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module CodeRay
require 'coderay/helpers/plugin'
# = Scanners
#
# $Id$
#
# This module holds the Scanner class and its subclasses.
# For example, the Ruby scanner is named CodeRay::Scanners::Ruby
# can be found in coderay/scanners/ruby.
#
# Scanner also provides methods and constants for the register
# mechanism and the [] method that returns the Scanner class
# belonging to the given lang.
#
# See PluginHost.
module Scanners
extend PluginHost
plugin_path 'coderay/scanners'
require 'strscan'
# = Scanner
#
# The base class for all Scanners.
#
# It is a subclass of Ruby's great +StringScanner+, which
# makes it easy to access the scanning methods inside.
#
# It is also +Enumerable+, so you can use it like an Array of
# Tokens:
#
# require 'coderay'
#
# c_scanner = CodeRay::Scanners[:c].new "if (*p == '{') nest++;"
#
# for text, kind in c_scanner
# puts text if kind == :operator
# end
#
# # prints: (*==)++;
#
# OK, this is a very simple example :)
# You can also use +map+, +any?+, +find+ and even +sort_by+,
# if you want.
class Scanner < StringScanner
extend Plugin
plugin_host Scanners
# Raised if a Scanner fails while scanning
ScanError = Class.new(Exception)
require 'coderay/helpers/word_list'
# The default options for all scanner classes.
#
# Define @default_options for subclasses.
DEFAULT_OPTIONS = { :stream => false }
class << self
# Returns if the Scanner can be used in streaming mode.
def streamable?
is_a? Streamable
end
end
=begin
## Excluded for speed reasons; protected seems to make methods slow.
# Save the StringScanner methods from being called.
# This would not be useful for highlighting.
strscan_public_methods =
StringScanner.instance_methods -
StringScanner.ancestors[1].instance_methods
protected(*strscan_public_methods)
=end
# Create a new Scanner.
#
# * +code+ is the input String and is handled by the superclass
# StringScanner.
# * +options+ is a Hash with Symbols as keys.
# It is merged with the default options of the class (you can
# overwrite default options here.)
# * +block+ is the callback for streamed highlighting.
#
# If you set :stream to +true+ in the options, the Scanner uses a
# TokenStream with the +block+ as callback to handle the tokens.
#
# Else, a Tokens object is used.
def initialize code, options = {}, &block
@options = self.class::DEFAULT_OPTIONS.merge options
raise "I am only the basic Scanner class. I can't scan "\
"anything. :( Use my subclasses." if self.class == Scanner
# I love this hack. It seems to silence
# all dos/unix/mac newline problems.
super code.gsub(/\r\n?/, "\n")
if @options[:stream]
warn "warning in CodeRay::Scanner.new: :stream is set, "\
"but no block was given" unless block_given?
raise NotStreamableError, self unless kind_of? Streamable
@tokens = TokenStream.new(&block)
else
warn "warning in CodeRay::Scanner.new: Block given, "\
"but :stream is #{@options[:stream]}" if block_given?
@tokens = Tokens.new
end
end
# More mnemonic accessor name for the input string.
alias code string
# Scans the code and returns all tokens in a Tokens object.
def tokenize options = {}
options = @options.merge({}) #options
if @options[:stream] # :stream must have been set already
reset ## what is this for?
scan_tokens @tokens, options
@tokens
else
@cached_tokens ||= scan_tokens @tokens, options
end
end
# You can also see tokenize as a read-only attribute
alias tokens tokenize
# Traverses the tokens.
def each &block
raise ArgumentError,
'Cannot traverse TokenStream.' if @options[:stream]
tokens.each(&block)
end
include Enumerable
# The current line position of the scanner.
#
# Beware, this is implemented inefficiently. It should be used
# for debugging only.
def line
string[0..pos].count("\n") + 1
end
protected
# This is the central method, and commonly the only one a
# subclass implements.
#
# Subclasses must implement this method; it must return +tokens+
# and must only use Tokens#<< for storing scanned tokens!
def scan_tokens tokens, options
raise NotImplementedError,
"#{self.class}#scan_tokens not implemented."
end
# Scanner error with additional status information
def raise_inspect msg, tokens, ambit = 30
raise ScanError, <<-EOE % [
***ERROR in %s: %s
tokens:
%s
current line: %d pos = %d
matched: %p
bol? = %p, eos? = %p
surrounding code:
%p ~~ %p
***ERROR***
EOE
File.basename(caller[0]),
msg,
tokens.last(10).map { |t| t.inspect }.join("\n"),
line, pos,
matched, bol?, eos?,
string[pos-ambit,ambit],
string[pos,ambit],
]
end
end
end
end
# vim:sw=2:ts=2:noet:tw=78
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