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Parse ERB template ruby output expressions (using the temple gem)
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# An example to extract the ruby output expressions from an ERB template using the temple gem: | |
# | |
# 1. Install 'temple' gem https://github.com/judofyr/temple | |
# 2. Require this erb_parser.rb file and run: | |
# | |
# ErbParser.call | |
# | |
# Dynamics will be: | |
# [[[:dynamic, " @page.title "], | |
# [:dynamic, " an_image "], | |
# [:dynamic, " a_heading "], | |
# [:dynamic, " simple_format some_text "], | |
# [:dynamic, " sanitize html_text "], | |
# [:dynamic, " shared_content( 'the_email' ) "]], | |
# | |
# Abstract Syntax Tree will be: | |
# [:multi, | |
# [:code, " @page_title = @page.title "], | |
# [:static, "\n"], | |
# [:newline], | |
# [:static, "<h1>\n"], | |
# [:newline], | |
# [:static, " "], | |
# [:escape, true, [:dynamic, " @page.title "]], | |
# [:static, "\n"], | |
# [:newline], | |
# [:static, "</h1>\n"], | |
# [:newline], | |
# [:static, "<p>\n"], | |
# [:newline], | |
# [:static, " <img src=\"/images/shinycms/"], | |
# [:escape, true, [:dynamic, " an_image "]], | |
# [:static, "\" alt=\"\">\n"], | |
# [:newline], | |
# [:static, "</p>\n"], | |
# [:newline], | |
# [:static, "<h2>\n"], | |
# [:newline], | |
# [:static, " "], | |
# [:escape, true, [:dynamic, " a_heading "]], | |
# [:static, "\n"], | |
# [:newline], | |
# [:static, "</h2>\n"], | |
# [:newline], | |
# [:static, "\n"], | |
# [:newline], | |
# [:escape, true, [:dynamic, " simple_format some_text "]], | |
# [:static, "\n"], | |
# [:newline], | |
# [:static, "\n"], | |
# [:newline], | |
# [:escape, true, [:dynamic, " sanitize html_text "]], | |
# [:static, "\n"], | |
# [:newline], | |
# [:static, "\n"], | |
# [:newline], | |
# [:static, "<p class=\"small\">\n"], | |
# [:newline], | |
# [:static, " Contact: "], | |
# [:escape, true, [:dynamic, " shared_content( 'the_email' ) "]], | |
# [:static, "\n"], | |
# [:newline], | |
# [:static, "</p>\n"], | |
# [:newline], | |
# [:static, ""]]] | |
class ErbParser | |
def self.call | |
self.new.call | |
end | |
def call | |
parser = Temple::ERB::Parser.new | |
erb_source = <<~ERB | |
<% @page_title = @page.title %> | |
<h1> | |
<%= @page.title %> | |
</h1> | |
<p> | |
<img src="/images/shinycms/<%= an_image %>" alt=""> | |
</p> | |
<h2> | |
<%= a_heading %> | |
</h2> | |
<%= simple_format some_text %> | |
<%= sanitize html_text %> | |
<p class="small"> | |
Contact: <%= shared_content( 'the_email' ) %> | |
</p> | |
ERB | |
# Abstract Syntax Tree | |
ast = parser.call(erb_source) | |
dynamics = extract_dynamics(ast) | |
[dynamics, ast] | |
end | |
def extract_dynamics(ast) | |
dynamics = [] | |
ast.each do |node| | |
next unless node.is_a?(Array) | |
if node[0] == :dynamic | |
dynamics << node | |
else | |
dynamics += extract_dynamics(node) | |
end | |
end | |
dynamics | |
end | |
end |
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