From: Kevin Howe <kh@...>
Date: 2005-02-13T11:34:59+09:00
Subject: [ANN] LXL (Like Excel) 0.3.0

LXL (Like Excel) is a mini-language that mimics Microsoft Excel formulas.
Easily extended with new constants and functions.

Version 0.3.0 supports the following features:

=Namespaces [NEW]

  Extending the language is now as easy as defining new constants
  and methods on an LXL::Namespace class, for immediate use in formulas.

    class MyLXLNamespace < LXL::Namespace
      NAME = 'John Doe'
      def upper(text) text.to_s.upcase end
    end

    class MyLXL < LXL::Parser
      def self.namespace_class() MyLXLNamespace end
    end

    MyLXL.eval('=UPPER(NAME)')
    # => JOHN DOE

=Ranges [NEW]

  B3:D5 => LXL::Range.new("B3","D5")

  LXL::Range is a subclass of Range which overrides
  the #each method to return Excel-style ranges.

  # Ruby Range
  Range.new("B3", "D5").collect
  # => ["B3", "B4", "B5", "B6", "B7", "B8", "B9",
        "C0", "C1", "C2", "C3", "C4", "C5", "C6", "C7", "C8", "C9",
        "D0", "D1", "D2", "D3", "D4", "D5"]

  # LXL Range
  LXL::Range.new("B3", "D5").collect
  # => ["B3", "B4", "B5", "C3", "C4", "C5", "D3", "D4", "D5"]

=Percentages [NEW]

  25% => .25

=Deferred function calls [NEW]

  Snapshots the symbol/arguments of a function call for later use.

  class MyNamespace < LXL::Namespace
    register_deferred :foo
  end
  LXL.new(MyNamespace.new).eval('=FOO(1, "two", 3)').inspect
  # => <LXL::Deferred @args=[1, "two", 3] @symbol=:foo>

=Symbol registration

  Register uppercase constants of the same name and value.

  class MyNamespace < LXL::Namespace
    register_symbols :foo, :bar
  end
  LXL.new(MyNamespace.new).eval('=LIST(FOO, BAR)').inspect
  # => [:FOO, :BAR]

=Operators

  a +  b # Add
  a -  b # Subtract
  a *  b # Multiply
  a /  b # Divide
  a =  b # Equal to
  a <> b # Not equal to
  a <  b # Less than
  a >  b # Greater than
  a <= b # Less than or equal to
  a >= b # Greater than or equal to

  a & b # String concentation [NEW]
  n ^ n # Exponential [NEW]

=Constants

  TRUE  # true
  FALSE # false
  NULL  # nil

=Functions

  Logical Functions

    AND (a,b)
    OR  (a,b)
    IF  (cond,true,false)

  Date/Time Functions

    TODAY    ()      # current date value
    NOW      ()      # current date/time value
    DATE     (y,m,d) # date value
    TIME     (h,m,s) # time value
    DATETIME (value) # convert a date/time string into a date/time value

  List Functions

    LIST (a,b,..)    # Variable length list
    IN   (find,list) # True if find value is in the given list (works on
strings too)

=Notes

 * The number zero is interpereted as FALSE
 * Return multiple results in an array by separating formulas with a
semi-colon (;)
 * Constant and Function names are case-insensitive
 * Values prefixed with = are formulas, anything else is assumed to be text:

     LXL.eval("5+5")  # => '5+5'
     LXL.eval("=5+5") # => 10

Regards,
Kevin