SWAMPy

✎ CARVE FLESH

EDITING: erb.rb

# Example that demonstrates how a simple erb-like parser could be constructed.

$:.unshift File.dirname(__FILE__) + "/../lib"

require 'parslet'

class ErbParser < Parslet::Parser
  rule(:ruby) { (str('%>').absent? >> any).repeat.as(:ruby) }
  
  rule(:expression) { (str('=') >> ruby).as(:expression) }
  rule(:comment) { (str('#') >> ruby).as(:comment) }
  rule(:code) { ruby.as(:code) }
  rule(:erb) { expression | comment | code }
  
  rule(:erb_with_tags) { str('<%') >> erb >> str('%>') }
  rule(:text) { (str('<%').absent? >> any).repeat(1) }
  
  rule(:text_with_ruby) { (text.as(:text) | erb_with_tags).repeat.as(:text) }
  root(:text_with_ruby)
end

parser = ErbParser.new
p parser.parse "The value of x is <%= x %>."
p parser.parse "<% 1 + 2 %>"
p parser.parse "<%# commented %>"

evaluator = Parslet::Transform.new do
  
  erb_binding = binding
  
  rule(:code => { :ruby => simple(:ruby) }) { eval(ruby, erb_binding); '' }  
  rule(:expression => { :ruby => simple(:ruby) }) { eval(ruby, erb_binding) }
  rule(:comment => { :ruby => simple(:ruby) }) { '' }
  
  rule(:text => simple(:text)) { text }
  rule(:text => sequence(:texts)) { texts.join }
  
end

puts evaluator.apply(parser.parse(<<-ERB
The <% a = 2 %>not printed result of "a = 2".
The <%# a = 1 %>not printed non-evaluated comment "a = 1", see the value of a below.
The <%= 'nicely' %> printed result.
The <% b = 3 %>value of a is <%= a %>, and b is <%= b %>.
ERB
))

CANCEL

Name	Type	Size	Modified	Actions
↩ ..	DIR	—	—
📁 output/	DIR	—	2023-09-24 03:47
📄 big.erb	ERB	5.3 KB	2023-09-24 03:47	EDIT
📄 boolean_algebra.rb	RB	1.9 KB	2023-09-24 03:47	EDIT
📄 calc.rb	RB	3.4 KB	2023-09-24 03:47	EDIT
📄 capture.rb	RB	1.4 KB	2023-09-24 03:47	EDIT
📄 comments.rb	RB	938 B	2023-09-24 03:47	EDIT
📄 deepest_errors.rb	RB	2.3 KB	2023-09-24 03:47	EDIT
📄 documentation.rb	RB	341 B	2023-09-24 03:47	EDIT
📄 email_parser.rb	RB	1.4 KB	2023-09-24 03:47	EDIT
📄 empty.rb	RB	292 B	2023-09-24 03:47	EDIT
📄 erb.rb	RB	1.4 KB	2023-09-24 03:47	EDIT
📄 ip_address.rb	RB	3.1 KB	2023-09-24 03:47	EDIT
📄 json.rb	RB	2.6 KB	2023-09-24 03:47	EDIT
📄 local.rb	RB	942 B	2023-09-24 03:47	EDIT
📄 mathn.rb	RB	1.2 KB	2023-09-24 03:47	EDIT
📄 minilisp.rb	RB	2.1 KB	2023-09-24 03:47	EDIT
📄 modularity.rb	RB	1.1 KB	2023-09-24 03:47	EDIT
📄 nested_errors.rb	RB	2.2 KB	2023-09-24 03:47	EDIT
📄 optimized_erb.rb	RB	1.3 KB	2023-09-24 03:47	EDIT
📄 parens.rb	RB	945 B	2023-09-24 03:47	EDIT
📄 prec_calc.rb	RB	1.8 KB	2023-09-24 03:47	EDIT
📄 readme.rb	RB	919 B	2023-09-24 03:47	EDIT
📄 scopes.rb	RB	274 B	2023-09-24 03:47	EDIT
📄 seasons.rb	RB	956 B	2023-09-24 03:47	EDIT
📄 sentence.rb	RB	1.5 KB	2023-09-24 03:47	EDIT
📄 simple.lit	LIT	42 B	2023-09-24 03:47	EDIT
📄 simple_xml.rb	RB	1.2 KB	2023-09-24 03:47	EDIT
📄 string_parser.rb	RB	1.4 KB	2023-09-24 03:47	EDIT
📄 test.lit	LIT	136 B	2023-09-24 03:47	EDIT