The match keyword is a control flow construct that allows a program to match a value against a set of patterns and execute code based on the match result. The match keyword statement is similar to a switch keyword statement in other languages, but match provides more powerful pattern matching capabilities.
A match statement typically has the following syntax:
match <value> {
<pattern_1> => <code_1>,
<pattern_2> => <code_2>,
...
<pattern_n> => <code_n>,
}The <value> is the expression that is being matched against, and the <pattern> expressions are the patterns that are being matched. Each <pattern> is followed by a => symbol, then a block of code that will be executed if the pattern matches the value.
In Rust, a pattern can take many forms, including literal values (e.g. 42, "hello"), variables (e.g. x, y), wldcards (e.g. _), ranges (e.g. 1..=5), enums (e.g. Some(value)), structs (e.g. Point { x, y }), tuples (e.g. (x, y)), and more.
The code in each match arm is executed if the pattern on the left-hand side of the => operator matches the value being matched. If none of the patterns match, the match statement will panic at runtime.
Rust's match statements are powerful and flexible, allowing for complex patterns and expressions to be matched. Match statements are commonly used in Rust to handle errors, parse command-line arguments, and implement state machines, among other use cases.
Overall, match statements are a key feature of Rust's control flow syntax, and provide a powerful mechanism for pattern matching and value extraction in Rust programs.