printf/lib/printf.js

var util = require('util');

var tokenize = function(/*String*/ str, /*RegExp*/ re, /*Function?*/ parseDelim, /*Object?*/ instance){
  // summary:
  //    Split a string by a regular expression with the ability to capture the delimeters
  // parseDelim:
  //    Each group (excluding the 0 group) is passed as a parameter. If the function returns
  //    a value, it's added to the list of tokens.
  // instance:
  //    Used as the "this' instance when calling parseDelim
  var tokens = [];
  var match, content, lastIndex = 0;
  while(match = re.exec(str)){
    content = str.slice(lastIndex, re.lastIndex - match[0].length);
    if(content.length){
      tokens.push(content);
    }
    if(parseDelim){
      var parsed = parseDelim.apply(instance, match.slice(1).concat(tokens.length));
      if(typeof parsed != 'undefined'){
        if(parsed.specifier === '%'){
          tokens.push('%');
        }else{
          tokens.push(parsed);
        }
      }
    }
    lastIndex = re.lastIndex;
  }
  content = str.slice(lastIndex);
  if(content.length){
    tokens.push(content);
  }
  return tokens;
}

var Formatter = function(/*String*/ format){
  var tokens = [];
  this._mapped = false;
  this._format = format;
  this._tokens = tokenize(format, this._re, this._parseDelim, this);
}

Formatter.prototype._re = /\%(?:\(([\w_]+)\)|([1-9]\d*)\$)?([0 +\-\#]*)(\*|\d+)?(\.)?(\*|\d+)?[hlL]?([\%bscdeEfFgGioOuxX])/g;
Formatter.prototype._parseDelim = function(mapping, intmapping, flags, minWidth, period, precision, specifier){
  if(mapping){
    this._mapped = true;
  }
  return {
    mapping: mapping,
    intmapping: intmapping,
    flags: flags,
    _minWidth: minWidth, // May be dependent on parameters
    period: period,
    _precision: precision, // May be dependent on parameters
    specifier: specifier
  };
};
Formatter.prototype._specifiers = {
  b: {
    base: 2,
    isInt: true
  },
  o: {
    base: 8,
    isInt: true
  },
  x: {
    base: 16,
    isInt: true
  },
  X: {
    extend: ['x'],
    toUpper: true
  },
  d: {
    base: 10,
    isInt: true
  },
  i: {
    extend: ['d']
  },
  u: {
    extend: ['d'],
    isUnsigned: true
  },
  c: {
    setArg: function(token){
      if(!isNaN(token.arg)){
        var num = parseInt(token.arg);
        if(num < 0 || num > 127){
          throw new Error('invalid character code passed to %c in printf');
        }
        token.arg = isNaN(num) ? '' + num : String.fromCharCode(num);
      }
    }
  },
  s: {
    setMaxWidth: function(token){
      token.maxWidth = (token.period == '.') ? token.precision : -1;
    }
  },
  e: {
    isDouble: true,
    doubleNotation: 'e'
  },
  E: {
    extend: ['e'],
    toUpper: true
  },
  f: {
    isDouble: true,
    doubleNotation: 'f'
  },
  F: {
    extend: ['f']
  },
  g: {
    isDouble: true,
    doubleNotation: 'g'
  },
  G: {
    extend: ['g'],
    toUpper: true
  },
  O: {
    isObject: true
  },
};
Formatter.prototype.format = function(/*mixed...*/ filler){
  if(this._mapped && typeof filler != 'object'){
    throw new Error('format requires a mapping');
  }

  var str = '';
  var position = 0;
  for(var i = 0, token; i < this._tokens.length; i++){
    token = this._tokens[i];
    
    if(typeof token == 'string'){
      str += token;
    }else{
      if(this._mapped){
        if(typeof filler[token.mapping] == 'undefined'){
          throw new Error('missing key ' + token.mapping);
        }
        token.arg = filler[token.mapping];
      }else{
        if(token.intmapping){
          position = parseInt(token.intmapping) - 1;
        }
        if(position >= arguments.length){
          throw new Error('got ' + arguments.length + ' printf arguments, insufficient for \'' + this._format + '\'');
        }
        token.arg = arguments[position++];
      }

      if(!token.compiled){
        token.compiled = true;
        token.sign = '';
        token.zeroPad = false;
        token.rightJustify = false;
        token.alternative = false;

        var flags = {};
        for(var fi = token.flags.length; fi--;){
          var flag = token.flags.charAt(fi);
          flags[flag] = true;
          switch(flag){
            case ' ':
              token.sign = ' ';
              break;
            case '+':
              token.sign = '+';
              break;
            case '0':
              token.zeroPad = (flags['-']) ? false : true;
              break;
            case '-':
              token.rightJustify = true;
              token.zeroPad = false;
              break;
            case '#':
              token.alternative = true;
              break;
            default:
              throw Error('bad formatting flag \'' + token.flags.charAt(fi) + '\'');
          }
        }

