521 lines
18 KiB
Rust
521 lines
18 KiB
Rust
use std::mem;
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use std::rc::Rc;
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use syntax::ast::{Expr, LitKind, Stmt};
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use syntax::ext::quote::rt::ToTokens;
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use syntax::codemap::Span;
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use syntax::errors::{DiagnosticBuilder, FatalError};
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use syntax::ext::base::ExtCtxt;
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use syntax::parse;
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use syntax::parse::parser::Parser as RustParser;
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use syntax::parse::token::{BinOpToken, DelimToken, Token};
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use syntax::parse::token::keywords;
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use syntax::print::pprust;
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use syntax::ptr::P;
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use syntax::tokenstream::{Delimited, TokenTree};
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use super::render::Renderer;
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use super::PResult;
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macro_rules! error {
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($cx:expr, $sp:expr, $msg:expr) => ({
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$cx.span_err($sp, $msg);
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return Err(::syntax::errors::FatalError);
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})
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}
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macro_rules! parse_error {
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($self_:expr, $sp:expr, $msg:expr) => (error!($self_.render.cx, $sp, $msg))
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}
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macro_rules! at {
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() => (TokenTree::Token(_, Token::At))
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}
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macro_rules! dot {
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() => (TokenTree::Token(_, Token::Dot))
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}
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macro_rules! eq {
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() => (TokenTree::Token(_, Token::Eq))
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}
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macro_rules! pound {
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() => (TokenTree::Token(_, Token::Pound))
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}
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macro_rules! question {
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() => (TokenTree::Token(_, Token::Question))
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}
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macro_rules! semi {
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() => (TokenTree::Token(_, Token::Semi))
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}
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macro_rules! colon {
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() => (TokenTree::Token(_, Token::Colon))
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}
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macro_rules! comma {
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() => (TokenTree::Token(_, Token::Comma))
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}
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macro_rules! fat_arrow {
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() => (TokenTree::Token(_, Token::FatArrow))
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}
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macro_rules! minus {
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() => (TokenTree::Token(_, Token::BinOp(BinOpToken::Minus)))
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}
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macro_rules! slash {
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() => (TokenTree::Token(_, Token::BinOp(BinOpToken::Slash)))
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}
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macro_rules! literal {
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() => (TokenTree::Token(_, Token::Literal(..)))
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}
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macro_rules! ident {
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($sp:pat, $x:pat) => (TokenTree::Token($sp, Token::Ident($x)))
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}
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macro_rules! keyword {
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($sp:pat, $x:ident) => (TokenTree::Token($sp, ref $x @ Token::Ident(..)))
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}
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pub fn parse(cx: &ExtCtxt, sp: Span, input: &[TokenTree]) -> PResult<P<Expr>> {
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let mut parser = Parser {
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in_attr: false,
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input: input,
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span: sp,
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render: Renderer::new(cx),
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};
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parser.markups()?;
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// Heuristic: the size of the resulting markup tends to correlate with the
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// code size of the template itself
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let size_hint = pprust::tts_to_string(input).len();
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Ok(parser.into_render().into_expr(size_hint))
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}
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struct Parser<'cx, 'a: 'cx, 'i> {
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in_attr: bool,
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input: &'i [TokenTree],
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span: Span,
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render: Renderer<'cx, 'a>,
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}
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impl<'cx, 'a, 'i> Parser<'cx, 'a, 'i> {
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/// Finalizes the `Parser`, returning the `Renderer` underneath.
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fn into_render(self) -> Renderer<'cx, 'a> {
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let Parser { render, .. } = self;
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render
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}
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/// Consumes `n` items from the input.
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fn shift(&mut self, n: usize) {
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self.input = &self.input[n..];
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}
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/// Constructs a Rust AST parser from the given token tree.
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fn with_rust_parser<F, T>(&self, tts: Vec<TokenTree>, callback: F) -> PResult<T> where
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F: FnOnce(&mut RustParser<'cx>) -> Result<T, DiagnosticBuilder<'cx>>
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{
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let mut parser = parse::tts_to_parser(self.render.cx.parse_sess, tts,
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self.render.cx.cfg.clone());
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let result = callback(&mut parser).map_err(|mut e| { e.emit(); FatalError });
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// Make sure all tokens were consumed
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if parser.token != Token::Eof {
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let token = parser.this_token_to_string();
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self.render.cx.span_err(parser.span,
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&format!("unexpected token: `{}`", token));
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}
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result
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}
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/// Parses and renders multiple blocks of markup.
