Class: Einstein::Expression

Inherits:

Object

• Object
• Einstein::Expression

Defined in:

lib/einstein/expression.rb

Overview

Node representing an entire Einstein statement. This is the root-level node of the parser. This node’s exp is the tree of expressions that make up a single logical statement.

Instance Attribute Summary

• #sexp ⇒ Object (also: #to_sexp) readonly

  The s-expression given to this Expression’s constructor.

Instance Method Summary

• #evaluate(scope = {}) ⇒ Object

  Evaluate this node against the given scope.

• #initialize(sexp) ⇒ Expression constructor

  Initialize a new expression wrapping the given sexp, which is expected to be an s-expression represented as a set of nested arrays.

• #to_s ⇒ Object (also: #inspect)

  Performs a “pretty print” of this expression.

Constructor Details

#initialize(sexp) ⇒ Expression

Initialize a new expression wrapping the given sexp, which is expected to be an s-expression represented as a set of nested arrays.

Example:

Expression.new([:lit, 10]) # => 10
Expression.new([:multiply, [:lit, 10], [:lit, 5]]) # => (10 * 5)

# File 'lib/einstein/expression.rb', line 15

def initialize(sexp)
  @sexp = sexp
end

Instance Attribute Details

#sexp ⇒ Object (readonly) Also known as: to_sexp

The s-expression given to this Expression’s constructor.

# File 'lib/einstein/expression.rb', line 20

def sexp
  @sexp
end

Instance Method Details

#evaluate(scope = {}) ⇒ Object

Evaluate this node against the given scope. Returns a numeric value calculated by walking the AST with an instance of EvaluateProcessor.

# File 'lib/einstein/expression.rb', line 25

def evaluate(scope = {})
  Evaluator.new(scope).process(to_sexp)
end

#to_s ⇒ Object Also known as: inspect

Performs a “pretty print” of this expression.

# File 'lib/einstein/expression.rb', line 30

def to_s
  PrettyPrinter.new.process(to_sexp)
end