mod expr;
use expr::LhsExpr;
+mod pat;
+
use crate::ast::{AngleBracketedArgs, ParenthesizedArgs, AttrStyle, BareFnTy};
use crate::ast::{GenericBound, TraitBoundModifier};
use crate::ast::Unsafety;
use crate::ast::{ForeignItem, ForeignItemKind, FunctionRetTy};
use crate::ast::{GenericParam, GenericParamKind};
use crate::ast::GenericArg;
-use crate::ast::{Ident, ImplItem, IsAsync, IsAuto, Item, ItemKind};
-use crate::ast::{Lifetime};
-use crate::ast::Local;
-use crate::ast::MacStmtStyle;
-use crate::ast::{Mac, Mac_, MacDelimiter};
+use crate::ast::{Ident, ImplItem, IsAsync, IsAuto, Item, ItemKind, Local, Lifetime};
+use crate::ast::{MacStmtStyle, Mac, Mac_, MacDelimiter};
use crate::ast::{MutTy, Mutability};
-use crate::ast::{Pat, PatKind, PathSegment};
+use crate::ast::{PathSegment};
use crate::ast::{PolyTraitRef, QSelf};
use crate::ast::{Stmt, StmtKind};
use crate::ast::{VariantData, StructField};
use crate::ast::{Ty, TyKind, AssocTyConstraint, AssocTyConstraintKind, GenericBounds};
use crate::ast::{Visibility, VisibilityKind, WhereClause, CrateSugar};
use crate::ast::{UseTree, UseTreeKind};
-use crate::ast::{RangeEnd, RangeSyntax};
use crate::{ast, attr};
use crate::ext::base::DummyResult;
use crate::ext::hygiene::SyntaxContext;
}
/// As maybe_whole_expr, but for things other than expressions
+#[macro_export]
macro_rules! maybe_whole {
($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
if let token::Interpolated(nt) = &$p.token.kind {
match ty {
Ok(ty) => {
let ident = Ident::new(kw::Invalid, self.prev_span);
- let pat = P(Pat {
- id: ast::DUMMY_NODE_ID,
- node: PatKind::Ident(
- BindingMode::ByValue(Mutability::Immutable), ident, None),
- span: ty.span,
- });
+ let bm = BindingMode::ByValue(Mutability::Immutable);
+ let pat = self.mk_pat_ident(ty.span, bm, ident);
(pat, ty)
}
Err(mut err) => {
}
}
- /// Parses patterns, separated by '|' s.
- fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
- // Allow a '|' before the pats (RFC 1925 + RFC 2530)
- self.eat(&token::BinOp(token::Or));
-
- let mut pats = Vec::new();
- loop {
- pats.push(self.parse_top_level_pat()?);
-
- if self.token == token::OrOr {
- self.struct_span_err(self.token.span, "unexpected token `||` after pattern")
- .span_suggestion(
- self.token.span,
- "use a single `|` to specify multiple patterns",
- "|".to_owned(),
- Applicability::MachineApplicable
- )
- .emit();
- self.bump();
- } else if self.eat(&token::BinOp(token::Or)) {
- // This is a No-op. Continue the loop to parse the next
- // pattern.
- } else {
- return Ok(pats);
- }
- };
- }
-
- fn parse_pat_field(
- &mut self,
- lo: Span,
- attrs: Vec<Attribute>
- ) -> PResult<'a, source_map::Spanned<ast::FieldPat>> {
- // Check if a colon exists one ahead. This means we're parsing a fieldname.
- let hi;
- let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
- // Parsing a pattern of the form "fieldname: pat"
- let fieldname = self.parse_field_name()?;
- self.bump();
- let pat = self.parse_pat(None)?;
- hi = pat.span;
- (pat, fieldname, false)
- } else {
- // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
- let is_box = self.eat_keyword(kw::Box);
- let boxed_span = self.token.span;
- let is_ref = self.eat_keyword(kw::Ref);
- let is_mut = self.eat_keyword(kw::Mut);
- let fieldname = self.parse_ident()?;
- hi = self.prev_span;
-
- let bind_type = match (is_ref, is_mut) {
- (true, true) => BindingMode::ByRef(Mutability::Mutable),
- (true, false) => BindingMode::ByRef(Mutability::Immutable),
- (false, true) => BindingMode::ByValue(Mutability::Mutable),
- (false, false) => BindingMode::ByValue(Mutability::Immutable),
- };
- let fieldpat = P(Pat {
- id: ast::DUMMY_NODE_ID,
- node: PatKind::Ident(bind_type, fieldname, None),
- span: boxed_span.to(hi),
- });
-
- let subpat = if is_box {
- P(Pat {
- id: ast::DUMMY_NODE_ID,
- node: PatKind::Box(fieldpat),
- span: lo.to(hi),
- })
- } else {
- fieldpat
- };
- (subpat, fieldname, true)
- };
-
- Ok(source_map::Spanned {
- span: lo.to(hi),
- node: ast::FieldPat {
- ident: fieldname,
- pat: subpat,
- is_shorthand,
- attrs: attrs.into(),
- }
- })
- }
-
- /// Parses the fields of a struct-like pattern.
- fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::FieldPat>>, bool)> {
- let mut fields = Vec::new();
- let mut etc = false;
- let mut ate_comma = true;
- let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
- let mut etc_span = None;
-
- while self.token != token::CloseDelim(token::Brace) {
- let attrs = match self.parse_outer_attributes() {
- Ok(attrs) => attrs,
- Err(err) => {
- if let Some(mut delayed) = delayed_err {
- delayed.emit();
- }
- return Err(err);
- },
- };
- let lo = self.token.span;
-
- // check that a comma comes after every field
- if !ate_comma {
- let err = self.struct_span_err(self.prev_span, "expected `,`");
- if let Some(mut delayed) = delayed_err {
- delayed.emit();
- }
- return Err(err);
- }
- ate_comma = false;
-
- if self.check(&token::DotDot) || self.token == token::DotDotDot {
- etc = true;
- let mut etc_sp = self.token.span;
-
- if self.token == token::DotDotDot { // Issue #46718
- // Accept `...` as if it were `..` to avoid further errors
- self.struct_span_err(self.token.span, "expected field pattern, found `...`")
- .span_suggestion(
- self.token.span,
- "to omit remaining fields, use one fewer `.`",
- "..".to_owned(),
- Applicability::MachineApplicable
- )
- .emit();
- }
- self.bump(); // `..` || `...`
-
- if self.token == token::CloseDelim(token::Brace) {
- etc_span = Some(etc_sp);
- break;
- }
- let token_str = self.this_token_descr();
- let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
-
- err.span_label(self.token.span, "expected `}`");
- let mut comma_sp = None;
- if self.token == token::Comma { // Issue #49257
- let nw_span = self.sess.source_map().span_until_non_whitespace(self.token.span);
- etc_sp = etc_sp.to(nw_span);
- err.span_label(etc_sp,
- "`..` must be at the end and cannot have a trailing comma");
- comma_sp = Some(self.token.span);
- self.bump();
- ate_comma = true;
- }
-
- etc_span = Some(etc_sp.until(self.token.span));
- if self.token == token::CloseDelim(token::Brace) {
- // If the struct looks otherwise well formed, recover and continue.
- if let Some(sp) = comma_sp {
- err.span_suggestion_short(
- sp,
- "remove this comma",
- String::new(),
- Applicability::MachineApplicable,
- );
- }
- err.emit();
- break;
- } else if self.token.is_ident() && ate_comma {
- // Accept fields coming after `..,`.
- // This way we avoid "pattern missing fields" errors afterwards.
- // We delay this error until the end in order to have a span for a
- // suggested fix.
- if let Some(mut delayed_err) = delayed_err {
- delayed_err.emit();
- return Err(err);
- } else {
- delayed_err = Some(err);
- }
- } else {
- if let Some(mut err) = delayed_err {
- err.emit();
- }
- return Err(err);
- }
- }
-
- fields.push(match self.parse_pat_field(lo, attrs) {
- Ok(field) => field,
- Err(err) => {
- if let Some(mut delayed_err) = delayed_err {
- delayed_err.emit();
- }
- return Err(err);
- }
- });
- ate_comma = self.eat(&token::Comma);
- }
-
- if let Some(mut err) = delayed_err {
- if let Some(etc_span) = etc_span {
- err.multipart_suggestion(
- "move the `..` to the end of the field list",
- vec![
- (etc_span, String::new()),
- (self.token.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
- ],
- Applicability::MachineApplicable,
- );
- }
- err.emit();
- }
- return Ok((fields, etc));
- }
-
- fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
- if self.token.is_path_start() {
- let lo = self.token.span;
- let (qself, path) = if self.eat_lt() {
- // Parse a qualified path
- let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
- (Some(qself), path)
- } else {
- // Parse an unqualified path
- (None, self.parse_path(PathStyle::Expr)?)
- };
- let hi = self.prev_span;
- Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
- } else {
- self.parse_literal_maybe_minus()
- }
- }
-
- /// Is the current token suitable as the start of a range patterns end?
- fn is_pat_range_end_start(&self) -> bool {
- self.token.is_path_start() // e.g. `MY_CONST`;
- || self.token == token::Dot // e.g. `.5` for recovery;
- || self.token.can_begin_literal_or_bool() // e.g. `42`.
- || self.token.is_whole_expr()
- }
-
- // Helper function to decide whether to parse as ident binding
- // or to try to do something more complex like range patterns.
- fn parse_as_ident(&mut self) -> bool {
- self.look_ahead(1, |t| match t.kind {
- token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
- token::DotDotDot | token::DotDotEq | token::DotDot |
- token::ModSep | token::Not => false,
- _ => true,
- })
- }
-
- /// Parse and throw away a parentesized comma separated
- /// sequence of patterns until `)` is reached.
- fn skip_pat_list(&mut self) -> PResult<'a, ()> {
- while !self.check(&token::CloseDelim(token::Paren)) {
- self.parse_pat(None)?;
- if !self.eat(&token::Comma) {
- return Ok(())
- }
- }
- Ok(())
- }
-
- /// A wrapper around `parse_pat` with some special error handling for the
- /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
- /// to subpatterns within such).
- fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
- let pat = self.parse_pat(None)?;
- if self.token == token::Comma {
- // An unexpected comma after a top-level pattern is a clue that the
- // user (perhaps more accustomed to some other language) forgot the
- // parentheses in what should have been a tuple pattern; return a
- // suggestion-enhanced error here rather than choking on the comma
- // later.
- let comma_span = self.token.span;
- self.bump();
- if let Err(mut err) = self.skip_pat_list() {
- // We didn't expect this to work anyway; we just wanted
- // to advance to the end of the comma-sequence so we know
- // the span to suggest parenthesizing
- err.cancel();
- }
- let seq_span = pat.span.to(self.prev_span);
- let mut err = self.struct_span_err(comma_span,
- "unexpected `,` in pattern");
- if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
- err.span_suggestion(
- seq_span,
- "try adding parentheses to match on a tuple..",
- format!("({})", seq_snippet),
- Applicability::MachineApplicable
- ).span_suggestion(
- seq_span,
- "..or a vertical bar to match on multiple alternatives",
- format!("{}", seq_snippet.replace(",", " |")),
- Applicability::MachineApplicable
- );
- }
- return Err(err);
- }
- Ok(pat)
- }
-
- /// Parses a pattern.
- pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
- self.parse_pat_with_range_pat(true, expected)
- }
-
- /// Parse a range-to pattern, e.g. `..X` and `..=X` for recovery.
- fn parse_pat_range_to(&mut self, re: RangeEnd, form: &str) -> PResult<'a, PatKind> {
- let lo = self.prev_span;
- let end = self.parse_pat_range_end()?;
- let range_span = lo.to(end.span);
- let begin = self.mk_expr(range_span, ExprKind::Err, ThinVec::new());
-
- self.diagnostic()
- .struct_span_err(range_span, &format!("`{}X` range patterns are not supported", form))
- .span_suggestion(
- range_span,
- "try using the minimum value for the type",
- format!("MIN{}{}", form, pprust::expr_to_string(&end)),
- Applicability::HasPlaceholders,
- )
- .emit();
-
- Ok(PatKind::Range(begin, end, respan(lo, re)))
- }
-
- /// Parse the end of a `X..Y`, `X..=Y`, or `X...Y` range pattern or recover
- /// if that end is missing treating it as `X..`, `X..=`, or `X...` respectively.
- fn parse_pat_range_end_opt(&mut self, begin: &Expr, form: &str) -> PResult<'a, P<Expr>> {
- if self.is_pat_range_end_start() {
- // Parsing e.g. `X..=Y`.
- self.parse_pat_range_end()
- } else {
- // Parsing e.g. `X..`.
- let range_span = begin.span.to(self.prev_span);
-
- self.diagnostic()
- .struct_span_err(
- range_span,
- &format!("`X{}` range patterns are not supported", form),
- )
- .span_suggestion(
- range_span,
- "try using the maximum value for the type",
- format!("{}{}MAX", pprust::expr_to_string(&begin), form),
- Applicability::HasPlaceholders,
- )
- .emit();
-
- Ok(self.mk_expr(range_span, ExprKind::Err, ThinVec::new()))
- }
- }
-
- /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
- /// allowed).
- fn parse_pat_with_range_pat(
- &mut self,
- allow_range_pat: bool,
- expected: Option<&'static str>,
- ) -> PResult<'a, P<Pat>> {
- maybe_recover_from_interpolated_ty_qpath!(self, true);
- maybe_whole!(self, NtPat, |x| x);
-
- let lo = self.token.span;
- let pat;
- match self.token.kind {
- token::BinOp(token::And) | token::AndAnd => {
- // Parse &pat / &mut pat
- self.expect_and()?;
- let mutbl = self.parse_mutability();
- if let token::Lifetime(name) = self.token.kind {
- let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern", name));
- err.span_label(self.token.span, "unexpected lifetime");
- return Err(err);
- }
- let subpat = self.parse_pat_with_range_pat(false, expected)?;
- pat = PatKind::Ref(subpat, mutbl);
- }
- token::OpenDelim(token::Paren) => {
- // Parse a tuple or parenthesis pattern.
- let (fields, trailing_comma) = self.parse_paren_comma_seq(|p| p.parse_pat(None))?;
-
- // Here, `(pat,)` is a tuple pattern.
- // For backward compatibility, `(..)` is a tuple pattern as well.
- pat = if fields.len() == 1 && !(trailing_comma || fields[0].is_rest()) {
- PatKind::Paren(fields.into_iter().nth(0).unwrap())
- } else {
- PatKind::Tuple(fields)
- };
- }
- token::OpenDelim(token::Bracket) => {
- // Parse `[pat, pat,...]` as a slice pattern.
- let (slice, _) = self.parse_delim_comma_seq(token::Bracket, |p| p.parse_pat(None))?;
- pat = PatKind::Slice(slice);
- }
- token::DotDot => {
- self.bump();
- pat = if self.is_pat_range_end_start() {
- // Parse `..42` for recovery.
- self.parse_pat_range_to(RangeEnd::Excluded, "..")?
- } else {
- // A rest pattern `..`.
- PatKind::Rest
- };
- }
- token::DotDotEq => {
- // Parse `..=42` for recovery.
- self.bump();
- pat = self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotEq), "..=")?;
- }
- token::DotDotDot => {
- // Parse `...42` for recovery.
- self.bump();
- pat = self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotDot), "...")?;
- }
- // At this point, token != &, &&, (, [
- _ => if self.eat_keyword(kw::Underscore) {
- // Parse _
- pat = PatKind::Wild;
- } else if self.eat_keyword(kw::Mut) {
- // Parse mut ident @ pat / mut ref ident @ pat
- let mutref_span = self.prev_span.to(self.token.span);
- let binding_mode = if self.eat_keyword(kw::Ref) {
- self.diagnostic()
- .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
- .span_suggestion(
- mutref_span,
- "try switching the order",
- "ref mut".into(),
- Applicability::MachineApplicable
- ).emit();
- BindingMode::ByRef(Mutability::Mutable)
- } else {
- BindingMode::ByValue(Mutability::Mutable)
- };
- pat = self.parse_pat_ident(binding_mode)?;
- } else if self.eat_keyword(kw::Ref) {
- // Parse ref ident @ pat / ref mut ident @ pat
- let mutbl = self.parse_mutability();
- pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
- } else if self.eat_keyword(kw::Box) {
- // Parse box pat
- let subpat = self.parse_pat_with_range_pat(false, None)?;
- pat = PatKind::Box(subpat);
- } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
- self.parse_as_ident() {
- // Parse ident @ pat
- // This can give false positives and parse nullary enums,
- // they are dealt with later in resolve
- let binding_mode = BindingMode::ByValue(Mutability::Immutable);
- pat = self.parse_pat_ident(binding_mode)?;
- } else if self.token.is_path_start() {
- // Parse pattern starting with a path
- let (qself, path) = if self.eat_lt() {
- // Parse a qualified path
- let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
- (Some(qself), path)
- } else {
- // Parse an unqualified path
- (None, self.parse_path(PathStyle::Expr)?)
