[format] Add 'x' format specifier and field width
Sometimes it is useful to print numbers in hex format - add the appropriate specifier. Also support a minimum field width to pad the formatted string with spaces (or zeros if the width is prefixed with '0'). https://bugzilla.gnome.org/show_bug.cgi?id=622597
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@ -6,8 +6,10 @@
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* It has to be set up using String.prototype.format = Format.format;
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* Usage:
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* "somestring %s %d".format('hello', 5);
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* It supports %s, %d and %f, for %f it also support precisions like
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* "%.2f".format(1.526)
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* It supports %s, %d, %x and %f, for %f it also support precisions like
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* "%.2f".format(1.526). All specifiers can be prefixed with a minimum
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* field width, e.g. "%5s".format("foo"). Unless the width is prefixed
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* with '0', the formatted string will be padded with spaces.
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*/
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function format() {
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@ -15,30 +17,44 @@ function format() {
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let i = 0;
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let args = arguments;
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return str.replace(/%(?:\.([0-9]+))?(.)/g, function (str, precisionGroup, genericGroup) {
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return str.replace(/%([0-9]+)?(?:\.([0-9]+))?(.)/g, function (str, widthGroup, precisionGroup, genericGroup) {
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if (precisionGroup != '' && genericGroup != 'f')
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throw new Error("Precision can only be specified for 'f'");
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let fillChar = (widthGroup[0] == '0') ? '0' : ' ';
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let width = parseInt(widthGroup, 10) || 0;
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function fillWidth(s, c, w) {
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let fill = '';
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for (let i = 0; i < w; i++)
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fill += c;
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return fill.substr(s.length) + s;
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}
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let s = '';
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switch (genericGroup) {
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case '%':
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return '%';
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break;
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case 's':
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return args[i++].toString();
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s = args[i++].toString();
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break;
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case 'd':
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return parseInt(args[i++]);
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s = parseInt(args[i++]).toString();
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break;
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case 'x':
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s = parseInt(args[i++]).toString(16);
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break;
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case 'f':
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if (precisionGroup == '')
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return parseFloat(args[i++]);
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s = parseFloat(args[i++]).toString();
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else
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return parseFloat(args[i++]).toFixed(parseInt(precisionGroup));
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s = parseFloat(args[i++]).toFixed(parseInt(precisionGroup));
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break;
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default:
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throw new Error('Unsupported conversion character %' + genericGroup);
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}
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return ""; // Suppress warning
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return fillWidth(s, fillChar, width);
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});
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}
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