You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/rustrogueliketutorial/chapter-50-stats/src/map_builders/waveform_collapse
    
    the code of the file until where you have to start completion: use super::{MetaMapBuilder, BuilderMap, Map, TileType};
use rltk::RandomNumberGenerator;
mod common;
use common::*;
mod constraints;
use constraints::*;
mod solver;
use solver::*;

/// Provides a map builder using the Wave Function Collapse algorithm.
pub struct WaveformCollapseBuilder {}

impl MetaMapBuilder for WaveformCollapseBuilder {
    fn build_map(&mut self, rng: &mut rltk::Ra
    
    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        const CHUNK_SIZE :i32 = 8;
        build_data.take_snapshot();

        let patterns = build_patterns(&build_data.map, CHUNK_SIZE, true, true);
        let constraints = patterns_to_constraints(patterns, CHUNK_SIZE);
        self.render_tile_gallery(&constraints, CHUNK_SIZE, build_data);

        let old_map = build_data.map.clone();

        build_data.map = Map::new(build_data.map.depth, build_data.width, build_data.height);
        build_data.spawn_list.clear();
        build_data.rooms = None;
        build_data.corridors = None;
        let mut tries = 0;
        loop {
            let mut solver = Solver::new(constraints.clone(), CHUNK_SIZE, &build_data.map);
            while !solver.iteration(&mut build_data.map, rng) {
                build_data.take_snapshot();
            }
            build_data.take_snapshot();
            if solver.possible { break; } // If it has hit an impossible condition, try again
            tries += 1;
            if tries > 10 { break; }
        }

        if tries > 10 {
            // Restore the old one
            build_data.map = old_map;
        }
    }