module.exports = /**
 * Known issues:
 *
 * - invalid hex string literals will be recognized as a double quoted strings
 *   but 'x' at the beginning of string will not be matched
 *
 * - delimited string literals are not checked for matching end delimiter
 *   (not possible to do with js regexp)
 *
 * - content of token string is colored as a string (i.e. no keyword coloring inside a token string)
 *   also, content of token string is not validated to contain only valid D tokens
 *
 * - special token sequence rule is not strictly following D grammar (anything following #line
 *   up to the end of line is matched as special token sequence)
 */

function(hljs) {

	/**
	 * Language keywords
	 *
	 * @type {Object}
	 */
	var D_KEYWORDS = {
		keyword:
			'abstract alias align asm assert auto body break byte case cast catch class ' +
			'const continue debug default delete deprecated do else enum export extern final ' +
			'finally for foreach foreach_reverse|10 goto if immutable import in inout int ' +
			'interface invariant is lazy macro mixin module new nothrow out override package ' +
			'pragma private protected public pure ref return scope shared static struct ' +
			'super switch synchronized template this throw try typedef typeid typeof union ' +
			'unittest version void volatile while with __FILE__ __LINE__ __gshared|10 ' +
			'__thread __traits __DATE__ __EOF__ __TIME__ __TIMESTAMP__ __VENDOR__ __VERSION__',
		built_in:
			'bool cdouble cent cfloat char creal dchar delegate double dstring float function ' +
			'idouble ifloat ireal long real short string ubyte ucent uint ulong ushort wchar ' +
			'wstring',
		literal:
			'false null true'
	};

	/**
	 * Number literal regexps
	 *
	 * @type {String}
	 */
	var decimal_integer_re = '(0|[1-9][\\d_]*)',
		decimal_integer_nosus_re = '(0|[1-9][\\d_]*|\\d[\\d_]*|[\\d_]+?\\d)',
		binary_integer_re = '0[bB][01_]+',
		hexadecimal_digits_re = '([\\da-fA-F][\\da-fA-F_]*|_[\\da-fA-F][\\da-fA-F_]*)',
		hexadecimal_integer_re = '0[xX]' + hexadecimal_digits_re,

		decimal_exponent_re = '([eE][+-]?' + decimal_integer_nosus_re + ')',
		decimal_float_re = '(' + decimal_integer_nosus_re + '(\\.\\d*|' + decimal_exponent_re + ')|' +
								'\\d+\\.' + decimal_integer_nosus_re + decimal_integer_nosus_re + '|' +
								'\\.' + decimal_integer_re + decimal_exponent_re + '?' +
							')',
		hexadecimal_float_re = '(0[xX](' +
									hexadecimal_digits_re + '\\.' + hexadecimal_digits_re + '|'+
									'\\.?' + hexadecimal_digits_re +
							   ')[pP][+-]?' + decimal_integer_nosus_re + ')',

		integer_re = '(' +
			decimal_integer_re + '|' +
			binary_integer_re  + '|' +
		 	hexadecimal_integer_re   +
		')',

		float_re = '(' +
			hexadecimal_float_re + '|' +
			decimal_float_re  +
		')';

	/**
	 * Escape sequence supported in D string and character literals
	 *
	 * @type {String}
	 */
	var escape_sequence_re = '\\\\(' +
							'[\'"\\?\\\\abfnrtv]|' +	// common escapes
							'u[\\dA-Fa-f]{4}|' + 		// four hex digit unicode codepoint
							'[0-7]{1,3}|' + 			// one to three octal digit ascii char code
							'x[\\dA-Fa-f]{2}|' +		// two hex digit ascii char code
							'U[\\dA-Fa-f]{8}' +			// eight hex digit unicode codepoint
						  ')|' +
						  '&[a-zA-Z\\d]{2,};';			// named character entity


	/**
	 * D integer number literals
	 *
	 * @type {Object}
	 */
	var D_INTEGER_MODE = {
		className: 'number',
    	begin: '\\b' + integer_re + '(L|u|U|Lu|LU|uL|UL)?',
    	relevance: 0
	};

