deimos-lang/ast-generator/src/struct_build_fn.rs

use crate::spec::{
    BooleanBuild, ChildSpec, SingleBooleanChildToBuild, SingleChildToBuild,
    SingleLiteralChildToBuild, SingleTypeChildToBuild, StructBuildSpec, VecChild, VecChildToBuild,
};
use convert_case::{Case, Casing};
use proc_macro2::{Ident, TokenStream};
use quote::{format_ident, quote};
use crate::util::make_build_pair;

fn make_vec_child_holder(vec_child: &VecChild) -> TokenStream {
    let (child_ident, child_type_ident) = match vec_child.build() {
        VecChildToBuild::Type(vec_type_child) => (
            format_ident!("{}", vec_type_child.var_name()),
            format_ident!("{}", vec_type_child.build()),
        ),
    };
    quote! {
        let mut #child_ident: Vec<Box<#child_type_ident>> = vec![]
    }
}

fn make_single_type_child_holder(single_type_child: &SingleTypeChildToBuild) -> TokenStream {
    let child_ident = format_ident!("{}", single_type_child.var_name());
    let child_type_ident = format_ident!("{}", single_type_child.build());
    quote! {
        let mut #child_ident: Option<Box<#child_type_ident>> = None
    }
}

fn make_single_boolean_child_holder(
    single_boolean_child: &SingleBooleanChildToBuild,
) -> TokenStream {
    let child_ident = format_ident!("{}", single_boolean_child.var_name());
    quote! {
        let mut #child_ident: bool = false
    }
}

fn make_literal_child_holder(
    literal_child: &SingleLiteralChildToBuild,
    literal_type_ident: Ident,
) -> TokenStream {
    let child_ident = format_ident!("{}", literal_child.var_name());
    quote! {
        let mut #child_ident: Option<#literal_type_ident> = None
    }
}

fn make_child_holder(child_spec: &ChildSpec) -> Option<TokenStream> {
    match child_spec {
        ChildSpec::SkipChild(_) => None,
        ChildSpec::VecChild(vec_child) => Some(make_vec_child_holder(vec_child)),
        ChildSpec::SingleChild(single_child) => match single_child.build() {
            SingleChildToBuild::Type(single_type_child) => {
                Some(make_single_type_child_holder(single_type_child))
            }
            SingleChildToBuild::Boolean(boolean_child) => {
                Some(make_single_boolean_child_holder(boolean_child))
            }
            SingleChildToBuild::Int(literal_child) => Some(make_literal_child_holder(
                literal_child,
                format_ident!("i32"),
            )),
            SingleChildToBuild::Long(literal_child) => Some(make_literal_child_holder(
                literal_child,
                format_ident!("i64"),
            )),
            SingleChildToBuild::Double(literal_child) => Some(make_literal_child_holder(
                literal_child,
                format_ident!("f64"),
            )),
            SingleChildToBuild::String(literal_child) => Some(make_literal_child_holder(
                literal_child,
                format_ident!("String"),
            )),
        },
    }
}

fn get_literal_child_ident(literal_child: &SingleLiteralChildToBuild) -> Ident {
    format_ident!("{}", literal_child.var_name())
}

fn make_match_action(child_spec: &ChildSpec) -> TokenStream {
    match child_spec {
        ChildSpec::SkipChild(_) => quote! {},
        ChildSpec::VecChild(vec_child) => {
            let (child_name_ident, build_fn_ident) = match vec_child.build() {
                VecChildToBuild::Type(vec_type_child) => (
                    format_ident!("{}", vec_type_child.var_name()),
                    format_ident!("{}", vec_type_child.with()),
                ),
            };
            quote! {
                #child_name_ident.push(Box::new(#build_fn_ident(inner_pair)))
            }
        }
        ChildSpec::SingleChild(single_child) => match single_child.build() {
            SingleChildToBuild::Type(single_type_child) => {
                let child_name_ident = format_ident!("{}", single_type_child.var_name());
                let build_fn_ident = format_ident!("{}", single_type_child.with());
                quote! {
                    #child_name_ident = Some(Box::new(#build_fn_ident(inner_pair)))
                }
            }
            SingleChildToBuild::Boolean(single_boolean_child) => {
                let child_name_ident = format_ident!("{}", single_boolean_child.var_name());
                match single_boolean_child.build() {
                    BooleanBuild::RulePresent => quote! {
                        #child_name_ident = true
                    },
                    BooleanBuild::ParseWholePair => quote! {
                        #child_name_ident = Some(inner_pair.as_str().parse().unwrap())
                    },
                }
            }
            SingleChildToBuild::Int(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                quote! {
                    #child_ident = Some(inner_pair.as_str().parse().unwrap())
                }
            }
            SingleChildToBuild::Long(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                quote! {
                    let as_string = inner_pair.as_str();
                    let without_el = &as_string[0..(as_string.len() - 1)];
                    #child_ident = Some(without_el.parse().unwrap())
                }
            }
            SingleChildToBuild::Double(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                quote! {
                    #child_ident = Some(inner_pair.as_str().parse().unwrap())
                }
            }
            SingleChildToBuild::String(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                quote! {
                    #child_ident = Some(inner_pair.as_str().to_string())
                }
            }
        },
    }
}

