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diff --git a/src/doc/book/nostarch/appendix_b.md b/src/doc/book/nostarch/appendix_b.md new file mode 100644 index 000000000..236608b6d --- /dev/null +++ b/src/doc/book/nostarch/appendix_b.md @@ -0,0 +1,241 @@ +<!-- DO NOT EDIT THIS FILE. + +This file is periodically generated from the content in the `/src/` +directory, so all fixes need to be made in `/src/`. +--> + +[TOC] + +## Appendix B: Operators and Symbols + +This appendix contains a glossary of Rust’s syntax, including operators and +other symbols that appear by themselves or in the context of paths, generics, +trait bounds, macros, attributes, comments, tuples, and brackets. + +## Operators + +Table B-1 contains the operators in Rust, an example of how the operator would +appear in context, a short explanation, and whether that operator is +overloadable. If an operator is overloadable, the relevant trait to use to +overload that operator is listed. + +Table B-1: Operators + +| Operator | Example | Explanation | Overloadable? | +|---|---|---|---| +| `!` | `ident!(...)`, `ident!{...}`, `ident![...]` | Macro expansion | | +| `!` | `!expr` | Bitwise or logical complement | `Not` | +| `!=` | `expr != expr` | Nonequality comparison | `PartialEq` | +| `%` | `expr % expr` | Arithmetic remainder | `Rem` | +| `%=` | `var %= expr` | Arithmetic remainder and assignment | `RemAssign` | +| `&` | `&expr`, `&mut expr` | Borrow | | +| `&` | `&type`, `&mut type`, `&'a type`, `&'a mut type` | Borrowed pointer +type | | +| `&` | `expr & expr` | Bitwise AND | `BitAnd` | +| `&=` | `var &= expr` | Bitwise AND and assignment | `BitAndAssign` | +| `&&` | `expr && expr` | Short-circuiting logical AND | | +| `*` | `expr * expr` | Arithmetic multiplication | `Mul` | +| `*=` | `var *= expr` | Arithmetic multiplication and assignment | `MulAssign` +| +| `*` | `*expr` | Dereference | `Deref` | +| `*` | `*const type`, `*mut type` | Raw pointer | | +| `+` | `trait + trait`, `'a + trait` | Compound type constraint | | +| `+` | `expr + expr` | Arithmetic addition | `Add` | +| `+=` | `var += expr` | Arithmetic addition and assignment | `AddAssign` | +| `,` | `expr, expr` | Argument and element separator | | +| `-` | `- expr` | Arithmetic negation | `Neg` | +| `-` | `expr - expr` | Arithmetic subtraction | `Sub` | +| `-=` | `var -= expr` | Arithmetic subtraction and assignment | `SubAssign` | +| `->` | `fn(...) -> type`, `|…| -> type` | Function and closure return type | +| +| `. | `expr.ident` | Member access | | +| `..` | `..`, `expr..`, `..expr`, `expr..expr` | Right-exclusive range literal +| `PartialOrd` | +| `..=` | `..=expr`, `expr..=expr` | Right-inclusive range literal | +`PartialOrd` | +| `..` | `..expr` | Struct literal update syntax | | +| `..` | `variant(x, ..)`, `struct_type { x, .. }` | “And the rest” pattern +binding | | +| `...` | `expr...expr` | (Deprecated, use `..=` instead) In a pattern: +inclusive range pattern | | +| `/` | `expr / expr` | Arithmetic division | `Div` | +| `/=` | `var /= expr` | Arithmetic division and assignment | `DivAssign` | +| `: | `pat: type`, `ident: type` | Constraints | | +| `:` | `ident: expr` | Struct field initializer | | +| `:` | `'a: loop {...}` | Loop label | | +| `;` | `expr;` | Statement and item terminator | | +| `;` | `[...; len]` | Part of fixed-size array syntax | | +| `<<` | `expr << expr` | Left-shift | `Shl` | +| `<<=` | `var <<= expr` | Left-shift and assignment | `ShlAssign` | +| `<` | `expr < expr` | Less than comparison | `PartialOrd` | +| `<=` | `expr <= expr` | Less than or equal to comparison | `PartialOrd` | +| `=` | `var = expr`, `ident = type` | Assignment/equivalence | | +| `==` | `expr == expr` | Equality comparison | `PartialEq` | +| `=>` | `pat => expr` | Part of match arm syntax | | +| `>` | `expr > expr` | Greater than comparison | `PartialOrd` | +| `>=` | `expr >= expr` | Greater than or equal to comparison | `PartialOrd` | +| `>>` | `expr >> expr` | Right-shift | `Shr` | +| `>>=` | `var >>= expr` | Right-shift and assignment | `ShrAssign` | +| `@` | `ident @ pat` | Pattern binding | | +| `^` | `expr ^ expr` | Bitwise exclusive OR | `BitXor` | +| `^=` | `var ^= expr` | Bitwise exclusive OR and assignment | `BitXorAssign` | +| `|` | `pat | pat` | Pattern alternatives | | +| `|` | `expr | expr` | Bitwise OR | `BitOr` | +| `|=` | `var |= expr` | Bitwise OR and assignment | `BitOrAssign` | +| `||` | `expr || expr` | Short-circuiting logical OR | | +| `?` | `expr?` | Error propagation | | + +## Non-operator Symbols + +The following tables contain all symbols that don’t function as operators; that +is, they don’t behave like a function or method call. + +Table B-2 shows symbols that appear on their own and are valid in a variety of +locations. + +Table B-2: Stand-Alone Syntax + +| Symbol | Explanation | +|---|---| +| `'ident` | Named lifetime or loop label | +| `...u8`, `...i32`, `...f64`, `...usize`, and so on | Numeric literal of +specific type | +| `"..."` | String literal | +| `r"..."`, `r#"..."#`, `r##"..."##`, and so on | Raw string literal; escape +characters not processed | +| `b"..."