Class: JavaClass::ClassFile::ClassVersion

Inherits:
Object
  • Object
show all
Defined in:
lib/javaclass/classfile/class_version.rb

Overview

Version of a class file.

Author

Peter Kofler

See

java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html#75883

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data, start = 4) ⇒ ClassVersion

Extract the class version from the bytes data starting at position start (which is usually 4).



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# File 'lib/javaclass/classfile/class_version.rb', line 15

def initialize(data, start=4)
  # parsing
  @minor = data.u2(start)
  @major = data.u2(start+2)
end

Instance Attribute Details

#major ⇒ Object (readonly)

Returns the value of attribute major.



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# File 'lib/javaclass/classfile/class_version.rb', line 12

def major
  @major
end

#minor ⇒ Object (readonly)

ZenTest FULL to find method to_s



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# File 'lib/javaclass/classfile/class_version.rb', line 11

def minor
  @minor
end

Instance Method Details

#dump ⇒ Object

Return a debug output of this version.



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# File 'lib/javaclass/classfile/class_version.rb', line 38

def dump
  ["  minor version: #{@minor}", "  major version: #{@major}"] 
end

#jdk_version ⇒ Object

Return the JDK version corresponding to this version like “1.6” or “unknown” if none matched.



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# File 'lib/javaclass/classfile/class_version.rb', line 43

def jdk_version
  v = to_f
  if v >= 45.0 && v <= 45.3 # 1.0.2 supports class file format versions 45.0 through 45.3 inclusive.
    '1.0'
  elsif v > 45.3 && v <= 45.65535 # 1.1.X can support class file formats of versions in the range 45.0 through 45.65535 inclusive
    '1.1'
  elsif v == 46.0 # JDK 1.2=46
    '1.2'
  elsif v == 47.0 # JDK 1.3=47
    '1.3'
  elsif v == 48.0 # JDK 1.4=48
    '1.4'
  elsif v == 49.0 # J2SE 5.0=49
    '1.5'
  elsif v == 50.0 # J2SE 6.0=50
    '1.6'
  else
    'unknown'
  end
end

#to_f ⇒ Object

Return the version as major.minor float.



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# File 'lib/javaclass/classfile/class_version.rb', line 27

def to_f
  if @minor <= 0
    denom = 1.0
  else
    denom = 1.0 * 10**(Math.log10(@minor).floor + 1)
  end
  
  @major + @minor/denom
end

#to_s ⇒ Object

Return the class file version as major.minor string like 48.0 (Java 1.4) or 50.0 (Java 6).



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# File 'lib/javaclass/classfile/class_version.rb', line 22

def to_s
  "#{@major}.#{@minor}"
end