move parse::attr -> parse::parser::attr
This commit is contained in:
Mazdak Farrokhzad
330
src/libsyntax/parse/parser/attr.rs
Normal file
330
src/libsyntax/parse/parser/attr.rs
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@@ -0,0 +1,330 @@
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use crate::attr;
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use crate::ast;
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use crate::parse::{SeqSep, PResult};
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use crate::parse::token::{self, Nonterminal, DelimToken};
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use crate::parse::parser::{Parser, TokenType, PathStyle};
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use crate::tokenstream::{TokenStream, TokenTree};
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use crate::source_map::Span;
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use log::debug;
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use smallvec::smallvec;
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#[derive(Debug)]
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enum InnerAttributeParsePolicy<'a> {
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Permitted,
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NotPermitted { reason: &'a str, saw_doc_comment: bool, prev_attr_sp: Option<Span> },
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}
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const DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG: &str = "an inner attribute is not \
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permitted in this context";
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impl<'a> Parser<'a> {
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/// Parses attributes that appear before an item.
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crate fn parse_outer_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
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let mut attrs: Vec<ast::Attribute> = Vec::new();
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let mut just_parsed_doc_comment = false;
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loop {
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debug!("parse_outer_attributes: self.token={:?}", self.token);
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match self.token.kind {
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token::Pound => {
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let inner_error_reason = if just_parsed_doc_comment {
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"an inner attribute is not permitted following an outer doc comment"
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} else if !attrs.is_empty() {
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"an inner attribute is not permitted following an outer attribute"
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} else {
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DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG
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};
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let inner_parse_policy =
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InnerAttributeParsePolicy::NotPermitted {
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reason: inner_error_reason,
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saw_doc_comment: just_parsed_doc_comment,
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prev_attr_sp: attrs.last().and_then(|a| Some(a.span))
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};
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let attr = self.parse_attribute_with_inner_parse_policy(inner_parse_policy)?;
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attrs.push(attr);
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just_parsed_doc_comment = false;
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}
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token::DocComment(s) => {
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let attr = attr::mk_sugared_doc_attr(s, self.token.span);
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if attr.style != ast::AttrStyle::Outer {
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let mut err = self.fatal("expected outer doc comment");
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err.note("inner doc comments like this (starting with \
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`//!` or `/*!`) can only appear before items");
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return Err(err);
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}
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attrs.push(attr);
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self.bump();
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just_parsed_doc_comment = true;
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}
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_ => break,
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}
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}
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Ok(attrs)
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}
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/// Matches `attribute = # ! [ meta_item ]`.
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///
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/// If `permit_inner` is `true`, then a leading `!` indicates an inner
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/// attribute.
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pub fn parse_attribute(&mut self, permit_inner: bool) -> PResult<'a, ast::Attribute> {
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debug!("parse_attribute: permit_inner={:?} self.token={:?}",
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permit_inner,
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self.token);
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let inner_parse_policy = if permit_inner {
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InnerAttributeParsePolicy::Permitted
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} else {
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InnerAttributeParsePolicy::NotPermitted {
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reason: DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG,
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saw_doc_comment: false,
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prev_attr_sp: None
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}
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};
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self.parse_attribute_with_inner_parse_policy(inner_parse_policy)
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}
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/// The same as `parse_attribute`, except it takes in an `InnerAttributeParsePolicy`
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/// that prescribes how to handle inner attributes.
