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Introduce hir::ExprKind::Let - Take 2

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This commit is contained in:
Caio 2021-08-08 11:49:13 -03:00
parent 2d9f2eae84
commit 6aa9937a76
128 changed files with 2080 additions and 2196 deletions
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124
compiler/rustc_hir_pretty/src/lib.rs
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@ -1092,53 +1092,30 @@ impl<'a> State<'a> {
}
fn print_else(&mut self, els: Option<&hir::Expr<'_>>) {
match els {
Some(else_) => {
match else_.kind {
// "another else-if"
hir::ExprKind::If(ref i, ref then, ref e) => {
self.cbox(INDENT_UNIT - 1);
self.ibox(0);
self.s.word(" else if ");
self.print_expr_as_cond(&i);
self.s.space();
self.print_expr(&then);
self.print_else(e.as_ref().map(|e| &**e))
}
// "final else"
hir::ExprKind::Block(ref b, _) => {
self.cbox(INDENT_UNIT - 1);
self.ibox(0);
self.s.word(" else ");
self.print_block(&b)
}
hir::ExprKind::Match(ref expr, arms, _) => {
// else if let desugared to match
assert!(arms.len() == 2, "if let desugars to match with two arms");
self.s.word(" else ");
self.s.word("{");
self.cbox(INDENT_UNIT);
self.ibox(INDENT_UNIT);
self.word_nbsp("match");
self.print_expr_as_cond(&expr);
self.s.space();
self.bopen();
for arm in arms {
self.print_arm(arm);
}
self.bclose(expr.span);
self.s.word("}");
}
// BLEAH, constraints would be great here
_ => {
panic!("print_if saw if with weird alternative");
}
if let Some(els_inner) = els {
match els_inner.kind {
// Another `else if` block.
hir::ExprKind::If(ref i, ref then, ref e) => {
self.cbox(INDENT_UNIT - 1);
self.ibox(0);
self.s.word(" else if ");
self.print_expr_as_cond(&i);
self.s.space();
self.print_expr(&then);
self.print_else(e.as_ref().map(|e| &**e))
}
// Final `else` block.
hir::ExprKind::Block(ref b, _) => {
self.cbox(INDENT_UNIT - 1);
self.ibox(0);
self.s.word(" else ");
self.print_block(&b)
}
// Constraints would be great here!
_ => {
panic!("print_if saw if with weird alternative");
}
}
_ => {}
}
}
@ -1165,34 +1142,49 @@ impl<'a> State<'a> {
self.pclose()
}
pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr<'_>, prec: i8) {
let needs_par = expr.precedence().order() < prec;
fn print_expr_maybe_paren(&mut self, expr: &hir::Expr<'_>, prec: i8) {
self.print_expr_cond_paren(expr, expr.precedence().order() < prec)
}
/// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
/// `if cond { ... }`.
pub fn print_expr_as_cond(&mut self, expr: &hir::Expr<'_>) {
self.print_expr_cond_paren(expr, Self::cond_needs_par(expr))
}
/// Prints `expr` or `(expr)` when `needs_par` holds.
fn print_expr_cond_paren(&mut self, expr: &hir::Expr<'_>, needs_par: bool) {
if needs_par {
self.popen();
}
self.print_expr(expr);
if let hir::ExprKind::DropTemps(ref actual_expr) = expr.kind {
self.print_expr(actual_expr);
} else {
self.print_expr(expr);
}
if needs_par {
self.pclose();
}
}
/// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
/// `if cond { ... }`.
pub fn print_expr_as_cond(&mut self, expr: &hir::Expr<'_>) {
let needs_par = match expr.kind {
// These cases need parens due to the parse error observed in #26461: `if return {}`
// parses as the erroneous construct `if (return {})`, not `if (return) {}`.
hir::ExprKind::Closure(..) | hir::ExprKind::Ret(..) | hir::ExprKind::Break(..) => true,
/// Print a `let pat = expr` expression.
fn print_let(&mut self, pat: &hir::Pat<'_>, expr: &hir::Expr<'_>) {
self.s.word("let ");
self.print_pat(pat);
self.s.space();
self.word_space("=");
let npals = || parser::needs_par_as_let_scrutinee(expr.precedence().order());
self.print_expr_cond_paren(expr, Self::cond_needs_par(expr) || npals())
}
// Does `expr` need parenthesis when printed in a condition position?
//
// These cases need parens due to the parse error observed in #26461: `if return {}`
// parses as the erroneous construct `if (return {})`, not `if (return) {}`.
fn cond_needs_par(expr: &hir::Expr<'_>) -> bool {
match expr.kind {
hir::ExprKind::Break(..) | hir::ExprKind::Closure(..) | hir::ExprKind::Ret(..) => true,
_ => contains_exterior_struct_lit(expr),
};
if needs_par {
self.popen();
}
self.print_expr(expr);
if needs_par {
self.pclose();
}
}
@ -1314,6 +1306,9 @@ impl<'a> State<'a> {
(&hir::ExprKind::Cast { .. }, hir::BinOpKind::Lt | hir::BinOpKind::Shl) => {
parser::PREC_FORCE_PAREN
}
(&hir::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
parser::PREC_FORCE_PAREN
}
_ => left_prec,
};
@ -1531,6 +1526,9 @@ impl<'a> State<'a> {
// Print `}`:
self.bclose_maybe_open(expr.span, true);
}
hir::ExprKind::Let(ref pat, ref scrutinee, _) => {
self.print_let(pat, scrutinee);
}
hir::ExprKind::If(ref test, ref blk, ref elseopt) => {
self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e));
}