first attempt at an sprintf function.

example/tput.js

@@ -7,6 +7,8 @@ var tput = Tput({
 
 console.log('Max colors: %d.', tput.max_colors);
 
+//process.stdout.write(Tput.sprintf('%-10s\n', 'hello'));
+
 //console.log(tput.info);
 
 //tput.compile();

lib/tput.js

@@ -551,8 +551,8 @@ Tput.prototype._compile = function(val) {
     //   as in printf, flags are [-+#] and space.  Use a `:' to allow the
     //   next character to be a `-' flag, avoiding interpreting "%-" as an
     //   operator.
-    // e.g. %:-d %+d %#x %+10d
-    if (read(/^%(:-|[+# ])?(\d+(?:\.\d+)?)?([doxXs])/)) {
+    // if (read(/^%(:-|[+# ])?(\d+(?:\.\d+)?)?([doxXs])/)) {
+    if (read(/^%((?::-|[+# ]){1,4})?(\d+(?:\.\d+)?)?([doxXs])/)) {
       // echo('sprintf("'+ cap[0].replace(':-', '-') + '", stack.pop())');
       // var flag = cap[1], width = cap[2], type = cap[3];
       echo('stack.pop()');
@@ -968,6 +968,107 @@ function merge(a, b) {
   return a;
 }
 
+/**
+ * sprintf
+ *  http://www.cplusplus.com/reference/cstdio/printf/
+ */
+
+function sprintf(src) {
+  var params = Array.prototype.slice.call(arguments, 1)
+    , rule = /%([\-+# ]{1,4})?(\d+(?:\.\d+)?)?([doxXsc])/g
+    , i = 0;
+
+  return src.replace(rule, function(_, flag, width, type) {
+    var flags = flag.split('')
+      , param = params[i++] || ''
+      , initial = param
+      , width = +width
+      , opt = {}
+      , pre = '';
+
+    switch (type) {
+      case 'd': // signed int
+        param = (+param).toString(10);
+        break;
+      case 'o': // unsigned octal
+        param = (+param).toString(8);
+        break;
+      case 'x': // unsigned hex int
+        param = (+param).toString(16);
+        break;
+      case 'X': // unsigned hex int uppercase
+        param = (+param).toString(16).toUppercase();
+        break;
+      case 's': // string
+        break;
+      case 'c': // char
+        // Should return here?
+        param = isFinite(param)
+          ? String.fromCharCode(param)
+          : param[0];
+        break;
+    }
+
+    flags.forEach(function(flag) {
+      switch (flag) {
+        // left-justify by width
+        case '-':
+          opt.left = true;
+          break;
+        // always precede numbers with their signs
+        case '+':
+          opt.signs = true;
+          break;
+        // used with o, x, X - value is preceded with 0, 0x, or 0X respectively.
+        // used with a, A, e, E, f, F, g, G - forces written output to contain
+        // a decimal point even if no more digits follow
+        case '#':
+          opt.hexpoint = true;
+          break;
+        // if no sign is going to be written, black space in front of the value
+        case ' ':
+          opt.space = true;
+          break;
+      }
+    });
+
+    if (opt.signs) {
+      if (+initial >= 0) {
+        pre += '+';
+      }
+    }
+
+    if (opt.space) {
+      if (!opt.signs && +initial >= 0) {
+        param = ' ' + param;
+      }
+    }
+
+    if (opt.hexpoint) {
+      switch (type) {
+        case 'o': // unsigned octal
+          pre += '0';
+          break;
+        case 'x': // unsigned hex int
+          pre += '0x';
+          break;
+        case 'X': // unsigned hex int uppercase
+          pre += '0X';
+          break;
+      }
+    }
+
+    if (opt.left) {
+      if (width > (pre.length + param.length)) {
+        width -= pre.length + param.length;
+        pre = Array(width + 1).join(' ') + pre;
+      }
+    }
+
+    return pre + param;
+  });
+}
+
 /**
  * Aliases
  */
@@ -1515,4 +1616,7 @@ Tput.strings = [
  * Expose
  */
 
-module.exports = Tput;
+exports = Tput;
+exports.sprintf = sprintf;
+
+module.exports = exports;