witx-codegen 0.11.4

WITX code generator for WebAssembly guest modules.
Documentation 
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use std::io::Write;

use super::*;

impl ZigGenerator {
    fn define_union_member_accessors<T: Write>(
        w: &mut PrettyWriter<T>,
        union_name: &str,
        _i: usize,
        member: &ASUnionMember,
    ) -> Result<(), Error> {
        let name = &member.name;
        let member_is_void = matches!(member.type_.as_ref(), ASType::Void);

        if member_is_void {
            // new_*
            w.write_line(format!(
                "fn new{}() {} {{",
                name.as_fn_suffix(),
                union_name.as_type()
            ))?;
            {
                let mut w = w.new_block();
                w.write_line(format!(
                    "return {} {{ .tag = .{} }};",
                    union_name.as_type(),
                    name.as_var(),
                ))?;
            }
            w.write_line("}")?.eob()?;
        } else {
            // !member_is_void
            // new_*
            w.write_line(format!(
                "fn new{}(val: {}) {} {{",
                name.as_fn_suffix(),
                member.type_.as_lang(),
                union_name.as_type()
            ))?;
            {
                let mut w = w.new_block();
                w.write_line(format!(
                    "return {}{{ .tag = .{}, .member = .{{ .{} = val }} }};",
                    union_name.as_type(),
                    name.as_var(),
                    name.as_var()
                ))?;
            }
            w.write_line("}")?.eob()?;

            // get_*
            w.write_line(format!(
                "pub fn {}(self: {}) {} {{",
                name.as_fn_suffix(),
                union_name.as_type(),
                member.type_.as_lang()
            ))?;
            {
                let mut w = w.new_block();
                w.write_line(format!("std.debug.assert(self.tag == .{});", name.as_var()))?;
                w.write_line(format!("return self.member.{};", member.name.as_var()))?;
            }
            w.write_line("}")?.eob()?;

            // set_*
            w.write_line(format!(
                "pub fn set{}(self: *{}, val: {}) void {{",
                name.as_fn_suffix(),
                union_name.as_type(),
                member.type_.as_lang()
            ))?;
            {
                let mut w = w.new_block();
                w.write_line(format!("std.debug.assert(self.tag == .{});", name.as_var()))?;
                w.write_line(format!("self.member.{} = val;", member.name.as_var()))?;
            }
            w.write_line("}")?.eob()?;
        }

        // is_*
        w.write_line(format!(
            "fn is{}(self: {}) bool {{",
            name.as_fn_suffix(),
            union_name.as_type(),
        ))?;
        {
            let mut w = w.new_block();
            w.write_line(format!("return self.tag == .{};", name.as_var()))?;
        }
        w.write_line("}")?.eob()?;

        Ok(())
    }

    fn define_union_member<T: Write>(
        w: &mut PrettyWriter<T>,
        union_name: &str,
        i: usize,
        member: &ASUnionMember,
    ) -> Result<(), Error> {
        Self::define_union_member_accessors(w, union_name, i, member)?;
        Ok(())
    }

    pub fn define_as_union<T: Write>(
        w: &mut PrettyWriter<T>,
        name: &str,
        union_: &ASUnion,
    ) -> Result<(), Error> {
        let tag_repr = union_.tag_repr.as_ref();
        w.write_line(format!("pub const {} = extern struct {{", name.as_type()))?;
        {
            let mut w = w.new_block();
            w.write_line(format!("tag: enum({}) {{", tag_repr.as_lang()))?;
            {
                let mut w = w.new_block();
                for (i, member) in union_.members.iter().enumerate() {
                    w.write_line(format!("{} = {},", member.name.as_var(), i))?;
                }
            }
            w.write_line("},")?;
            let pad_len = union_.padding_after_tag;
            for i in 0..(pad_len & 1) {
                w.write_line(format!("__pad8_{}: u8 = undefined,", i))?;
            }
            for i in 0..(pad_len & 3) / 2 {
                w.write_line(format!("__pad16_{}: u16 = undefined,", i))?;
            }
            for i in 0..(pad_len & 7) / 4 {
                w.write_line(format!("__pad32_{}: u32 = undefined,", i))?;
            }
            for i in 0..pad_len / 8 {
                w.write_line(format!("__pad64_{}: u64 = undefined,", i))?;
            }
            w.write_line("member = extern union {")?;
            {
                let mut w = w.new_block();
                for member in union_.members.iter() {
                    let member_is_void = matches!(member.type_.as_ref(), ASType::Void);
                    if !member_is_void {
                        w.write_line(format!(
                            "{}: {},",
                            member.name.as_var(),
                            member.type_.as_lang(),
                        ))?;
                    }
                }
            }
            w.write_line("},")?;
        }
        w.eob()?;

        for (i, member) in union_.members.iter().enumerate() {
            w.eob()?;
            Self::define_union_member(w, name, i, member)?;
        }
        w.write_line("};")?.eob()?;
        Ok(())
    }
}