Class: Ovec::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/ovec/parser.rb

Overview

TODO: verbatimy; TeX prikazy obsahujici kusy k ovlnkovani

Constant Summary collapse

NORMAL_REGEX = 
/\A([^\\$%])+/
COMMAND_REGEX =

A command: (letters) or (a single nonletter)

/\A\\([a-z@A-Z0-9]+|[^a-zA-Z])/
COMMENT_REGEX = 
/\A%.*$/
TEXT_COMMANDS = 
%w(textit textbf textsc title author)
NONTEXT_CONTENT_COMMANDS =

TODO: seznam prikazu, ve kterych se nevlnkuje

%w(
VERBATIM_COMMANDS =

TODO: treba begin, end, …

%w(verbatim verb)

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(debug: false) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/ovec/parser.rb', line 43

def initialize(debug: false)
	@debug = debug
end

Class Method Details

.delimiter_right_side(left) ⇒ Object 



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# File 'lib/ovec/parser.rb', line 47

def self.delimiter_right_side(left)
	{
		'{' => '}', '[' => ']', '(' => ')', '<' => '>'
	}[left] || left
end

Instance Method Details

#eat_node(code, index) ⇒ Object

Raises:



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# File 'lib/ovec/parser.rb', line 53

def eat_node(code, index)
	to_eat = code[index...code.length]

	if to_eat.empty?
		raise ParseError, "Parsing an empty string"
	end

	# Cut off comments
	match = COMMENT_REGEX.match(to_eat)
	unless match.nil?
		match = match[0]
		node = CommentNode.new(match)

		debug "Eaten #{match.length} chars of comments."
		return node, match.length
	end

	# Cut off normal text
	match = NORMAL_REGEX.match(to_eat)
	unless match.nil?
		match = match[0]
		node = TextNode.new(match)

		debug "Eaten #{match.length} chars of normal text."
		return node, match.length
	end

	# Parse a command. If the command looks like a text-command, try to eat everything between { and }.
	match = COMMAND_REGEX.match(to_eat)
	unless match.nil?
		command = match[1]
		match_len = match[0].length
		debug "Eating command #{command}."

		if TEXT_COMMANDS.include?(command) || NONTEXT_CONTENT_COMMANDS.include?(command)
			if to_eat.length > match_len && to_eat[match_len] == '{'
				debug "Looks like a text command, trying to parse recursively."
				begin
					other_side = find_other_side(to_eat, match_len, '{', '}')

					content = parse(code[index + match_len + 1...index + other_side])
					# TODO: rename textcommands to something better: command with params?
					node = TextCommandsNode.new(command, content, text: TEXT_COMMANDS.include?(command))

					debug "Eaten #{other_side + 1} chars of text command."
					return node, (other_side + 1)
				rescue ParseError
					debug "Parse error encountered. Giving up on this node."
				end
			end
		end

		if VERBATIM_COMMANDS.include?(command)
			if to_eat.length <= match_len
				raise ParseError, "Verbatim at EOF with no delimiter."
			end

			left_delimiter = to_eat[match_len]
			right_delimiter = self.class.delimiter_right_side(left_delimiter)

			# TODO: nesting in verbatims ???
			other_side = find_other_side(to_eat, match_len, left_delimiter, right_delimiter)

			content = to_eat[match_len + 1...other_side]

			node = VerbatimNode.new(command, left_delimiter, content)

			debug "Eaten #{other_side + 1} chars of verbatim."
			return node, (other_side + 1)
		end

		node = CommandsNode.new(command)
		
		debug "Eaten #{match_len} chars of commands."
		return node, match_len
	end

	if to_eat.length > 1 && to_eat[0..1] == "$$"
		# Lookaround assertion to handle escaped dollars in math.
		ending = to_eat[2...to_eat.length].index(/(?<!\\)\$\$/)
		
		if ending.nil?
			raise ParseError, "Unterminated $$ starting at #{index}"
		end

		node = MathNode.new(MathNode::DISPLAY, to_eat[2...ending+2])
		eaten = ending + 4
		debug "Eaten #{eaten} chars of inline math."
		return node, eaten
	end

	if to_eat[0] == '$'
		# Lookaround assertion to handle escaped dollars in math.
		ending = to_eat[1...to_eat.length].index(/(?<!\\)\$/)

		if ending.nil?
			raise ParseError, "Unterminated $ starting at #{index}"
		end

		node = MathNode.new(MathNode::INLINE, to_eat[1...ending+1])
		eaten = ending + 2
		debug "Eaten #{eaten} chars of inline math."
		return node, eaten
	end

	raise ParseError, "Don't know how to parse '#{to_eat}'."
end

#parse(code) ⇒ Object 



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# File 'lib/ovec/parser.rb', line 161

def parse(code)
	result = CombinedNode.new

	index = 0
	while index < code.length
		node, shift = eat_node(code, index)
		index += shift

		result << node
	end

	return result
end