Documentation

This complete Lexer/Lexical Scanner produces over 115+ tokens for a string or a file path entry. The output is a Vector for the user to handle according to their needs. All tokens are included (including whitespace) as that is left to the user to decide how to use the tokens.

If you have any questions, comments, or need help, feel free to add a discussion here:

https://github.com/mjehrhart/lexical_scanner/discussions

To see an example of an output, check out the wiki page:

https://github.com/mjehrhart/lexical_scanner/wiki/Example

Setup

Add this depedency to TOML

[dependencies]
lexical_scanner = "0.1.17"

Basic Usage

The two ways to perform a lexical scan is to pass in file path or pass in a string. Passing in a string is mostly used for testing while passing in a file path is common for every day work. A lexical scanner can produces thousands and thousands of tokens very quickly. For this reason, it is best to use a file path.

use lexical_scanner;

fn main() {
    let path = "/Users/gues/my_file_to_read_into_tokens/temp.txt";
    let token_list = lexical_scanner::lexer(&path); 
}

That is all there is to do! The lexical scanner returns a Vec for the user to handle as needed.

To test with a string, all you need to do is call this

use lexical_scanner;

fn main() {
    let text = "The number 5.0 is > 1;";
    let token_list = lexical_scanner::lexer_as_str(&text); 
}

Below is a simple way to view the tokens for unit testing:

for (i, token) in token_list.iter().enumerate(){
    println!("{}. {:?}", i, token);
}

output -> 
0. Word("The")
1. WhiteSpace
2. Word("number")
3. WhiteSpace
4. Floating("5.0")
5. WhiteSpace
6. Word("is")
7. WhiteSpace
8. Gt
9. WhiteSpace
10. Numeric("1")
11. Semi

Custom keywords

There is a way to add in your own keyword identifiers. Doing so will help manage parsing of the tokens.

use lexical_scanner;

fn main() {
    let text = "The number 5.0 is left and nor right of the up and down 1;";
    let user_keywords = ["up", "down", "left", "right"];
    let token_list = lexical_scanner::lexer_with_user_keywords(&text, user_keywords.to_vec()); 
}

Below is a simple way to view the tokens for unit testing:

for (i, token) in token_list.iter().enumerate(){
    println!("{}. {:?}", i, token);
}

output -> 
0. Word("The")
1. WhiteSpace
2. Word("number")
3. WhiteSpace
4. Floating("5.0")
5. WhiteSpace
6. Word("is")
7. WhiteSpace
8. KW_UserDefined("left")
9. WhiteSpace
10. Word("and")
11. WhiteSpace
12. Word("nor")
13. WhiteSpace
14. KW_UserDefined("right")
15. WhiteSpace
16. Word("of")
17. WhiteSpace
18. Word("the")
19. WhiteSpace
20. KW_UserDefined("up")
21. WhiteSpace
22. Word("and")
23. WhiteSpace
24. KW_UserDefined("down")
25. WhiteSpace
26. Numeric("1")
27. Semi

Supported Tokens

& => And,
&& => AndAnd,
&= => AndEq,
@ => At,
\ => Backslash,
BitCharacterCode7(String),
BitCharacterCode8(String),
/* => BlockCommentStart(String),
*/ => BlockCommentStop(String),
[ => BracketLeft,
] => BracketRight,
b'H' => Byte(String),
b"Hello" => ByteString(String),
^ => Caret,
^ => CaretEq,
\r\n => CarriageReturn,
Character(String),
: => Colon,
, => Comma,
{ => CurlyBraceLeft,
} => CurlyBraceRight,
$ => Dollar,
. => Dot,
.. => DotDot,
... => DotDotDot,
..= => DotDotEq,
" => DoubleQuote,
= => Eq,
== => EqEq,
>= => Ge,
> => Gt,
=> => FatArrow,
//! => InnerBlockDoc(String),
/*! => InnerLineDoc(String),
< => Le,
// => LineComment(String),
<= Lt,
- => Minus,
-= => MinusEq,
| => Or,
|= => OrEq,
|| => OrOr,
/** => OuterBlockDoc(String),
/// => OuterLineDoc(String),
\n => Newline,
! => Not,
!= => NotEq,
Null,
3.14 => Floating(String),
314 => Numeric(String),
( => ParenLeft,
) => ParenRight,
:: => PathSep,
% => Percent,
%= => PercentEq,
+ => Plus,
+= => PlusEq,
# => Pound,
? => Question,
-> => RArrow,
r#"Hello"# => RawString(String),
rb#"Hello"# => RawByteString(String),
; => Semi,
<< => Shl,
<<= => ShlEq,
>> => Shr,
>>= => ShrEq,
' => SingleQuote,
/ => Slash,
/= => SlashEq,
* => Star,
*= => StarEq,
Stopped(String), //for debugging
"Hello" => String(String),
\t => Tab,
Undefined,
_ => Underscore,
' ' => WhiteSpace,
Word(String),
KW_As,
KW_Async,
KW_Await,
KW_Break,
KW_Const,
KW_Contine,
KW_Crate,
KW_Dyn,
KW_Else,
KW_Enum,
KW_Extern,
KW_False,
KW_Fn,
KW_For,
KW_If,
KW_Impl,
KW_In,
KW_Let,
KW_Loop,
KW_Match,
KW_Mod,
KW_Move,
KW_Mut,
KW_Pub,
KW_Ref,
KW_Return,
KW_SELF,
KW_Self,
KW_Static,
KW_Struct,
KW_Super,
KW_Trait,
KW_True,
KW_Type,
KW_Union,
KW_Unsafe,
KW_Use,
KW_UserDefined(String),
KW_Where,
KW_While,

crates.io => https://crates.io/crates/lexical_scanner github.com => https://github.com/mjehrhart/lexical_scanner