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pub struct MatchIndices<'a, P>MatchIndices — Created with the method match_indices.
...DefId) -> ParamEnv<'tcx> {
if tcx.describe_def(def_id) match Some(Def::Existential(_))
&& tcx.hir.as_local_node_id(def_id) match Some(node_id)
&& tcx.hir.get(node_id) match hir::map::NodeItem(item)
&& item.node match hir::ItemExistential(ref exist_ty)
&& exist_ty.impl_trait_fn match Some...
...must_match takes 1 string argument. It will error if the field mentioned is missing or has a different type than the field the attribute is on. Examples: #[validate(must_match = "password2")] #[validate(must_match(other = "password2"))] contains Tests whether the string contains the substring given or if a key...
...We can match on this to call the appropriate visitor methods. Here is a cut down
version of deserialize_any:
fn deserialize_any<V>(mut self, v: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
match self.tag {
Tag::Byte => v.visit_i8(self.de.input.consume_byte()? as...
Strongly Typed Mimes mime Support MIME (Media Types) as strong types in Rust. Documentation Usage extern crate mime; // common types are constants let text = mime::TEXT_PLAIN; // deconstruct Mimes to match on them match (text.type_(), text.subtype()) { (mime::TEXT, mime::PLAIN) => { // plain text! }, (mime::TEXT, _) => { // structured text! }, _ => { // not text! } }
...When we apply `match` to a
dereferenced borrowed pointer, we cannot move because we don't have
ownership. Changing the `match_and_print` function to take a value
would work again.
~~~{.rust}
fn match_and_print(e: MyEnum) {
match e {
MyEnum::X(x) => println!("{}", x),
MyEnum::Y(y) => println!("{}", *y...
pub fn rsplit<P>(&self, pat: P) -> RSplit<'_, P>str::rsplit — Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern and yielded in reverse order.
The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.
Iterator behavior
The returned...
...Dots (.) between field names denote concatenation-- "match this field, then that field":$ cat sample.json | jg 'roommates[0].name'
roommates.[0].name:
"Alice"BashWildcards match any single key (*) or any array index ([*]):$ cat sample.json | jg 'favorite_drinks[*]'
favorite_drinks.[0]:
"coffee"
favorite_drinks.[1]:
"Dr. Pepper"
favorite_drinks.[2...
pub fn split_terminator<P>(&self, pat: P) -> SplitTerminator<'_, P>str::split_terminator — Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern.
The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.
Equivalent to split, except that the trailing substring...
...dev is fuzzy local versions on top of all the others, which are added with a + and have implicitly typed string and number segments no semver-caret ( ^ ), but a pseudo-semver tilde ( ~= ) ordering contradicts matching: We have e.g. 1.0+local > 1.0 when sorting, but ==1.0 matches...
...let mut result = match results.get_mut(i) {
Some(v) => v,
None => panic!("error! no value!")
};
The return value of get_mut() is just an enum, but in Rust enums may contain additionally a value. This leads to constructs like above. The match keyword introduces a pattern matching construct and...
...let index_quote = {
let match_quote = _mm256_cmpeq_epi8(block, _mm256_set1_epi8(b'"' as i8));
let index_quote = _mm256_movemask_epi8(match_quote);
let match_escape = _mm256_cmpeq_epi8(block, _mm256_set1_epi8(b'\\' as i8));
let index_escape = _mm256_movemask_epi8(match_escape);
index_quote | index_escape
};
The...
...Token) -> bool {
self.tokens.get(self.pos) == Some(&expected)
}
fn expect_identifier(&mut self) -> anyhow::Result<&str> {
self.expect_matching(|t| matches!(t, Token::Identifier(_)))
.map(|t| t.as_identifier().unwrap())
}
fn expect_eq(&mut self, expected: Token) -> anyhow::Result<&Token> {
self.expect_matching(|t| *t == expected)
}
fn expect_matching...
...let mut s = String::new();
match process.stdout.unwrap().read_to_string(&mut s) {
Err(why) => panic!("couldn't read wc stdout: {}", why),
Ok(_) => print!("wc responded with:\n{}", s),
}
}
...The language models it as an enum with generics on each value:
#[derive(Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
pub enum Result<T, E> {
Ok(T),
Err(E),
}
Because Rust manages completeness of matches, matching on Result enforces that you handle both branches:
match fn_that_returns_a_result...
...rust-lang/rust#44495
Summary
Currently when using an if let statement and an irrefutable pattern (read always match) is used the compiler complains with an E0162: irrefutable if-let pattern.
The current state breaks macros who want to accept patterns generically and this RFC proposes changing this error to...
...Vec<String>) -> Result<Matches, ParseError> {
let mut args_iter = args.into_iter();
let exec_name = match args_iter.next() {
Some(s) => s,
None => return Err(ParseError::MissingProgramName),
};
Next we setup our storage and populate the defaults with our helper function.
// pub fn parse(&self, args: Vec<String>) -> Result<Matches, ParseError...
...Vec<String>) -> Result<Matches, ParseError> {
let mut args_iter = args.into_iter();
let exec_name = match args_iter.next() {
Some(s) => s,
None => return Err(ParseError::MissingProgramName),
};
Next we setup our storage and populate the defaults with our helper function.
// pub fn parse(&self, args: Vec<String>) -> Result<Matches, ParseError...
...loop {
use Instruction::*;
match self.instructions[self.program_counter] {
// ...
Clear => self.memory[self.pointer] = 0,
}
// ...
}
And every time we parse a ] we check if the previous instructions match the
“clear cell” operation, and replace it by the new instruction.
b']' => {
let curr_address = instructions.len();
match bracket_stack.pop() {
Some...
...if the closing delimiter is on the same line, ignore both
if there is only one opening delimiter on that line, the set only contains
the horizontal position of the first non-whitespace character of that line
otherwise we need to match the position of the first non-whitespace character...
"it's funny, every time I run into a baffling borrow error, it's preventing me from committing a real, serious mistake
but it can take some thinking t..."