deb-version-compare/lib/Version.js

Compare Version according to debian policy

'use strict';
function Version(v){
    var version = /^([0-9]*(?=:))?:(.*)/.exec(v);
    this.epoch = (version)?version[1]:0;
    version = (version && version[2])?version[2]:v;
    version = version.split("-");
    this.debian = (version.length>1)?version.pop():"";
    this.upstream = version.join("-");
}
Version.prototype.compare = function(b){
  if((this.epoch>0 || b.epoch>0) && Math.sign(this.epoch-b.epoch)!=0){
    return Math.sign(this.epoch-b.epoch);
  }
  if(this.compareStrings(this.upstream,b.upstream) !=0){
    return this.compareStrings(this.upstream,b.upstream);
  }else{
    return this.compareStrings(this.debian,b.debian);
  }
}
Version.prototype.charCode = function(c){ //the lower the charcode the lower the version.
  if(c == "~")
    return 0; //tilde sort before anything
  else if(/[a-zA-Z]/.test(c))
    return c.charCodeAt(0)-"A".charCodeAt(0)+1;
  else if(/[.:+-:]/.test(c))
    return c.charCodeAt(0)+"z".charCodeAt(0)+1 //charcodes are 46..58
}

//find index of "val" in "ar".
Version.prototype.findIndex = function(ar,fn){

  for(var i = 0;i < ar.length; i++){
    if(fn(ar[i],i)){
      return i;
    }
  }
  return -1;
}

Version.prototype.compareChunk = function(a,b){
  var ca = a.split(""),cb=b.split("");
  var diff = this.findIndex(ca, function(c,index){
    if(cb[index] && c == cb[index]) return false;
    return true;
  });
  if(diff === -1){
    if(cb.length >ca.length){
      if(cb[ca.length] == "~"){
        return 1;
      }else{
        return -1;
      }
    }
    return 0; //no diff found and same length
  }else if(!cb[diff]){
    return (ca[diff] === "~")?-1:1;
  }else{
    return (this.charCode(ca[diff])>this.charCode(cb[diff]))?1:-1;
  }
}

Version.prototype.compareStrings = function(a,b){
  if(a==b) return 0;
  var parseA = /([^0-9]+|[0-9]+)/g;
  var parseB = /([^0-9]+|[0-9]+)/g;
  var ra,rb;
  while((ra=parseA.exec(a)) !== null && (rb = parseB.exec(b)) !== null ){
    if((isNaN(ra[1]) || isNaN(rb[1])) && ra[1] != rb[1] ){ //a or b is not a number and they're not equal. Note : "" IS a number so both null is impossible
      return this.compareChunk(ra[1],rb[1]);
    }else{ //both are numbers
      if(ra[1]!=rb[1]){
        return (parseInt(ra[1])>parseInt(rb[1]))?1:-1;
      }
    }
  }
  if(!ra && rb){ //rb doesn't get exec-ed when ra == null
    return (parseB.exec(b)[1].split("")[0] == "~")?1:-1
  }else if(ra && !rb){
    return (ra[1].split("")[0] == "~")?-1:1
  }else{
    return 0;
  }
}

module.exports = Version;