2.1. Lexical Structure
2.1.1. Identifiers
Identifiers start with an alphabetic character or the symbol ‘_’ followed by any number of alphabetic characters, ‘_’ or digits ([0-9]). Squirrel 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.
2.1.2. 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__ |
rawcall |
Keywords are covered in detail later in this document.
2.1.3. Operators
Squirrel recognizes the following operators:
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2.1.4. Other tokens
Other significant tokens are:
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2.1.5. Literals
Squirrel accepts integer numbers, floating point numbers and string literals.
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Integer number(base 10) |
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Integer number(base 16) |
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Integer number(base 8) |
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Integer number |
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Floating point number |
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Floating point number |
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Floating point number |
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String |
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String |
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String |
Pesudo BNF
IntegerLiteral ::= [1-9][0-9]* | '0x' [0-9A-Fa-f]+ | ''' [.]+ ''' | 0[0-7]+ FloatLiteral ::= [0-9]+ '.' [0-9]+ FloatLiteral ::= [0-9]+ '.' 'e'|'E' '+'|'-' [0-9]+ StringLiteral ::= '"'[.]* '"' VerbatimStringLiteral ::= '@''"'[.]* '"'
2.1.6. 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.: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.”:The character
#
is an alternative syntax for single line comment.:# this is also a single line comment.
This to facilitate the use of squirrel in UNIX-style shell scripts.