- };
- match self.token.kind {
- token::Not if qself.is_none() => {
- // Parse macro invocation
- self.bump();
- let (delim, tts) = self.expect_delimited_token_tree()?;
- let mac = respan(lo.to(self.prev_span), Mac_ {
- path,
- tts,
- delim,
- prior_type_ascription: self.last_type_ascription,
- });
- pat = PatKind::Mac(mac);
- }
- token::DotDotDot | token::DotDotEq | token::DotDot => {
- let (end_kind, form) = match self.token.kind {
- token::DotDot => (RangeEnd::Excluded, ".."),
- token::DotDotDot => (RangeEnd::Included(RangeSyntax::DotDotDot), "..."),
- token::DotDotEq => (RangeEnd::Included(RangeSyntax::DotDotEq), "..="),
- _ => panic!("can only parse `..`/`...`/`..=` for ranges \
- (checked above)"),
- };
- let op_span = self.token.span;
- // Parse range
- let span = lo.to(self.prev_span);
- let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
- self.bump();
- let end = self.parse_pat_range_end_opt(&begin, form)?;
- pat = PatKind::Range(begin, end, respan(op_span, end_kind));
- }
- token::OpenDelim(token::Brace) => {
- if qself.is_some() {
- let msg = "unexpected `{` after qualified path";
- let mut err = self.fatal(msg);
- err.span_label(self.token.span, msg);
- return Err(err);
- }
- // Parse struct pattern
- self.bump();
- let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
- e.emit();
- self.recover_stmt();
- (vec![], true)
- });
- self.bump();
- pat = PatKind::Struct(path, fields, etc);
- }
- token::OpenDelim(token::Paren) => {
- if qself.is_some() {
- let msg = "unexpected `(` after qualified path";
- let mut err = self.fatal(msg);
- err.span_label(self.token.span, msg);
- return Err(err);
- }
- // Parse tuple struct or enum pattern
- let (fields, _) = self.parse_paren_comma_seq(|p| p.parse_pat(None))?;
- pat = PatKind::TupleStruct(path, fields)
- }
- _ => pat = PatKind::Path(qself, path),
- }
- } else {
- // Try to parse everything else as literal with optional minus
- match self.parse_literal_maybe_minus() {
- Ok(begin) => {
- let op_span = self.token.span;
- if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
- self.check(&token::DotDotDot) {
- let (end_kind, form) = if self.eat(&token::DotDotDot) {
- (RangeEnd::Included(RangeSyntax::DotDotDot), "...")
- } else if self.eat(&token::DotDotEq) {
- (RangeEnd::Included(RangeSyntax::DotDotEq), "..=")
- } else if self.eat(&token::DotDot) {
- (RangeEnd::Excluded, "..")
- } else {
- panic!("impossible case: we already matched \
- on a range-operator token")
- };
- let end = self.parse_pat_range_end_opt(&begin, form)?;
- pat = PatKind::Range(begin, end, respan(op_span, end_kind))
- } else {
- pat = PatKind::Lit(begin);
- }
- }
- Err(mut err) => {
- self.cancel(&mut err);
- let expected = expected.unwrap_or("pattern");
- let msg = format!(
- "expected {}, found {}",
- expected,
- self.this_token_descr(),
- );
- let mut err = self.fatal(&msg);
- err.span_label(self.token.span, format!("expected {}", expected));
- let sp = self.sess.source_map().start_point(self.token.span);
- if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
- self.sess.expr_parentheses_needed(&mut err, *sp, None);
- }
- return Err(err);
- }
- }
- }
- }
-
- let pat = P(Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID });
- let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
-
- if !allow_range_pat {
- match pat.node {
- PatKind::Range(
- _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
- ) => {},
- PatKind::Range(..) => {
- let mut err = self.struct_span_err(
- pat.span,
- "the range pattern here has ambiguous interpretation",
- );
- err.span_suggestion(
- pat.span,
- "add parentheses to clarify the precedence",
- format!("({})", pprust::pat_to_string(&pat)),
- // "ambiguous interpretation" implies that we have to be guessing
- Applicability::MaybeIncorrect
- );
- return Err(err);
- }
- _ => {}
- }
- }
-
- Ok(pat)
- }
-
- /// Parses `ident` or `ident @ pat`.
- /// used by the copy foo and ref foo patterns to give a good
- /// error message when parsing mistakes like `ref foo(a, b)`.
- fn parse_pat_ident(&mut self,
- binding_mode: ast::BindingMode)
- -> PResult<'a, PatKind> {
- let ident = self.parse_ident()?;
- let sub = if self.eat(&token::At) {
- Some(self.parse_pat(Some("binding pattern"))?)
