Struct Pairs

pub struct Pairs<'i, R> { /* private fields */ }

An iterator over Pairs. It is created by pest::state and Pair::into_inner.

Implementations

impl<'i, R: RuleType> Pairs<'i, R>

pub fn single(pair: Pair<'i, R>) -> Self

Create a new Pairs iterator containing just the single Pair.

impl<'i, R: RuleType> Pairs<'i, R>

pub fn as_str(&self) -> &'i str

Captures a slice from the &str defined by the starting position of the first token Pair and the ending position of the last token Pair of the Pairs. This also captures the input between those two token Pairs.

Examples

enum Rule {
    a,
    b
}

let input = "a b";
let pairs = pest::state(input, |state| {
    // generating Token pairs with Rule::a and Rule::b ...
}).unwrap();

assert_eq!(pairs.as_str(), "a b");

pub fn get_input(&self) -> &'i str

Returns the input string of Pairs.

This function returns the input string of Pairs as a &str. This is the source string from which Pairs was created. The returned &str can be used to examine the contents of Pairs or to perform further processing on the string.

Examples

enum Rule {
    a,
    b
}

// Example: Get input string from Pairs

let input = "a b";
let pairs = pest::state(input, |state| {
    // generating Token pairs with Rule::a and Rule::b ...
}).unwrap();

assert_eq!(pairs.as_str(), "a b");
assert_eq!(input, pairs.get_input());

pub fn concat(&self) -> String

Captures inner token Pairs and concatenates resulting &strs. This does not capture the input between token Pairs.

Examples

enum Rule {
    a,
    b
}

let input = "a b";
let pairs = pest::state(input, |state| {
    // generating Token pairs with Rule::a and Rule::b ...
}).unwrap();

assert_eq!(pairs.concat(), "ab");

pub fn flatten(self) -> FlatPairs<'i, R>

Flattens the Pairs.

Examples

enum Rule {
    a,
    b
}

let input = "";
let pairs = pest::state(input, |state| {
    // generating nested Token pair with Rule::b inside Rule::a
}).unwrap();
let tokens: Vec<_> = pairs.flatten().tokens().collect();

assert_eq!(tokens.len(), 4);

pub fn find_first_tagged(&self, tag: &'i str) -> Option<Pair<'i, R>>

Finds the first pair that has its node or branch tagged with the provided label. Searches in the flattened Pairs iterator.

Examples

Try to recognize the branch between add and mul

use pest::{state, ParseResult, ParserState};
#[allow(non_camel_case_types)]
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
enum Rule {
    number, // 0..9
    add,    // num + num
    mul,    // num * num
}
fn mark_branch(
    state: Box<ParserState<'_, Rule>>,
) -> ParseResult<Box<ParserState<'_, Rule>>> {
    expr(state, Rule::mul, "*")
        .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("mul")))
        .or_else(|state| expr(state, Rule::add, "+"))
        .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("add")))
}
fn expr<'a>(
    state: Box<ParserState<'a, Rule>>,
    r: Rule,
    o: &'static str,
) -> ParseResult<Box<ParserState<'a, Rule>>> {
    state.rule(r, |state| {
        state.sequence(|state| {
            number(state)
                .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("lhs")))
                .and_then(|state| state.match_string(o))
                .and_then(number)
                .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("rhs")))
        })
    })
}
fn number(state: Box<ParserState<'_, Rule>>) -> ParseResult<Box<ParserState<'_, Rule>>> {
    state.rule(Rule::number, |state| state.match_range('0'..'9'))
}
let input = "1+2";
let pairs = state(input, mark_branch).unwrap();
assert_eq!(pairs.find_first_tagged("add").unwrap().as_rule(), Rule::add);
assert_eq!(pairs.find_first_tagged("mul"), None);

pub fn find_tagged( self, tag: &'i str, ) -> Filter<FlatPairs<'i, R>, impl FnMut(&Pair<'i, R>) -> bool + '_>

Returns the iterator over pairs that have their node or branch tagged with the provided label. The iterator is built from a flattened Pairs iterator.

Examples

Try to recognize the node between left and right hand side

use pest::{state, ParseResult, ParserState};
#[allow(non_camel_case_types)]
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
enum Rule {
    number, // 0..9
    add,    // num + num
    mul,    // num * num
}
fn mark_branch(
    state: Box<ParserState<'_, Rule>>,
) -> ParseResult<Box<ParserState<'_, Rule>>> {
    expr(state, Rule::mul, "*")
        .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("mul")))
        .or_else(|state| expr(state, Rule::add, "+"))
        .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("add")))
}
fn expr<'a>(
    state: Box<ParserState<'a, Rule>>,
    r: Rule,
    o: &'static str,
) -> ParseResult<Box<ParserState<'a, Rule>>> {
    state.rule(r, |state| {
        state.sequence(|state| {
            number(state)
                .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("lhs")))
                .and_then(|state| state.match_string(o))
                .and_then(number)
                .and_then(|state| state.tag_node(std::borrow::Cow::Borrowed("rhs")))
        })
    })
}
fn number(state: Box<ParserState<'_, Rule>>) -> ParseResult<Box<ParserState<'_, Rule>>> {
    state.rule(Rule::number, |state| state.match_range('0'..'9'))
}

let input = "1+2";
let pairs = state(input, mark_branch).unwrap();
let mut left_numbers = pairs.find_tagged("lhs");
assert_eq!(left_numbers.next().unwrap().as_str(), "1");
assert_eq!(left_numbers.next(), None);

pub fn tokens(self) -> Tokens<'i, R>

Returns the Tokens for the Pairs.

