oak 0.8.0

A typed parser generator syntax extension for Parsing Expression Grammar (PEG).
Documentation 
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// Copyright 2015 Pierre Talbot (IRCAM)

// 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.

use proc_macro2::Ident;
use quote::format_ident;

fn modify_path(mut path: syn::Path, prefix: &str) -> syn::Path {
  let segment = path.segments.last_mut().expect("rule path");
  let x = format_ident!("{}_{}", prefix, segment.ident);
  segment.ident = x;
  path
}

pub fn parser_name(rule_path: syn::Path) -> syn::Path {
  modify_path(rule_path, "parse")
}

pub fn recognizer_name(rule_path: syn::Path) -> syn::Path {
  modify_path(rule_path, "recognize")
}

pub fn parser_id(id: Ident) -> Ident {
  format_ident!("parse_{}", id)
}

pub fn recognizer_id(id: Ident) -> Ident {
  format_ident!("recognize_{}", id)
}

pub struct NameFactory
{
  prefix_uid: usize,
  mark_uid: usize,
  branch_failed_uid: usize,
  counter_uid: usize,
  closure_uid: usize
}

impl NameFactory
{
  pub fn new() -> NameFactory {
    NameFactory {
      prefix_uid: 1,
      mark_uid: 0,
      branch_failed_uid: 0,
      counter_uid: 0,
      closure_uid: 0
    }
  }

  pub fn next_mark_name(&mut self) -> Ident {
    self.mark_uid += 1;
    format_ident!("mark{}", self.mark_uid)
  }

  pub fn next_branch_failed_name(&mut self) -> Ident {
    self.branch_failed_uid += 1;
    format_ident!("branch_failed_{}", self.branch_failed_uid)
  }

  pub fn next_closure_name(&mut self) -> Ident {
    self.closure_uid += 1;
    format_ident!("success_continuation_{}", self.closure_uid)
  }

  pub fn next_counter_name(&mut self) -> Ident {
    self.counter_uid += 1;
    format_ident!("counter{}", self.counter_uid)
  }

  pub fn fresh_vars(&mut self, cardinality: usize) -> Vec<Ident> {
    let prefix = self.next_var_prefix();
    (0..cardinality)
      .map(|i| format_ident!("{}{}", prefix, i))
      .collect()
  }

  pub fn next_var_prefix(&mut self) -> String {
    const LETTERS: &'static [u8] = b"abcdefghijklmnopqrstuvwxyz";
    let mut prefix = String::new();
    let mut num_letter = self.prefix_uid;
    while num_letter > 0 {
      let x = num_letter % LETTERS.len();
      num_letter /= LETTERS.len();
      prefix.push(LETTERS[x] as char);
    }
    self.prefix_uid += 1;
    prefix
  }
}