rust-analyzer/crates/ra_ide_api/src/display.rs

//! This module contains utilities for rendering turning things into something
//! that may be used to render in UI.
use super::*;
use std::fmt::{self, Display};
use join_to_string::join;

/// Contains information about a function signature
#[derive(Debug)]
pub struct FunctionSignature {
    /// Optional visibility
    pub visibility: Option<String>,
    /// Name of the function
    pub name: Option<String>,
    /// Documentation for the function
    pub doc: Option<Documentation>,
    /// Generic parameters
    pub generic_parameters: Vec<String>,
    /// Parameters of the function
    pub parameters: Vec<String>,
    /// Optional return type
    pub ret_type: Option<String>,
    /// Where predicates
    pub where_predicates: Vec<String>,
}

impl FunctionSignature {
    pub(crate) fn with_doc_opt(mut self, doc: Option<Documentation>) -> Self {
        self.doc = doc;
        self
    }
}

impl Display for FunctionSignature {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if let Some(t) = &self.visibility {
            write!(f, "{} ", t)?;
        }

        if let Some(name) = &self.name {
            write!(f, "fn {}", name)?;
        }

        if !self.generic_parameters.is_empty() {
            join(self.generic_parameters.iter())
                .separator(", ")
                .surround_with("<", ">")
                .to_fmt(f)?;
        }

        join(self.parameters.iter()).separator(", ").surround_with("(", ")").to_fmt(f)?;

        if let Some(t) = &self.ret_type {
            write!(f, " -> {}", t)?;
        }

        if !self.where_predicates.is_empty() {
            write!(f, "\nwhere ")?;
            join(self.where_predicates.iter()).separator(",\n      ").to_fmt(f)?;
        }

        Ok(())
    }
}