pub(crate) fn extract_variable(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
    if ctx.frange.range.is_empty() {
        return None;
    }
    let node = ctx.covering_element();
    if node.kind() == COMMENT {
        cov_mark::hit!(extract_var_in_comment_is_not_applicable);
        return None;
    }
    let to_extract = node.ancestors().find_map(valid_target_expr)?;
    let anchor = Anchor::from(&to_extract)?;
    let indent = anchor.syntax().prev_sibling_or_token()?.as_token()?.clone();
    let target = to_extract.syntax().text_range();
    acc.add(
        AssistId("extract_variable", AssistKind::RefactorExtract),
        "Extract into variable",
        target,
        move |edit| {
            let field_shorthand =
                match to_extract.syntax().parent().and_then(ast::RecordExprField::cast) {
                    Some(field) => field.name_ref(),
                    None => None,
                };

            let mut buf = String::new();

            let var_name = match &field_shorthand {
                Some(it) => it.to_string(),
                None => suggest_name::variable(&to_extract, &ctx.sema),
            };
            let expr_range = match &field_shorthand {
                Some(it) => it.syntax().text_range().cover(to_extract.syntax().text_range()),
                None => to_extract.syntax().text_range(),
            };

            if let Anchor::WrapInBlock(_) = anchor {
                format_to!(buf, "{{ let {} = ", var_name);
            } else {
                format_to!(buf, "let {} = ", var_name);
            };
            format_to!(buf, "{}", to_extract.syntax());

            if let Anchor::Replace(stmt) = anchor {
                cov_mark::hit!(test_extract_var_expr_stmt);
                if stmt.semicolon_token().is_none() {
                    buf.push_str(";");
                }
                match ctx.config.snippet_cap {
                    Some(cap) => {
                        let snip = buf
                            .replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
                        edit.replace_snippet(cap, expr_range, snip)
                    }
                    None => edit.replace(expr_range, buf),
                }
                return;
            }

            buf.push_str(";");

            // We want to maintain the indent level,
            // but we do not want to duplicate possible
            // extra newlines in the indent block
            let text = indent.text();
            if text.starts_with('\n') {
                buf.push('\n');
                buf.push_str(text.trim_start_matches('\n'));
            } else {
                buf.push_str(text);
            }

            edit.replace(expr_range, var_name.clone());
            let offset = anchor.syntax().text_range().start();
            match ctx.config.snippet_cap {
                Some(cap) => {
                    let snip =
                        buf.replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
                    edit.insert_snippet(cap, offset, snip)
                }
                None => edit.insert(offset, buf),
            }

            if let Anchor::WrapInBlock(_) = anchor {
                edit.insert(anchor.syntax().text_range().end(), " }");
            }
        },
    )
}
// Assist: extract_variable
//
// Extracts subexpression into a variable.
//
// ```
// fn main() {
//     $0(1 + 2)$0 * 4;
// }
// ```
// ->
// ```
// fn main() {
//     let $0var_name = (1 + 2);
//     var_name * 4;
// }
// ```
extract_variable
Extracts subexpression into a variable.


