The Parser is responsible for taking a string template and converting it into an array of tokens and, really, expressions. It raises SyntaxError if there is anything it doesn’t understand and knows which sigil corresponds to which tag type.
For example, given this template:
Hi {{thing}}!
Run through the Parser we’ll get these tokens:
[:multi, [:static, "Hi "], [:mustache, :etag, "thing"], [:static, "!\n"]]
You can see the array of tokens for any template with the mustache(1) command line tool:
$ mustache --tokens test.mustache [:multi, [:static, "Hi "], [:mustache, :etag, "thing"], [:static, "!\n"]]
- C
- E
- N
- O
- P
- R
- S
SKIP_WHITESPACE | = | [ '#', '^', '/' ] |
After these types of tags, all whitespace will be skipped. |
||
ALLOWED_CONTENT | = | /(\w|[?!\/-])*/ |
The content allowed in a tag name. |
||
ANY_CONTENT | = | [ '!', '=' ] |
These types of tags allow any content, the rest only allow ALLOWED_CONTENT. |
[R] | scanner | |
[R] | result | |
[W] | otag | |
[W] | ctag |
Accepts an options hash which does nothing but may be used in the future.
Given a string template, returns an array of tokens.
# File lib/mustache/parser.rb, line 78 def compile(template) if template.respond_to?(:encoding) @encoding = template.encoding template = template.dup.force_encoding("BINARY") else @encoding = nil end # Keeps information about opened sections. @sections = [] @result = [:multi] @scanner = StringScanner.new(template) # Scan until the end of the template. until @scanner.eos? scan_tags || scan_text end if !@sections.empty? # We have parsed the whole file, but there's still opened sections. type, pos, result = @sections.pop error "Unclosed section #{type.inspect}", pos end @result end
The closing tag delimiter. This too may be changed at runtime.
Raises a SyntaxError. The message should be the name of the error - other details such as line number and position are handled for you.
The opening tag delimiter. This may be changed at runtime.
Returns [lineno, column, line]
# File lib/mustache/parser.rb, line 206 def position # The rest of the current line rest = @scanner.check_until(/\n|\Z/).to_s.chomp # What we have parsed so far parsed = @scanner.string[0...@scanner.pos] lines = parsed.split("\n") [ lines.size, lines.last.size - 1, lines.last + rest ] end
Used to quickly convert a string into a regular expression usable by the string scanner.
Find {{mustaches}} and add them to the @result array.
# File lib/mustache/parser.rb, line 106 def scan_tags # Scan until we hit an opening delimiter. return unless @scanner.scan(regexp(otag)) # Since {{= rewrites ctag, we store the ctag which should be used # when parsing this specific tag. current_ctag = self.ctag type = @scanner.scan(/#|\^|\/|=|!|<|>|&|\{/) @scanner.skip(/\s*/) # ANY_CONTENT tags allow any character inside of them, while # other tags (such as variables) are more strict. if ANY_CONTENT.include?(type) r = /\s*#{regexp(type)}?#{regexp(current_ctag)}/ content = scan_until_exclusive(r) else content = @scanner.scan(ALLOWED_CONTENT) end # We found {{ but we can't figure out what's going on inside. error "Illegal content in tag" if content.empty? # Based on the sigil, do what needs to be done. case type when '#' block = [:multi] @result << [:mustache, :section, content, block] @sections << [content, position, @result] @result = block when '^' block = [:multi] @result << [:mustache, :inverted_section, content, block] @sections << [content, position, @result] @result = block when '/' section, pos, result = @sections.pop @result = result if section.nil? error "Closing unopened #{content.inspect}" elsif section != content error "Unclosed section #{section.inspect}", pos end when '!' # ignore comments when '=' self.otag, self.ctag = content.split(' ', 2) when '>', '<' @result << [:mustache, :partial, content] when '{', '&' # The closing } in unescaped tags is just a hack for # aesthetics. type = "}" if type == "{" @result << [:mustache, :utag, content] else @result << [:mustache, :etag, content] end # Skip whitespace and any balancing sigils after the content # inside this tag. @scanner.skip(/\s+/) @scanner.skip(regexp(type)) if type # Try to find the closing tag. unless close = @scanner.scan(regexp(current_ctag)) error "Unclosed tag" end # Skip whitespace following this tag if we need to. @scanner.skip(/\s+/) if SKIP_WHITESPACE.include?(type) end
Try to find static text, e.g. raw HTML with no {{mustaches}}.
# File lib/mustache/parser.rb, line 179 def scan_text text = scan_until_exclusive(regexp(otag)) if text.nil? # Couldn't find any otag, which means the rest is just static text. text = @scanner.rest # Mark as done. @scanner.clear end text.force_encoding(@encoding) if @encoding @result << [:static, text] end
Scans the string until the pattern is matched. Returns the substring excluding the end of the match, advancing the scan pointer to that location. If there is no match, nil is returned.