Class: Voodoo::CommonCodeGenerator::Environment

Inherits:
Object
  • Object
show all
Defined in:
lib/voodoo/generators/common_code_generator.rb

Overview

Used for scoping. Maintains a symbol table and keeps track of the number of bytes that have been allocated on the stack.

Constant Summary collapse

@@gensym_counter = 
0

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(parent = nil) ⇒ Environment

Creates a new environment. If parent is specified, it will become the new environment’s parent. The new environment inherits all symbols from the parent environment.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 651

def initialize parent = nil
  ## Parent environment
  @parent = parent
  ## Symbol lookup table
  @symbols = parent ? parent.symbols.dup : {}
  ## Number of arguments
  @args = parent ? parent.args : 0
  ## Number of local variables
  @locals = parent ? parent.locals : 0
  ## Offset between base pointer and end of frame.
  @offset = parent ? parent.offset : 0
  ## Number of bytes allocated in this environment.
  @bytes = 0
end

Instance Attribute Details

#args ⇒ Object (readonly)

Returns the value of attribute args.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 646

def args
  @args
end

#bytes ⇒ Object

Returns the value of attribute bytes.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 645

def bytes
  @bytes
end

#locals ⇒ Object (readonly)

Returns the value of attribute locals.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 646

def locals
  @locals
end

#offset ⇒ Object

Returns the value of attribute offset.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 645

def offset
  @offset
end

#parent ⇒ Object (readonly)

Returns the value of attribute parent.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 646

def parent
  @parent
end

#symbols ⇒ Object (readonly)

Returns the value of attribute symbols.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 646

def symbols
  @symbols
end

Class Method Details

.gensym ⇒ Object

Generates a new, unique symbol.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 721

def self.gensym
  @@gensym_counter = @@gensym_counter + 1
  "_G#{@@gensym_counter}".to_sym
end

.initial_environment ⇒ Object

Returns an initial, top-level environment.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 727

def self.initial_environment
  Environment.new
end

Instance Method Details

#[](symbol) ⇒ Object

Looks up symbol in this environment.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 716

def [] symbol
  @symbols[symbol]
end

#add_arg(symbol, info = nil) ⇒ Object

Adds symbol as an argument in this environment. info can be used by the code generator to store information it needs about the symbol.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 669

def add_arg symbol, info = nil
  @symbols[symbol] = info
  @args = @args + 1
end

#add_args(symbols) ⇒ Object

Adds each of symbols to the arguments in this environment. Each entry in symbols can be either a symbol, or an array where the first element is the symbol and the second element is extra information to be stored with the symbol.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 679

def add_args symbols
  symbols.each do |sym|
    if sym.respond_to? :[]
      add_arg *sym
    else
      add_arg sym
    end
  end
end

#add_local(symbol, info = nil) ⇒ Object

Adds symbol as a local variable in this environment.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 690

def add_local symbol, info = nil
  @symbols[symbol] = info
  @locals = @locals + 1
end

#add_locals(symbols) ⇒ Object

Adds each of symbols to the local variables in this environment. Each entry in symbols can be either a symbol, or an array where the first element is the symbol and the second element is extra information to be stored with the symbol.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 700

def add_locals symbols
  symbols.each do |sym|
    if sym.respond_to? :[]
      add_local *sym
    else
      add_local sym
    end
  end
end

#gensym ⇒ Object

Generates a new, unique symbol.



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# File 'lib/voodoo/generators/common_code_generator.rb', line 711

def gensym
  Environment.gensym
end