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Use strongly-typed ast building for early-return assist

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This commit is contained in:
Aleksey Kladov 2019-11-13 11:40:51 +03:00
parent 2a69d584d6
commit e177c65e36
2 changed files with 102 additions and 45 deletions
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95
crates/ra_assists/src/assists/early_return.rs
View file

@ -1,4 +1,4 @@
use std::ops::RangeInclusive;
use std::{iter::once, ops::RangeInclusive};
use hir::db::HirDatabase;
use ra_syntax::{
@ -45,19 +45,22 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
let cond = if_expr.condition()?;
// Check if there is an IfLet that we can handle.
let bound_ident = match cond.pat() {
let if_let_pat = match cond.pat() {
None => None, // No IfLet, supported.
Some(TupleStructPat(pat)) if pat.args().count() == 1 => {
let path = pat.path()?;
match path.qualifier() {
None => Some(path.segment()?.name_ref()?),
None => {
let bound_ident = pat.args().next().unwrap();
Some((path, bound_ident))
}
Some(_) => return None,
}
}
Some(_) => return None, // Unsupported IfLet.
};
let expr = cond.expr()?;
let cond_expr = cond.expr()?;
let then_block = if_expr.then_branch()?.block()?;
let parent_block = if_expr.syntax().parent()?.ancestors().find_map(ast::Block::cast)?;
@ -79,11 +82,11 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
let parent_container = parent_block.syntax().parent()?.parent()?;
let early_expression = match parent_container.kind() {
WHILE_EXPR | LOOP_EXPR => Some("continue"),
FN_DEF => Some("return"),
_ => None,
}?;
let early_expression: ast::Expr = match parent_container.kind() {
WHILE_EXPR | LOOP_EXPR => make::expr_continue().into(),
FN_DEF => make::expr_return().into(),
_ => return None,
};
if then_block.syntax().first_child_or_token().map(|t| t.kind() == L_CURLY).is_none() {
return None;
@ -94,22 +97,43 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
ctx.add_assist(AssistId("convert_to_guarded_return"), "convert to guarded return", |edit| {
let if_indent_level = IndentLevel::from_node(&if_expr.syntax());
let new_block = match bound_ident {
let new_block = match if_let_pat {
None => {
// If.
let early_expression = &(early_expression.to_owned() + ";");
let new_expr =
if_indent_level.increase_indent(make::if_expression(&expr, early_expression));
let early_expression = &(early_expression.syntax().to_string() + ";");
let new_expr = if_indent_level
.increase_indent(make::if_expression(&cond_expr, early_expression));
replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
}
Some(bound_ident) => {
Some((path, bound_ident)) => {
// If-let.
let new_expr = if_indent_level.increase_indent(make::let_match_early(
expr,
&bound_ident.syntax().to_string(),
early_expression,
));
replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
let match_expr = {
let happy_arm = make::match_arm(
once(
make::tuple_struct_pat(
path,
once(make::bind_pat(make::name("it")).into()),
)
.into(),
),
make::expr_path(make::path_from_name_ref(make::name_ref("it"))).into(),
);
let sad_arm = make::match_arm(
// FIXME: would be cool to use `None` or `Err(_)` if appropriate
once(make::placeholder_pat().into()),
early_expression.into(),
);
make::expr_match(cond_expr, make::match_arm_list(vec![happy_arm, sad_arm]))
};
let let_stmt = make::let_stmt(
make::bind_pat(make::name(&bound_ident.syntax().to_string())).into(),
Some(match_expr.into()),
);
let let_stmt = if_indent_level.increase_indent(let_stmt);
replace(let_stmt.syntax(), &then_block, &parent_block, &if_expr)
}
};
edit.target(if_expr.syntax().text_range());
@ -205,7 +229,7 @@ mod tests {
bar();
le<|>t n = match n {
Some(it) => it,
None => return,
_ => return,
};
foo(n);
@ -216,6 +240,29 @@ mod tests {
);
}
#[test]
fn convert_if_let_result() {
check_assist(
convert_to_guarded_return,
r#"
fn main() {
if<|> let Ok(x) = Err(92) {
foo(x);
}
}
"#,
r#"
fn main() {
le<|>t x = match Err(92) {
Ok(it) => it,
_ => return,
};
foo(x);
}
"#,
);
}
#[test]
fn convert_let_ok_inside_fn() {
check_assist(
@ -236,7 +283,7 @@ mod tests {
bar();
le<|>t n = match n {
Ok(it) => it,
None => return,
_ => return,
};
foo(n);
@ -294,7 +341,7 @@ mod tests {
while true {
le<|>t n = match n {
Some(it) => it,
None => continue,
_ => continue,
};
foo(n);
bar();
@ -351,7 +398,7 @@ mod tests {
loop {
le<|>t n = match n {
Some(it) => it,
None => continue,
_ => continue,
};
foo(n);
bar();

