Module ch.randelshofer.fastdoubleparser
Package ch.randelshofer.fastdoubleparser

Class AbstractJavaFloatingPointBitsFromCharSequence

java.lang.Object
ch.randelshofer.fastdoubleparser.AbstractNumberParser
ch.randelshofer.fastdoubleparser.AbstractFloatValueParser
ch.randelshofer.fastdoubleparser.AbstractJavaFloatingPointBitsFromCharSequence
Direct Known Subclasses:
JavaDoubleBitsFromCharSequence, JavaFloatBitsFromCharSequence
abstract class AbstractJavaFloatingPointBitsFromCharSequence extends AbstractFloatValueParser
Parses a Java FloatingPointLiteral from a CharSequence.

This class should have a type parameter for the return value of its parse methods. Unfortunately Java does not support type parameters for primitive types. As a workaround we use long. A long has enough bits to fit a double value or a float value.

See JavaDoubleParser for the grammar of FloatingPointLiteral.

  • Constructor Details

    • AbstractJavaFloatingPointBitsFromCharSequence

      AbstractJavaFloatingPointBitsFromCharSequence()

  • Method Details

    • skipWhitespace

      private static int skipWhitespace(CharSequence str, int index, int endIndex)
      Skips optional white space in the provided string
      Parameters:
      str - a string
      index - start index (inclusive) of the optional white space
      endIndex - end index (exclusive) of the optional white space
      Returns:
      index after the optional white space

    • nan

      abstract long nan()
      Returns:
      a NaN constant in the specialized type wrapped in a long

    • negativeInfinity

      abstract long negativeInfinity()
      Returns:
      a negative infinity constant in the specialized type wrapped in a long

    • parseDecFloatLiteral

      private long parseDecFloatLiteral(CharSequence str, int index, int startIndex, int endIndex, boolean isNegative)
      Parses a DecimalFloatingPointLiteral production with optional trailing white space until the end of the text. Given that we have already consumed the optional leading zero of the DecSignificand.
      DecimalFloatingPointLiteralWithWhiteSpace:
      DecimalFloatingPointLiteral [WhiteSpace] EOT
      See JavaDoubleParser for the grammar of DecimalFloatingPointLiteral and DecSignificand.
      Parameters:
      str - a string
      index - the current index
      startIndex - start index inclusive of the DecimalFloatingPointLiteralWithWhiteSpace
      endIndex - end index (exclusive)
      isNegative - true if the float value is negative
      Returns:
      the bit pattern of the parsed value, if the input is legal; otherwise, -1L.

    • parseFloatingPointLiteral

      public final long parseFloatingPointLiteral(CharSequence str, int offset, int length)
      Parses a FloatingPointLiteral production with optional leading and trailing white space.
      FloatingPointLiteralWithWhiteSpace:
      [WhiteSpace] FloatingPointLiteral [WhiteSpace]
      See JavaDoubleParser for the grammar of FloatingPointLiteral.
      Parameters:
      str - a string containing a FloatingPointLiteralWithWhiteSpace
      offset - start offset of FloatingPointLiteralWithWhiteSpace in str
      length - length of FloatingPointLiteralWithWhiteSpace in str
      Returns:
      the bit pattern of the parsed value, if the input is legal; otherwise, -1L.

    • parseHexFloatLiteral

      private long parseHexFloatLiteral(CharSequence str, int index, int startIndex, int endIndex, boolean isNegative)
      Parses the following rules (more rules are defined in AbstractFloatValueParser):
      RestOfHexFloatingPointLiteral:
      RestOfHexSignificand BinaryExponent
      RestOfHexSignificand:
      HexDigits
      HexDigits .
      [HexDigits] . HexDigits
      Parameters:
      str - the input string
      index - index to the first character of RestOfHexFloatingPointLiteral
      startIndex - the start index of the string
      endIndex - the end index of the string
      isNegative - if the resulting number is negative
      Returns:
      the bit pattern of the parsed value, if the input is legal; otherwise, -1L.

    • parseNaNOrInfinity

      private long parseNaNOrInfinity(CharSequence str, int index, int endIndex, boolean isNegative)

    • positiveInfinity

      abstract long positiveInfinity()
      Returns:
      a positive infinity constant in the specialized type wrapped in a long

    • valueOfFloatLiteral

      abstract long valueOfFloatLiteral(CharSequence str, int startIndex, int endIndex, boolean isNegative, long significand, int exponent, boolean isSignificandTruncated, int exponentOfTruncatedSignificand)
      Computes a float value from the given components of a decimal float literal.
      Parameters:
      str - the string that contains the float literal (and maybe more)
      startIndex - the start index (inclusive) of the float literal inside the string
      endIndex - the end index (exclusive) of the float literal inside the string
      isNegative - whether the float value is negative
      significand - the significand of the float value (can be truncated)
      exponent - the exponent of the float value
      isSignificandTruncated - whether the significand is truncated
      exponentOfTruncatedSignificand - the exponent value of the truncated significand
      Returns:
      the bit pattern of the parsed value, if the input is legal; otherwise, -1L.

    • valueOfHexLiteral

      abstract long valueOfHexLiteral(CharSequence str, int startIndex, int endIndex, boolean isNegative, long significand, int exponent, boolean isSignificandTruncated, int exponentOfTruncatedSignificand)
      Computes a float value from the given components of a hexadecimal float literal.
      Parameters:
      str - the string that contains the float literal (and maybe more)
      startIndex - the start index (inclusive) of the float literal inside the string
      endIndex - the end index (exclusive) of the float literal inside the string
      isNegative - whether the float value is negative
      significand - the significand of the float value (can be truncated)
      exponent - the exponent of the float value
      isSignificandTruncated - whether the significand is truncated
      exponentOfTruncatedSignificand - the exponent value of the truncated significand
      Returns:
      the bit pattern of the parsed value, if the input is legal; otherwise, -1L.