- } else {
- None
- };
-
- // just to be friendly, if they write something like
- // ref Some(i)
- // we end up here with ( as the current token. This shortly
- // leads to a parse error. Note that if there is no explicit
- // binding mode then we do not end up here, because the lookahead
- // will direct us over to parse_enum_variant()
- if self.token == token::OpenDelim(token::Paren) {
- return Err(self.span_fatal(
- self.prev_span,
- "expected identifier, found enum pattern"))
- }
-
- Ok(PatKind::Ident(binding_mode, ident, sub))
- }
-
/// Parses a local variable declaration.
fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
let lo = self.prev_span;
--- /dev/null
+use super::{Parser, PResult, PathStyle};
+
+use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
+use crate::ptr::P;
+use crate::ast::{self, Attribute, Pat, PatKind, FieldPat, RangeEnd, RangeSyntax, Mac_};
+use crate::ast::{BindingMode, Ident, Mutability, Expr, ExprKind};
+use crate::parse::token::{self};
+use crate::print::pprust;
+use crate::source_map::{respan, Span, Spanned};
+use crate::symbol::kw;
+use crate::ThinVec;
+
+use errors::{Applicability, DiagnosticBuilder};
+
+impl<'a> Parser<'a> {
+ /// Parses a pattern.
+ pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
+ self.parse_pat_with_range_pat(true, expected)
+ }
+
+ /// Parses patterns, separated by '|' s.
+ pub(super) fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
+ // Allow a '|' before the pats (RFC 1925 + RFC 2530)
+ self.eat(&token::BinOp(token::Or));
+
+ let mut pats = Vec::new();
+ loop {
+ pats.push(self.parse_top_level_pat()?);
+
+ if self.token == token::OrOr {
+ self.struct_span_err(self.token.span, "unexpected token `||` after pattern")
+ .span_suggestion(
+ self.token.span,
+ "use a single `|` to specify multiple patterns",
+ "|".to_owned(),
+ Applicability::MachineApplicable
+ )
+ .emit();
+ self.bump();
+ } else if self.eat(&token::BinOp(token::Or)) {
+ // This is a No-op. Continue the loop to parse the next
+ // pattern.
+ } else {
+ return Ok(pats);
+ }
+ };
+ }
+
+ /// A wrapper around `parse_pat` with some special error handling for the
+ /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
+ /// to subpatterns within such).
+ pub(super) fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
+ let pat = self.parse_pat(None)?;
+ if self.token == token::Comma {
+ // An unexpected comma after a top-level pattern is a clue that the
+ // user (perhaps more accustomed to some other language) forgot the
+ // parentheses in what should have been a tuple pattern; return a
+ // suggestion-enhanced error here rather than choking on the comma
+ // later.
+ let comma_span = self.token.span;
+ self.bump();
+ if let Err(mut err) = self.skip_pat_list() {
+ // We didn't expect this to work anyway; we just wanted
+ // to advance to the end of the comma-sequence so we know
+ // the span to suggest parenthesizing
+ err.cancel();
+ }
+ let seq_span = pat.span.to(self.prev_span);
+ let mut err = self.struct_span_err(comma_span, "unexpected `,` in pattern");
+ if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
+ err.span_suggestion(
+ seq_span,
+ "try adding parentheses to match on a tuple..",
+ format!("({})", seq_snippet),
+ Applicability::MachineApplicable
+ ).span_suggestion(
+ seq_span,
+ "..or a vertical bar to match on multiple alternatives",
+ format!("{}", seq_snippet.replace(",", " |")),
+ Applicability::MachineApplicable
+ );
+ }
+ return Err(err);
+ }
+ Ok(pat)
+ }
+
+ /// Parse and throw away a parentesized comma separated
+ /// sequence of patterns until `)` is reached.
+ fn skip_pat_list(&mut self) -> PResult<'a, ()> {
+ while !self.check(&token::CloseDelim(token::Paren)) {
+ self.parse_pat(None)?;
+ if !self.eat(&token::Comma) {
+ return Ok(())
+ }
+ }
+ Ok(())
+ }
+
+ /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
+ /// allowed).
+ fn parse_pat_with_range_pat(
+ &mut self,
+ allow_range_pat: bool,
+ expected: Option<&'static str>,
+ ) -> PResult<'a, P<Pat>> {
+ maybe_recover_from_interpolated_ty_qpath!(self, true);
+ maybe_whole!(self, NtPat, |x| x);
+
+ let lo = self.token.span;
+ let pat;
+ match self.token.kind {
+ token::BinOp(token::And) | token::AndAnd => {
+ // Parse &pat / &mut pat
+ self.expect_and()?;
+ let mutbl = self.parse_mutability();
+ if let token::Lifetime(name) = self.token.kind {
+ let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern", name));
+ err.span_label(self.token.span, "unexpected lifetime");
+ return Err(err);
+ }
+ let subpat = self.parse_pat_with_range_pat(false, expected)?;
+ pat = PatKind::Ref(subpat, mutbl);
+ }
+ token::OpenDelim(token::Paren) => {
+ // Parse a tuple or parenthesis pattern.
+ let (fields, trailing_comma) = self.parse_paren_comma_seq(|p| p.parse_pat(None))?;
+
+ // Here, `(pat,)` is a tuple pattern.
+ // For backward compatibility, `(..)` is a tuple pattern as well.
+ pat = if fields.len() == 1 && !(trailing_comma || fields[0].is_rest()) {
+ PatKind::Paren(fields.into_iter().nth(0).unwrap())
+ } else {
+ PatKind::Tuple(fields)
+ };
+ }
+ token::OpenDelim(token::Bracket) => {
+ // Parse `[pat, pat,...]` as a slice pattern.
+ let (slice, _) = self.parse_delim_comma_seq(token::Bracket, |p| p.parse_pat(None))?;
+ pat = PatKind::Slice(slice);
+ }
+ token::DotDot => {
+ self.bump();
+ pat = if self.is_pat_range_end_start() {
+ // Parse `..42` for recovery.
+ self.parse_pat_range_to(RangeEnd::Excluded, "..")?
+ } else {
+ // A rest pattern `..`.
+ PatKind::Rest
+ };
+ }
+ token::DotDotEq => {
+ // Parse `..=42` for recovery.
