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package bjc.utils.funcutils;
import java.util.regex.Pattern;
/*
* Checks if a string would pass Double.parseDouble.
*
* Uses a regex from the javadoc for Double.valueOf()
*/
class DoubleMatcher {
private static final String Digits = "(\\p{Digit}+)";
private static final String HexDigits = "(\\p{XDigit}+)";
/*
* an exponent is 'e' or 'E' followed by an optionally signed decimal
* integer.
*/
private static final String Exp = "[eE][+-]?" + Digits;
private static final String fpRegex = "[\\x00-\\x20]*" + // Optional
// leading
// "whitespace"
"[+-]?(" + // Optional sign character
"NaN|" + // "NaN" string
"Infinity|" + // "Infinity" string
/*
* A decimal floating-point string representing a finite
* positive number without a leading sign has at most
* five basic pieces: Digits . Digits ExponentPart
* FloatTypeSuffix
*
* Since this method allows integer-only strings as
* input in addition to strings of floating-point
* literals, the two sub-patterns below are
* simplifications of the grammar productions from
* section 3.10.2 of The Java™ Language Specification.
*/
/*
* Digits ._opt Digits_opt ExponentPart_opt
* FloatTypeSuffix_opt
*/
"(((" + Digits + "(\\.)?(" + Digits + "?)(" + Exp + ")?)|" +
/*
* . Digits ExponentPart_opt FloatTypeSuffix_opt
*/
"(\\.(" + Digits + ")(" + Exp + ")?)|" +
/*
* Hexadecimal strings
*/
"((" +
/*
* 0[xX] HexDigits ._opt BinaryExponent
* FloatTypeSuffix_opt
*/
"(0[xX]" + HexDigits + "(\\.)?)|" +
/*
* 0[xX] HexDigits_opt . HexDigits BinaryExponent
* FloatTypeSuffix_opt
*/
"(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
")[pP][+-]?" + Digits + "))" + "[fFdD]?))" + "[\\x00-\\x20]*"; // Optional
// trailing
// "whitespace"
public static final Pattern floatingLiteral = Pattern.compile("\\A" + fpRegex + "\\Z");
}
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