rust-quiz:022-macro-tokenize-number.rs

rust-quiz:001-macro-count-statements.rs rust-quiz:002-bitand-or-reference.rs rust-quiz:003-mutate-const.rs rust-quiz:004-dotdot-in-tuple.rs rust-quiz:005-trait-resolution-hrtb.rs rust-quiz:006-value-of-assignment.rs rust-quiz:007-surprise-wildcard-match.rs rust-quiz:008-tokenize-punctuation.rs rust-quiz:009-opaque-metavariable.rs rust-quiz:010-shadowed-trait-object-method.rs rust-quiz:011-function-pointer-comparison.rs rust-quiz:012-binding-drop-behavior.rs rust-quiz:013-mutable-zst.rs rust-quiz:014-trait-autoref.rs rust-quiz:015-inference-of-number-type.rs rust-quiz:016-prefix-decrement.rs rust-quiz:017-unary-decrement.rs rust-quiz:018-method-or-function-pointer.rs rust-quiz:019-dropped-by-underscore.rs rust-quiz:020-break-return-in-condition.rs rust-quiz:021-closure-or-logical-or.rs rust-quiz:022-macro-tokenize-number.rs rust-quiz:023-inherent-vs-trait-method.md rust-quiz:024-local-and-const-hygiene.rs rust-quiz:025-unit-infallible-match.rs rust-quiz:026-iterator-lazy-map.rs rust-quiz:027-subtrait-dispatch.rs rust-quiz:028-underscore-prefix.rs rust-quiz:029-tuple-trailing-commas.rs rust-quiz:030-clone-pointers.rs rust-quiz:031-method-lookup.rs rust-quiz:032-or-pattern-guard.rs rust-quiz:033-range-full-method.rs

macro_rules! m {
    ($a:tt) => { print!("1") };
    ($a:tt $b:tt) => { print!("2") };
    ($a:tt $b:tt $c:tt) => { print!("3") };
    ($a:tt $b:tt $c:tt $d:tt) => { print!("4") };
    ($a:tt $b:tt $c:tt $d:tt $e:tt) => { print!("5") };
    ($a:tt $b:tt $c:tt $d:tt $e:tt $f:tt) => { print!("6") };
    ($a:tt $b:tt $c:tt $d:tt $e:tt $f:tt $g:tt) => { print!("7") };
}

fn main() {
    m!(-1);
    m!(-1.);
    m!(-1.0);
    m!(-1.0e1);
    m!(-1.0e-1);
}

-
負號-是獨立進行解析的，如果不進行特殊宣告，計算的時候也會分離。
```
let a = -2i32.pow(2); // -4
let b = (-2i32).pow(2); // 4
```
integer
數值都是整體當做一個`token``進行解析。

這裡主要檢測TokenTree的數量，按照上述的原理，其實全部匹配的都是2。

22222

本作品採用《CC 協議》，轉載必須註明作者和本文連結

rust-quiz:022-macro-tokenize-number.rs

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