+ self.bump();
+ pat = self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotEq), "..=")?;
+ }
+ token::DotDotDot => {
+ // Parse `...42` for recovery.
+ self.bump();
+ pat = self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotDot), "...")?;
+ }
+ // At this point, token != &, &&, (, [
+ _ => if self.eat_keyword(kw::Underscore) {
+ // Parse _
+ pat = PatKind::Wild;
+ } else if self.eat_keyword(kw::Mut) {
+ // Parse mut ident @ pat / mut ref ident @ pat
+ let mutref_span = self.prev_span.to(self.token.span);
+ let binding_mode = if self.eat_keyword(kw::Ref) {
+ self.diagnostic()
+ .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
+ .span_suggestion(
+ mutref_span,
+ "try switching the order",
+ "ref mut".into(),
+ Applicability::MachineApplicable
+ ).emit();
+ BindingMode::ByRef(Mutability::Mutable)
+ } else {
+ BindingMode::ByValue(Mutability::Mutable)
+ };
+ pat = self.parse_pat_ident(binding_mode)?;
+ } else if self.eat_keyword(kw::Ref) {
+ // Parse ref ident @ pat / ref mut ident @ pat
+ let mutbl = self.parse_mutability();
+ pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
+ } else if self.eat_keyword(kw::Box) {
+ // Parse box pat
+ let subpat = self.parse_pat_with_range_pat(false, None)?;
+ pat = PatKind::Box(subpat);
+ } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
+ self.parse_as_ident() {
+ // Parse ident @ pat
+ // This can give false positives and parse nullary enums,
+ // they are dealt with later in resolve
+ let binding_mode = BindingMode::ByValue(Mutability::Immutable);
+ pat = self.parse_pat_ident(binding_mode)?;
+ } else if self.token.is_path_start() {
+ // Parse pattern starting with a path
+ let (qself, path) = if self.eat_lt() {
+ // Parse a qualified path
+ let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
+ (Some(qself), path)
+ } else {
+ // Parse an unqualified path
+ (None, self.parse_path(PathStyle::Expr)?)
+ };
+ match self.token.kind {
+ token::Not if qself.is_none() => {
+ // Parse macro invocation
+ self.bump();
+ let (delim, tts) = self.expect_delimited_token_tree()?;
+ let mac = respan(lo.to(self.prev_span), Mac_ {
+ path,
+ tts,
+ delim,
+ prior_type_ascription: self.last_type_ascription,
+ });
+ pat = PatKind::Mac(mac);
+ }
+ token::DotDotDot | token::DotDotEq | token::DotDot => {
+ let (end_kind, form) = match self.token.kind {
+ token::DotDot => (RangeEnd::Excluded, ".."),
+ token::DotDotDot => (RangeEnd::Included(RangeSyntax::DotDotDot), "..."),
+ token::DotDotEq => (RangeEnd::Included(RangeSyntax::DotDotEq), "..="),
+ _ => panic!("can only parse `..`/`...`/`..=` for ranges \
+ (checked above)"),
+ };
+ let op_span = self.token.span;
+ // Parse range
+ let span = lo.to(self.prev_span);
+ let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
+ self.bump();
+ let end = self.parse_pat_range_end_opt(&begin, form)?;
+ pat = PatKind::Range(begin, end, respan(op_span, end_kind));
+ }
+ token::OpenDelim(token::Brace) => {
+ if qself.is_some() {
+ let msg = "unexpected `{` after qualified path";
+ let mut err = self.fatal(msg);
+ err.span_label(self.token.span, msg);
+ return Err(err);
+ }
+ // Parse struct pattern
+ self.bump();
+ let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
+ e.emit();
+ self.recover_stmt();
+ (vec![], true)
+ });
+ self.bump();
+ pat = PatKind::Struct(path, fields, etc);
+ }
+ token::OpenDelim(token::Paren) => {
+ if qself.is_some() {
+ let msg = "unexpected `(` after qualified path";
+ let mut err = self.fatal(msg);
+ err.span_label(self.token.span, msg);
+ return Err(err);
+ }
+ // Parse tuple struct or enum pattern
+ let (fields, _) = self.parse_paren_comma_seq(|p| p.parse_pat(None))?;
+ pat = PatKind::TupleStruct(path, fields)
+ }
+ _ => pat = PatKind::Path(qself, path),
+ }
+ } else {
+ // Try to parse everything else as literal with optional minus
+ match self.parse_literal_maybe_minus() {
+ Ok(begin) => {
+ let op_span = self.token.span;
+ if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
+ self.check(&token::DotDotDot) {
+ let (end_kind, form) = if self.eat(&token::DotDotDot) {
+ (RangeEnd::Included(RangeSyntax::DotDotDot), "...")
+ } else if self.eat(&token::DotDotEq) {
+ (RangeEnd::Included(RangeSyntax::DotDotEq), "..=")
+ } else if self.eat(&token::DotDot) {
+ (RangeEnd::Excluded, "..")
