updated parsing library to recognize prefixes, version bump,

also updated the examples, updated README, added 'getUnitType' function

README.md

@@ -15,6 +15,7 @@ npm install node-units
 * `importDB(file_name, cb)` - imports a custom unit database, `cb` takes a single argument `err`
 * `importDBSync(file_name)` - the sync version of `importDB`
 * `getDB()` - returns he currently used database of units as an object
+* `getUnitType(unit)` - given a single unit it will return back `{'type': <unit_group>, 'unit': <base_unit>, 'modifier': <unit_modifier>}`
 * `convert(conversion_string)` - where `conversion_string` is of the form `<value> <from_unit> to <to_unit>`
 
 ### Properties
@@ -72,6 +73,27 @@ var result = units.convert('5 minutes to s');
 // result == 250
 ```
 
+## Values
+`node-units` uses `numberizer` which is used to convert string versions of numbers into digits, for example, `forty two` becomes `42` and `one fifth` becomes `0.2`.
+
+What is currently not supported is mathematical symbols like `1/5 days`.
+
+## Prefixes
+
+`node-units` comes with a plethora of built in long and shortname unit prefixes like:
+* nano-, n-
+* micro-, mu-
+* mega-
+* giga-
+* milli-, m-
+* centi-, c-
+* and others
+
+## Variations
+
+`node-units` also understands that it makes more sense to say things like `five days` rather than `five day` so when a unit is not know it will automatically look if the unit
+ends with either `s`, `es` or `ies`.
+
 ## License
 
 The MIT License (MIT)

examples/custom/index.js

@@ -4,7 +4,9 @@ var units = require('../../');
 var db = path.join(path.dirname(module.filename), 'my_custom.units');
 units.importDBSync(db);
 
-console.log(units.convert('5 buttons to widgets'));
+console.dir(units.getUnitType('jong'));
+console.dir(units.getUnitType('megajongs'));
 
+console.log(units.convert('5 buttons to widgets'));
 
 console.log(units.convert('30 jings to jong'));

examples/simple/index.js

@@ -1,10 +1,11 @@
 var units = require('../../');
 
-var result = units.convert('20 quarts to gallons');
+console.dir(units.getUnitType('gallons'));
+console.dir(units.getUnitType('milliliters'));
 
+var result = units.convert('20 quarts to gallons');
 console.log(result === 5);
 
-
 try{
     var value = units.convert('5 days to gallon');
     console.log(value);

lib/index.js

@@ -11,6 +11,92 @@ var unit_database = {};
 
 var forms = [/s$/i, /es$/i, /ies$/i];
 
+var short_prefixes = [
+    {'pattern': /^da/,
+     'modifier': 10},
+    {'pattern': /^mu/,
+     'modifier': 1e-6},
+    {'pattern': /^m/,
+     'modifier': 1e-3},
+    {'pattern': /^h/,
+     'modifier': 100},
+    {'pattern': /^k/,
+     'modifier': 1000},
+    {'pattern': /^M/,
+     'modifier': 1e6},
+    {'pattern': /^G/,
+     'modifier': 1e9},
+    {'pattern': /^T/,
+     'modifier': 1e12},
+    {'pattern': /^P/,
+     'modifier': 1e15},
+    {'pattern': /^E/,
+     'modifier': 1e18},
+    {'pattern': /^Z/,
+     'modifier': 1e21},
+    {'pattern': /^Y/,
+     'modifier': 1e24},
+    {'pattern': /^n/,
+     'modifier': 1e-9},
+    {'pattern': /^p/,
+     'modifier': 1e-12},
+    {'pattern': /^c/,
+     'modifier': 1e-2},
+    {'pattern': /^d/,
+     'modifier': 1e-1},
+    {'pattern': /^f/,
+     'modifier': 1e-15},
+    {'pattern': /^a/,
+     'modifier': 1e-18},
+    {'pattern': /^z/,
+     'modifier': 1e-21},
+    {'pattern': /^y/,
+     'modifier': 1e-24},
+];
+
+var long_prefixes = [
+    {'pattern': /^milli/i,
+     'modifier': 1e-3},
+    {'pattern': /^micro/i,
+     'modifier': 1e-6},
+    {'pattern': /^nano/i,
+     'modifier': 1e-9},
+    {'pattern':  /^pico/i,
+     'modifier': 1e-12},
+    {'pattern': /^centi/i,
+     'modifier': 1e-2},
+    {'pattern': /^deci/i,
+     'modifier': 1e-1},
+    {'pattern': /^femto/i,
+     'modifier': 1e-15},
+    {'pattern': /^atto/i,
+     'modifier': 1e-18},
+    {'pattern': /^zepto/i,
+     'modifier': 1e-21},
+    {'pattern': /^yocto/i,
+     'modifier': 1e-24},
+    {'pattern': /^deka/i,
