simple_term_rewriter 0.3.0

A basic interface to rewrite concrete tree terms according to a set of rules
Documentation 
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/*
Copyright 2024 Erwan Mahe (github.com/erwanM974)

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 std::hash::Hash;
use std::fmt;



/** 
 * An object that keeps track of positions in a concrete 
 * term of the Language which we are considering.
 * **/
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct PositionInLanguageTerm {
    absolute_coordinates_from_root : Vec<usize>
}


impl PositionInLanguageTerm {

    pub fn from_absolute_coordinates(absolute_coordinates_from_root : Vec<usize>) -> Self {
        Self { absolute_coordinates_from_root }
    }

    pub fn get_parent_position(&self) -> Option<Self> {
        if self.absolute_coordinates_from_root.is_empty() {
            None 
        } else {
            let depth = self.get_depth();
            let parent = Self::from_absolute_coordinates(
                self.absolute_coordinates_from_root[0..(depth-1)].to_vec()
            );
            Some(parent)
        }
    }

    pub fn get_depth(&self) -> usize {
        self.absolute_coordinates_from_root.len()
    }

    /** 
     * Get position epsilon i.e. that of the toot of the term.
     * **/
     pub fn get_root_position() -> Self {
        PositionInLanguageTerm{
            absolute_coordinates_from_root : vec![]
        }
     }

     /** 
      * If x is at position p in y, Then x is at position:
      * - 1.p in z(y,.,.)
      * - 2.p in z(.,y,.)
      * - etc
      * **/
    pub fn get_position_of_nth_child(&self, n : usize) -> Self {
        let mut absolute_coords = self.absolute_coordinates_from_root.clone();
        absolute_coords.push(n);
        Self::from_absolute_coordinates(absolute_coords)
    }
    
    pub fn get_absolute_coordinates_from_root(&self) -> &[usize] {
        &self.absolute_coordinates_from_root
    }

}


impl fmt::Display for PositionInLanguageTerm {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if self.absolute_coordinates_from_root.is_empty() {
            write!(f,"ε")
        } else {
            let as_strs : Vec<String> = self.absolute_coordinates_from_root.iter().map(|x| x.to_string()).collect();
            write!(f,"{:}",as_strs.join("_"))
        }
    }
}