3.1. Lexical Structure

3.1.1. Identifiers

Identifiers start with an alphabetic character or the symbol ‘_’ followed by any number of alphabetic characters, ‘_’ or digits ([0-9]). Quirrel is a case sensitive language meaning that the lowercase and uppercase representation of the same alphabetic character are considered different characters. For instance, “foo”, “Foo” and “fOo” are treated as 3 distinct identifiers.

3.1.2. Keywords

The following words are reserved and cannot be used as identifiers:

base

break

case

catch

class

clone

continue

const

default

delete

else

enum

extends

for

foreach

function

if

in

local

null

resume

return

switch

this

throw

try

typeof

while

yield

constructor

instanceof

true

false

static

__LINE__

__FILE__

Keywords are covered in detail later in this document.

3.1.3. Operators

Quirrel recognizes the following operators:

!

!=

||

==

&&

>=

<=

>

<=>

+

+=

-

-=

/

/=

*

*=

%

%=

++

--

<-

=

&

^

|

~

>>

<<

>>>

??

3.1.4. Other tokens

Other significant tokens are:

{

}

[

]

.

:

::

'

;

"

@"

3.1.5. Literals

Quirrel accepts integer numbers, floating point numbers and string literals.

34

Integer number(base 10)

0xFF00A120

Integer number(base 16)

0753

Integer number(base 8)

'a'

Integer number

1.52

Floating point number

1.e2

Floating point number

1.e-2

Floating point number

"I'm a string"

String

@"I'm a verbatim string"

String

@" I'm a multiline verbatim string "

String

Pesudo BNF

IntegerLiteral        ::=  [1-9][0-9]* | '0x' [0-9A-Fa-f]+ | ''' [.]+ ''' | 0[0-7]+
FloatLiteral          ::=  [0-9]+ '.' [0-9]+
FloatLiteralExp       ::=  [0-9]+ '.' 'e'|'E' '+'|'-' [0-9]+
StringLiteral         ::=  '"'[.]* '"'
VerbatimStringLiteral ::=  '@''"'[.]* '"'

3.1.6. Comments

A comment is text that the compiler ignores but that is useful for programmers. Comments are normally used to embed annotations in the code. The compiler treats them as white space.

A comment can be /* (slash, asterisk) characters, followed by any sequence of characters (including new lines), followed by the */ characters. This syntax is the same as ANSI C.:

/*
this is
a multiline comment.
this lines will be ignored by the compiler
*/

A comment can also be // (two slashes) characters, followed by any sequence of characters. A new line not immediately preceded by a backslash terminates this form of comment. It is commonly called a “single-line comment.”:

//this is a single line comment. this line will be ignored by the compiler