` | Byte string literal; constructs an array of bytes instead of a +string | +| `br"..."`, `br#"..."#`, `br##"..."##`, and so on | Raw byte string literal; +combination of raw and byte string literal | +| `'...'` | Character literal | +| `b'...'` | ASCII byte literal | +| `|…| expr` | Closure | +| `!` | Always-empty bottom type for diverging functions | +| `_` | “Ignored” pattern binding; also used to make integer literals readable | + +Table B-3 shows symbols that appear in the context of a path through the module +hierarchy to an item. + +Table B-3: Path-Related Syntax + +| Symbol | Explanation | +|---|---| +| `ident::ident` | Namespace path | +| `::path` | Path relative to the crate root (that is, an explicitly absolute +path) | +| `self::path` | Path relative to the current module (that is, an explicitly +relative path) | +| `super::path` | Path relative to the parent of the current module | +| `type::ident`, `<type as trait>::ident` | Associated constants, functions, +and types | +| `<type>::...` | Associated item for a type that cannot be directly named (for +example, `<&T>::...`, `<[T]>::...`, and so on) | +| `trait::method(...)` | Disambiguating a method call by naming the trait that +defines it | +| `type::method(...)` | Disambiguating a method call by naming the type for +which it’s defined | +| `<type as trait>::method(...)` | Disambiguating a method call by naming the +trait and type | + +Table B-4 shows symbols that appear in the context of using generic type +parameters. + +Table B-4: Generics + +| Symbol | Explanation | +|---|---| +| `path<...>` | Specifies parameters to a generic type in a type (for example, +`Vec<u8>`) | +| `path::<...>, method::<...>` | Specifies parameters to a generic type, +function, or method in an expression; often referred to as turbofish (for +example, `"42".parse::<i32>()`) | +| `fn ident<...> ...` | Define generic function | +| `struct ident<...> ...` | Define generic structure | +| `enum ident<...> ...` | Define generic enumeration | +| `impl<...> ...` | Define generic implementation | +| `for<...> type` | Higher-ranked lifetime bounds | +| `type<ident=type>` | A generic type where one or more associated types have +specific assignments (for example, `Iterator<Item=T>`) | + +Table B-5 shows symbols that appear in the context of constraining generic type +parameters with trait bounds. + +Table B-5: Trait Bound Constraints + +| Symbol | Explanation | +|---|---| +| T: U` | Generic parameter `T` constrained to types that implement `U` | +| `T: 'a` | Generic type `T` must outlive lifetime `'a` (meaning the type +cannot transitively contain any references with lifetimes shorter than `'a`) | +| `T: 'static` | Generic type `T` contains no borrowed references other than +`'static` ones | +| `'b: 'a` | Generic lifetime `'b` must outlive lifetime `'a` | +| `T: ?Sized` | Allow generic type parameter to be a dynamically sized type | +| `'a + trait`, `trait + trait` | Compound type constraint | + +Table B-6 shows symbols that appear in the context of calling or defining +macros and specifying attributes on an item. + +Table B-6: Macros and Attributes + +| Symbol | Explanation | +|---|---| +| `#[meta]` | Outer attribute | +| `#![meta]` | Inner attribute | +| `$ident` | Macro substitution | +| `$ident:kind` | Macro capture | +| `$(…)…` | Macro repetition | +| `ident!(...)`, `ident!{...}`, `ident![...]` | Macro invocation | + +Table B-7 shows symbols that create comments. + +Table B-7: Comments + +| Symbol | Explanation | +|---|---| +| `//` | Line comment | +| `//!` | Inner line doc comment | +| `///` | Outer line doc comment | +| `/*...*/` | Block comment | +| `/*!...*/` | Inner block doc comment | +| `/**...*/` | Outer block doc comment | + +Table B-8 shows symbols that appear in the context of using tuples. + +Table B-8: Tuples + +| Symbol | Explanation | +|---|---| +| `()` | Empty tuple (aka unit), both literal and type | +| `(expr)` | Parenthesized expression | +| `(expr,)` | Single-element tuple expression | +| `(type,)` | Single-element tuple type | +| `(expr, ...)` | Tuple expression | +| `(type, ...)` | Tuple type | +| `expr(expr, ...)` | Function call expression; also used to initialize tuple +`struct`s and tuple `enum` variants | +| `expr.0`, `expr.1`, and so on | Tuple indexing | + +Table B-9 shows the contexts in which curly brackets are used. + +Table B-9: Curly Brackets + +| Context | Explanation | +|---|---| +| `{...}` | Block expression | +| `Type {...}` | `struct` literal | + +Table B-10 shows the contexts in which square brackets are used. + +Table B-10: Square Brackets + +| Context | Explanation | +|---|---| +| `[...]` | Array literal | +| `[expr; len]` | Array literal containing `len` copies of `expr` | +| `[type; len]` | Array type containing `len` instances of `type` | +| `expr[expr]` | Collection indexing; overloadable (`Index`, `IndexMut`) | +| `expr[..]`, `expr[a..]`, `expr[..b]`, `expr[a..b]` | Collection indexing +pretending to be collection slicing, using `Range`, `RangeFrom`, `RangeTo`, or +`RangeFull` as the “index” | + |