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fn markups(&mut self) -> PResult<()> {
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loop {
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match *self.input {
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[] => return Ok(()),
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[semi!(), ..] => self.shift(1),
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[_, ..] => self.markup()?,
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}
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}
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}
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/// Parses and renders a single block of markup.
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fn markup(&mut self) -> PResult<()> {
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match *self.input {
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// Literal
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[ref tt @ literal!(), ..] => {
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self.shift(1);
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self.literal(tt)?;
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},
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// If
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[at!(), keyword!(sp, k), ..] if k.is_keyword(keywords::If) => {
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self.shift(2);
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self.if_expr(sp)?;
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},
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// For
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[at!(), keyword!(sp, k), ..] if k.is_keyword(keywords::For) => {
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self.shift(2);
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self.for_expr(sp)?;
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},
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// Match
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[at!(), keyword!(sp, k), ..] if k.is_keyword(keywords::Match) => {
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self.shift(2);
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self.match_expr(sp)?;
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},
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// Element
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[ident!(sp, _), ..] => {
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let name = self.namespaced_name().unwrap();
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self.element(sp, &name)?;
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},
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// Splice
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[TokenTree::Delimited(_, ref d), ..] if d.delim == DelimToken::Paren => {
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self.shift(1);
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let expr = self.with_rust_parser(d.tts.clone(), RustParser::parse_expr)?;
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self.render.splice(expr);
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}
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// Block
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[TokenTree::Delimited(_, ref d), ..] if d.delim == DelimToken::Brace => {
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self.shift(1);
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{
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// Parse the contents of the block, emitting the
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// result inline
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let mut i = &d.tts[..];
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mem::swap(&mut self.input, &mut i);
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self.markups()?;
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mem::swap(&mut self.input, &mut i);
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}
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},
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// ???
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_ => {
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if let [ref tt, ..] = *self.input {
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parse_error!(self, tt.get_span(), "invalid syntax");
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} else {
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parse_error!(self, self.span, "unexpected end of block");
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}
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},
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}
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Ok(())
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}
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/// Parses and renders a literal string.
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fn literal(&mut self, tt: &TokenTree) -> PResult<()> {
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let lit = self.with_rust_parser(vec![tt.clone()], RustParser::parse_lit)?;
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if let LitKind::Str(s, _) = lit.node {
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self.render.string(&s);
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Ok(())
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} else {
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parse_error!(self, lit.span, "literal strings must be surrounded by quotes (\"like this\")")
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}
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}
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/// Parses and renders an `@if` expression.
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///
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/// The leading `@if` should already be consumed.
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fn if_expr(&mut self, sp: Span) -> PResult<()> {
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// Parse the initial if
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let mut if_cond = vec![];
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let if_body;
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loop { match *self.input {
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[TokenTree::Delimited(sp, ref d), ..] if d.delim == DelimToken::Brace => {
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self.shift(1);
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if_body = self.block(sp, &d.tts)?;
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break;
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},
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[ref tt, ..] => {
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self.shift(1);
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if_cond.push(tt.clone());
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},
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[] => parse_error!(self, sp, "expected body for this @if"),
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}}
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// Parse the (optional) @else
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let else_body = match *self.input {
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[at!(), keyword!(_, k), ..] if k.is_keyword(keywords::Else) => {
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self.shift(2);
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match *self.input {
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[keyword!(sp, k), ..] if k.is_keyword(keywords::If) => {
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self.shift(1);
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let else_body = {
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// Parse an if expression, but capture the result
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// rather than emitting it right away
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let mut r = self.render.fork();
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mem::swap(&mut self.render, &mut r);
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self.if_expr(sp)?;
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mem::swap(&mut self.render, &mut r);
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r.into_stmts()
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};
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Some(else_body)
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},
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[TokenTree::Delimited(sp, ref d), ..] if d.delim == DelimToken::Brace => {
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self.shift(1);
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Some(self.block(sp, &d.tts)?)