52
crates/ra_syntax/src/ast/make.rs
View file

@ -4,6 +4,10 @@ use itertools::Itertools;
use crate::{ast, AstNode, SourceFile};
pub fn name(text: &str) -> ast::Name {
ast_from_text(&format!("mod {};", text))
}
pub fn name_ref(text: &str) -> ast::NameRef {
ast_from_text(&format!("fn f() {{ {}; }}", text))
}
@ -43,6 +47,21 @@ pub fn expr_unit() -> ast::Expr {
pub fn expr_unimplemented() -> ast::Expr {
expr_from_text("unimplemented!()")
}
pub fn expr_path(path: ast::Path) -> ast::Expr {
expr_from_text(&path.syntax().to_string())
}
pub fn expr_continue() -> ast::Expr {
expr_from_text("continue")
}
pub fn expr_break() -> ast::Expr {
expr_from_text("break")
}
pub fn expr_return() -> ast::Expr {
expr_from_text("return")
}
pub fn expr_match(expr: ast::Expr, match_arm_list: ast::MatchArmList) -> ast::Expr {
expr_from_text(&format!("match {} {}", expr.syntax(), match_arm_list.syntax()))
}
fn expr_from_text(text: &str) -> ast::Expr {
ast_from_text(&format!("const C: () = {};", text))
}
@ -92,8 +111,8 @@ pub fn path_pat(path: ast::Path) -> ast::PathPat {
}
}
pub fn match_arm(pats: impl Iterator<Item = ast::Pat>, expr: ast::Expr) -> ast::MatchArm {
let pats_str = pats.map(|p| p.syntax().to_string()).join(" | ");
pub fn match_arm(pats: impl IntoIterator<Item = ast::Pat>, expr: ast::Expr) -> ast::MatchArm {
let pats_str = pats.into_iter().map(|p| p.syntax().to_string()).join(" | ");
return from_text(&format!("{} => {}", pats_str, expr.syntax()));
fn from_text(text: &str) -> ast::MatchArm {
@ -101,8 +120,8 @@ pub fn match_arm(pats: impl Iterator<Item = ast::Pat>, expr: ast::Expr) -> ast::
}
}
pub fn match_arm_list(arms: impl Iterator<Item = ast::MatchArm>) -> ast::MatchArmList {
let arms_str = arms.map(|arm| format!("\n {}", arm.syntax())).join(",");
pub fn match_arm_list(arms: impl IntoIterator<Item = ast::MatchArm>) -> ast::MatchArmList {
let arms_str = arms.into_iter().map(|arm| format!("\n {}", arm.syntax())).join(",");
return from_text(&format!("{},\n", arms_str));
fn from_text(text: &str) -> ast::MatchArmList {
@ -110,23 +129,6 @@ pub fn match_arm_list(arms: impl Iterator<Item = ast::MatchArm>) -> ast::MatchAr
}
}
pub fn let_match_early(expr: ast::Expr, path: &str, early_expression: &str) -> ast::LetStmt {
return from_text(&format!(
r#"let {} = match {} {{
{}(it) => it,
None => {},
}};"#,
expr.syntax().text(),
expr.syntax().text(),
path,
early_expression
));
fn from_text(text: &str) -> ast::LetStmt {
ast_from_text(&format!("fn f() {{ {} }}", text))
}
}
pub fn where_pred(path: ast::Path, bounds: impl Iterator<Item = ast::TypeBound>) -> ast::WherePred {
let bounds = bounds.map(|b| b.syntax().to_string()).join(" + ");
return from_text(&format!("{}: {}", path.syntax(), bounds));
@ -153,6 +155,14 @@ pub fn if_expression(condition: &ast::Expr, statement: &str) -> ast::IfExpr {
))
}
pub fn let_stmt(pattern: ast::Pat, initializer: Option<ast::Expr>) -> ast::LetStmt {
let text = match initializer {
Some(it) => format!("let {} = {};", pattern.syntax(), it.syntax()),
None => format!("let {};", pattern.syntax()),
};
ast_from_text(&format!("fn f() {{ {} }}", text))
}
fn ast_from_text<N: AstNode>(text: &str) -> N {
let parse = SourceFile::parse(text);
let res = parse.tree().syntax().descendants().find_map(N::cast).unwrap();