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https://github.com/dtolnay/thiserror.git
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Import expr scanner from syn 2.0.87
This commit is contained in:
David Tolnay
parent
561e29eb80
commit
c0050558f7
3 changed files with 266 additions and 1 deletions
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@ -14,7 +14,7 @@ proc-macro = true
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[dependencies]
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proc-macro2 = "1.0.74"
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quote = "1.0.35"
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syn = "2.0.86"
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syn = "2.0.87"
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[package.metadata.docs.rs]
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targets = ["x86_64-unknown-linux-gnu"]
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@ -23,6 +23,7 @@ mod expand;
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mod fmt;
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mod generics;
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mod prop;
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mod scan_expr;
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mod span;
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mod valid;
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264
impl/src/scan_expr.rs
Normal file
264
impl/src/scan_expr.rs
Normal file
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@ -0,0 +1,264 @@
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use self::{Action::*, Input::*};
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use proc_macro2::{Delimiter, Ident, Spacing, TokenTree};
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use syn::parse::{ParseStream, Result};
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use syn::{AngleBracketedGenericArguments, BinOp, Expr, ExprPath, Lifetime, Lit, Token, Type};
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enum Input {
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Keyword(&'static str),
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Punct(&'static str),
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ConsumeAny,
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ConsumeBinOp,
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ConsumeBrace,
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ConsumeDelimiter,
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ConsumeIdent,
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ConsumeLifetime,
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ConsumeLiteral,
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ConsumeNestedBrace,
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ExpectPath,
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ExpectTurbofish,
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ExpectType,
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CanBeginExpr,
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Otherwise,
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Empty,
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}
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enum Action {
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SetState(&'static [(Input, Action)]),
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IncDepth,
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DecDepth,
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Finish,
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}
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static INIT: [(Input, Action); 28] = [
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(ConsumeDelimiter, SetState(&POSTFIX)),
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(Keyword("async"), SetState(&ASYNC)),
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(Keyword("break"), SetState(&BREAK_LABEL)),
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(Keyword("const"), SetState(&CONST)),
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(Keyword("continue"), SetState(&CONTINUE)),
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(Keyword("for"), SetState(&FOR)),
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(Keyword("if"), IncDepth),
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(Keyword("let"), SetState(&PATTERN)),
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(Keyword("loop"), SetState(&BLOCK)),
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(Keyword("match"), IncDepth),
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(Keyword("move"), SetState(&CLOSURE)),
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(Keyword("return"), SetState(&RETURN)),
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(Keyword("static"), SetState(&CLOSURE)),
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(Keyword("unsafe"), SetState(&BLOCK)),
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(Keyword("while"), IncDepth),
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(Keyword("yield"), SetState(&RETURN)),
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(Keyword("_"), SetState(&POSTFIX)),
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(Punct("!"), SetState(&INIT)),
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(Punct("#"), SetState(&[(ConsumeDelimiter, SetState(&INIT))])),
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(Punct("&"), SetState(&REFERENCE)),
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(Punct("*"), SetState(&INIT)),
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(Punct("-"), SetState(&INIT)),
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(Punct("..="), SetState(&INIT)),
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(Punct(".."), SetState(&RANGE)),
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(Punct("|"), SetState(&CLOSURE_ARGS)),
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(ConsumeLifetime, SetState(&[(Punct(":"), SetState(&INIT))])),
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(ConsumeLiteral, SetState(&POSTFIX)),
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(ExpectPath, SetState(&PATH)),
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];
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static POSTFIX: [(Input, Action); 10] = [
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(Keyword("as"), SetState(&[(ExpectType, SetState(&POSTFIX))])),
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(Punct("..="), SetState(&INIT)),
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(Punct(".."), SetState(&RANGE)),
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(Punct("."), SetState(&DOT)),
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(Punct("?"), SetState(&POSTFIX)),
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(ConsumeBinOp, SetState(&INIT)),
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(Punct("="), SetState(&INIT)),
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(ConsumeNestedBrace, SetState(&IF_THEN)),
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(ConsumeDelimiter, SetState(&POSTFIX)),
