Object
The Parser class is used by the formatting subsystem to take the raw tokens from the Lexer class and wrap them in "instructions", which are then used by the LayoutBuilder to determine how each token should be rendered.
The parser also ensures that tags are opened and closed consistently. It is not forgiving at all--if you forget to close a tag, the parser will raise an exception (TagError).
It will also raise an exception if a tag is encountered with no style definition for it.
Creates a new parser associated with the given document, and which will parse the given text. The options may include either of two optional keys:
:tags is used to specify the hash of tags and their associated styles. Any tag not specified here will not be recognized by the parser, and will cause an error if it is encountered in text.
:styles is used to specify the mapping of style classes to their definitions. The keys should be symbols, and the values should be hashes. The values have the same format as for the :tags map.
:style is the default style for any text not otherwise wrapped by tags.
Example:
parser = Parser.new(@pdf, "<b class='ruby'>hello</b>", :tags => { :b => { :font_weight => :bold } }, :styles => { :ruby => { :color => "red" } }, :style => { :font_family => "Times-Roman" })
See Format::State for a description of the supported style options.
# File lib/prawn/format/parser.rb, line 53 def initialize(document, text, options={}) @document = document @lexer = Lexer.new(text) @tags = options[:tags] || {} @styles = options[:styles] || {} @state = State.new(document, :style => options[:style]) @lexer.verbatim = (@state.white_space == :pre) @action = :start @saved = [] @tag_stack = [] end
Returns true if the end of the stream has been reached. Subsequent calls to peek or next will return nil.
# File lib/prawn/format/parser.rb, line 103 def eos? peek.nil? end
Returns the next instruction from the stream. If there are no more instructions in the stream (e.g., the end has been encountered), this returns nil.
# File lib/prawn/format/parser.rb, line 75 def next return @saved.pop if @saved.any? case @action when :start then start_parse when :text then text_parse else raise "BUG: unknown parser action: #{@action.inspect}" end end
This is identical to next, except it does not consume the instruction. This means that peek returns the instruction that will be returned by the next call to next. It is useful for testing the next instruction in the stream without advancing the stream.
# File lib/prawn/format/parser.rb, line 95 def peek save = self.next push(save) if save return save end
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