"Advanced" features of the format function

Readme.md

@@ -47,6 +47,9 @@ INSERT INTO books VALUES('O''Reilly')
 - `%L` quotes the argument value as an SQL literal. A null value is displayed as the string NULL, without quotes.
 - `%%` In addition to the format specifiers described above, the special sequence %% may be used to output a literal % character.
 
+Also all other "advanced" features (postition, flag, width) of the `format` function are implemented,
+see [the Postgresql documentation](http://www.postgresql.org/docs/current/static/functions-string.html#FUNCTIONS-STRING-FORMAT).
+
 # License
 
-  MIT
+  MIT

index.js

@@ -5,6 +5,7 @@
 
 var assert = require('assert');
 var fs = require('fs');
+var XRegExp = require('xregexp').XRegExp;
 
 /**
  * Reserved word map.
@@ -16,6 +17,85 @@ var reserved = txt.split('\n').reduce(function(map, word){
   return map;
 }, {});
 
+/**
+ * setup the regex stuff/lib
+ */
+
+var RegExpMain = (function(){
+  var reLib = {};
+  reLib.posInt   = /[1-9][0-9]*/;
+  reLib.star     = /\*/;
+  reLib.nth      = XRegExp.build('{{star}}(?<widthNth>{{posInt}})[$]', reLib);
+  reLib.flag     = XRegExp('(?<flag>[-])');
+  reLib.position = XRegExp.build('(?<position>{{posInt}})[$]', reLib);
+  reLib.width    = XRegExp.build('(?<widthInt>{{posInt}})|(?<widthStar>{{star}})|{{nth}}', reLib);
+  reLib.type     = XRegExp('(?<type>[sIL])');
+
+  var reMain = XRegExp.build('%((?<percent>%)|{{position}}?{{flag}}?{{width}}?{{type}})', reLib, 'g');
+
+  return reMain;
+})();
+
+/**
+ * Helper class for argument handling
+ *
+ * @param {Array} args
+ * @api private
+ */
+function Args(args) {
+  var curIndex = 1;
+
+  this.get = function(idx) {
+    curIndex = idx ? parseInt(idx, 10) : curIndex;
+    assert(curIndex > 0, 'Minimum usable index is 1'); 
+    return args[curIndex++];
+  };
+};
+
+/**
+ * get the current argument depending on all the format magic
+ *
+ * @param {Args} args
+ * @param {Object} matches
+ * @return {String}
+ * @api private
+ */
+
+function getArg(args, matches) {
+  var width = matches.widthInt;
+  var spacesOnLeft = matches.flag !== '-';
+  var pos = matches.position || null;
+  var arg = args.get(pos);
+
+  if (matches.widthStar === '*') {
+    width = arg;
+    arg = args.get(pos);
+  }
+
+  if (matches.widthNth) {
+    var argIdx = parseInt(matches.widthNth, 10);
+    width = args.get(argIdx);
+    arg = args.get(pos);
+  }
+
+  width = parseInt(width, 10);
+
+  if (width < 0) {
+    width *= -1;
+    if (spacesOnLeft) {
+      spacesOnLeft = !spacesOnLeft;
+    }
+  }
+
+  var numSpaces = width - arg.length;
+  if (numSpaces > 0) {
+    var spaces = (new Array(numSpaces+1)).join(' ');
+    arg = spacesOnLeft ? spaces.concat(arg) : arg.concat(spaces);
+  }
+
+  return arg;
+}
+
 /**
  * Expose `format()`.
  */
@@ -32,13 +112,14 @@ exports = module.exports = format;
  */
 
 function format(fmt) {
-  var i = 1;
-  var args = arguments;
-  return fmt.replace(/%([%sIL])/g, function(_, type){
-    if ('%' == type) return '%';
+  var args = new Args(arguments);
 
-    var arg = args[i++];
-    switch (type) {
+  return XRegExp.replace(fmt, RegExpMain, function(matches, type){
+    if (matches.percent !== undefined) return '%';
+
+    var arg = getArg(args, matches);
+
+    switch (matches.type) {
       case 's': return exports.string(arg);
       case 'I': return exports.ident(arg);
       case 'L': return exports.literal(arg);
@@ -112,4 +193,4 @@ function validIdent(id) {
 function quoteIdent(id) {
   id = id.replace(/"/g, '""');
   return '"' + id + '"';
-}
+}

package.json

@@ -9,10 +9,12 @@
     "escape",
     "query"
   ],
-  "dependencies": {},
+  "dependencies": {
+    "xregexp": "^2.0.0"
+  },
   "devDependencies": {
     "mocha": "*",
     "should": "*"
   },
   "license": "MIT"
-}
+}

test/advanced.js

@@ -0,0 +1,54 @@
+var assert = require('assert');
+var escape = require('..');
+
+describe('advanced escape(fmt, ...)', function(){
+  it('should handle |%10s|', function(){
+    escape('|%10s|', 'foo')
+      .should.equal('|       foo|');
+  });
+
+  it('should handle |%-10s|', function(){
+    escape('|%-10s|', 'foo')
+      .should.equal('|foo       |');
+  });
+
+  it('should handle |%*s|', function(){
+    escape('|%*s|', 10, 'foo')
+      .should.equal('|       foo|');
+  });
+
+  it('should handle |%*s|', function(){
+    escape('|%*s|', -10, 'foo')
+      .should.equal('|foo       |');
+  });
+
+  it('should handle |%-*s|', function(){
+    escape('|%-*s|', 10, 'foo')
+      .should.equal('|foo       |');
+  });
+
+  it('should handle |%-*s|', function(){
+    escape('|%-*s|', -10, 'foo')
+      .should.equal('|foo       |');
+  });
+
+  it('should handle %3$s, %2$s, %1$s', function(){
+    escape('Testing %3$s, %2$s, %1$s', 'one', 'two', 'three')
+      .should.equal('Testing three, two, one');
+  });
+
+  it('should handle |%*2$s|', function(){
+    escape('|%*2$s|', 'foo', 10, 'bar')
+      .should.equal('|       bar|');
+  });
+
+  it('should handle |%1$*2$s|', function(){
+    escape('|%1$*2$s|', 'foo', 10, 'bar')
+      .should.equal('|       foo|');
+  });
+
+  it('should handle advanced position', function(){
+    escape('Testing %3$s, %2$s, %s', 'one', 'two', 'three')
+      .should.equal('Testing three, two, three');
+  });
+});