crates/ide_assists/src/handlers/convert_while_to_loop.rs

   1 use std::iter::once;
   2
   3 use ide_db::helpers::node_ext::is_pattern_cond;
   4 use syntax::{
   5     ast::{
   6         self,
   7         edit::{AstNodeEdit, IndentLevel},
   8         make, HasLoopBody,
   9     },
  10     AstNode, T,
  11 };
  12
  13 use crate::{
  14     assist_context::{AssistContext, Assists},
  15     utils::invert_boolean_expression,
  16     AssistId, AssistKind,
  17 };
  18
  19 // Assist: convert_while_to_loop
  20 //
  21 // Replace a while with a loop.
  22 //
  23 // ```
  24 // fn main() {
  25 //     $0while cond {
  26 //         foo();
  27 //     }
  28 // }
  29 // ```
  30 // ->
  31 // ```
  32 // fn main() {
  33 //     loop {
  34 //         if !cond {
  35 //             break;
  36 //         }
  37 //         foo();
  38 //     }
  39 // }
  40 // ```
  41 pub(crate) fn convert_while_to_loop(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
  42     let while_kw = ctx.find_token_syntax_at_offset(T![while])?;
  43     let while_expr = while_kw.parent().and_then(ast::WhileExpr::cast)?;
  44     let while_body = while_expr.loop_body()?;
  45     let while_cond = while_expr.condition()?;
  46
  47     let target = while_expr.syntax().text_range();
  48     acc.add(
  49         AssistId("convert_while_to_loop", AssistKind::RefactorRewrite),
  50         "Convert while to loop",
  51         target,
  52         |edit| {
  53             let while_indent_level = IndentLevel::from_node(while_expr.syntax());
  54
  55             let break_block =
  56                 make::block_expr(once(make::expr_stmt(make::expr_break(None)).into()), None)
  57                     .indent(while_indent_level);
  58             let block_expr = if is_pattern_cond(while_cond.clone()) {
  59                 let if_expr = make::expr_if(while_cond, while_body, Some(break_block.into()));
  60                 let stmts = once(make::expr_stmt(if_expr).into());
  61                 make::block_expr(stmts, None)
  62             } else {
  63                 let if_cond = invert_boolean_expression(while_cond);
  64                 let if_expr = make::expr_if(if_cond, break_block, None);
  65                 let stmts = once(make::expr_stmt(if_expr).into()).chain(while_body.statements());
  66                 make::block_expr(stmts, while_body.tail_expr())
  67             };
  68
  69             let replacement = make::expr_loop(block_expr.indent(while_indent_level));
  70             edit.replace(target, replacement.syntax().text())
  71         },
  72     )
  73 }
  74
  75 #[cfg(test)]
  76 mod tests {
  77     use crate::tests::{check_assist, check_assist_not_applicable};
  78
  79     use super::*;
  80
  81     #[test]
  82     fn convert_inside_fn() {
  83         check_assist(
  84             convert_while_to_loop,
  85             r#"
  86 fn main() {
  87     while$0 cond {
  88         foo();
  89     }
  90 }
  91 "#,
  92             r#"
  93 fn main() {
  94     loop {
  95         if !cond {
  96             break;
  97         }
  98         foo();
  99     }
 100 }
 101 "#,
 102         );
 103     }
 104
 105     #[test]
 106     fn convert_busy_wait() {
 107         check_assist(
 108             convert_while_to_loop,
 109             r#"
 110 fn main() {
 111     while$0 cond() {}
 112 }
 113 "#,
 114             r#"
 115 fn main() {
 116     loop {
 117         if !cond() {
 118             break;
 119         }
 120     }
 121 }
 122 "#,
 123         );
 124     }
 125
 126     #[test]
 127     fn convert_trailing_expr() {
 128         check_assist(
 129             convert_while_to_loop,
 130             r#"
 131 fn main() {
 132     while$0 cond() {
 133         bar()
 134     }
 135 }
 136 "#,
 137             r#"
 138 fn main() {
 139     loop {
 140         if !cond() {
 141             break;
 142         }
 143         bar()
 144     }
 145 }
 146 "#,
 147         );
 148     }
 149
 150     #[test]
 151     fn convert_while_let() {
 152         check_assist(
 153             convert_while_to_loop,
 154             r#"
 155 fn main() {
 156     while$0 let Some(_) = foo() {
 157         bar();
 158     }
 159 }
 160 "#,
 161             r#"
 162 fn main() {
 163     loop {
 164         if let Some(_) = foo() {
 165             bar();
 166         } else {
 167             break;
 168         }
 169     }
 170 }
 171 "#,
 172         );
 173     }
 174
 175     #[test]
 176     fn ignore_cursor_in_body() {
 177         check_assist_not_applicable(
 178             convert_while_to_loop,
 179             r#"
 180 fn main() {
 181     while cond {$0
 182         bar();
 183     }
 184 }
 185 "#,
 186         );
 187     }
 188 }