Class: Pdfrb::Arlington::Predicate::Evaluator

Inherits:
Object
  • Object
show all
Defined in:
lib/pdfrb/arlington/predicate/evaluator.rb

Overview

Evaluates a predicate AST against a Context. Returns a Ruby value (typically Boolean for predicates; Integer/String for arithmetic helpers like ArrayLength, FileSize).

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(context) ⇒ Evaluator

Returns a new instance of Evaluator.



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# File 'lib/pdfrb/arlington/predicate/evaluator.rb', line 12

def initialize(context)
  @context = context
end

Instance Attribute Details

#context ⇒ Object (readonly)

Returns the value of attribute context.



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# File 'lib/pdfrb/arlington/predicate/evaluator.rb', line 10

def context
  @context
end

Class Method Details

.call(ast, context) ⇒ Object 



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# File 'lib/pdfrb/arlington/predicate/evaluator.rb', line 16

def self.call(ast, context)
  new(context).evaluate(ast)
end

Instance Method Details

#evaluate(node) ⇒ Object 



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# File 'lib/pdfrb/arlington/predicate/evaluator.rb', line 20

def evaluate(node)
  return nil if node.nil?

  case node
  when AST::FunctionCall then dispatch_function(node)
  when AST::AtKey then resolve_at_key(node.name)
  when AST::PathExpr then resolve_path(node.segments)
  when AST::Literal then node.value
  when AST::ArrayLit then node.values
  when AST::BinOp then eval_binop(node)
  when AST::UnaryOp then eval_unaryop(node)
  when AST::LogicalOp then eval_logical(node)
  else
    raise Pdfrb::Error, "unknown AST node #{node.class}"
  end
end