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Document that literals with any suffixes are valid as tokens #612

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merged 3 commits into from
May 31, 2019
Merged

Document that literals with any suffixes are valid as tokens #612

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66416bc
Document that literals with any suffixes are valid as tokens
petrochenkov May 31, 2019
fbff649
Tell what a literal suffix is
petrochenkov May 31, 2019
8c75c7a
Update src/tokens.md
petrochenkov May 31, 2019
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19 changes: 18 additions & 1 deletion src/tokens.md
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Expand Up @@ -32,7 +32,7 @@ evaluated (primarily) at compile time.
|----------------------------------------------|-----------------|-------------|-------------|---------------------|
| [Character](#character-literals) | `'H'` | 0 | All Unicode | [Quote](#quote-escapes) & [ASCII](#ascii-escapes) & [Unicode](#unicode-escapes) |
| [String](#string-literals) | `"hello"` | 0 | All Unicode | [Quote](#quote-escapes) & [ASCII](#ascii-escapes) & [Unicode](#unicode-escapes) |
| [Raw](#raw-string-literals) | `r#"hello"#` | 0 or more\* | All Unicode | `N/A` |
| [Raw string](#raw-string-literals) | `r#"hello"#` | 0 or more\* | All Unicode | `N/A` |
| [Byte](#byte-literals) | `b'H'` | 0 | All ASCII | [Quote](#quote-escapes) & [Byte](#byte-escapes) |
| [Byte string](#byte-string-literals) | `b"hello"` | 0 | All ASCII | [Quote](#quote-escapes) & [Byte](#byte-escapes) |
| [Raw byte string](#raw-byte-string-literals) | `br#"hello"#` | 0 or more\* | All ASCII | `N/A` |
Expand Down Expand Up @@ -88,6 +88,23 @@ evaluated (primarily) at compile time.

#### Suffixes

A suffix is a non-raw identifier immediately (without whitespace)
following the primary part of a literal.

Any kind of literal (string, integer, etc) with any suffix is valid as a token,
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and can be passed to a macro without producing an error.
The macro itself will decide how to interpret such a token and whether to produce an error or not.

```rust
macro_rules! blackhole { ($tt:tt) => () }

blackhole!("string"suffix); // OK
```

However, suffixes on literal tokens parsed as Rust code are restricted.
Any suffixes are rejected on non-numeric literal tokens,
and numeric literal tokens are accepted only with suffixes from the list below.

| Integer | Floating-point |
|---------|----------------|
| `u8`, `i8`, `u16`, `i16`, `u32`, `i32`, `u64`, `i64`, `u128`, `i128`, `usize`, `isize` | `f32`, `f64` |
Expand Down