uri-resolver.js

/* global rdf:true */
'use strict';


var URIResolver = function() {};

URIResolver.SCHEME = /^[A-Za-z][A-Za-z0-9\+\-\.]*\:/;

URIResolver.prototype.parseURI = function(uri) {
  var match = URIResolver.SCHEME.exec(uri);
  if (!match) {
    throw "Bad URI value, no scheme: "+uri;
  }
  var parsed = { spec: uri };
  parsed.scheme = match[0].substring(0,match[0].length-1);
  parsed.schemeSpecificPart = parsed.spec.substring(match[0].length);
  if (parsed.schemeSpecificPart.charAt(0)=='/' && parsed.schemeSpecificPart.charAt(1)=='/') {
    this.parseGeneric(parsed);
  } else {
    parsed.isGeneric = false;
  }
  parsed.normalize = function() {
    if (!this.isGeneric) {
      return;
    }
    if (this.segments.length==0) {
      return;
    }
    // edge case of ending in "/."
    if (this.path.length>1 && this.path.substring(this.path.length-2)=="/.") {
      this.path = this.path.substring(0,this.path.length-1);
      this.segments.splice(this.segments.length-1,1);
      this.schemeSpecificPart = "//"+this.authority+this.path;
      if (typeof this.query != "undefined") {
        this.schemeSpecificPart += "?" + this.query;
      }
      if (typeof this.fragment != "undefined") {
        this.schemeSpecificPart += "#" + this.fragment;
      }
      this.spec = this.scheme+":"+this.schemeSpecificPart;
      return;
    }
    var end = this.path.charAt(this.path.length-1);
    if (end!="/") {
      end = "";
    }
    for (var i=0; i<this.segments.length; i++) {
      if (i>0 && this.segments[i]=="..") {
        this.segments.splice(i-1,2);
        i -= 2;
      }
      if (this.segments[i]==".") {
        this.segments.splice(i,1);
        i--;
      }
    }
    this.path = this.segments.length==0 ? "/" : "/"+this.segments.join("/")+end;
    this.schemeSpecificPart = "//"+this.authority+this.path;
    if (typeof this.query != "undefined") {
      this.schemeSpecificPart += "?" + this.query;
    }
    if (typeof this.fragment != "undefined") {
      this.schemeSpecificPart += "#" + this.fragment;
    }
    this.spec = this.scheme+":"+this.schemeSpecificPart;
  }
  parsed.resolve = function(href) {
    if (!href) {
      return this.spec;
    }
    if (href.charAt(0)=='#') {
      var lastHash = this.spec.lastIndexOf('#');
      return lastHash<0 ? this.spec+href : this.spec.substring(0,lastHash)+href;
    }
    if (!this.isGeneric) {
      throw "Cannot resolve uri against non-generic URI: "+this.spec;
    }
    var colon = href.indexOf(':');
    if (href.charAt(0)=='/') {
      return this.scheme+"://"+this.authority+href;
    } else if (href.charAt(0)=='.' && href.charAt(1)=='/') {
      if (this.path.charAt(this.path.length-1)=='/') {
        return this.scheme+"://"+this.authority+this.path+href.substring(2);
      } else {
        var last = this.path.lastIndexOf('/');
        return this.scheme+"://"+this.authority+this.path.substring(0,last)+href.substring(1);
      }
    } else if (URIResolver.SCHEME.test(href)) {
      return href;
    } else if (href.charAt(0)=="?") {
      return this.scheme+"://"+this.authority+this.path+href;
    } else {
      if (this.path.charAt(this.path.length-1)=='/') {
        return this.scheme+"://"+this.authority+this.path+href;
      } else {
        var last = this.path.lastIndexOf('/');
        return this.scheme+"://"+this.authority+this.path.substring(0,last+1)+href;
      }
    }
  };
  parsed.relativeTo = function(otherURI) {
    if (otherURI.scheme!=this.scheme) {
      return this.spec;
    }
    if (!this.isGeneric) {
      throw "A non generic URI cannot be made relative: "+this.spec;
    }
    if (!otherURI.isGeneric) {
      throw "Cannot make a relative URI against a non-generic URI: "+otherURI.spec;
    }
    if (otherURI.authority!=this.authority) {
      return this.spec;
    }
    var i=0;
    for (; i<this.segments.length && i<otherURI.segments.length; i++) {
      if (this.segments[i]!=otherURI.segments[i]) {
        //alert(this.path+" different from "+otherURI.path+" at '"+this.segments[i]+"' vs '"+otherURI.segments[i]+"'");
        var relative = "";
        for (var j=i; j<otherURI.segments.length; j++) {
          relative += "../";
        }
        for (var j=i; j<this.segments.length; j++) {
          relative += this.segments[j];
          if ((j+1)<this.segments.length) {
            relative += "/";
          }
        }
        if (this.path.charAt(this.path.length-1)=='/') {
          relative += "/";
        }
        return relative;
      }
    }
    if (this.segments.length==otherURI.segments.length) {
      return this.hash ? this.hash : (this.query ? this.query : "");
    } else if (i<this.segments.length) {
      var relative = "";
      for (var j=i; j<this.segments.length; j++) {
        relative += this.segments[j];
        if ((j+1)<this.segments.length) {
          relative += "/";
        }
      }
      if (this.path.charAt(this.path.length-1)=='/') {
        relative += "/";
      }
      return relative;
    } else {
      throw "Cannot calculate a relative URI for "+this.spec+" against "+otherURI.spec;
    }
  };
  return parsed;
}

