fn output_preamble()

in serde-generate/src/rust.rs [180:216]

• 35 lines of code
• 9 McCabe index (conditional complexity)

    fn output_preamble(&mut self) -> Result<()> {
        let external_names = self
            .generator
            .config
            .external_definitions
            .values()
            .cloned()
            .flatten()
            .collect::<HashSet<_>>();
        writeln!(self.out, "#![allow(unused_imports)]")?;
        if !external_names.contains("Map") {
            writeln!(self.out, "use std::collections::BTreeMap as Map;")?;
        }
        if self.generator.config.serialization {
            writeln!(self.out, "use serde::{{Serialize, Deserialize}};")?;
        }
        if self.generator.config.serialization && !external_names.contains("Bytes") {
            writeln!(self.out, "use serde_bytes::ByteBuf as Bytes;")?;
        }
        for (module, definitions) in &self.generator.config.external_definitions {
            // Skip the empty module name.
            if !module.is_empty() {
                writeln!(
                    self.out,
                    "use {}::{{{}}};",
                    module,
                    definitions.to_vec().join(", "),
                )?;
            }
        }
        writeln!(self.out)?;
        if !self.generator.config.serialization && !external_names.contains("Bytes") {
            // If we are not going to use Serde derive macros, use plain vectors.
            writeln!(self.out, "type Bytes = Vec<u8>;\n")?;
        }
        Ok(())
    }