edge2reader.js

var fs = require('fs');

function edgewrite(outputfile, g, cb) {
    var data = "";
    var i = 0;

    data += "" + g.num_vertices + " " + g.num_edges + "\n";
    while (i < g.adj_begin.length) {
	var pos = g.adj_begin[i];
	var j = 0;
	while (j < g.adj_length[i]) {
	    data += "" + i + " " + g.adj_list[pos+j] + "\n";
	    j++;
	}
	i++;
    }
    fs.writeFile(outputfile,data,function(){cb(null);})
}

function edgeread(inputfile, cb) {

    var linenumber = 0;
    var error = false;
    
    var llreader = require('line-by-line');
    lr = new llreader(inputfile);

    lr.on('error', function (err) {
	// 'err' contains error object
	error = true;
	cb(err);
    });

    var indexmap = {};
    var next_index = 0;
    var num_edges = 0;
    var num_vertices = 0;
    var from, to;
    var data = [];
    var N, M;
    
    lr.on('line', function (line) {
	linenumber++;

	if (linenumber == 1) {
	    a = line.split(" ");
	    if (a.length < 2) {
		console.log("error:" + linenumber + "format error");
		return;
	    }
	    if (a.length == 1) {
		M = parseInt(a[0]); // edge count
	    } else if (a.length == 2) {
		N = parseInt(a[0]); // vertex count
		M = parseInt(a[1]); // edge count
	    }
	    return;
	}

	// 'line' contains the current line without the trailing newline character.
//	console.log(line);
	a = line.split(" ");
	if (a.length != 2) {
	    console.log("error:" + linenumber + "format error");
	    return;
	}
	var from = parseInt(a[0]);
	var to = parseInt(a[1]);
//	console.log(from, to);
	if (indexmap[from] == undefined) {
//	    console.log("map", from, next_index);
	    indexmap[from] = next_index++;
	}
	if (indexmap[to] == undefined) {
//	    console.log("map", to, next_index);
	    indexmap[to] = next_index++;
	}
	num_edges++;

	data.push(a);
    });

    var adj_begin = [];
    var adj_length = [];
    var adj_vec = [];
    var adj_list = [];

    function max(i, j) { return (i>j)?i:j; }
    function syscopy(targ, targfrom, src, srcfrom, count)
    {
//	console.log("syscpy", targfrom, srcfrom, count);
	var i = 0;
	while (i < count) {
	    targ[targfrom+i] = src[srcfrom+i];
	    i++;
	}
    }
    function alength(o) {
	return Object.keys(o).length;
    }
    lr.on('end', function () {
	if (error) return;
	
	// All lines are read, file is closed now.
	num_vertices = next_index;
//	console.log("um_vertices", 	num_vertices);
	var i = 0;
	while (i < num_vertices) {
	    adj_begin[i] = 0;
	    adj_length[i] = 0;
	    adj_vec[i] = [];
	    i++;
	}
	i = 0;
	while (i < num_edges) {
	    adj_list[i] = 0;
	    i++;
	}
	i = 0;
	var max_degree = -1;
	while (i < data.length) {
	    var a = data[i];
//	    console.log(a[0]);
	    from = a[0];
	    to = a[1];
//	    console.log("x=",indexmap[from]);
	    adj_vec[indexmap[from]].push(indexmap[to]);
	    i++;
	}

	var next_offset = 0;
	i = 0;
	while (i < num_vertices)
	{
	    var list_size = alength(adj_vec[i]);

	    adj_begin[i] = next_offset;
	    adj_length[i] = list_size;

//	    console.log("syscpy", next_offset, 0, list_size);
	    syscopy(adj_list, next_offset, adj_vec[i], 0, list_size);
	    next_offset += list_size;

	    i++;
	}


	var arg = {
	    vertices: indexmap,
	    num_vertices: num_vertices,
	    num_edges:num_edges,
	    max_degree: max_degree,
	    adj_begin: adj_begin,
	    adj_length: adj_length,
	    adjs: adj_vec,
	    adj_list: adj_list};
	cb(null, arg);
    });

}

module.exports.read = edgeread;
module.exports.write = edgewrite;