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package jdk.nashorn.api.scripting;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
Formatter is a class to get the type conversion between javascript types and
java types for the format (sprintf) method working.
In javascript the type for numbers can be different from the format type
specifier. For format type '%d', '%o', '%x', '%X' double need to be
converted to integer. For format type 'e', 'E', 'f', 'g', 'G', 'a', 'A'
integer needs to be converted to double.
Format type "%c" and javascript string needs special handling.
The javascript date objects can be handled if they are type double (the
related javascript code will convert with Date.getTime() to double). So
double date types are converted to long.
Pattern and the logic for parameter position: java.util.Formatter
/**
* Formatter is a class to get the type conversion between javascript types and
* java types for the format (sprintf) method working.
*
* <p>In javascript the type for numbers can be different from the format type
* specifier. For format type '%d', '%o', '%x', '%X' double need to be
* converted to integer. For format type 'e', 'E', 'f', 'g', 'G', 'a', 'A'
* integer needs to be converted to double.
*
* <p>Format type "%c" and javascript string needs special handling.
*
* <p>The javascript date objects can be handled if they are type double (the
* related javascript code will convert with Date.getTime() to double). So
* double date types are converted to long.
*
* <p>Pattern and the logic for parameter position: java.util.Formatter
*
*/
final class Formatter {
private Formatter() {
}
Method which converts javascript types to java types for the
String.format method (jrunscript function sprintf).
Params: - format – a format string
- args – arguments referenced by the format specifiers in format
Returns: a formatted string
/**
* Method which converts javascript types to java types for the
* String.format method (jrunscript function sprintf).
*
* @param format a format string
* @param args arguments referenced by the format specifiers in format
* @return a formatted string
*/
static String format(final String format, final Object[] args) {
final Matcher m = FS_PATTERN.matcher(format);
int positionalParameter = 1;
while (m.find()) {
int index = index(m.group(1));
final boolean previous = isPreviousArgument(m.group(2));
final char conversion = m.group(6).charAt(0);
// skip over some formats
if (index < 0 || previous
|| conversion == 'n' || conversion == '%') {
continue;
}
// index 0 here means take a positional parameter
if (index == 0) {
index = positionalParameter++;
}
// out of index, String.format will handle
if (index > args.length) {
continue;
}
// current argument
final Object arg = args[index - 1];
// for date we convert double to long
if (m.group(5) != null) {
// convert double to long
if (arg instanceof Double) {
args[index - 1] = ((Double) arg).longValue();
}
} else {
// we have to convert some types
switch (conversion) {
case 'd':
case 'o':
case 'x':
case 'X':
if (arg instanceof Double) {
// convert double to long
args[index - 1] = ((Double) arg).longValue();
} else if (arg instanceof String
&& ((String) arg).length() > 0) {
// convert string (first character) to int
args[index - 1] = (int) ((String) arg).charAt(0);
}
break;
case 'e':
case 'E':
case 'f':
case 'g':
case 'G':
case 'a':
case 'A':
if (arg instanceof Integer) {
// convert integer to double
args[index - 1] = ((Integer) arg).doubleValue();
}
break;
case 'c':
if (arg instanceof Double) {
// convert double to integer
args[index - 1] = ((Double) arg).intValue();
} else if (arg instanceof String
&& ((String) arg).length() > 0) {
// get the first character from string
args[index - 1] = (int) ((String) arg).charAt(0);
}
break;
default:
break;
}
}
}
return String.format(format, args);
}
Method to parse the integer of the argument index.
Params: - s – string to parse
Returns: -1 if parsing failed, 0 if string is null, > 0 integer
/**
* Method to parse the integer of the argument index.
*
* @param s string to parse
* @return -1 if parsing failed, 0 if string is null, > 0 integer
*/
private static int index(final String s) {
int index = -1;
if (s != null) {
try {
index = Integer.parseInt(s.substring(0, s.length() - 1));
} catch (final NumberFormatException e) {
//ignored
}
} else {
index = 0;
}
return index;
}
Method to check if a string contains '<'. This is used to find out if
previous parameter is used.
Params: - s – string to check
Returns: true if '<' is in the string, else false
/**
* Method to check if a string contains '<'. This is used to find out if
* previous parameter is used.
*
* @param s string to check
* @return true if '<' is in the string, else false
*/
private static boolean isPreviousArgument(final String s) {
return (s != null && s.indexOf('<') >= 0);
}
// %[argument_index$][flags][width][.precision][t]conversion
private static final String formatSpecifier =
"%(\\d+\\$)?([-#+ 0,(\\<]*)?(\\d+)?(\\.\\d+)?([tT])?([a-zA-Z%])";
// compiled format string
private static final Pattern FS_PATTERN;
static {
FS_PATTERN = Pattern.compile(formatSpecifier);
}
}