Shebang
A shebang is an optional line that is typically used in Unix-like systems to specify an interpreter for executing the file.
Example
#!/usr/bin/env rustx fn main() { println!("Hello!"); }
Lexer
SHEBANG →
#! !( ( WHITESPACE | LINE_COMMENT | BLOCK_COMMENT )* [ )
~LF* ( LF | EOF )
Tests with this rule:
The shebang starts with the characters #! and extends through the first U+000A (LF) or through EOF if no LF is present. If the #! characters are followed by [ (ignoring any intervening comments or whitespace), the line is not considered a shebang (to avoid ambiguity with an inner attribute).
The shebang may appear immediately at the start of the file or after the optional byte order mark.