        token.minWidth = (token._minWidth) ? parseInt(token._minWidth) : 0;
        token.maxWidth = -1;
        token.toUpper = false;
        token.isUnsigned = false;
        token.isInt = false;
        token.isDouble = false;
        token.isObject = false;
        token.precision = 1;
        if(token.period == '.'){
          if(token._precision){
            token.precision = parseInt(token._precision);
          }else{
            token.precision = 0;
          }
        }

        var mixins = this._specifiers[token.specifier];
        if(typeof mixins == 'undefined'){
          throw new Error('unexpected specifier \'' + token.specifier + '\'');
        }
        if(mixins.extend){
          var s = this._specifiers[mixins.extend];
          for(var k in s){
            mixins[k] = s[k]
          }
          delete mixins.extend;
        }
        for(var l in mixins){
          token[l] = mixins[l];
        }
      }

      if(typeof token.setArg == 'function'){
        token.setArg(token);
      }

      if(typeof token.setMaxWidth == 'function'){
        token.setMaxWidth(token);
      }

      if(token._minWidth == '*'){
        if(this._mapped){
          throw new Error('* width not supported in mapped formats');
        }
        token.minWidth = parseInt(arguments[position++]);
        if(isNaN(token.minWidth)){
          throw new Error('the argument for * width at position ' + position + ' is not a number in ' + this._format);
        }
        // negative width means rightJustify
        if (token.minWidth < 0) {
          token.rightJustify = true;
          token.minWidth = -token.minWidth;
        }
      }

      if(token._precision == '*' && token.period == '.'){
        if(this._mapped){
          throw new Error('* precision not supported in mapped formats');
        }
        token.precision = parseInt(arguments[position++]);
        if(isNaN(token.precision)){
          throw Error('the argument for * precision at position ' + position + ' is not a number in ' + this._format);
        }
        // negative precision means unspecified
        if (token.precision < 0) {
          token.precision = 1;
          token.period = '';
        }
      }
      if(token.isInt){
        // a specified precision means no zero padding
        if(token.period == '.'){
          token.zeroPad = false;
        }
        this.formatInt(token);
      }else if(token.isDouble){
        if(token.period != '.'){
          token.precision = 6;
        }
        this.formatDouble(token); 
      }else if(token.isObject){
        this.formatObject(token);
      }
      this.fitField(token);

      str += '' + token.arg;
    }
  }

  return str;
};
Formatter.prototype._zeros10 = '0000000000';
Formatter.prototype._spaces10 = '          ';
Formatter.prototype.formatInt = function(token) {
  var i = parseInt(token.arg);
  if(!isFinite(i)){ // isNaN(f) || f == Number.POSITIVE_INFINITY || f == Number.NEGATIVE_INFINITY)
    // allow this only if arg is number
    if(typeof token.arg != 'number'){
      throw new Error('format argument \'' + token.arg + '\' not an integer; parseInt returned ' + i);
    }
    //return '' + i;
    i = 0;
  }

  // if not base 10, make negatives be positive
  // otherwise, (-10).toString(16) is '-a' instead of 'fffffff6'
  if(i < 0 && (token.isUnsigned || token.base != 10)){
    i = 0xffffffff + i + 1;
  } 

  if(i < 0){
    token.arg = (- i).toString(token.base);
    this.zeroPad(token);
    token.arg = '-' + token.arg;
  }else{
    token.arg = i.toString(token.base);
    // need to make sure that argument 0 with precision==0 is formatted as ''
    if(!i && !token.precision){
      token.arg = '';
    }else{
      this.zeroPad(token);
    }
    if(token.sign){
      token.arg = token.sign + token.arg;
    }
  }
  if(token.base == 16){
    if(token.alternative){
      token.arg = '0x' + token.arg;
    }
    token.arg = token.toUpper ? token.arg.toUpperCase() : token.arg.toLowerCase();
  }
  if(token.base == 8){
    if(token.alternative && token.arg.charAt(0) != '0'){
      token.arg = '0' + token.arg;
    }
  }
};
Formatter.prototype.formatDouble = function(token) {
  var f = parseFloat(token.arg);
  if(!isFinite(f)){ // isNaN(f) || f == Number.POSITIVE_INFINITY || f == Number.NEGATIVE_INFINITY)
    // allow this only if arg is number
    if(typeof token.arg != 'number'){
      throw new Error('format argument \'' + token.arg + '\' not a float; parseFloat returned ' + f);
    }
    // C99 says that for 'f':
    //   infinity -> '[-]inf' or '[-]infinity' ('[-]INF' or '[-]INFINITY' for 'F')
    //   NaN -> a string  starting with 'nan' ('NAN' for 'F')
    // this is not commonly implemented though.
    //return '' + f;
    f = 0;
  }

