committed by
Brian Anderson
parent
ff6cde7882
commit
7dcbaedd32
132
src/libsyntax/parse/attr.rs
Normal file
132
src/libsyntax/parse/attr.rs
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import either::{either, left, right};
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import ast_util::spanned;
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import common::{parser_common, seq_sep};
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export attr_or_ext;
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export parser_attr;
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// A type to distingush between the parsing of item attributes or syntax
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// extensions, which both begin with token.POUND
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type attr_or_ext = option<either<[ast::attribute], @ast::expr>>;
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impl parser_attr for parser {
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fn parse_outer_attrs_or_ext(first_item_attrs: [ast::attribute])
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-> attr_or_ext
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{
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let expect_item_next = vec::is_not_empty(first_item_attrs);
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if self.token == token::POUND {
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let lo = self.span.lo;
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if self.look_ahead(1u) == token::LBRACKET {
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self.bump();
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let first_attr =
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self.parse_attribute_naked(ast::attr_outer, lo);
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ret some(left([first_attr] + self.parse_outer_attributes()));
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} else if !(self.look_ahead(1u) == token::LT
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|| self.look_ahead(1u) == token::LBRACKET
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|| expect_item_next) {
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self.bump();
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ret some(right(self.parse_syntax_ext_naked(lo)));
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} else { ret none; }
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} else { ret none; }
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}
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// Parse attributes that appear before an item
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fn parse_outer_attributes() -> [ast::attribute] {
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let mut attrs: [ast::attribute] = [];
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while self.token == token::POUND
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&& self.look_ahead(1u) == token::LBRACKET {
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attrs += [self.parse_attribute(ast::attr_outer)];
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}
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ret attrs;
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}
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fn parse_attribute(style: ast::attr_style) -> ast::attribute {
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let lo = self.span.lo;
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self.expect(token::POUND);
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ret self.parse_attribute_naked(style, lo);
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}
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fn parse_attribute_naked(style: ast::attr_style, lo: uint) ->
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ast::attribute {
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self.expect(token::LBRACKET);
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let meta_item = self.parse_meta_item();
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self.expect(token::RBRACKET);
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let mut hi = self.span.hi;
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ret spanned(lo, hi, {style: style, value: *meta_item});
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}
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// Parse attributes that appear after the opening of an item, each
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// terminated by a semicolon. In addition to a vector of inner attributes,
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// this function also returns a vector that may contain the first outer
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// attribute of the next item (since we can't know whether the attribute
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// is an inner attribute of the containing item or an outer attribute of
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// the first contained item until we see the semi).
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fn parse_inner_attrs_and_next() ->
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{inner: [ast::attribute], next: [ast::attribute]} {
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let mut inner_attrs: [ast::attribute] = [];
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let mut next_outer_attrs: [ast::attribute] = [];
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while self.token == token::POUND {
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if self.look_ahead(1u) != token::LBRACKET {
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// This is an extension
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break;
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}
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let attr = self.parse_attribute(ast::attr_inner);
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if self.token == token::SEMI {
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self.bump();
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inner_attrs += [attr];
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} else {
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// It's not really an inner attribute
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let outer_attr =
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spanned(attr.span.lo, attr.span.hi,
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{style: ast::attr_outer, value: attr.node.value});
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next_outer_attrs += [outer_attr];
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break;
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}
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}
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ret {inner: inner_attrs, next: next_outer_attrs};
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}
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fn parse_meta_item() -> @ast::meta_item {
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let lo = self.span.lo;
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let ident = self.parse_ident();
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alt self.token {
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token::EQ {
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self.bump();
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let lit = self.parse_lit();
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let mut hi = self.span.hi;
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ret @spanned(lo, hi, ast::meta_name_value(ident, lit));
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}
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token::LPAREN {
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let inner_items = self.parse_meta_seq();
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let mut hi = self.span.hi;
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ret @spanned(lo, hi, ast::meta_list(ident, inner_items));
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}
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_ {
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let mut hi = self.span.hi;
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ret @spanned(lo, hi, ast::meta_word(ident));
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}
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}
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}
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fn parse_meta_seq() -> [@ast::meta_item] {
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ret self.parse_seq(token::LPAREN, token::RPAREN,
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seq_sep(token::COMMA),
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{|p| p.parse_meta_item()}).node;
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}
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fn parse_optional_meta() -> [@ast::meta_item] {
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alt self.token { token::LPAREN { ret self.parse_meta_seq(); }
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_ { ret []; } }
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}
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}
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//
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// Local Variables:
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// mode: rust
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// fill-column: 78;
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// indent-tabs-mode: nil
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// c-basic-offset: 4
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// buffer-file-coding-system: utf-8-unix
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// End:
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//
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