Cheap-n-cheerful HTML page template system. You create a template containing:
variable names between percent signs (%fred%
)
blocks of repeating stuff:
START:key ... stuff END:key
You feed the code a hash. For simple variables, the values are resolved
directly from the hash. For blocks, the hash entry corresponding to
key
will be an array of hashes. The block will be generated
once for each entry. Blocks can be nested arbitrarily deeply.
The template may also contain
IF:key ... stuff ENDIF:key
stuff will only be included in the output if the corresponding key is set in the value hash.
Usage: Given a set of templates T1, T2,
etc
values = { "name" => "Dave", state => "TX" } t = TemplatePage.new(T1, T2, T3) File.open(name, "w") {|f| t.write_html_on(f, values)} or res = '' t.write_html_on(res, values)
templates
is an array of strings containing the templates. We
start at the first, and substitute in subsequent ones where the string
!INCLUDE!
occurs. For example, we could have the overall page
template containing
<html><body> <h1>Master</h1> !INCLUDE! </bost></html>
and substitute subpages in to it by passing [master, sub_page]. This gives us a cheap way of framing pages
# File rdoc/template.rb, line 132 def initialize(*templates) result = "!INCLUDE!" templates.each do |content| result.sub!(/!INCLUDE!/, content) end @lines = LineReader.new(result.split($/)) end
Given an individual line, we look for %xxx% constructs and HREF:ref:name: constructs, substituting for each.
# File rdoc/template.rb, line 201 def expand_line(line) # Generate a cross reference if a reference is given, # otherwise just fill in the name part line.gsub!(/HREF:(\w+?):(\w+?):/) { ref = @context.lookup($1) name = @context.find_scalar($2) if ref and !ref.kind_of?(Array) "<a href=\"#{ref}\">#{name}</a>" else name end } # Substitute in values for %xxx% constructs. This is made complex # because the replacement string may contain characters that are # meaningful to the regexp (like \1) line = line.gsub(/%([a-zA-Z]\w*)%/) { val = @context.find_scalar($1) val.tr('\\', "\000") } line rescue Exception => e $stderr.puts "Error in template: #{e}" $stderr.puts "Original line: #{line}" exit end
Substitute a set of key/value pairs into the given template. Keys with
scalar values have them substituted directly into the page. Those with
array values invoke substitute_array
(below), which examples a
block of the template once for each row in the array.
This routine also copes with the IF:
key directive,
removing chunks of the template if the corresponding key does not appear in
the hash, and the START: directive, which loops its contents for each value
in an array
# File rdoc/template.rb, line 161 def substitute_into(lines, values) @context.push(values) skip_to = nil result = [] while line = lines.read case line when /^IF:(\w+)/ lines.read_up_to(/^ENDIF:#$1/) unless @context.lookup($1) when /^IFNOT:(\w+)/ lines.read_up_to(/^ENDIF:#$1/) if @context.lookup($1) when /^ENDIF:/ ; when /^START:(\w+)/ tag = $1 body = lines.read_up_to(/^END:#{tag}/) inner_values = @context.lookup(tag) raise "unknown tag: #{tag}" unless inner_values raise "not array: #{tag}" unless inner_values.kind_of?(Array) inner_values.each do |vals| result << substitute_into(body.dup, vals) end else result << expand_line(line.dup) end end @context.pop result.join("\n") end
Render the templates into HTML, storing the result on op
using the method <<
. The value_hash
contains key/value pairs used to drive the substitution (as described
above)
# File rdoc/template.rb, line 144 def write_html_on(op, value_hash) @context = Context.new op << substitute_into(@lines, value_hash).tr("\000", '\\') end