fn make_rule_matcher(child_spec: &ChildSpec) -> TokenStream {
    let rule_ident = match child_spec {
        ChildSpec::SkipChild(skip_child) => format_ident!("{}", skip_child.rule()),
        ChildSpec::VecChild(vec_child) => format_ident!("{}", vec_child.rule()),
        ChildSpec::SingleChild(single_child) => format_ident!("{}", single_child.rule()),
    };
    let action = make_match_action(child_spec);

    quote! {
        Rule::#rule_ident => {
            #action;
        }
    }
}

fn make_child_arg(child_spec: &ChildSpec) -> Option<TokenStream> {
    match child_spec {
        ChildSpec::SkipChild(_) => None,
        ChildSpec::VecChild(vec_child) => {
            let child_ident = match vec_child.build() {
                VecChildToBuild::Type(vec_type_child) => {
                    format_ident!("{}", vec_type_child.var_name())
                }
            };
            Some(quote! { #child_ident })
        }
        ChildSpec::SingleChild(single_child) => match single_child.build() {
            SingleChildToBuild::Type(single_type_child) => {
                let child_ident = format_ident!("{}", single_type_child.var_name());
                if single_type_child.optional() {
                    Some(quote! { #child_ident })
                } else if let Some(or_else) = single_type_child.or_else() {
                    let child_type_ident = format_ident!("{}", single_type_child.build());
                    let or_else_ident = format_ident!("{}", or_else);
                    Some(quote! {
                        #child_ident.unwrap_or_else(|| Box::new(#child_type_ident::#or_else_ident()))
                    })
                } else {
                    Some(quote! { #child_ident.unwrap() })
                }
            }
            SingleChildToBuild::Boolean(single_boolean_child) => {
                let child_ident = format_ident!("{}", single_boolean_child.var_name());
                Some(quote! { #child_ident })
            }
            SingleChildToBuild::Int(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                Some(quote! { #child_ident.unwrap() })
            }
            SingleChildToBuild::Long(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                Some(quote! { #child_ident.unwrap() })
            }
            SingleChildToBuild::Double(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                Some(quote! { #child_ident.unwrap() })
            }
            SingleChildToBuild::String(literal_child) => {
                let child_ident = get_literal_child_ident(literal_child);
                Some(quote! { #child_ident.unwrap() })
            }
        },
    }
}

fn make_return_value_stream(build_spec: &StructBuildSpec) -> TokenStream {
    let type_ident = format_ident!("{}", build_spec.build());
    let child_args = build_spec
        .children()
        .iter()
        .map(|child| make_child_arg(child))
        .filter(|child_arg| child_arg.is_some())
        .map(|child_arg| child_arg.unwrap())
        .collect::<Vec<_>>();

    quote! {
        #type_ident::new(
            #(#child_args,)*
        )
    }
}

pub fn make_struct_build_fn(build_spec: &StructBuildSpec) -> TokenStream {
    let build_fn_ident = format_ident!("{}", build_spec.with()); // TODO: get rid of with
    let pair_ident = format_ident!("{}", make_build_pair(build_spec.var_name())); // TODO: get rid of var_name
    let return_type_ident = format_ident!("{}", build_spec.build());

    let child_holders = build_spec
        .children()
        .iter()
        .map(|child_spec| make_child_holder(child_spec))
        .filter(|child_holder| child_holder.is_some())
        .map(|child_holder| child_holder.unwrap())
        .collect::<Vec<_>>();

    let rule_matchers = build_spec
        .children()
        .iter()
        .map(|child_spec| make_rule_matcher(child_spec))
        .collect::<Vec<_>>();

    let iter_stream = quote! {
        for inner_pair in #pair_ident.into_inner() {
            match inner_pair.as_rule() {
                #(#rule_matchers)*
            }
        }
    };

    let new_stream = make_return_value_stream(build_spec);

    quote! {
        fn #build_fn_ident(#pair_ident: Pair<Rule>) -> #return_type_ident {
            #(#child_holders;)*

            #iter_stream

            #new_stream
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::spec::VecTypeChildToBuild;

    #[test]
    fn vec_child_holder() {
        let vec_child = VecChild::new(
            "test_child",
            "Test",
            VecChildToBuild::Type(VecTypeChildToBuild::new(
                "TestType",
                "test_child",
                "build_test_child",
            )),
        );
        assert_eq!(
            make_vec_child_holder(&vec_child).to_string(),
            quote! {
                let mut test_child: Vec<Box<TestType>> = vec![]
            }
            .to_string()
        );
    }

    #[test]
    fn single_type_child_holder() {
        let single_type_child = SingleTypeChildToBuild::from_build_or_rule("TestType", None, false);
        assert_eq!(
            make_single_type_child_holder(&single_type_child).to_string(),
            quote! {
                let mut test_type: Option<Box<TestType>> = None
            }
            .to_string()
        );
    }

    #[test]
    fn single_boolean_child_holder() {
        let single_boolean_child =
            SingleBooleanChildToBuild::new("test_child", BooleanBuild::RulePresent);
        assert_eq!(
            make_single_boolean_child_holder(&single_boolean_child).to_string(),
            quote! {
                let mut test_child: bool = false
            }
            .to_string()
        );
    }
}