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|
use syntax::ast::{self, AstNode};
use crate::{utils::invert_boolean_expression, AssistContext, AssistId, AssistKind, Assists};
// Assist: apply_demorgan
//
// Apply https://en.wikipedia.org/wiki/De_Morgan%27s_laws[De Morgan's law].
// This transforms expressions of the form `!l || !r` into `!(l && r)`.
// This also works with `&&`. This assist can only be applied with the cursor
// on either `||` or `&&`.
//
// ```
// fn main() {
// if x != 4 ||$0 y < 3.14 {}
// }
// ```
// ->
// ```
// fn main() {
// if !(x == 4 && !(y < 3.14)) {}
// }
// ```
pub(crate) fn apply_demorgan(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
let expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
let op = expr.op_kind()?;
let op_range = expr.op_token()?.text_range();
let opposite_op = opposite_logic_op(op)?;
let cursor_in_range = op_range.contains_range(ctx.frange.range);
if !cursor_in_range {
return None;
}
let lhs = expr.lhs()?;
let lhs_range = lhs.syntax().text_range();
let not_lhs = invert_boolean_expression(&ctx.sema, lhs);
let rhs = expr.rhs()?;
let rhs_range = rhs.syntax().text_range();
let not_rhs = invert_boolean_expression(&ctx.sema, rhs);
acc.add(
AssistId("apply_demorgan", AssistKind::RefactorRewrite),
"Apply De Morgan's law",
op_range,
|edit| {
edit.replace(op_range, opposite_op);
edit.replace(lhs_range, format!("!({}", not_lhs.syntax().text()));
edit.replace(rhs_range, format!("{})", not_rhs.syntax().text()));
},
)
}
// Return the opposite text for a given logical operator, if it makes sense
fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
match kind {
ast::BinOp::BooleanOr => Some("&&"),
ast::BinOp::BooleanAnd => Some("||"),
_ => None,
}
}
#[cfg(test)]
mod tests {
use ide_db::helpers::FamousDefs;
use super::*;
use crate::tests::{check_assist, check_assist_not_applicable};
const ORDABLE_FIXTURE: &'static str = r"
//- /lib.rs deps:core crate:ordable
struct NonOrderable;
struct Orderable;
impl core::cmp::Ord for Orderable {}
";
fn check(ra_fixture_before: &str, ra_fixture_after: &str) {
let before = &format!(
"//- /main.rs crate:main deps:core,ordable\n{}\n{}{}",
ra_fixture_before,
FamousDefs::FIXTURE,
ORDABLE_FIXTURE
);
check_assist(apply_demorgan, before, &format!("{}\n", ra_fixture_after));
}
#[test]
fn demorgan_handles_leq() {
check(
r"use ordable::Orderable;
fn f() {
Orderable < Orderable &&$0 Orderable <= Orderable
}",
r"use ordable::Orderable;
fn f() {
!(Orderable >= Orderable || Orderable > Orderable)
}",
);
check(
r"use ordable::NonOrderable;
fn f() {
NonOrderable < NonOrderable &&$0 NonOrderable <= NonOrderable
}",
r"use ordable::NonOrderable;
fn f() {
!(!(NonOrderable < NonOrderable) || !(NonOrderable <= NonOrderable))
}",
);
}
#[test]
fn demorgan_handles_geq() {
check(
r"use ordable::Orderable;
fn f() {
Orderable > Orderable &&$0 Orderable >= Orderable
}",
r"use ordable::Orderable;
fn f() {
!(Orderable <= Orderable || Orderable < Orderable)
}",
);
check(
r"use ordable::NonOrderable;
fn f() {
Orderable > Orderable &&$0 Orderable >= Orderable
}",
r"use ordable::NonOrderable;
fn f() {
!(!(Orderable > Orderable) || !(Orderable >= Orderable))
}",
);
}
#[test]
fn demorgan_turns_and_into_or() {
check_assist(apply_demorgan, "fn f() { !x &&$0 !x }", "fn f() { !(x || x) }")
}
#[test]
fn demorgan_turns_or_into_and() {
check_assist(apply_demorgan, "fn f() { !x ||$0 !x }", "fn f() { !(x && x) }")
}
#[test]
fn demorgan_removes_inequality() {
check_assist(apply_demorgan, "fn f() { x != x ||$0 !x }", "fn f() { !(x == x && x) }")
}
#[test]
fn demorgan_general_case() {
check_assist(apply_demorgan, "fn f() { x ||$0 x }", "fn f() { !(!x && !x) }")
}
#[test]
fn demorgan_doesnt_apply_with_cursor_not_on_op() {
check_assist_not_applicable(apply_demorgan, "fn f() { $0 !x || !x }")
}
}
|