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},
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_ => parse_error!(self, sp, "expected body for this @else"),
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}
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},
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_ => None,
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};
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self.render.emit_if(if_cond, if_body, else_body);
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Ok(())
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}
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/// Parses and renders a `@for` expression.
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///
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/// The leading `@for` should already be consumed.
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fn for_expr(&mut self, sp: Span) -> PResult<()> {
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let mut pattern = vec![];
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loop { match *self.input {
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[keyword!(_, k), ..] if k.is_keyword(keywords::In) => {
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self.shift(1);
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break;
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},
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[ref tt, ..] => {
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self.shift(1);
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pattern.push(tt.clone());
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},
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_ => parse_error!(self, sp, "invalid @for"),
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}}
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let pattern = self.with_rust_parser(pattern, RustParser::parse_pat)?;
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let mut iterable = vec![];
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let body;
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loop { match *self.input {
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[TokenTree::Delimited(sp, ref d), ..] if d.delim == DelimToken::Brace => {
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self.shift(1);
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body = self.block(sp, &d.tts)?;
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break;
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},
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[ref tt, ..] => {
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self.shift(1);
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iterable.push(tt.clone());
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},
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_ => parse_error!(self, sp, "invalid @for"),
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}}
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let iterable = self.with_rust_parser(iterable, RustParser::parse_expr)?;
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self.render.emit_for(pattern, iterable, body);
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Ok(())
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}
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/// Parses and renders a `@match` expression.
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///
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/// The leading `@match` should already be consumed.
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fn match_expr(&mut self, sp: Span) -> PResult<()> {
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// Parse the initial match
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let mut match_var = vec![];
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let match_bodies;
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loop { match *self.input {
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[TokenTree::Delimited(sp, ref d), ..] if d.delim == DelimToken::Brace => {
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self.shift(1);
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match_bodies = Parser {
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in_attr: self.in_attr,
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input: &d.tts,
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span: sp,
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render: self.render.fork(),
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}.match_bodies()?;
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break;
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},
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[ref tt, ..] => {
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self.shift(1);
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match_var.push(tt.clone());
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},
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[] => parse_error!(self, sp, "expected body for this @match"),
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}}
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let match_var = self.with_rust_parser(match_var, RustParser::parse_expr)?;
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self.render.emit_match(match_var, match_bodies);
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Ok(())
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}
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fn match_bodies(&mut self) -> PResult<Vec<TokenTree>> {
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let mut bodies = Vec::new();
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loop { match *self.input {
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[] => break,
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[ref tt @ comma!(), ..] => {
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self.shift(1);
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bodies.push(tt.clone());
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},
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[TokenTree::Token(sp, _), ..] | [TokenTree::Delimited(sp, _), ..] | [TokenTree::Sequence(sp, _), ..] => {
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bodies.append(&mut self.match_body(sp)?);
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},
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}}
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Ok(bodies)
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}
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fn match_body(&mut self, sp: Span) -> PResult<Vec<TokenTree>> {
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let mut body = vec![];
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loop { match *self.input {
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[ref tt @ fat_arrow!(), ..] => {
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self.shift(1);
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body.push(tt.clone());
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break;
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},
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[ref tt, ..] => {
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self.shift(1);
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body.push(tt.clone());
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},
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_ => parse_error!(self, sp, "invalid @match pattern"),
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}}
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let mut expr = Vec::new();
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loop { match *self.input {
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[TokenTree::Delimited(sp, ref d), ..] if d.delim == DelimToken::Brace => {
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if expr.is_empty() {
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self.shift(1);
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expr = self.block(sp, &d.tts)?.to_tokens(self.render.cx);
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break;
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} else {
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self.shift(1);
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expr.push(TokenTree::Delimited(sp, d.clone()));
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}
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},
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[comma!(), ..] | [] => {
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if expr.is_empty() {
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parse_error!(self, sp, "expected body for this @match arm");
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} else {
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expr = self.block(sp, &expr)?.to_tokens(self.render.cx);
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break;
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}
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},
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[ref tt, ..] => {
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self.shift(1);
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expr.push(tt.clone());
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},
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}}
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body.push(TokenTree::Delimited(sp, Rc::new(Delimited {
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delim: DelimToken::Brace,
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open_span: sp,
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tts: expr,
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close_span: sp,
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})));
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Ok(body)
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}
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/// Parses and renders an element node.