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fn parse_attribute_with_inner_parse_policy(&mut self,
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inner_parse_policy: InnerAttributeParsePolicy<'_>)
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-> PResult<'a, ast::Attribute> {
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debug!("parse_attribute_with_inner_parse_policy: inner_parse_policy={:?} self.token={:?}",
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inner_parse_policy,
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self.token);
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let (span, item, style) = match self.token.kind {
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token::Pound => {
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let lo = self.token.span;
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self.bump();
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if let InnerAttributeParsePolicy::Permitted = inner_parse_policy {
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self.expected_tokens.push(TokenType::Token(token::Not));
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}
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let style = if self.token == token::Not {
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self.bump();
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ast::AttrStyle::Inner
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} else {
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ast::AttrStyle::Outer
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};
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self.expect(&token::OpenDelim(token::Bracket))?;
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let item = self.parse_attr_item()?;
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self.expect(&token::CloseDelim(token::Bracket))?;
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let hi = self.prev_span;
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let attr_sp = lo.to(hi);
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// Emit error if inner attribute is encountered and not permitted
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if style == ast::AttrStyle::Inner {
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if let InnerAttributeParsePolicy::NotPermitted { reason,
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saw_doc_comment, prev_attr_sp } = inner_parse_policy {
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let prev_attr_note = if saw_doc_comment {
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"previous doc comment"
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} else {
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"previous outer attribute"
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};
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let mut diagnostic = self
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.diagnostic()
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.struct_span_err(attr_sp, reason);
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if let Some(prev_attr_sp) = prev_attr_sp {
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diagnostic
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.span_label(attr_sp, "not permitted following an outer attibute")
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.span_label(prev_attr_sp, prev_attr_note);
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}
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diagnostic
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.note("inner attributes, like `#![no_std]`, annotate the item \
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enclosing them, and are usually found at the beginning of \
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source files. Outer attributes, like `#[test]`, annotate the \
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item following them.")
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.emit()
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}
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}
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(attr_sp, item, style)
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}
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_ => {
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let token_str = self.this_token_to_string();
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return Err(self.fatal(&format!("expected `#`, found `{}`", token_str)));
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}
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};
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Ok(ast::Attribute {
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item,
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id: attr::mk_attr_id(),
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style,
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is_sugared_doc: false,
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span,
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})
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}
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/// Parses an inner part of an attribute (the path and following tokens).
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/// The tokens must be either a delimited token stream, or empty token stream,
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/// or the "legacy" key-value form.
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/// PATH `(` TOKEN_STREAM `)`
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/// PATH `[` TOKEN_STREAM `]`
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/// PATH `{` TOKEN_STREAM `}`
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/// PATH
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/// PATH `=` UNSUFFIXED_LIT
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/// The delimiters or `=` are still put into the resulting token stream.
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pub fn parse_attr_item(&mut self) -> PResult<'a, ast::AttrItem> {
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let item = match self.token.kind {
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token::Interpolated(ref nt) => match **nt {
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Nonterminal::NtMeta(ref item) => Some(item.clone()),
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_ => None,
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},
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_ => None,
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};
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Ok(if let Some(item) = item {
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self.bump();
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item
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} else {
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let path = self.parse_path(PathStyle::Mod)?;
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let tokens = if self.check(&token::OpenDelim(DelimToken::Paren)) ||
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self.check(&token::OpenDelim(DelimToken::Bracket)) ||
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self.check(&token::OpenDelim(DelimToken::Brace)) {
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self.parse_token_tree().into()
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} else if self.eat(&token::Eq) {
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let eq = TokenTree::token(token::Eq, self.prev_span);
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let mut is_interpolated_expr = false;
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if let token::Interpolated(nt) = &self.token.kind {
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if let token::NtExpr(..) = **nt {
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is_interpolated_expr = true;
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}
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}
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let tokens = if is_interpolated_expr {
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// We need to accept arbitrary interpolated expressions to continue
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// supporting things like `doc = $expr` that work on stable.
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// Non-literal interpolated expressions are rejected after expansion.
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self.parse_token_tree().into()
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} else {
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self.parse_unsuffixed_lit()?.tokens()
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};
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TokenStream::from_streams(smallvec![eq.into(), tokens])
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} else {
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TokenStream::default()
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};
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ast::AttrItem { path, tokens }
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})
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}
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/// Parses attributes that appear after the opening of an item. These should
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/// be preceded by an exclamation mark, but we accept and warn about one
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/// terminated by a semicolon.
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///
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/// Matches `inner_attrs*`.