+     'modifier': 10},
+    {'pattern': /^hecto/i,
+     'modifier': 100},
+    {'pattern': /^kilo/i,
+     'modifier': 1000},
+    {'pattern': /^mega/i,
+     'modifier': 1e6},
+    {'pattern': /^giga/i,
+     'modifier': 1e9},
+    {'pattern': /^tera/i,
+     'modifier': 1e12},
+    {'pattern': /^peta/i,
+     'modifier': 1e15},
+    {'pattern': /^exa/i,
+     'modifier': 1e18},
+    {'pattern': /^zeta/i,
+     'modifier': 1e21},
+    {'pattern': /^yotta/i,
+     'modifier': 1e24},
+];
+
 var parseSection = function(section){
     var lines = section.split('\n');
     var section_name = lines.shift();
@@ -32,8 +118,8 @@ var parseSection = function(section){
 	value = parseFloat(value[0]);
 
 	names.forEach(function(name){
-	    unit_database[section_name][name.toLowerCase()] = {'unit': unit,
-							       'value': value};
+	    unit_database[section_name][name] = {'unit': unit,
+						 'value': value};
 	});
     }
 };
@@ -61,7 +147,7 @@ var convert = function(type, value, from, to, max_calls){
     if(max_calls <= 0){
 	return undefined;
     }
-    var section = unit_database[type.toLowerCase()];
+    var section = unit_database[type];
     if(!section){
 	return undefined;
     }
@@ -88,6 +174,10 @@ var convert = function(type, value, from, to, max_calls){
 
 var get_variations = function(unit){
     var variations = [unit];
+    if(unit.length == 2){
+	return variations;
+    }
+
     forms.forEach(function(form){
 	if(unit.match(form)){
 	    variations.push(unit.replace(form, ''));
@@ -97,11 +187,32 @@ var get_variations = function(unit){
 };
 
 
+var get_modifier = function(unit){
+    var prefixes = short_prefixes;
+    if(unit.length > 3){
+	prefixes = long_prefixes;
+    }
+    for(var i in prefixes){
+	var prefix = prefixes[i];
+	if(unit.match(prefix.pattern)){
+	    return {'unit': unit.replace(prefix.pattern, ''),
+		    'modifier': prefix.modifier};
+	}
+    }
+    return {'unit': unit,
+	    'modifier': 1};
+};
+
 var determine_type = function(variations){
     for(var i in types){
 	for(var k in variations){
 	    if(unit_database[types[i]][variations[k]] !== undefined){
-		return {'type': types[i], 'unit': variations[k]};
+		return {'type': types[i], 'unit': variations[k], 'modifier': 1};
+	    } else{
+		var modified = get_modifier(variations[k]);
+		if(unit_database[types[i]][modified.unit] !== undefined){
+		    return {'type': types[i], 'unit': modified.unit, 'modifier': modified.modifier};
+		}
 	    }
 	}
     }
@@ -117,8 +228,17 @@ return module.exports = {
     getDB: function(){
 	return unit_database;
     },
+    getUnitType: function(unit){
+	var type = determine_type(get_variations(unit));
+	if(!type){
+	    return null;
+	}
+
+	return type;
+    },
     convert: function(str){
-	var type, value, from, to, max_tries;
+	var type, value, from, to;
+	var max_tries = 5;
 
 	var parts = conversion_regex.exec(str);
 	if(parts == null){
@@ -127,8 +247,8 @@ return module.exports = {
 	}
 
 	value = parseFloat(numerizer(parts[1]));
-	var from_variations = get_variations(parts[2].toLowerCase());
-	var to_variations = get_variations(parts[3].toLowerCase());
+	var from_variations = get_variations(parts[2]);
+	var to_variations = get_variations(parts[3]);
 
 	var from_type = determine_type(from_variations);
 	var to_type = determine_type(to_variations);
@@ -147,6 +267,7 @@ return module.exports = {
 	    return;
 	}
 
+	value = value * from_type.modifier;
 	type = from_type.type;
 	from = from_type.unit;
 	to = to_type.unit;
@@ -155,7 +276,7 @@ return module.exports = {
 	if(result == undefined){
 	    throw 'Conversion of "' + from + '" to "' + to + '" was not possible';
 	} else{
-	    return result;
+	    return result / to_type.modifier;
 	}
     },
 };

package.json

@@ -1,6 +1,6 @@
 {
   "name": "node-units",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "description": "Node.JS unit conversion library with customizable units",
   "main": "lib/index.js",
   "directories": {