  switch(token.doubleNotation) {
    case 'e': {
      token.arg = f.toExponential(token.precision); 
      break;
    }
    case 'f': {
      token.arg = f.toFixed(token.precision); 
      break;
    }
    case 'g': {
      // C says use 'e' notation if exponent is < -4 or is >= prec
      // ECMAScript for toPrecision says use exponential notation if exponent is >= prec,
      // though step 17 of toPrecision indicates a test for < -6 to force exponential.
      if(Math.abs(f) < 0.0001){
        //print('forcing exponential notation for f=' + f);
        token.arg = f.toExponential(token.precision > 0 ? token.precision - 1 : token.precision);
      }else{
        token.arg = f.toPrecision(token.precision); 
      }

      // In C, unlike 'f', 'gG' removes trailing 0s from fractional part, unless alternative format flag ('#').
      // But ECMAScript formats toPrecision as 0.00100000. So remove trailing 0s.
      if(!token.alternative){ 
        //print('replacing trailing 0 in \'' + s + '\'');
        token.arg = token.arg.replace(/(\..*[^0])0*e/, '$1e');
        // if fractional part is entirely 0, remove it and decimal point
        token.arg = token.arg.replace(/\.0*e/, 'e').replace(/\.0$/,'');
      }
      break;
    }
    default: throw new Error('unexpected double notation \'' + token.doubleNotation + '\'');
  }

  // C says that exponent must have at least two digits.
  // But ECMAScript does not; toExponential results in things like '1.000000e-8' and '1.000000e+8'.
  // Note that s.replace(/e([\+\-])(\d)/, 'e$10$2') won't work because of the '$10' instead of '$1'.
  // And replace(re, func) isn't supported on IE50 or Safari1.
  token.arg = token.arg.replace(/e\+(\d)$/, 'e+0$1').replace(/e\-(\d)$/, 'e-0$1');

  // if alt, ensure a decimal point
  if(token.alternative){
    token.arg = token.arg.replace(/^(\d+)$/,'$1.');
    token.arg = token.arg.replace(/^(\d+)e/,'$1.e');
  }

  if(f >= 0 && token.sign){
    token.arg = token.sign + token.arg;
  }

  token.arg = token.toUpper ? token.arg.toUpperCase() : token.arg.toLowerCase();
};
Formatter.prototype.formatObject = function(token) {
  // If no precision is specified, then reset it to null (infinite depth).
  var precision = (token.period === '.') ? token.precision : null;
  token.arg = util.inspect(token.arg, !token.alternative, precision);
};
Formatter.prototype.zeroPad = function(token, /*Int*/ length) {
  length = (arguments.length == 2) ? length : token.precision;
  var negative = false;
  if(typeof token.arg != "string"){
    token.arg = "" + token.arg;
  }
  if (token.arg.substr(0,1) === '-') {
    negative = true;
    token.arg = token.arg.substr(1);
  }

  var tenless = length - 10;
  while(token.arg.length < tenless){
    token.arg = (token.rightJustify) ? token.arg + this._zeros10 : this._zeros10 + token.arg;
  }
  var pad = length - token.arg.length;
  token.arg = (token.rightJustify) ? token.arg + this._zeros10.substring(0, pad) : this._zeros10.substring(0, pad) + token.arg;
  if (negative) token.arg = '-' + token.arg;
};
Formatter.prototype.fitField = function(token) {
  if(token.maxWidth >= 0 && token.arg.length > token.maxWidth){
    return token.arg.substring(0, token.maxWidth);
  }
  if(token.zeroPad){
    this.zeroPad(token, token.minWidth);
    return;
  }
  this.spacePad(token);
};
Formatter.prototype.spacePad = function(token, /*Int*/ length) {
  length = (arguments.length == 2) ? length : token.minWidth;
  if(typeof token.arg != 'string'){
    token.arg = '' + token.arg;
  }
  var tenless = length - 10;
  while(token.arg.length < tenless){
    token.arg = (token.rightJustify) ? token.arg + this._spaces10 : this._spaces10 + token.arg;
  }
  var pad = length - token.arg.length;
  token.arg = (token.rightJustify) ? token.arg + this._spaces10.substring(0, pad) : this._spaces10.substring(0, pad) + token.arg;
};


module.exports = function(){
  var args = Array.prototype.slice.call(arguments),
    stream, format;
  if(args[0] instanceof require('stream').Stream){
    stream = args.shift();
  }
  format = args.shift();
  var formatter = new Formatter(format);
  var string = formatter.format.apply(formatter, args);
  if(stream){
    stream.write(string);
  }else{
    return string;
  }
};

module.exports.Formatter = Formatter;