state_id = state_id - 1;
        from_state_to_block_match.extend(quote! {
            #first_state_id..=#last_state_id => {
                let b = b - #first_state_id;
                Box::new(#block_struct_name {
                    #from_state_to_block_inner
                })
            },
        });
        from_registry_block_to_block_match.extend(quote! {
            azalea_registry::Block::#block_name_pascal_case => Box::new(#block_struct_name::default()),
        });
        from_registry_block_to_blockstate_match.extend(quote! {
            azalea_registry::Block::#block_name_pascal_case => BlockState::new_const(#default_state_id),
        });
        from_registry_block_to_blockstates_match.extend(quote! {
            azalea_registry::Block::#block_name_pascal_case => BlockStates::from(#first_state_id..=#last_state_id),
        });

        let mut block_default_fields = quote! {};
        for PropertyWithNameAndDefault {
            name_ident,
            default: property_default,
            ..
        } in properties_with_name
        {
            block_default_fields.extend(quote! { #name_ident: #property_default, });
        }

        let block_behavior = &block.behavior;
        let block_id = block.name.to_string();

        let from_block_to_state_match = if block.properties_and_defaults.is_empty() {
            quote! { BlockState::new_const(#first_state_id) }
        } else {
            quote! {
                match self {
                    #from_block_to_state_match_inner
                }
            }
        };

        let block_struct = quote! {
            #[derive(Debug, Copy, Clone)]
            pub struct #block_struct_name {
                #block_struct_fields
            }

            impl BlockTrait for #block_struct_name {
                fn behavior(&self) -> BlockBehavior {
                    #block_behavior
                }
                fn id(&self) -> &'static str {
                    #block_id
                }
                fn as_block_state(&self) -> BlockState {
                    #from_block_to_state_match
                }
                fn as_registry_block(&self) -> azalea_registry::Block {
                    azalea_registry::Block::#block_name_pascal_case
                }
            }

            impl From<#block_struct_name> for BlockState {
                fn from(b: #block_struct_name) -> Self {
                    b.as_block_state()
                }
            }

            impl Default for #block_struct_name {
                fn default() -> Self {
                    Self {
                        #block_default_fields
                    }
                }
            }
        };

        block_structs.extend(block_struct);
    }

    let last_state_id = state_id - 1;
    let mut generated = quote! {
        impl BlockState {
            /// The highest possible block state ID.
            pub const MAX_STATE: crate::block_state::BlockStateIntegerRepr = #last_state_id;

            /// Get a property from this block state. Will be `None` if the block can't have the property.
            ///
            /// ```
            /// fn is_waterlogged(block_state: azalea_block::BlockState) -> bool {
            ///     block_state.property::<azalea_block::properties::Waterlogged>().unwrap_or_default()
            /// }
            /// ```
            pub fn property<P: Property>(self) -> Option<P::Value> {
                P::try_from_block_state(self)
            }
        }
    };

    // now impl Property for every property
    // ```
    // match state_id {
    //     // this is just an example of how it might look, these state ids are definitely not correct
    //     0 | 3 | 6 => Some(Self::Axis::X),
    //     1 | 4 | 7 => Some(Self::Axis::Y),
    //     2 | 5 | 8 => Some(Self::Axis::Z),
    //     _ => None,
    // }
    // ```
    let mut property_impls = quote! {};
    for (property_struct_name, property_values) in properties_to_state_ids {
        let mut enum_inner_generated = quote! {};

        let mut is_enum_ = false;

        for PropertyVariantData {
            block_state_ids,
            ident,
            is_enum,
        } in property_values
        {
            enum_inner_generated.extend(if is_enum {
                quote! {
                    #(#block_state_ids)|* => Some(Self::#ident),
                }
            } else {
                quote! {
                    #(#block_state_ids)|* => Some(#ident),
                }
            });
            is_enum_ = is_enum;
        }
        let is_enum = is_enum_;

        let property_struct_name =
            Ident::new(&property_struct_name, proc_macro2::Span::call_site());

        let value = if is_enum {
            quote! { Self }
        } else {
            quote! { bool }
        };

        let property_impl = quote! {
            impl Property for #property_struct_name {
                type Value = #value;

                fn try_from_block_state(block_state: BlockState) -> Option<Self::Value> {
                    match block_state.id() {
                        #enum_inner_generated
                        _ => None
                    }
                }
            }
        };
        property_impls.extend(property_impl);
    }

    generated.extend(quote! {
        pub mod properties {
            use super::*;

            #property_enums

            #property_impls
        }

        pub mod blocks {
            use super::*;

            #block_structs

            impl From<BlockState> for Box<dyn BlockTrait> {
                fn from(block_state: BlockState) -> Self {
                    let b = block_state.id();
                    match b {
                        #from_state_to_block_match
                        _ => panic!("Invalid block state: {}", b),
                    }
                }
            }
            impl From<azalea_registry::Block> for Box<dyn BlockTrait> {
                fn from(block: azalea_registry::Block) -> Self {
                    match block {
                        #from_registry_block_to_block_match
                        _ => unreachable!("There should always be a block struct for every azalea_registry::Block variant")
                    }
                }
            }
            impl From<azalea_registry::Block> for BlockState {
                fn from(block: azalea_registry::Block) -> Self {
                    match block {
                        #from_registry_block_to_blockstate_match
                        _ => unreachable!("There should always be a block state for every azalea_registry::Block variant")
                    }
                }
            }
            impl From<azalea_registry::Block> for BlockStates {
                fn from(block: azalea_registry::Block) -> Self {
                    match block {
                        #from_registry_block_to_blockstates_match
                        _ => unreachable!("There should always be a block state for every azalea_registry::Block variant")
                    }
                }
            }
        }
    });

    generated.into()
}

/// Convert a name to a Rust identifier, replacing some Rust keywords with
/// alternatives (e.g. `type` -> `kind`).
fn name_to_ident(name: &str) -> Ident {
    let ident_str = match name {
        "type" => "kind",
        _ => name,
    };
    Ident::new(ident_str, proc_macro2::Span::call_site())
}