LuaString: port strx2number for accurate double scanning, handle plus signs when converting strings to numbers

src/core/org/luaj/vm2/LuaString.java

@@ -750,6 +750,22 @@ public class LuaString extends LuaValue {
 		return Double.isNaN(d)? NIL: valueOf(d);
 	}
 
+	private boolean isspace(byte c) {
+		return c == ' ' || (c >= '\t' && c <= '\r');
+	}
+
+	private boolean isdigit(byte c) {
+		return (c >= '0' && c <= '9');
+	}
+
+	private boolean isxdigit(byte c) {
+		return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
+	}
+
+	private int hexvalue(byte c) {
+		return c <= '9' ? c - '0' : c <= 'F' ? c + 10 - 'A' : c + 10 - 'a';
+	}
+
 	/** 
 	 * Convert to a number in base 10, or base 16 if the string starts with '0x', 
 	 * or return Double.NaN if it cannot be converted to a number.
@@ -757,14 +773,63 @@ public class LuaString extends LuaValue {
 	 */
 	public double scannumber() {
 		int i = m_offset, j = m_offset + m_length;
-		while ( i<j && m_bytes[i]==' ' ) ++i;
-		while ( i<j && m_bytes[j-1]==' ' ) --j;
+		while (i < j && isspace(m_bytes[i]))
+			++i;
+		while (i < j && isspace(m_bytes[j - 1]))
+			--j;
 		if (i >= j)
 			return Double.NaN;
-		if ( m_bytes[i]=='0' && i+1<j && (m_bytes[i+1]=='x'||m_bytes[i+1]=='X'))
-			return scanlong(16, i+2, j);
-		double l = scanlong(10, i, j);
-		return Double.isNaN(l)? scandouble(i,j): l;
+		if (indexOf((byte) 'x', i - m_offset) != -1 || indexOf((byte) 'X', i - m_offset) != -1)
+			return strx2number(i, j);
+		return scandouble(i, j);
+	}
+
+	private double strx2number(int start, int end) {
+		double sgn = (m_bytes[start] == '-') ? -1.0 : 1.0;
+		if (sgn == -1.0 || m_bytes[start] == '+')
+			++start;
+		if (start + 2 >= end)
+			return Double.NaN;
+		if (m_bytes[start++] != '0')
+			return Double.NaN;
+		if (m_bytes[start] != 'x' && m_bytes[start] != 'X')
+			return Double.NaN;
+		++start;
+		double m = 0;
+		int e = 0;
+		boolean i = isxdigit(m_bytes[start]);
+		while (start < end && isxdigit(m_bytes[start]))
+			m = (m * 16) + hexvalue(m_bytes[start++]);
+		if (start < end && m_bytes[start] == '.') {
+			++start;
+			while (start < end && isxdigit(m_bytes[start])) {
+				m = (m * 16) + hexvalue(m_bytes[start++]);
+				e -= 4;
+			}
+		}
+		if (!i && e == 0)
+			return Double.NaN;
+		if (start < end && (m_bytes[start] == 'p' || m_bytes[start] == 'P')) {
+			++start;
+			int exp1 = 0;
+			boolean neg1 = false;
+			if (start < end) {
+				if (m_bytes[start] == '-')
+					neg1 = true;
+				if (neg1 || m_bytes[start] == '+')
+					++start;
+			}
+			if (start >= end || !isdigit(m_bytes[start]))
+				return Double.NaN;
+			while (start < end && isdigit(m_bytes[start]))
+				exp1 = exp1 * 10 + m_bytes[start++] - '0';
+			if (neg1)
+				exp1 = -exp1;
+			e += exp1;
+		}
+		if (start != end)
+			return Double.NaN;
+		return sgn * m * MathLib.dpow_d(2.0, e);
 	}
 	
 	/** 
@@ -776,8 +841,8 @@ public class LuaString extends LuaValue {
 		if ( base < 2 || base > 36 )
 			return Double.NaN;
 		int i=m_offset,j=m_offset+m_length;
-		while ( i<j && m_bytes[i]==' ' ) ++i;
-		while ( i<j && m_bytes[j-1]==' ' ) --j;
+		while ( i<j && isspace(m_bytes[i]) ) ++i;
+		while ( i<j && isspace(m_bytes[j-1]) ) --j;
 		if ( i>=j )
 			return Double.NaN;
 		return scanlong( base, i, j );
@@ -794,7 +859,8 @@ public class LuaString extends LuaValue {
 	private double scanlong( int base, int start, int end ) {
 		long x = 0;
 		boolean neg = (m_bytes[start] == '-');
-		for ( int i=(neg?start+1:start); i<end; i++ ) {
+		if (neg || m_bytes[start] == '+') start++;
+		for ( int i=start; i<end; i++ ) {
 			int digit = m_bytes[i] - (base<=10||(m_bytes[i]>='0'&&m_bytes[i]<='9')? '0':
 					m_bytes[i]>='A'&&m_bytes[i]<='Z'? ('A'-10): ('a'-10));
 			if ( digit < 0 || digit >= base )