extract_variable Extracts subexpression into a variable .
pub(crate) fn extract_variable(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
    if ctx.frange.range.is_empty() {
        return None;
    }
    let node = ctx.covering_element();
    if node.kind() == COMMENT {
        cov_mark::hit!(extract_var_in_comment_is_not_applicable);
        return None;
    }
    let to_extract = node.ancestors().find_map(valid_target_expr)?;
    let anchor = Anchor::from(&to_extract)?;
    let indent = anchor.syntax().prev_sibling_or_token()?.as_token()?.clone();
    let target = to_extract.syntax().text_range();
    acc.add(
        AssistId("extract_variable", AssistKind::RefactorExtract),
        "Extract into variable",
        target,
        move |edit| {
            let field_shorthand =
                match to_extract.syntax().parent().and_then(ast::RecordExprField::cast) {
                    Some(field) => field.name_ref(),
                    None => None,
                };
            let mut buf = String::new();
            let var_name = match &field_shorthand {
                Some(it) => it.to_string(),
                None => suggest_name::variable(&to_extract, &ctx.sema),
            };
            let expr_range = match &field_shorthand {
                Some(it) => it.syntax().text_range().cover(to_extract.syntax().text_range()),
                None => to_extract.syntax().text_range(),
            };
            if let Anchor::WrapInBlock(_) = anchor {
                format_to!(buf, "{{ let {} = ", var_name);
            } else {
                format_to!(buf, "let {} = ", var_name);
            };
            format_to!(buf, "{}", to_extract.syntax());
            if let Anchor::Replace(stmt) = anchor {
                cov_mark::hit!(test_extract_var_expr_stmt);
                if stmt.semicolon_token().is_none() {
                    buf.push_str(";");
                }
                match ctx.config.snippet_cap {
                    Some(cap) => {
                        let snip = buf
                            .replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
                        edit.replace_snippet(cap, expr_range, snip)
                    }
                    None => edit.replace(expr_range, buf),
                }
                return;
            }
            buf.push_str(";");
            // We want to maintain the indent level,
            // but we do not want to duplicate possible
            // extra newlines in the indent block
            let text = indent.text();
            if text.starts_with('\n') {
                buf.push('\n');
                buf.push_str(text.trim_start_matches('\n'));
            } else {
                buf.push_str(text);
            }
            edit.replace(expr_range, var_name.clone());
            let offset = anchor.syntax().text_range().start();
            match ctx.config.snippet_cap {
                Some(cap) => {
                    let snip =
                        buf.replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
                    edit.insert_snippet(cap, offset, snip)
                }
                None => edit.insert(offset, buf),
            }
            if let Anchor::WrapInBlock(_) = anchor {
                edit.insert(anchor.syntax().text_range().end(), " }");
            }
        },
    )
}
pub ( crate ) fn extract_variable ( acc : & mut Assists , ctx : & AssistContext ) -> Option < ( ) > { if ctx . frange . range . is_empty ( ) { return None ; } let node = ctx . covering_element ( ) ; if node . kind ( ) == COMMENT { cov_mark :: hit ! ( extract_var_in_comment_is_not_applicable ) ; return None ; } let to_extract = node . ancestors ( ) . find_map ( valid_target_expr ) ? ; let anchor = Anchor :: from ( & to_extract ) ? ; let indent = anchor . syntax ( ) . prev_sibling_or_token ( ) ? . as_token ( ) ? . clone ( ) ; let target = to_extract . syntax ( ) . text_range ( ) ; acc . add ( AssistId ( " " , AssistKind :: RefactorExtract ) , " " , target , move | edit | { let field_shorthand = match to_extract . syntax ( ) . parent ( ) . and_then ( ast :: RecordExprField :: cast ) { Some ( field ) => field . name_ref ( ) , None => None , } ; let mut buf = String :: new ( ) ; let var_name = match & field_shorthand { Some ( it ) => it . to_string ( ) , None => suggest_name :: variable ( & to_extract , & ctx . sema ) , } ; let expr_range = match & field_shorthand { Some ( it ) => it . syntax ( ) . text_range ( ) . cover ( to_extract . syntax ( ) . text_range ( ) ) , None => to_extract . syntax ( ) . text_range ( ) , } ; if let Anchor :: WrapInBlock ( _ ) = anchor { format_to ! ( buf " " var_name ) ; } else { format_to ! ( buf " " var_name ) ; } ; format_to ! ( buf " " to_extract syntax ( ) ) ; if let Anchor :: Replace ( stmt ) = anchor { cov_mark :: hit ! ( test_extract_var_expr_stmt ) ; if stmt . semicolon_token ( ) . is_none ( ) { buf . push_str ( " " ) ; } match ctx . config . snippet_cap { Some ( cap ) => { let snip = buf . replace ( & format ! ( " " var_name ) , & format ! ( " " var_name ) ) ; edit . replace_snippet ( cap , expr_range , snip ) } None => edit . replace ( expr_range , buf ) , } return ; } buf . push_str ( " " ) ; // We want to maintain the indent level, // but we do not want to duplicate possible // extra newlines in the indent block let text = indent . text ( ) ; if text . starts_with ( '\n' ) { buf . push ( '\n' ) ; buf . push_str ( text . trim_start_matches ( '\n' ) ) ; } else { buf . push_str ( text ) ; } edit . replace ( expr_range , var_name . clone ( ) ) ; let offset = anchor . syntax ( ) . text_range ( ) . start ( ) ; match ctx . config . snippet_cap { Some ( cap ) => { let snip = buf . replace ( & format ! ( " " var_name ) , & format ! ( " " var_name ) ) ; edit . insert_snippet ( cap , offset , snip ) } None => edit . insert ( offset , buf ) , } if let Anchor :: WrapInBlock ( _ ) = anchor { edit . insert ( anchor . syntax ( ) . text_range ( ) . end ( ) , " " ) ; } } , ) }
Assist: extract_variable
Extracts subexpression into a variable.
Assist : extract_variable Extracts subexpression into a variable .
acc
&mut Assists
ctx
&AssistContext