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///
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/// The element name should already be consumed.
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fn element(&mut self, sp: Span, name: &str) -> PResult<()> {
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if self.in_attr {
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parse_error!(self, sp, "unexpected element, you silly bumpkin");
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}
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self.render.element_open_start(name);
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self.attrs()?;
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self.render.element_open_end();
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if let [slash!(), ..] = *self.input {
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self.shift(1);
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} else {
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self.markup()?;
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self.render.element_close(name);
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}
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Ok(())
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}
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/// Parses and renders the attributes of an element.
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fn attrs(&mut self) -> PResult<()> {
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let mut classes = Vec::new();
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let mut ids = Vec::new();
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loop {
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let old_input = self.input;
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let maybe_name = self.namespaced_name();
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match (maybe_name, self.input) {
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(Ok(name), &[eq!(), ..]) => {
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// Non-empty attribute
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self.shift(1);
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self.render.attribute_start(&name);
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{
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// Parse a value under an attribute context
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let mut in_attr = true;
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mem::swap(&mut self.in_attr, &mut in_attr);
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self.markup()?;
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mem::swap(&mut self.in_attr, &mut in_attr);
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}
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self.render.attribute_end();
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},
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(Ok(name), &[question!(), ..]) => {
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// Empty attribute
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self.shift(1);
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match *self.input {
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[TokenTree::Delimited(_, ref d), ..] if d.delim == DelimToken::Paren => {
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// Toggle the attribute based on a boolean expression
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self.shift(1);
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let cond = self.with_rust_parser(d.tts.clone(), RustParser::parse_expr)?;
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let cond = cond.to_tokens(self.render.cx);
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let body = {
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let mut r = self.render.fork();
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r.attribute_empty(&name);
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r.into_stmts()
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};
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self.render.emit_if(cond, body, None);
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},
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_ => {
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// Write the attribute unconditionally
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self.render.attribute_empty(&name);
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},
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}
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},
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(Err(_), &[dot!(), ident!(_, _), ..]) => {
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// Class shorthand
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self.shift(1);
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classes.push(self.name().unwrap());
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},
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(Err(_), &[pound!(), ident!(_, _), ..]) => {
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// ID shorthand
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self.shift(1);
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ids.push(self.name().unwrap());
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},
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_ => {
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self.input = old_input;
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break;
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},
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}
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}
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if !classes.is_empty() {
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self.render.attribute_start("class");
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self.render.string(&classes.join(" "));
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self.render.attribute_end();
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}
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if !ids.is_empty() {
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self.render.attribute_start("id");
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self.render.string(&ids.join(" "));
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self.render.attribute_end();
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}
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Ok(())
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}
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/// Parses an identifier, without dealing with namespaces.
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fn name(&mut self) -> PResult<String> {
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let mut s = match *self.input {
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[ident!(_, name), ..] => {
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self.shift(1);
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String::from(&name.name.as_str() as &str)
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},
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_ => return Err(FatalError),
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};
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let mut expect_ident = false;
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loop {
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expect_ident = match *self.input {
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[minus!(), ..] => {
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self.shift(1);
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s.push('-');
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true
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},
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[ident!(_, name), ..] if expect_ident => {
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self.shift(1);
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s.push_str(&name.name.as_str());
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false
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},
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_ => break,
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};
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}
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Ok(s)
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}
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/// Parses a HTML element or attribute name, along with a namespace
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/// if necessary.
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fn namespaced_name(&mut self) -> PResult<String> {
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let mut s = self.name()?;
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if let [colon!(), ident!(_, _), ..] = *self.input {
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self.shift(1);
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s.push(':');
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s.push_str(&self.name().unwrap());
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}
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Ok(s)
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}
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/// Parses the given token tree, returning a vector of statements.
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fn block(&mut self, sp: Span, tts: &[TokenTree]) -> PResult<Vec<Stmt>> {
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let mut parse = Parser {
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in_attr: self.in_attr,
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input: tts,
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span: sp,
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render: self.render.fork(),
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};
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parse.markups()?;
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Ok(parse.into_render().into_stmts())
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}
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}
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