bop-lang 0.3.0

A small, embeddable, dynamically-typed programming language with zero dependencies
Documentation 
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#[cfg(feature = "no_std")]
use alloc::format;

use crate::error::BopError;

const RESERVED_KEYWORDS: &[&str] = &[
    // Core language
    "let", "fn", "return", "if", "else", "while", "for", "in", "repeat", "break", "continue",
    "use", "match", "struct", "enum", "try",
    // Literals
    "true", "false", "none",
    // Future
    "on", "event", "entity", "spawn", "state", "loop", "class", "self", "from",
    // Common-mistake prevention: keywords in neighbouring languages
    // that users might reach for — warn if they try to use one as
    // an identifier so the diagnostic points at the right fix.
    // `import` lives here now that `use` is the actual Bop keyword.
    "import", "catch", "throw", "async", "await", "yield", "const", "var", "pub", "mod", "type",
    // Confusion prevention
    "null",
];

pub fn check(code: &str) -> Option<BopError> {
    for &keyword in RESERVED_KEYWORDS {
        let let_pattern = format!("let {} ", keyword);
        if code.contains(&let_pattern) {
            let line = code
                .lines()
                .enumerate()
                .find(|(_, line)| line.contains(&let_pattern))
                .map(|(i, _)| i as u32 + 1);

            return Some(BopError {
                line,
                column: None,
                message: format!("`{}` is a reserved word in Bop", keyword),
                friendly_hint: Some(format!(
                    "You can't use `{}` as a variable name — try something like `my_{}` instead!",
                    keyword, keyword
                )),
                is_fatal: false,
                is_try_return: false,
            });
        }

        let fn_pattern = format!("fn {}(", keyword);
        let fn_pattern_space = format!("fn {} (", keyword);
        if code.contains(&fn_pattern) || code.contains(&fn_pattern_space) {
            let line = code
                .lines()
                .enumerate()
                .find(|(_, line)| {
                    line.contains(&fn_pattern) || line.contains(&fn_pattern_space)
                })
                .map(|(i, _)| i as u32 + 1);

            return Some(BopError {
                line,
                column: None,
                message: format!("`{}` is a reserved word in Bop", keyword),
                friendly_hint: Some(format!(
                    "You can't name a function `{}` — try something like `do_{}` instead!",
                    keyword, keyword
                )),
                is_fatal: false,
                is_try_return: false,
            });
        }
    }

    None
}