Class: ASTDistance

Inherits:
Object
  • Object
show all
Defined in:
lib/ast_distance.rb,
lib/ast_distance/node.rb,
lib/ast_distance/forest.rb,
lib/ast_distance/version.rb

Defined Under Namespace

Classes: Forest, Node

Constant Summary collapse

VERSION = 
'0.1.0'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ast1, ast2) ⇒ ASTDistance

Returns a new instance of ASTDistance.



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# File 'lib/ast_distance.rb', line 12

def initialize(ast1, ast2)
  @left_ast = ast1
  @right_ast = ast2

  @f1 = Forest.ast_to_forest(ast: ast1)
  @f2 = Forest.ast_to_forest(ast: ast2)
end

Instance Attribute Details

#left_ast ⇒ Object (readonly)

Returns the value of attribute left_ast.



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# File 'lib/ast_distance.rb', line 6

def left_ast
  @left_ast
end

#right_ast ⇒ Object (readonly)

Returns the value of attribute right_ast.



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# File 'lib/ast_distance.rb', line 6

def right_ast
  @right_ast
end

Class Method Details

.tree_edit_distance(ast1, ast2) ⇒ Object 



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# File 'lib/ast_distance.rb', line 8

def self.tree_edit_distance(ast1, ast2)
  new(ast1, ast2).tree_edit_distance
end

Instance Method Details

#forest_dist(f1, f2) ⇒ Object 



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# File 'lib/ast_distance.rb', line 25

def forest_dist(f1, f2)
  return @memo[f1.id][f2.id] if @memo[f1.id][f2.id]

  return f2.node_count if f1.empty?
  return f1.node_count if f2.empty?

  f1_rmf = f1.rightmost_forest
  f2_rmf = f2.rightmost_forest

  a = forest_dist(
    Forest.new(
      left: f1_rmf.left,
      right: f1_rmf.right,
      node_index_tbl: f1.node_index_tbl
    ),
    Forest.new(
      left: f2_rmf.left,
      right: f2_rmf.right,
      node_index_tbl: f2_rmf.node_index_tbl
    )
  )

  b = forest_dist(
    Forest.new(
      left: f1.left,
      right: f1_rmf.left,
      node_index_tbl: f1.node_index_tbl
    ),
    Forest.new(
      left: f2.left,
      right: f2_rmf.left,
      node_index_tbl: f2.node_index_tbl
    )
  )

  c = f1.root_node.type == f2.root_node.type ? 0 : 1

  d1 = a + b + c

  d2 = forest_dist(
    f1,
    Forest.new(
      left: f2.left,
      right: f2_rmf.right,
      node_index_tbl: f2.node_index_tbl
    )
  ) + 1

  d3 = forest_dist(
    Forest.new(
      left: f1.left,
      right: f1_rmf.right,
      node_index_tbl: f1.node_index_tbl
    ),
    f2
  ) + 1

  @memo[f1.id][f2.id] = [d1, d2, d3].min
end

#tree_edit_distance ⇒ Object 



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# File 'lib/ast_distance.rb', line 20

def tree_edit_distance
  pre_proc
  forest_dist(@f1, @f2)
end