ucg/src/convert/flags.rs

// Copyright 2017 Jeremy Wall <jeremy@marzhillstudios.com>
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

//! Contains code for converting a UCG Val into the command line flag output target.
use std::rc::Rc;
use std::io::Write;
use std::io::Result;

use build::Val;
use convert::traits::Converter;

/// FlagConverter implements the conversion logic for converting a Val into a set of command line flags.
pub struct FlagConverter {}

impl FlagConverter {
    pub fn new() -> Self {
        FlagConverter {}
    }

    fn write_flag_name(&self, pfx: &str, name: &str, w: &mut Write) -> Result<()> {
        if name.chars().count() > 1 || pfx.chars().count() > 0 {
            try!(write!(w, "--{}{} ", pfx, name));
        } else {
            try!(write!(w, "-{} ", name));
        }
        return Ok(());
    }

    fn write(&self, pfx: &str, v: &Val, w: &mut Write) -> Result<()> {
        match v {
            &Val::Empty => {
                // Empty is a noop.
                return Ok(());
            }
            &Val::Float(ref f) => {
                try!(write!(w, "{} ", f));
            }
            &Val::Int(ref i) => {
                try!(write!(w, "{} ", i));
            }
            &Val::String(ref s) => {
                try!(write!(w, "'{}' ", s));
            }
            &Val::List(ref _def) => {
                // FIXME(jwall): Fill this in?
                eprintln!("Skipping List...");
            }
            &Val::Tuple(ref flds) => {
                for &(ref name, ref val) in flds.iter() {
                    if let &Val::Empty = val.as_ref() {
                        try!(self.write_flag_name(pfx, &name.val, w));
                        continue;
                    }
                    if val.is_tuple() {
                        let new_pfx = format!("{}{}.", pfx, name);
                        try!(self.write(&new_pfx, val, w));
                    } else {
                        try!(self.write_flag_name(pfx, &name.val, w));
                        // TODO(jwall): What if the value is a tuple?
                        try!(self.write(pfx, &val, w));
                    }
                }
            }
            &Val::Macro(ref _def) => {
                // This is ignored
                eprintln!("Skipping macro...");
            }
        }
        Ok(())
    }
}

impl Converter for FlagConverter {
    fn convert(&self, v: Rc<Val>, mut w: Box<Write>) -> Result<()> {
        self.write("", &v, &mut w)
    }
}

// We need some unit tests for this now :D