fortitude 0.3.0

A Fortran linter, written in Rust and installable with Python
Documentation 
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use crate::ast::FortitudeNode;
use crate::settings::Settings;
use crate::{ASTRule, Rule, Violation};
use tree_sitter::Node;
/// Defines rules to avoid the 'double precision' and 'double complex' types.

// TODO rule to prefer 1.23e4_sp over 1.23e4, and 1.23e4_dp over 1.23d4

fn double_precision_err_msg(dtype: &str) -> Option<String> {
    match dtype {
        "double precision" => Some(String::from(
            "prefer 'real(real64)' to 'double precision' (see 'iso_fortran_env')",
        )),
        "double complex" => Some(String::from(
            "prefer 'complex(real64)' to 'double complex' (see 'iso_fortran_env')",
        )),
        _ => None,
    }
}

pub struct DoublePrecision {}

impl Rule for DoublePrecision {
    fn new(_settings: &Settings) -> Self {
        Self {}
    }

    fn explain(&self) -> &'static str {
        "
        The 'double precision' type does not guarantee a 64-bit floating point number
        as one might expect. It is instead required to be twice the size of a default
        'real', which may vary depending on your system and can be modified by compiler
        arguments. For portability, it is recommended to use `real(dp)`, with `dp` set
        in one of the following ways:

        - `use, intrinsic :: iso_fortran_env, only: dp => real64`
        - `integer, parameter :: dp = selected_real_kind(15, 307)`

        For code that should be compatible with C, you should instead use
        `real(c_double)`, which may be found in the intrinsic module `iso_c_binding`.
        "
    }
}

impl ASTRule for DoublePrecision {
    fn check(&self, node: &Node, src: &str) -> Option<Vec<Violation>> {
        let txt = node.to_text(src)?.to_lowercase();
        if let Some(msg) = double_precision_err_msg(txt.as_str()) {
            return some_vec![Violation::from_node(msg.as_str(), node)];
        }
        None
    }

    fn entrypoints(&self) -> Vec<&'static str> {
        vec!["intrinsic_type"]
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::settings::default_settings;
    use crate::violation;
    use pretty_assertions::assert_eq;
    use textwrap::dedent;

    #[test]
    fn test_double_precision() -> anyhow::Result<()> {
        let source = dedent(
            "
            double precision function double(x)
              double precision, intent(in) :: x
              double = 2 * x
            end function

            subroutine triple(x)
              double precision, intent(inout) :: x
              x = 3 * x
            end subroutine

            function complex_mul(x, y)
              double precision, intent(in) :: x
              double complex, intent(in) :: y
              double complex :: complex_mul
              complex_mul = x * y
            end function
            ",
        );
        let expected: Vec<Violation> = [
            (2, 1, "double precision"),
            (3, 3, "double precision"),
            (8, 3, "double precision"),
            (13, 3, "double precision"),
            (14, 3, "double complex"),
            (15, 3, "double complex"),
        ]
        .iter()
        .map(|(line, col, kind)| {
            let msg = double_precision_err_msg(kind).unwrap();
            violation!(&msg, *line, *col)
        })
        .collect();
        let rule = DoublePrecision::new(&default_settings());
        let actual = rule.apply(source.as_str())?;
        assert_eq!(actual, expected);
        Ok(())
    }
}