+ } else {
+ panic!("impossible case: we already matched \
+ on a range-operator token")
+ };
+ let end = self.parse_pat_range_end_opt(&begin, form)?;
+ pat = PatKind::Range(begin, end, respan(op_span, end_kind))
+ } else {
+ pat = PatKind::Lit(begin);
+ }
+ }
+ Err(mut err) => {
+ self.cancel(&mut err);
+ let expected = expected.unwrap_or("pattern");
+ let msg = format!(
+ "expected {}, found {}",
+ expected,
+ self.this_token_descr(),
+ );
+ let mut err = self.fatal(&msg);
+ err.span_label(self.token.span, format!("expected {}", expected));
+ let sp = self.sess.source_map().start_point(self.token.span);
+ if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
+ self.sess.expr_parentheses_needed(&mut err, *sp, None);
+ }
+ return Err(err);
+ }
+ }
+ }
+ }
+
+ let pat = self.mk_pat(lo.to(self.prev_span), pat);
+ let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
+
+ if !allow_range_pat {
+ match pat.node {
+ PatKind::Range(
+ _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
+ ) => {},
+ PatKind::Range(..) => {
+ let mut err = self.struct_span_err(
+ pat.span,
+ "the range pattern here has ambiguous interpretation",
+ );
+ err.span_suggestion(
+ pat.span,
+ "add parentheses to clarify the precedence",
+ format!("({})", pprust::pat_to_string(&pat)),
+ // "ambiguous interpretation" implies that we have to be guessing
+ Applicability::MaybeIncorrect
+ );
+ return Err(err);
+ }
+ _ => {}
+ }
+ }
+
+ Ok(pat)
+ }
+
+ // Helper function to decide whether to parse as ident binding
+ // or to try to do something more complex like range patterns.
+ fn parse_as_ident(&mut self) -> bool {
+ self.look_ahead(1, |t| match t.kind {
+ token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
+ token::DotDotDot | token::DotDotEq | token::DotDot |
+ token::ModSep | token::Not => false,
+ _ => true,
+ })
+ }
+
+ /// Is the current token suitable as the start of a range patterns end?
+ fn is_pat_range_end_start(&self) -> bool {
+ self.token.is_path_start() // e.g. `MY_CONST`;
+ || self.token == token::Dot // e.g. `.5` for recovery;
+ || self.token.can_begin_literal_or_bool() // e.g. `42`.
+ || self.token.is_whole_expr()
+ }
+
+ /// Parse a range-to pattern, e.g. `..X` and `..=X` for recovery.
+ fn parse_pat_range_to(&mut self, re: RangeEnd, form: &str) -> PResult<'a, PatKind> {
+ let lo = self.prev_span;
+ let end = self.parse_pat_range_end()?;
+ let range_span = lo.to(end.span);
+ let begin = self.mk_expr(range_span, ExprKind::Err, ThinVec::new());
+
+ self.diagnostic()
+ .struct_span_err(range_span, &format!("`{}X` range patterns are not supported", form))
+ .span_suggestion(
+ range_span,
+ "try using the minimum value for the type",
+ format!("MIN{}{}", form, pprust::expr_to_string(&end)),
+ Applicability::HasPlaceholders,
+ )
+ .emit();
+
+ Ok(PatKind::Range(begin, end, respan(lo, re)))
+ }
+
+ /// Parse the end of a `X..Y`, `X..=Y`, or `X...Y` range pattern or recover
+ /// if that end is missing treating it as `X..`, `X..=`, or `X...` respectively.
+ fn parse_pat_range_end_opt(&mut self, begin: &Expr, form: &str) -> PResult<'a, P<Expr>> {
+ if self.is_pat_range_end_start() {
+ // Parsing e.g. `X..=Y`.
+ self.parse_pat_range_end()
+ } else {
+ // Parsing e.g. `X..`.
+ let range_span = begin.span.to(self.prev_span);
+
+ self.diagnostic()
+ .struct_span_err(
+ range_span,
+ &format!("`X{}` range patterns are not supported", form),
+ )
+ .span_suggestion(
+ range_span,
+ "try using the maximum value for the type",
+ format!("{}{}MAX", pprust::expr_to_string(&begin), form),
+ Applicability::HasPlaceholders,
+ )
+ .emit();
+
+ Ok(self.mk_expr(range_span, ExprKind::Err, ThinVec::new()))
+ }
+ }
+
+ fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
+ if self.token.is_path_start() {
+ let lo = self.token.span;
+ let (qself, path) = if self.eat_lt() {
+ // Parse a qualified path
+ let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
+ (Some(qself), path)
+ } else {
+ // Parse an unqualified path
+ (None, self.parse_path(PathStyle::Expr)?)
+ };
+ let hi = self.prev_span;
+ Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
+ } else {
+ self.parse_literal_maybe_minus()
+ }
+ }
+
+ /// Parses `ident` or `ident @ pat`.
+ /// used by the copy foo and ref foo patterns to give a good
+ /// error message when parsing mistakes like `ref foo(a, b)`.
+ fn parse_pat_ident(&mut self,
+ binding_mode: ast::BindingMode)
+ -> PResult<'a, PatKind> {
+ let ident = self.parse_ident()?;
+ let sub = if self.eat(&token::At) {
+ Some(self.parse_pat(Some("binding pattern"))?)
+ } else {
+ None
+ };
+
+ // just to be friendly, if they write something like
+ // ref Some(i)
+ // we end up here with ( as the current token. This shortly
+ // leads to a parse error. Note that if there is no explicit
+ // binding mode then we do not end up here, because the lookahead
+ // will direct us over to parse_enum_variant()
+ if self.token == token::OpenDelim(token::Paren) {
+ return Err(self.span_fatal(
+ self.prev_span,
+ "expected identifier, found enum pattern"))
+ }
+
+ Ok(PatKind::Ident(binding_mode, ident, sub))
+ }
+
+ /// Parses the fields of a struct-like pattern.
+ fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<Spanned<FieldPat>>, bool)> {
+ let mut fields = Vec::new();
+ let mut etc = false;
+ let mut ate_comma = true;
+ let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
+ let mut etc_span = None;
+
+ while self.token != token::CloseDelim(token::Brace) {
+ let attrs = match self.parse_outer_attributes() {
+ Ok(attrs) => attrs,
+ Err(err) => {
+ if let Some(mut delayed) = delayed_err {
+ delayed.emit();
+ }
+ return Err(err);
+ },
+ };
+ let lo = self.token.span;
+
+ // check that a comma comes after every field
+ if !ate_comma {
+ let err = self.struct_span_err(self.prev_span, "expected `,`");
+ if let Some(mut delayed) = delayed_err {
+ delayed.emit();
+ }
+ return Err(err);
+ }
+ ate_comma = false;
+
+ if self.check(&token::DotDot) || self.token == token::DotDotDot {
+ etc = true;
+ let mut etc_sp = self.token.span;
+
+ if self.token == token::DotDotDot { // Issue #46718
+ // Accept `...` as if it were `..` to avoid further errors
+ self.struct_span_err(self.token.span, "expected field pattern, found `...`")
+ .span_suggestion(
+ self.token.span,
+ "to omit remaining fields, use one fewer `.`",
+ "..".to_owned(),
+ Applicability::MachineApplicable
+ )
+ .emit();
+ }
+ self.bump(); // `..` || `...`
+
+ if self.token == token::CloseDelim(token::Brace) {
+ etc_span = Some(etc_sp);
+ break;
+ }
+ let token_str = self.this_token_descr();
+ let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
+
+ err.span_label(self.token.span, "expected `}`");
+ let mut comma_sp = None;
+ if self.token == token::Comma { // Issue #49257
+ let nw_span = self.sess.source_map().span_until_non_whitespace(self.token.span);
+ etc_sp = etc_sp.to(nw_span);
+ err.span_label(etc_sp,
+ "`..` must be at the end and cannot have a trailing comma");
+ comma_sp = Some(self.token.span);
+ self.bump();
+ ate_comma = true;
+ }
+
+ etc_span = Some(etc_sp.until(self.token.span));
+ if self.token == token::CloseDelim(token::Brace) {
+ // If the struct looks otherwise well formed, recover and continue.
+ if let Some(sp) = comma_sp {
+ err.span_suggestion_short(
+ sp,
+ "remove this comma",
+ String::new(),
+ Applicability::MachineApplicable,
+ );
+ }
+ err.emit();
+ break;
+ } else if self.token.is_ident() && ate_comma {
+ // Accept fields coming after `..,`.
+ // This way we avoid "pattern missing fields" errors afterwards.
+ // We delay this error until the end in order to have a span for a
+ // suggested fix.
+ if let Some(mut delayed_err) = delayed_err {
+ delayed_err.emit();
+ return Err(err);
+ } else {
+ delayed_err = Some(err);
+ }
+ } else {
+ if let Some(mut err) = delayed_err {
+ err.emit();
+ }
+ return Err(err);
+ }
+ }
+
+ fields.push(match self.parse_pat_field(lo, attrs) {
+ Ok(field) => field,
+ Err(err) => {
+ if let Some(mut delayed_err) = delayed_err {
+ delayed_err.emit();
+ }
+ return Err(err);
+ }
+ });
+ ate_comma = self.eat(&token::Comma);
+ }
+
+ if let Some(mut err) = delayed_err {
+ if let Some(etc_span) = etc_span {
+ err.multipart_suggestion(
+ "move the `..` to the end of the field list",
+ vec![
+ (etc_span, String::new()),
+ (self.token.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
+ ],
+ Applicability::MachineApplicable,
+ );
+ }
+ err.emit();
+ }
+ return Ok((fields, etc));
+ }
+
+ fn parse_pat_field(
+ &mut self,
+ lo: Span,
+ attrs: Vec<Attribute>
+ ) -> PResult<'a, Spanned<FieldPat>> {
+ // Check if a colon exists one ahead. This means we're parsing a fieldname.
+ let hi;
+ let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
+ // Parsing a pattern of the form "fieldname: pat"
+ let fieldname = self.parse_field_name()?;
+ self.bump();
+ let pat = self.parse_pat(None)?;
+ hi = pat.span;
+ (pat, fieldname, false)
+ } else {
+ // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
+ let is_box = self.eat_keyword(kw::Box);
+ let boxed_span = self.token.span;
+ let is_ref = self.eat_keyword(kw::Ref);
+ let is_mut = self.eat_keyword(kw::Mut);
+ let fieldname = self.parse_ident()?;
+ hi = self.prev_span;
+
+ let bind_type = match (is_ref, is_mut) {
+ (true, true) => BindingMode::ByRef(Mutability::Mutable),
+ (true, false) => BindingMode::ByRef(Mutability::Immutable),
+ (false, true) => BindingMode::ByValue(Mutability::Mutable),
+ (false, false) => BindingMode::ByValue(Mutability::Immutable),
+ };
+
+ let fieldpat = self.mk_pat_ident(boxed_span.to(hi), bind_type, fieldname);
+ let subpat = if is_box {
+ self.mk_pat(lo.to(hi), PatKind::Box(fieldpat))
+ } else {
+ fieldpat
+ };
+ (subpat, fieldname, true)
+ };
+
+ Ok(Spanned {
+ span: lo.to(hi),
+ node: FieldPat {
+ ident: fieldname,
+ pat: subpat,
+ is_shorthand,
+ attrs: attrs.into(),
+ }
+ })
+ }
+
+ pub(super) fn mk_pat_ident(&self, span: Span, bm: BindingMode, ident: Ident) -> P<Pat> {
+ self.mk_pat(span, PatKind::Ident(bm, ident, None))
+ }
+
+ fn mk_pat(&self, span: Span, node: PatKind) -> P<Pat> {
+ P(Pat { node, span, id: ast::DUMMY_NODE_ID })
+ }
+}
projects / rust.git / commitdiff