model.js

/*
 model.js

 Model Class

 read a from model.xml
 store model in string etc


 model.xml example:

 <modelleertaal>
 <startwaarden>
     Fmotor = 500 'N
     m = 800 'kg
     dt = 1e-2 's
     v = 0'm/s
     s = 0 'm/s
     t = 0 's
 </startwaarden>
 <modelregels>
     Fres= Fmotor
     a = Fres/m
     dv = a * dt
     v = v + dv
     ds = v * dt
     s = s + ds
     t = t + dt
     als (0)
     dan
       Stop
     EindAls
 </modelregels>

 </modelleertaal>
*/


//jshint es3:true

var fs = require('fs');

function Model() {
    this.modelregels = '';
    this.startwaarden = '';
}


Model.prototype.readBogusXMLFile = function(filename) {
    // This read a "bogus" XML file that still includes < instead of &lt;
    var buf = fs.readFileSync(filename, "utf8");

    this.parseBogusXMLString(buf);
};

Model.prototype.parseBogusXMLString = function(xmlString) {

    var action = 0; // 0 = do nothing, 1 = modelregels, 2 = startwaarden
    var equationRe = /([A-Za-z])[ ]*\=[ ]*(\d*)/g;  // Match N = 1000

    this.startwaarden = '';
    this.modelregels = '';

    var lines = xmlString.split('\n');

    for(var line = 1; line < lines.length; line++) {

        //console.log(action, lines[line]);
        // try to extra N = ... from model
        if (action === 0) {
          var matches = equationRe.exec(lines[line]);
          if (matches !== null) {
            if (matches[1] == 'N')
              this.N = parseInt(matches[2], 10);
              if (this.debug) console.log('Found N = '+this.N+' in model.xml');
          }
        }
        switch(lines[line].replace('\r','')) {
            // < and > mess things up in the browser
            case '<modelregels>': { action = 1; continue; }
            case '</modelregels>': { action = 0; continue; }
            case '<startwaarden>': { action = 2; continue; }
            case '</startwaarden>': { action = 0; continue; }
        }
        if (action==1) this.modelregels += lines[line]+'\n';
        if (action==2) this.startwaarden += lines[line]+'\n';
    }
    //console.log('DEBUG: in model.js parseBogusXMLString endresult this.modelregels:');
    //console.log(this.modelregels);
    //console.log('DEBUG: in model.js parseBogusXMLString endresult this.startwaarden:');
    //console.log(this.startwaarden);

};

Model.prototype.createBogusXMLString = function() {

    // TODO replace this with a function that exports all options.
    var Nstring = '';
    if (this.N !== undefined)
            Nstring = 'N = ' + this.N + '\n';
    return '<modelleertaal>\n' +
            Nstring +
            '<startwaarden>\n' +
            this.startwaarden +
            '\n</startwaarden>\n<modelregels>\n' +
            this.modelregels +
            '\n</modelregels>\n</modelleertaal>\n';
};



exports.Model = Model;