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(Empty, Finish),
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];
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static ASYNC: [(Input, Action); 3] = [
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(Keyword("move"), SetState(&ASYNC)),
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(Punct("|"), SetState(&CLOSURE_ARGS)),
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(ConsumeBrace, SetState(&POSTFIX)),
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];
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static BLOCK: [(Input, Action); 1] = [(ConsumeBrace, SetState(&POSTFIX))];
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static BREAK_LABEL: [(Input, Action); 2] = [
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(ConsumeLifetime, SetState(&BREAK_VALUE)),
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(Otherwise, SetState(&BREAK_VALUE)),
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];
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static BREAK_VALUE: [(Input, Action); 3] = [
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(ConsumeNestedBrace, SetState(&IF_THEN)),
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(CanBeginExpr, SetState(&INIT)),
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(Otherwise, SetState(&POSTFIX)),
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];
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static CLOSURE: [(Input, Action); 6] = [
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(Keyword("async"), SetState(&CLOSURE)),
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(Keyword("move"), SetState(&CLOSURE)),
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(Punct(","), SetState(&CLOSURE)),
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(Punct(">"), SetState(&CLOSURE)),
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(Punct("|"), SetState(&CLOSURE_ARGS)),
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(ConsumeLifetime, SetState(&CLOSURE)),
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];
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static CLOSURE_ARGS: [(Input, Action); 2] = [
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(Punct("|"), SetState(&CLOSURE_RET)),
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(ConsumeAny, SetState(&CLOSURE_ARGS)),
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];
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static CLOSURE_RET: [(Input, Action); 2] = [
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(Punct("->"), SetState(&[(ExpectType, SetState(&BLOCK))])),
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(Otherwise, SetState(&INIT)),
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];
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static CONST: [(Input, Action); 2] = [
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(Punct("|"), SetState(&CLOSURE_ARGS)),
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(ConsumeBrace, SetState(&POSTFIX)),
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];
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static CONTINUE: [(Input, Action); 2] = [
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(ConsumeLifetime, SetState(&POSTFIX)),
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(Otherwise, SetState(&POSTFIX)),
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];
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static DOT: [(Input, Action); 3] = [
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(Keyword("await"), SetState(&POSTFIX)),
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(ConsumeIdent, SetState(&METHOD)),
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(ConsumeLiteral, SetState(&POSTFIX)),
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];
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static FOR: [(Input, Action); 2] = [
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(Punct("<"), SetState(&CLOSURE)),
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(Otherwise, SetState(&PATTERN)),
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];
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static IF_ELSE: [(Input, Action); 2] = [(Keyword("if"), SetState(&INIT)), (ConsumeBrace, DecDepth)];
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static IF_THEN: [(Input, Action); 2] =
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[(Keyword("else"), SetState(&IF_ELSE)), (Otherwise, DecDepth)];
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static METHOD: [(Input, Action); 1] = [(ExpectTurbofish, SetState(&POSTFIX))];
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static PATH: [(Input, Action); 4] = [
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(Punct("!="), SetState(&INIT)),
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(Punct("!"), SetState(&INIT)),
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(ConsumeNestedBrace, SetState(&IF_THEN)),
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(Otherwise, SetState(&POSTFIX)),
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];
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static PATTERN: [(Input, Action); 15] = [
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(ConsumeDelimiter, SetState(&PATTERN)),
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(Keyword("box"), SetState(&PATTERN)),
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(Keyword("in"), IncDepth),
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(Keyword("mut"), SetState(&PATTERN)),
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(Keyword("ref"), SetState(&PATTERN)),
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(Keyword("_"), SetState(&PATTERN)),
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(Punct("!"), SetState(&PATTERN)),
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(Punct("&"), SetState(&PATTERN)),
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(Punct("..="), SetState(&PATTERN)),
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(Punct(".."), SetState(&PATTERN)),
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(Punct("="), SetState(&INIT)),
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(Punct("@"), SetState(&PATTERN)),
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(Punct("|"), SetState(&PATTERN)),
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(ConsumeLiteral, SetState(&PATTERN)),
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(ExpectPath, SetState(&PATTERN)),
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];
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static RANGE: [(Input, Action); 6] = [
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(Punct("..="), SetState(&INIT)),
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(Punct(".."), SetState(&RANGE)),
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(Punct("."), SetState(&DOT)),
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(ConsumeNestedBrace, SetState(&IF_THEN)),
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(Empty, Finish),
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(Otherwise, SetState(&INIT)),
