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// A search utility for arbitrary (new) tileUpdates.
// Provides `add` functionality, which auto-checks adjacency with other blocks. Subsequently, it searches them
// Provides `del` functionality, which should be used with auto-deletion
const bs = require('binary-search');
const Space = require('../space');
const comb = require('../utils/comb')
const vec = require('../utils/vec');
function getComp(index){
return (element,needle) => (element[index] - needle[index] || element[1-index] - needle[1-index])
}
function tileToChar(coord){
let cofactor = [8,16];
return [coord[0]*cofactor[0], coord[1]*cofactor[1]];
}
function Search(searchBlock){ // searchBlock should be a Space object.
this.tiles = {}; // Object which stores Spaces.
this.sort = [[],[]]; // Vertically/horizontally sorted list of tiles for fast addition, deletion, and searching
this.add = function(loc, space){ // loc should be [tileY,tileX] and space Space.
this.tiles[loc] = space;
this.tiles[loc].loc = vec.tileToChar(loc);
let inds = Array(2); // Records horizontal and vertical indices for insertion. Then actually inserts the item.
[0,1].forEach( ind => { // ind chooses y-or-x
inds[ind] = -bs(this.sort[ind], loc, getComp(ind))-1;
if (inds[ind] < 0) throw "loc should not be a part of the list";
this.sort[ind].splice(inds[ind], 0, loc);
});
let block = this.block(loc, inds);
let searchspace = new Space();
block.forEach( (tile) => {
searchspace.comb( this.tiles[tile], comb.add );
});
coords = searchspace.search(searchBlock); // According to space docs, [] on failure and a character location on success
return vec.add(coords, searchspace.loc);
}
this.block = function(loc,inds,exclude){
if (! exclude) exclude = new Set(); // If not given, replace.
let adjacent = new Set([loc]);
exclude.add(loc);
[0,1].forEach( ind => {
// inds[ind] is address, so check neighbors on sort[ind] (up, then down)
// until sort[ind][inds[ind]][ind] != sort[ind][otherind][ind].
// on each, if sort[ind][otherind][1-ind] == sort[ind][inds[ind]][1-ind],
// add to adjacent and search it with exclude=adjacent. Add that to adjacent
let sort = this.sort[ind];
let chkind = inds[ind];
[-1, 1].forEach( sgn => {
let curind = chkind + sgn;
while (sort[curind] && sort[chkind][ind] == sort[curind][ind]){
if (! exclude.has(sort[curind])){
adjacent.add(...this.block(sort[curind], [curind, bs(sort, sort[curind], getComp(1-ind))], exclude));
}
curind += sgn;
}
});
});
return adjacent;
}
this.del = function(loc){
delete this.tiles[loc];
[0, 1].forEach( ind => {
let theind = bs(this.sort[ind], loc, getComp(ind));
if (theind < 0) throw "loc must already be a part of the list";
this.sort[ind].splice(bs(this.sort[ind], loc, getComp(ind)), 1);
})
}
this.has = function(loc){
if (bs(this.sort[0], loc, getComp(0)) < 0) return false; // Could use ind = 1 just as well, but doesn't really matter
// bs returns negative if not found.
else return true;
}
}
module.exports = Search;
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