objj-runtime
Version:
JavaScript (ECMAScript) and Objective-J runtime
173 lines (140 loc) • 6.38 kB
JavaScript
// Ash Searle
// Ported by Kris Kowal
/** provides printf and sprintf.
This code is unrestricted: you are free to use it however you like.
The functions should work as expected, performing left or right alignment,
truncating strings, outputting numbers with a required precision etc.
For complex cases, these functions follow the Perl implementations of
(s)printf, allowing arguments to be passed out-of-order, and to set the
precision or length of the output based on arguments instead of fixed
numbers.
See http://perldoc.perl.org/functions/sprintf.html for more information.
Implemented:
- zero and space-padding
- right and left-alignment,
- base X prefix (binary, octal and hex)
- positive number prefix
- (minimum) width
- precision / truncation / maximum width
- out of order arguments
Not implemented (yet):
- vector flag
- size (bytes, words, long-words etc.)
Will not implement:
- %n or %p (no pointers in JavaScript)
by Ash Searle, 2007-04-27
Integrated into Chiron by Kris Kowal, 2007-10-19
Integrated into Narwhal by Kris Kowal, 2009-07-27
*/
exports.printf = function () {
print(exports.sprintf.apply(null, arguments));
};
exports.fprintf = function () {
var args = Array.prototype.slice.call(arguments);
var stream = args.shift();
stream.print(exports.sprintf.apply(null, args));
};
exports.sprintf = function () {
var a = arguments, i = 1, format = a[0];
return format.replace(regex, function ($0, valueIndex, flags, minWidth, precision, type) {
if ($0 == '%%') return '%';
// parse flags
var leftJustify = flags.indexOf('-') > -1,
positivePrefix = (flags.match(/[ +]/g) || ['']).pop(),
zeroPad = flags.indexOf('0') > -1,
prefixBaseX = flags.indexOf('#') > -1;
// parameters may be null, undefined, empty-string or real valued
// we want to ignore null, undefined and empty-string values
if (!minWidth)
minWidth = 0;
else if (minWidth == '*')
minWidth = +a[i++];
else if (minWidth.charAt(0) == '*')
minWidth = +a[minWidth.slice(1, -1)];
else
minWidth = +minWidth;
// Note: undocumented perl feature:
if (minWidth < 0) {
minWidth = -minWidth;
leftJustify = true;
}
if (!isFinite(minWidth))
throw new Error('sprintf: (minimum-)width must be finite');
if (!precision)
precision = 'fFeE'.indexOf(type) > -1 ? 6 : (type == 'd' ? 0 : void(0));
else if (precision == '*')
precision = +a[i++];
else if (precision.charAt(0) == '*')
precision = +a[precision.slice(1, -1)];
else
precision = +precision;
// grab value using valueIndex if required?
var value = valueIndex ? a[valueIndex] : a[i++];
switch (type) {
case 's': return formatString(String(value), leftJustify, minWidth, precision, zeroPad);
case 'c': return formatString(String.fromCharCode(+value), leftJustify, minWidth, precision, zeroPad);
case 'b': return formatBaseX(value, 2, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
case 'o': return formatBaseX(value, 8, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
case 'x': return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
case 'X': return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad).toUpperCase();
case 'u': return formatBaseX(value, 10, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
case 'i':
case 'd': {
var number = parseInt(+value);
var prefix = number < 0 ? '-' : positivePrefix;
value = prefix + pad(String(Math.abs(number)), precision, '0', false);
return justify(value, prefix, leftJustify, minWidth, zeroPad);
}
case 'e':
case 'E':
case 'f':
case 'F':
case 'g':
case 'G': {
var number = +value;
var prefix = number < 0 ? '-' : positivePrefix;
var method = ['toExponential', 'toFixed', 'toPrecision']['efg'.indexOf(type.toLowerCase())];
var textTransform = ['toString', 'toUpperCase']['eEfFgG'.indexOf(type) % 2];
value = prefix + Math.abs(number)[method](precision);
return justify(value, prefix, leftJustify, minWidth, zeroPad)[textTransform]();
}
default: return $0;
}
});
}
var pad = function (str, len, chr, leftJustify) {
var padding = (str.length >= len) ? '' : Array(1 + len - str.length >>> 0).join(chr);
return leftJustify ? str + padding : padding + str;
};
var justify = function (value, prefix, leftJustify, minWidth, zeroPad) {
var diff = minWidth - value.length;
if (diff > 0) {
if (leftJustify || !zeroPad) {
value = pad(value, minWidth, ' ', leftJustify);
} else {
value = value.slice(0, prefix.length) + pad('', diff, '0', true) + value.slice(prefix.length);
}
}
return value;
};
var formatBaseX = function (value, base, prefix, leftJustify, minWidth, precision, zeroPad) {
// Note: casts negative numbers to positive ones
var number = value >>> 0;
prefix = prefix && number && {'2': '0b', '8': '0', '16': '0x'}[base] || '';
value = prefix + pad(number.toString(base), precision || 0, '0', false);
return justify(value, prefix, leftJustify, minWidth, zeroPad);
};
var formatString = function (value, leftJustify, minWidth, precision, zeroPad) {
if (precision != null) {
value = value.slice(0, precision);
}
return justify(value, '', leftJustify, minWidth, zeroPad);
};
var regex = /%(?:%|(?:(\d+)\$)?([-+#0 ]*)([1-9][0-9]*|\*(?:[0-9]+\$)?)?(?:\.([0-9]+|\*(?:[0-9]+\$)?))?([csduoxefgXEGbi]))/g;
/*
References
==========
http://www.webtoolkit.info/javascript-sprintf.html
An alternate implementation, if this one does not perform well
in practice.
*/