path: root/lib/coderay.rb

# = CodeRay Library
#
# $Id$
#
# CodeRay is a Ruby library for syntax highlighting.
#
# I try to make CodeRay easy to use and intuitive, but at the same time fully featured, complete,
# fast and efficient.
# 
# See README.
# 
# It consists mainly of
# * the main engine: CodeRay (Scanners::Scanner, Tokens/TokenStream, Encoders::Encoder), PluginHost
# * the scanners in CodeRay::Scanners
# * the encoders in CodeRay::Encoders
# 
# Here's a fancy graphic to light up this gray docu:
# 
# http://rd.cYcnus.de/coderay/scheme.png
# 
# == Documentation
#
# See CodeRay, Encoders, Scanners, Tokens.
#
# == Usage
#
# Remember you need RubyGems to use CodeRay. Run Ruby with -rubygems option
# if required.
#
# === Highlight Ruby code in a string as html
# 
#   require 'coderay'
#   print CodeRay.scan('puts "Hello, world!"', :ruby).html
#
#   # prints something like this:
#   puts <span class="s">&quot;Hello, world!&quot;</span>
# 
# 
# === Highlight C code from a file in a html div
# 
#   require 'coderay'
#   print CodeRay.scan(File.read('ruby.h'), :c).div
#   print CodeRay.scan_file('ruby.h').html.div
# 
# You can include this div in your page. The used CSS styles can be printed with
# 
#   % ruby -rcoderay -e "print CodeRay::Encoders[:html]::CSS"
# 
# === Highlight without typing too much
#
# If you are one of the hasty (or lazy, or extremely curious) people, just run this file:
#
#   % ruby -rubygems coderay.rb
# 
# If the output was to fast for you, try
# 
#   % ruby -rubygems coderay.rb > example.html
#
# and look at the file it created.
# 
# = CodeRay Module
#
# The CodeRay module provides convenience methods for the engine.
#
# * The +lang+ and +format+ arguments select Scanner and Encoder to use. These are
#   simply lower-case symbols, like <tt>:python</tt> or <tt>:html</tt>.
# * All methods take an optional hash as last parameter, +options+, that is send to
#   the Encoder / Scanner.
# * Input and language are always sorted in this order: +code+, +lang+.
# 	(This is in alphabetical order, if you need a mnemonic ;)
# 
# You should be able to highlight everything you want just using these methods;
# so there is no need to dive into CodeRay's deep class hierarchy.
#
# The examples in the demo directory demonstrate common cases using this interface.
#	
# = Basic Access Ways
#
# Read this to get a general view what CodeRay provides.
# 
# == Scanning
#	
#	Scanning means analysing an input string, splitting it up into Tokens.
#	Each Token knows about what type it is: string, comment, class name, etc.
#
#	Each +lang+ (language) has its own Scanner; for example, <tt>:ruby</tt> code is
#	handled by CodeRay::Scanners::Ruby.
# 
# CodeRay.scan:: Scan a string in a given language into Tokens.
#                This is the most common method to use.
# CodeRay.scan_file:: Scan a file and guess the language using FileType.
# 
# The Tokens object you get from these methods can encode itself; see Tokens.
# 
# == Encoding
#
# Encoding means compiling Tokens into an output. This can be colored HTML or
# LaTeX, a textual statistic or just the number of non-whitespace tokens.
# 
# Each Encoder provides output in a specific +format+, so you select Encoders via
# formats like <tt>:html</tt> or <tt>:statistic</tt>.
# 
# CodeRay.encode:: Scan and encode a string in a given language.
# CodeRay.encode_tokens:: Encode the given tokens.
# CodeRay.encode_file:: Scan a file, guess the language using FileType and encode it.
#
# == Streaming
#
# Streaming saves RAM by running Scanner and Encoder in some sort of
# pipe mode; see TokenStream.
# 
# CodeRay.scan_stream:: Scan in stream mode.
# 
#	== All-in-One Encoding
#
# CodeRay.encode:: Highlight a string with a given input and output format.
#
# == Instanciating
#	
#	You can use an Encoder instance to highlight multiple inputs. This way, the setup
#	for this Encoder must only be done once.
#	
# CodeRay.encoder:: Create an Encoder instance with format and options.
#
# There is no CodeRay.scanner method because Scanners are bound to an input string
# on creation; you can't re-use them with another string.
#
#	The scanning methods provide more flexibility; we recommend to use these.
module CodeRay
	
	# Version: Major.Minor.Teeny[.Revision]
	# Major: 0 for pre-release
	# Minor: odd for beta, even for stable
	# Teeny: development state
	# Revision: Subversion Revision number (generated on rake)
	Version = '0.7'
	
	require 'coderay/tokens'
	require 'coderay/scanner'
	require 'coderay/encoder'
	require 'coderay/duo'
	require 'coderay/style'


	class << self

		# Scans the given +code+ (a String) with the Scanner for +lang+.
		# 
		# This is a simple way to use CodeRay. Example:
		#  require 'coderay'
		#  page = CodeRay.scan("puts 'Hello, world!'", :ruby).html
		#
		# See also demo/demo_simple.
		def scan code, lang, options = {}, &block
			scanner = Scanners[lang].new code, options, &block
			scanner.tokenize
		end