URIResolver.prototype.parseGeneric = function(parsed) {
  if (parsed.schemeSpecificPart.charAt(0)!='/' || parsed.schemeSpecificPart.charAt(1)!='/') {
    throw "Generic URI values should start with '//':"+parsed.spec;
  }

  var work = parsed.schemeSpecificPart.substring(2);
  var pathStart = work.indexOf("/");
  parsed.authority = pathStart<0 ? work : work.substring(0,pathStart);
  parsed.path = pathStart<0 ? "" : work.substring(pathStart);
  var hash = parsed.path.indexOf('#');
  if (hash>=0) {
    parsed.fragment = parsed.path.substring(hash+1);
    parsed.path = parsed.path.substring(0,hash);
  }
  var questionMark = parsed.path.indexOf('?');
  if (questionMark>=0) {
    parsed.query = parsed.path.substring(questionMark+1);
    parsed.path = parsed.path.substring(0,questionMark);
  }
  if (parsed.path=="/" || parsed.path=="") {
    parsed.segments = [];
  } else {
    parsed.segments = parsed.path.split(/\//);
    if (parsed.segments.length>0 && parsed.segments[0]=='' && parsed.path.length>1 && parsed.path.charAt(1)!='/') {
      // empty segment at the start, remove it
      parsed.segments.shift();
    }
    if (parsed.segments.length>0 && parsed.path.length>0 && parsed.path.charAt(parsed.path.length-1)=='/' && parsed.segments[parsed.segments.length-1]=='') {
      // we may have an empty the end
      // check to see if it is legimate
      if (parsed.path.length>1 && parsed.path.charAt(parsed.path.length-2)!='/') {
        parsed.segments.pop();
      }
    }
    // check for non-escaped characters
    for (var i=0; i<parsed.segments.length; i++) {
      var check = parsed.segments[i].split(/%[A-Za-z0-9][A-Za-z0-9]|[\ud800-\udfff][\ud800-\udfff]|[A-Za-z0-9\-\._~!$&'()*+,;=@:\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+/);

      for (var j=0; j<check.length; j++) {
        if (check[j].length>0) {
          throw "Unecaped character "+check[j].charAt(0)+" ("+check[j].charCodeAt(0)+") in URI "+parsed.spec;
        }
      }
    }
  }
  parsed.isGeneric = true;
};


module.exports = URIResolver;