better support for floating point precision (closes #6)

Readme.md

@@ -35,11 +35,12 @@ Supported format specifiers: b, c, d, f, o, s, x, and X.
 
 See `man 3 printf` or `man 1 printf` for details.
 
+Precision is supported for floating point numbers.
 
 License
 =======
 
-Copyright 2010 - 2013 Sami Samhuri sami@samhuri.net
+Copyright 2010 - 2014 Sami Samhuri sami@samhuri.net
 
 [MIT license](http://sjs.mit-license.org)
 

component.json

@@ -3,7 +3,7 @@
   "repo": "samsonjs/format",
   "description": "printf, sprintf, and vsprintf for JavaScript",
   "keywords": ["format", "printf", "sprintf", "vsprintf", "string"],
-  "version": "0.2.1",
+  "version": "0.2.2",
   "main": "format.js",
   "scripts": ["format.js"]
 }

format.js

@@ -49,12 +49,16 @@
       , c
       , escaped = false
       , arg
+      , tmp
+      , leadingZero = false
       , precision
       , nextArg = function() { return args[argIndex++]; }
       , slurpNumber = function() {
           var digits = '';
-          while (fmt[i].match(/\d/))
+          while (/\d/.test(fmt[i])) {
             digits += fmt[i++];
+            c = fmt[i];
+          }
           return digits.length > 0 ? parseInt(digits) : null;
         }
       ;
@@ -62,6 +66,18 @@
       c = fmt[i];
       if (escaped) {
         escaped = false;
+        if (c == '.') {
+          leadingZero = false;
+          c = fmt[++i];
+        }
+        else if (c == '0' && fmt[i + 1] == '.') {
+          leadingZero = true;
+          i += 2;
+          c = fmt[i];
+        }
+        else {
+          leadingZero = true;
+        }
         precision = slurpNumber();
         switch (c) {
         case 'b': // number in binary
@@ -78,7 +94,8 @@
           result += parseInt(nextArg(), 10);
           break;
         case 'f': // floating point number
-          result += parseFloat(nextArg()).toFixed(precision || 6);
+          tmp = String(parseFloat(nextArg()).toFixed(precision || 6));
+          result += leadingZero ? tmp : tmp.replace(/^0/, '');
           break;
         case 'o': // number in octal
           result += '0' + parseInt(nextArg(), 10).toString(8);

package.json

@@ -1,7 +1,7 @@
 {
   "name": "format",
   "description": "printf, sprintf, and vsprintf for JavaScript",
-  "version": "0.2.1",
+  "version": "0.2.2",
   "homepage": "http://samhuri.net/proj/format",
   "author": "Sami Samhuri <sami@samhuri.net>",
   "repository": {

test_format.js

@@ -3,23 +3,50 @@ var filename = process.argv[2] || './format.js'
   , printf = format.printf
   ;
 
-console.log('Testing printf:');
+function desc(x, indentLevel) {
-printf('hello');
+  indentLevel = indentLevel || 0;
-console.log('(expected "hello")');
+  var indent = new Array(indentLevel).join('  ');
-printf('hello %s', 'sami');
+  if (typeof x == 'string' || (x && x.__proto__ == String.prototype)) {
-console.log('(expected "hello sami")');
+    return indent + '"' + x + '"';
-printf('b: %b\nc: %c\nd: %d\nf: %f\no: %o\ns: %s\nx: %x\nX: %X', 42, 65, 42*42, 42*42*42/1000000000, 255, 'sami', 0xfeedface, 0xc0ffee);
+  }
-console.log('(expected "b: 101010\nc: A\nd: 1764\nf: 0.000074\no: 0377\ns: sami\nx: 0xfeedface\nX: 0xC0FFEE")');
+  else if (Array.isArray(x)) {
-console.log('(passed if the output looks ok)');
+    return indent + '[ ' + x.map(desc).join(', ') + ' ]';
+  }
+  else {
+    return '' + x;
+  }
+}
 
-function assertEqual(a, b) {
+function assertFormat(args, expected) {
-    if (a !== b) throw new Error('assertion failed, ' + a + ' !== ' + b);
+  var fmt = args[0];
+  var result = format.format.apply(format, args);
+  if (result !== expected) {
+    console.log('FORMAT: "' + fmt + '"');
+    console.log('ARGS:   ' + desc(args.slice(1)));
+    console.log('RESULT: "' + result + '"');
+    throw new Error('assertion failed, ' + result + ' !== ' + expected);
+  }
 }
 
 console.log('Testing format:');
-assertEqual(format.format('hello'), 'hello');
+
-assertEqual(format.format('hello %s', 'sami'), 'hello sami');
+var tests = [
-assertEqual(format.format('b: %b\nc: %c\nd: %d\nf: %f\no: %o\ns: %s\nx: %x\nX: %X', 42, 65, 42*42, 42*42*42/1000000000, 255, 'sami', 0xfeedface, 0xc0ffee), "b: 101010\nc: A\nd: 1764\nf: 0.000074\no: 0377\ns: sami\nx: 0xfeedface\nX: 0xC0FFEE");
+  [['hello'], 'hello'],
-console.log('(pass)');
+  [['hello %s', 'sami'], 'hello sami'],
+  [
+    ['b: %b\nc: %c\nd: %d\nf: %f\no: %o\ns: %s\nx: %x\nX: %X', 42, 65, 42*42, 42*42*42/1000000000, 255, 'sami', 0xfeedface, 0xc0ffee],
+    "b: 101010\nc: A\nd: 1764\nf: 0.000074\no: 0377\ns: sami\nx: 0xfeedface\nX: 0xC0FFEE"
+  ],
+  [['%.2f', 3.14159], '3.14'],
+  [['%0.2f', 3.14159], '3.14'],
+  [['%.2f', 0.1234], '.12'],
+  [['%0.2f', 0.1234], '0.12']
+];
+tests.forEach(function(spec) {
+  var args = spec[0];
+  var expected = spec[1];
+  assertFormat(args, expected);
+  console.log('pass (format ' + args[0] + ' == ' + expected + ')');
+});
 
 console.log('all passed');