2 files changed, 75 insertions, 0 deletions
diff --git a/BJC-Utils2/src/main/java/bjc/utils/funcutils/DoubleMatcher.java b/BJC-Utils2/src/main/java/bjc/utils/funcutils/DoubleMatcher.java
new file mode 100644
index 0000000..d6e77c7
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/funcutils/DoubleMatcher.java
@@ -0,0 +1,65 @@
+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");
+}
diff --git a/BJC-Utils2/src/main/java/bjc/utils/funcutils/StringUtils.java b/BJC-Utils2/src/main/java/bjc/utils/funcutils/StringUtils.java
index 718514c..2307f11 100644
--- a/BJC-Utils2/src/main/java/bjc/utils/funcutils/StringUtils.java
+++ b/BJC-Utils2/src/main/java/bjc/utils/funcutils/StringUtils.java
@@ -204,4 +204,14 @@ public class StringUtils {
 
 		return new String(Character.toChars(codepoint));
 	}
+
+	public static boolean isDouble(String inp) {
+		return DoubleMatcher.floatingLiteral.matcher(inp).matches();
+	}
+
+	private static Pattern intLitPattern = Pattern.compile("\\A[+\\-]?\\d+\\Z");
+
+	public static boolean isInt(String inp) {
+		return intLitPattern.matcher(inp).matches();
+	}
 }