Rust Pattern Matching
Syntax
- _ // wildcard pattern, matches anything¹
- ident // binding pattern, matches anything and binds it to ident¹
- ident @ pat // same as above, but allow to further match what is binded
- ref ident // binding pattern, matches anything and binds it to a reference ident¹
- ref mut ident // binding pattern, matches anything and binds it to a mutable reference ident¹
- &pat // matches a reference (pat is therefore not a reference but the referee)¹
- &mut pat // same as above with a mutable reference¹
- CONST // matches a named constant
- Struct { field1, field2 } // matches and deconstructs a structure value, see below the note about fields¹
- EnumVariant // matches an enumeration variant
- EnumVariant(pat1, pat2) // matches a enumeration variant and the corresponding parameters
- EnumVariant(pat1, pat2, .., patn) // same as above but skips all but the first, second and last parameters
- (pat1, pat2) // matches a tuple and the corresponding elements¹
- (pat1, pat2, .., patn) // same as above but skips all but the first, second and last elements¹
- lit // matches a literal constant (char, numeric types, boolean and string)
- pat1...pat2 // matches a value in that (inclusive) range (char and numeric types)
Remarks
When deconstructing a structure value, the field should be either of the form field_name or field_name: pattern. If no pattern is specified, an implicit binding is done:
let Point { x, y } = p;
// equivalent to
let Point { x: x, y: y } = p;
let Point { ref x, ref y } = p;
// equivalent to
let Point { x: ref x, y: ref y } = p;
1: Irrefutable pattern
