= Operast README

Release: $Release$

http://rubyforge.org/projects/operast

http://operast.rubyforge.org/



== About

Operast (Operator + AST) is a library to convert Ruby expression
into other language.
Currently, only SQL is supported.

Operast requires Ruby 1.8 or later.


== Example

    require 'operast'
    require 'operast/translator/sql'
    
    x = Operast::Variable.new('x')
    y = Operast::Variable.new('y')
    t = Operast::SqlTranslator.new
  
    p t.translate(x)                     #=> "x"
    p t.translate(x + 1)                 #=> "(x + 1)"
    p t.translate(x + y)                 #=> "(x + y)"
    p t.translate(x * y + 2)             #=> "((x * y) + 2)"
    p t.translate(x + y * 2)             #=> "(x + (y * 2))"
    p t.translate(x ** y)                #=> "power(x,y)"
    p t.translate(x > 0)                 #=> "(x > 0)"
    p t.translate(y < 1)                 #=> "(y < 1)"
    p t.translate(x == 0)                #=> "(x = 0)"
    p t.translate(y ^ "who's who")       #=> "(y <> 'who\\'s who')"
    p t.translate(y <=> 3.14)            #=> "(y <> 3.14)"
    p t.translate((x > 0) & (y < 1))     #=> "((x > 0) and (y < 1))"
    p t.translate((x == 0) | (y ^ 1))    #=> "((x = 0) or (y <> 1))"
    p t.translate(x == nil)              #=> "(x is null)"
    p t.translate(x <=> nil)             #=> "(x is not null)"
    p t.translate(x =~ '%pattern%')      #=> "(x like '%pattern%')"
    p t.translate(x.in?([10,20,30]))     #=> "(x in (10,20,30))"
    p t.translate(x.in?(10..30))         #=> "(x between 10 and 30)"


== Restrictions

* 'x + 1' is OK, but '1 + x' is NG.
* 'x & y' is OK, but 'x && y' is NG.
* 'x != y' is NG in Ruby 1.8. Use 'x ^ y' or 'x <=> y' instead.
* function (such as sum() or avg()) is not supported.


== License

$License$


== Author

makoto kuwata <kwa.at.kuwata-lab.com>