	/**
	 * [D_FLOAT_MODE description]
	 * @type {Object}
	 */
	var D_FLOAT_MODE = {
		className: 'number',
		begin: '\\b(' +
				float_re + '([fF]|L|i|[fF]i|Li)?|' +
				integer_re + '(i|[fF]i|Li)' +
			')',
		relevance: 0
	};

	/**
	 * D character literal
	 *
	 * @type {Object}
	 */
	var D_CHARACTER_MODE = {
		className: 'string',
		begin: '\'(' + escape_sequence_re + '|.)', end: '\'',
		illegal: '.'
	};

	/**
	 * D string escape sequence
	 *
	 * @type {Object}
	 */
	var D_ESCAPE_SEQUENCE = {
		begin: escape_sequence_re,
		relevance: 0
	}

	/**
	 * D double quoted string literal
	 *
	 * @type {Object}
	 */
	var D_STRING_MODE = {
		className: 'string',
		begin: '"',
		contains: [D_ESCAPE_SEQUENCE],
		end: '"[cwd]?'
	};

	/**
	 * D wysiwyg and delimited string literals
	 *
	 * @type {Object}
	 */
	var D_WYSIWYG_DELIMITED_STRING_MODE = {
		className: 'string',
		begin: '[rq]"',
		end: '"[cwd]?',
		relevance: 5
	};

	/**
	 * D alternate wysiwyg string literal
	 *
	 * @type {Object}
	 */
	var D_ALTERNATE_WYSIWYG_STRING_MODE = {
		className: 'string',
		begin: '`',
		end: '`[cwd]?'
	};

	/**
	 * D hexadecimal string literal
	 *
	 * @type {Object}
	 */
	var D_HEX_STRING_MODE = {
		className: 'string',
		begin: 'x"[\\da-fA-F\\s\\n\\r]*"[cwd]?',
		relevance: 10
	};

	/**
	 * D delimited string literal
	 *
	 * @type {Object}
	 */
	var D_TOKEN_STRING_MODE = {
		className: 'string',
		begin: 'q"\\{',
		end: '\\}"'
	};

	/**
	 * Hashbang support
	 *
	 * @type {Object}
	 */
	var D_HASHBANG_MODE = {
		className: 'shebang',
		begin: '^#!',
		end: '$',
		relevance: 5
	};

	/**
	 * D special token sequence
	 *
	 * @type {Object}
	 */
	var D_SPECIAL_TOKEN_SEQUENCE_MODE = {
		className: 'preprocessor',
		begin: '#(line)',
		end: '$',
		relevance: 5
	};

	/**
	 * D attributes
	 *
	 * @type {Object}
	 */
	var D_ATTRIBUTE_MODE = {
		className: 'keyword',
		begin: '@[a-zA-Z_][a-zA-Z_\\d]*'
	};

	/**
	 * D nesting comment
	 *
	 * @type {Object}
	 */
	var D_NESTING_COMMENT_MODE = {
		className: 'comment',
		begin: '\\/\\+',
		contains: ['self'],
		end: '\\+\\/',
		relevance: 10
	}

	return {
		lexemes: hljs.UNDERSCORE_IDENT_RE,
		keywords: D_KEYWORDS,
		contains: [
			hljs.C_LINE_COMMENT_MODE,
  			hljs.C_BLOCK_COMMENT_MODE,
  			D_NESTING_COMMENT_MODE,
  			D_HEX_STRING_MODE,
  			D_STRING_MODE,
  			D_WYSIWYG_DELIMITED_STRING_MODE,
  			D_ALTERNATE_WYSIWYG_STRING_MODE,
  			D_TOKEN_STRING_MODE,
  			D_FLOAT_MODE,
  			D_INTEGER_MODE,
  			D_CHARACTER_MODE,
  			D_HASHBANG_MODE,
  			D_SPECIAL_TOKEN_SEQUENCE_MODE,
  			D_ATTRIBUTE_MODE
		]
	};
};