cbindgen 0.4.1

A tool for generating C bindings to Rust code.
Documentation 
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/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use std::io::Write;
use std::mem;

use syn;

use bindgen::config::{Config, Language};
use bindgen::ir::{AnnotationSet, Cfg, Documentation, Item, ItemContainer, Type};
use bindgen::writer::{Source, SourceWriter};

#[derive(Debug, Clone)]
pub struct LiteralExpr(String);

impl LiteralExpr {
    pub fn load(expr: &syn::Expr) -> Result<LiteralExpr, String> {
        match &expr.node {
            &syn::ExprKind::Lit(syn::Lit::Str(ref text, ..)) => {
                Ok(LiteralExpr(format!("u8\"{}\"", text)))
            }
            &syn::ExprKind::Lit(syn::Lit::Byte(value)) => Ok(LiteralExpr(format!("{}", value))),
            &syn::ExprKind::Lit(syn::Lit::Char(value)) => Ok(LiteralExpr(format!("{}", value))),
            &syn::ExprKind::Lit(syn::Lit::Int(value, ref ty)) => match ty {
                &syn::IntTy::Usize
                | &syn::IntTy::U8
                | &syn::IntTy::U16
                | &syn::IntTy::U32
                | &syn::IntTy::U64
                | &syn::IntTy::Unsuffixed => Ok(LiteralExpr(format!("{}", value))),
                &syn::IntTy::Isize
                | &syn::IntTy::I8
                | &syn::IntTy::I16
                | &syn::IntTy::I32
                | &syn::IntTy::I64 => unsafe {
                    Ok(LiteralExpr(format!(
                        "{}",
                        mem::transmute::<u64, i64>(value)
                    )))
                },
            },
            &syn::ExprKind::Lit(syn::Lit::Float(ref value, ref _ty)) => {
                Ok(LiteralExpr(format!("{}", value)))
            }
            &syn::ExprKind::Lit(syn::Lit::Bool(value)) => Ok(LiteralExpr(format!("{}", value))),
            _ => Err("Unsupported literal expression.".to_owned()),
        }
    }
}

#[derive(Debug, Clone)]
pub struct Constant {
    pub name: String,
    pub ty: Type,
    pub value: LiteralExpr,
    pub cfg: Option<Cfg>,
    pub annotations: AnnotationSet,
    pub documentation: Documentation,
}

impl Constant {
    pub fn load(
        name: String,
        ty: &syn::Ty,
        expr: &syn::Expr,
        attrs: &Vec<syn::Attribute>,
        mod_cfg: &Option<Cfg>,
    ) -> Result<Constant, String> {
        let ty = Type::load(ty)?;

        if ty.is_none() {
            return Err("Cannot have a zero sized const definition.".to_owned());
        }

        let ty = ty.unwrap();

        if !ty.is_primitive_or_ptr_primitive() {
            return Err("Cannot have a non primitive const definition.".to_owned());
        }

        Ok(Constant {
            name: name,
            ty: ty,
            value: LiteralExpr::load(expr)?,
            cfg: Cfg::append(mod_cfg, Cfg::load(attrs)),
            annotations: AnnotationSet::load(attrs)?,
            documentation: Documentation::load(attrs),
        })
    }
}

impl Item for Constant {
    fn name(&self) -> &str {
        &self.name
    }

    fn cfg(&self) -> &Option<Cfg> {
        &self.cfg
    }

    fn annotations(&self) -> &AnnotationSet {
        &self.annotations
    }

    fn annotations_mut(&mut self) -> &mut AnnotationSet {
        &mut self.annotations
    }

    fn container(&self) -> ItemContainer {
        ItemContainer::Constant(self.clone())
    }

    fn rename_for_config(&mut self, config: &Config) {
        config.export.rename(&mut self.name);
    }
}

impl Source for Constant {
    fn write<F: Write>(&self, config: &Config, out: &mut SourceWriter<F>) {
        if config.constant.allow_static_const && config.language == Language::Cxx {
            if let Type::ConstPtr(..) = self.ty {
                out.write("static ");
            } else {
                out.write("static const ");
            }
            self.ty.write(config, out);
            write!(out, " {} = {};", self.name, self.value.0)
        } else {
            write!(out, "#define {} {}", self.name, self.value.0)
        }
    }
}