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];
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static RAW: [(Input, Action); 3] = [
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(Keyword("const"), SetState(&INIT)),
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(Keyword("mut"), SetState(&INIT)),
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(Otherwise, SetState(&POSTFIX)),
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];
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static REFERENCE: [(Input, Action); 3] = [
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(Keyword("mut"), SetState(&INIT)),
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(Keyword("raw"), SetState(&RAW)),
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(Otherwise, SetState(&INIT)),
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];
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static RETURN: [(Input, Action); 2] = [
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(CanBeginExpr, SetState(&INIT)),
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(Otherwise, SetState(&POSTFIX)),
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];
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pub(crate) fn scan_expr(input: ParseStream) -> Result<()> {
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let mut state = INIT.as_slice();
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let mut depth = 0usize;
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'table: loop {
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for rule in state {
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if match rule.0 {
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Input::Keyword(expected) => input.step(|cursor| match cursor.ident() {
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Some((ident, rest)) if ident == expected => Ok((true, rest)),
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_ => Ok((false, *cursor)),
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})?,
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Input::Punct(expected) => input.step(|cursor| {
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let begin = *cursor;
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let mut cursor = begin;
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for (i, ch) in expected.chars().enumerate() {
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match cursor.punct() {
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Some((punct, _)) if punct.as_char() != ch => break,
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Some((_, rest)) if i == expected.len() - 1 => {
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return Ok((true, rest));
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}
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Some((punct, rest)) if punct.spacing() == Spacing::Joint => {
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cursor = rest;
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}
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_ => break,
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}
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}
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Ok((false, begin))
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})?,
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Input::ConsumeAny => input.parse::<Option<TokenTree>>()?.is_some(),
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Input::ConsumeBinOp => input.parse::<BinOp>().is_ok(),
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Input::ConsumeBrace | Input::ConsumeNestedBrace => {
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(matches!(rule.0, Input::ConsumeBrace) || depth > 0)
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&& input.step(|cursor| match cursor.group(Delimiter::Brace) {
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Some((_inside, _span, rest)) => Ok((true, rest)),
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None => Ok((false, *cursor)),
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})?
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}
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Input::ConsumeDelimiter => input.step(|cursor| match cursor.any_group() {
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Some((_inside, _delimiter, _span, rest)) => Ok((true, rest)),
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None => Ok((false, *cursor)),
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})?,
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Input::ConsumeIdent => input.parse::<Option<Ident>>()?.is_some(),
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Input::ConsumeLifetime => input.parse::<Option<Lifetime>>()?.is_some(),
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Input::ConsumeLiteral => input.parse::<Option<Lit>>()?.is_some(),
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Input::ExpectPath => {
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input.parse::<ExprPath>()?;
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true
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}
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Input::ExpectTurbofish => {
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if input.peek(Token![::]) {
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input.parse::<AngleBracketedGenericArguments>()?;
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}
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true
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}
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Input::ExpectType => {
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Type::without_plus(input)?;
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true
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}
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Input::CanBeginExpr => Expr::peek(input),
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Input::Otherwise => true,
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Input::Empty => input.is_empty() || input.peek(Token![,]),
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} {
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state = match rule.1 {
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Action::SetState(next) => next,
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Action::IncDepth => (depth += 1, &INIT).1,
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Action::DecDepth => (depth -= 1, &POSTFIX).1,
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Action::Finish => return if depth == 0 { Ok(()) } else { break },
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};
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continue 'table;
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}
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}
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return Err(input.error("unsupported expression"));
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}
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}
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