A extensible unit conversion library for Node.JS
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var path = require('path');
var fs = require('fs');
var types = {};
var db_regex = /[a-zA-Z]+:\n([\s\t]+([a-zA-Z]+,?)+[\s\t]+[0-9.]+[a-zA-Z]+\n)+/g;
var unit_database = {};
var parseSection = function(section){
var lines = section.split('\n');
var section_name = lines.shift();
section_name = section_name.replace(/[\r\n\t\s:]/g, '').toLowerCase();
if(!unit_database[section_name]){
types[section_name.toUpperCase()] = section_name;
unit_database[section_name] = {};
}
while(lines.length){
var next = lines.shift().split(/\t+/g);
if(next.length != 2){
continue;
}
var names = next[0].replace(/[\s\t]/g, '').split(',');
var value = next[1].replace(/[\s\t]/g, '').match(/([0-9.]+)|([a-zA-Z]+)/g);
var unit = value[1];
value = parseFloat(value[0]);
names.forEach(function(name){
unit_database[section_name][name] = {'unit': unit,
'value': value};
});
}
};
var importDBSync = function(file_name){
var fp = fs.readFileSync(file_name).toString();
var parts = fp.match(db_regex);
parts.forEach(parseSection);
};
var importDB = function(file_name, cb){
fs.readFile(file_name, function(err, fp){
if(!err){
var parts = fp.toString().match(db_regex);
parts.forEach(parseSection);
}
if(cb != undefined){
cb(err);
}
});
};
var convert = function(type, value, from, to, max_calls){
if(max_calls <= 0){
return undefined;
}
var section = unit_database[type.toLowerCase()];
if(!section){
return undefined;
}
var from_base = section[from];
var to_base = section[to];
if(from_base == undefined || to_base == undefined){
return undefined;
}
if(from_base.unit == to){
return value * from_base.value;
} else if(to_base.unit == from_base.unit){
return (value * from_base.value / to_base.value);
} else{
var result = convert(type, from_base.value, from_base.unit, to, max_calls - 1);
if(result == undefined || result == null || result == NaN){
return undefined;
} else{
return value * result;
}
}
};
var default_db = path.join(path.dirname(module.filename), 'default.units');
importDBSync(default_db);
return module.exports = {
types: types,
importDBSync: importDBSync,
importDB: importDB,
getDB: function(){
return unit_database;
},
convert: function(type, value, from, to){
type = type.toLowerCase();
if(unit_database[type] == undefined){
throw 'Unit group ' + type + ' does not exist';
} else if(unit_database[type][from] == undefined){
throw 'Unit ' + from + ' does not belong to unit group ' + type;
} else if(unit_database[type][to] == undefined){
throw 'Unit ' + to + ' does not belong to unit group ' + type;
}
var result = convert(type, value, from, to, 5);
if(result == undefined){
throw 'Conversion of ' + from + ' to ' + to + ' was not possible';
} else{
return result;
}
},
};