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crate fn parse_inner_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
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let mut attrs: Vec<ast::Attribute> = vec![];
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loop {
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match self.token.kind {
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token::Pound => {
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// Don't even try to parse if it's not an inner attribute.
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if !self.look_ahead(1, |t| t == &token::Not) {
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break;
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}
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let attr = self.parse_attribute(true)?;
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assert_eq!(attr.style, ast::AttrStyle::Inner);
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attrs.push(attr);
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}
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token::DocComment(s) => {
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// We need to get the position of this token before we bump.
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let attr = attr::mk_sugared_doc_attr(s, self.token.span);
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if attr.style == ast::AttrStyle::Inner {
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attrs.push(attr);
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self.bump();
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} else {
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break;
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}
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}
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_ => break,
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}
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}
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Ok(attrs)
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}
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fn parse_unsuffixed_lit(&mut self) -> PResult<'a, ast::Lit> {
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let lit = self.parse_lit()?;
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debug!("checking if {:?} is unusuffixed", lit);
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if !lit.kind.is_unsuffixed() {
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let msg = "suffixed literals are not allowed in attributes";
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self.diagnostic().struct_span_err(lit.span, msg)
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.help("instead of using a suffixed literal \
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(1u8, 1.0f32, etc.), use an unsuffixed version \
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(1, 1.0, etc.).")
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.emit()
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}
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Ok(lit)
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}
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/// Matches the following grammar (per RFC 1559).
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///
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/// meta_item : PATH ( '=' UNSUFFIXED_LIT | '(' meta_item_inner? ')' )? ;
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/// meta_item_inner : (meta_item | UNSUFFIXED_LIT) (',' meta_item_inner)? ;
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pub fn parse_meta_item(&mut self) -> PResult<'a, ast::MetaItem> {
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let nt_meta = match self.token.kind {
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token::Interpolated(ref nt) => match **nt {
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token::NtMeta(ref e) => Some(e.clone()),
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_ => None,
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},
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_ => None,
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};
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if let Some(item) = nt_meta {
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return match item.meta(item.path.span) {
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Some(meta) => {
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self.bump();
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Ok(meta)
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}
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None => self.unexpected(),
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}
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}
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let lo = self.token.span;
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let path = self.parse_path(PathStyle::Mod)?;
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let kind = self.parse_meta_item_kind()?;
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let span = lo.to(self.prev_span);
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Ok(ast::MetaItem { path, kind, span })
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}
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crate fn parse_meta_item_kind(&mut self) -> PResult<'a, ast::MetaItemKind> {
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Ok(if self.eat(&token::Eq) {
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ast::MetaItemKind::NameValue(self.parse_unsuffixed_lit()?)
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} else if self.eat(&token::OpenDelim(token::Paren)) {
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ast::MetaItemKind::List(self.parse_meta_seq()?)
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} else {
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ast::MetaItemKind::Word
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})
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}
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/// Matches `meta_item_inner : (meta_item | UNSUFFIXED_LIT) ;`.
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fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::NestedMetaItem> {
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match self.parse_unsuffixed_lit() {
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Ok(lit) => {
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return Ok(ast::NestedMetaItem::Literal(lit))
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}
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Err(ref mut err) => err.cancel(),
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}
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match self.parse_meta_item() {
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Ok(mi) => {
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return Ok(ast::NestedMetaItem::MetaItem(mi))
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}
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Err(ref mut err) => err.cancel(),
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}
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let found = self.this_token_to_string();
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let msg = format!("expected unsuffixed literal or identifier, found `{}`", found);
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Err(self.diagnostic().struct_span_err(self.token.span, &msg))
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}
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/// Matches `meta_seq = ( COMMASEP(meta_item_inner) )`.
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fn parse_meta_seq(&mut self) -> PResult<'a, Vec<ast::NestedMetaItem>> {
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self.parse_seq_to_end(&token::CloseDelim(token::Paren),
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SeqSep::trailing_allowed(token::Comma),
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|p: &mut Parser<'a>| p.parse_meta_item_inner())
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}
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}
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