		# Scans +filename+ (a path to a code file) with the Scanner for +lang+.
		# 
		# If +lang+ is :auto or omitted, the CodeRay::FileType module is used to
		# determine it. If it cannot find out what type it is, it uses
		# CodeRay::Scanners::Plaintext.
		#
		# Calls CodeRay.scan.
		# 
		# Example:
		#  require 'coderay'
		#  page = CodeRay.scan_file('some_c_code.c').html
		def scan_file filename, lang = :auto, options = {}, &block
			file = IO.read filename
			if lang == :auto
				require 'coderay/helpers/filetype'
				lang = FileType.fetch filename, :plaintext, true
			end
			scan file, lang, options = {}, &block
		end

		# Scan the +code+ (a string) with the scanner for +lang+.
		# 
		# Calls scan.
		# 
		# See CodeRay.scan.
		def scan_stream code, lang, options = {}, &block
			options[:stream] = true
			scan code, lang, options, &block
		end

		# Encode a string in Streaming mode.
		# 
		# This starts scanning +code+ with the the Scanner for +lang+ 
		# while encodes the output with the Encoder for +format+.
		# +options+ will be passed to the Encoder.
		#
		# See CodeRay::Encoder.encode_stream
		def encode_stream code, lang, format, options = {}
			encoder(format, options).encode_stream code, lang, options
		end

		# Encode a string.
		# 
		# This scans +code+ with the the Scanner for +lang+ and then
		# encodes it with the Encoder for +format+.
		# +options+ will be passed to the Encoder.
		#
		# See CodeRay::Encoder.encode
		def encode code, lang, format, options = {}
			encoder(format, options).encode code, lang, options
		end
		
		# Highlight a string into a HTML <div>.
		#
		# CSS styles use classes, so you have to include a stylesheet
		# in your output.
		# 
		# See encode.
		def highlight code, lang, options = { :css => :class }, format = :div
			encode code, lang, format, options
		end
		
		# Encode pre-scanned Tokens.
		# Use this together with CodeRay.scan:
		# 
		#  require 'coderay'
		#  
		#  # Highlight a short Ruby code example in a HTML span
		#  tokens = CodeRay.scan '1 + 2', :ruby
		#  puts CodeRay.encode_tokens(tokens, :span)
		#
		def encode_tokens tokens, format, options = {}
			encoder(format, options).encode_tokens tokens, options
		end

		# Encodes +filename+ (a path to a code file) with the Scanner for +lang+.
		# 
		# See CodeRay.scan_file.
		# Notice that the second argument is the output +format+, not the input language.
		# 
		# Example:
		#  require 'coderay'
		#  page = CodeRay.encode_file 'some_c_code.c', :html
		def encode_file filename, format, options = {}
			tokens = scan_file filename, :auto, get_scanner_options(options)
			encode_tokens tokens, format, options
		end

		# Highlight a file into a HTML <div>.
		#
		# CSS styles use classes, so you have to include a stylesheet
		# in your output.
		# 
		# See encode.
		def highlight_file filename, options = { :css => :class }, format = :div
			encode_file filename, format, options
		end
		
		# Finds the Encoder class for +format+ and creates an instance, passing
		# +options+ to it.
		# 
		# Example:
		#  require 'coderay'
		#  
		#  stats = CodeRay.encoder(:statistic)
		#  stats.encode("puts 17 + 4\n", :ruby)
		#  
		#  puts '%d out of %d tokens have the kind :integer.' % [
		#  	stats.type_stats[:integer].count,
		#  	stats.real_token_count
		#  ]
		#  #-> 2 out of 4 tokens have the kind :integer.
		def encoder format, options = {}
			Encoders[format].new options
		end

		# Finds the Scanner class for +lang+ and creates an instance, passing
		# +options+ to it.
		#
		# See Scanner.new.
		def scanner lang, options = {}
			Scanners[lang].new '', options
		end

		# Extract the options for the scanner from the +options+ hash.
		#
		#	Returns an empty Hash if <tt>:scanner_options</tt> is not set.
		#	
		# This is used if a method like CodeRay.encode has to provide options
		# for Encoder _and_ scanner.
		def get_scanner_options options
			options.fetch :scanner_options, {}
		end

	end

	# This Exception is raised when you try to stream with something that is not
	# capable of streaming.
	class NotStreamableError < Exception
		def initialize obj
			@obj = obj
		end

		def to_s
			'%s is not Streamable!' % @obj.class
		end
	end
	
	# A dummy module that is included by subclasses of CodeRay::Scanner an CodeRay::Encoder
	# to show that they are able to handle streams.
	module Streamable
	end
	
end

# Run a test script.
if $0 == __FILE__
	$stderr.print 'Press key to print demo.'; gets
	code = File.read($0)[/module CodeRay.*/m]
	print CodeRay.scan(code, :ruby).html
end