Examples

enum Rule {
    a
}

let input = "";
let pairs = pest::state(input, |state| {
    // generating Token pair with Rule::a ...
}).unwrap();
let tokens: Vec<_> = pairs.tokens().collect();

assert_eq!(tokens.len(), 2);

pub fn peek(&self) -> Option<Pair<'i, R>>

Peek at the first inner Pair without changing the position of this iterator.

Trait Implementations

impl<'i, R: Clone> Clone for Pairs<'i, R>

fn clone(&self) -> Pairs<'i, R>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'i, R: RuleType> Debug for Pairs<'i, R>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'i, R: RuleType> Display for Pairs<'i, R>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'i, R: RuleType> DoubleEndedIterator for Pairs<'i, R>

fn next_back(&mut self) -> Option<Self::Item>

Removes and returns an element from the end of the iterator.

fn advance_back_by(&mut self, n: usize) -> Result<(), NonZero<usize>>

🔬This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator from the back by n elements.

fn nth_back(&mut self, n: usize) -> Option<Self::Item>

Returns the nth element from the end of the iterator.

fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R

where Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Output = B>,

This is the reverse version of Iterator::try_fold(): it takes elements starting from the back of the iterator.

fn rfold<B, F>(self, init: B, f: F) -> B

where Self: Sized, F: FnMut(B, Self::Item) -> B,

An iterator method that reduces the iterator’s elements to a single, final value, starting from the back.

fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item>

where Self: Sized, P: FnMut(&Self::Item) -> bool,

Searches for an element of an iterator from the back that satisfies a predicate.

impl<'i, R: RuleType> ExactSizeIterator for Pairs<'i, R>

fn len(&self) -> usize

Returns the exact remaining length of the iterator.

fn is_empty(&self) -> bool

🔬This is a nightly-only experimental API. (exact_size_is_empty)

Returns true if the iterator is empty.

impl<'i, R: Hash> Hash for Pairs<'i, R>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<'i, R: RuleType> Iterator for Pairs<'i, R>

type Item = Pair<'i, R>

The type of the elements being iterated over.

fn next(&mut self) -> Option<Self::Item>

Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

fn next_chunk<const N: usize>( &mut self, ) -> Result<[Self::Item; N], IntoIter<Self::Item, N>>

where Self: Sized,

🔬This is a nightly-only experimental API. (iter_next_chunk)

Advances the iterator and returns an array containing the next N values.

fn count(self) -> usize

where Self: Sized,

Consumes the iterator, counting the number of iterations and returning it.

fn last(self) -> Option<Self::Item>

where Self: Sized,

Consumes the iterator, returning the last element.

fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>>

🔬This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator by n elements.

fn nth(&mut self, n: usize) -> Option<Self::Item>

Returns the nth element of the iterator.

fn step_by(self, step: usize) -> StepBy<Self>

where Self: Sized,

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter>

where Self: Sized, U: IntoIterator<Item = Self::Item>,

Takes two iterators and creates a new iterator over both in sequence.

fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter>

where Self: Sized, U: IntoIterator,

‘Zips up’ two iterators into a single iterator of pairs.

fn intersperse(self, separator: Self::Item) -> Intersperse<Self>

where Self: Sized, Self::Item: Clone,

🔬This is a nightly-only experimental API. (iter_intersperse)

Creates a new iterator which places a copy of separator between adjacent items of the original iterator.

fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G>

where Self: Sized, G: FnMut() -> Self::Item,

🔬This is a nightly-only experimental API. (iter_intersperse)

Creates a new iterator which places an item generated by separator between adjacent items of the original iterator.

fn map<B, F>(self, f: F) -> Map<Self, F>

where Self: Sized, F: FnMut(Self::Item) -> B,

Takes a closure and creates an iterator which calls that closure on each element.

fn for_each<F>(self, f: F)

where Self: Sized, F: FnMut(Self::Item),

Calls a closure on each element of an iterator.

fn filter<P>(self, predicate: P) -> Filter<Self, P>

where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator which uses a closure to determine if an element should be yielded.

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F>

where Self: Sized, F: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both filters and maps.

fn enumerate(self) -> Enumerate<Self>

where Self: Sized,

Creates an iterator which gives the current iteration count as well as the next value.

fn peekable(self) -> Peekable<Self>

where Self: Sized,

Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information.

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P>

where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator that skips elements based on a predicate.

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P>

where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator that yields elements based on a predicate.

fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P>

where Self: Sized, P: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both yields elements based on a predicate and maps.

fn skip(self, n: usize) -> Skip<Self>

where Self: Sized,

Creates an iterator that skips the first n elements.

fn take(self, n: usize) -> Take<Self>

where Self: Sized,

Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner.

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F>

where Self: Sized, F: FnMut(&mut St, Self::Item) -> Option<B>,

An iterator adapter which, like fold, holds internal state, but unlike fold, produces a new iterator.

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>

where Self: Sized, U: IntoIterator, F: FnMut(Self::Item) -> U,

Creates an iterator that works like map, but flattens nested structure.

fn map_windows<F, R, const N: usize>(self, f: F) -> MapWindows<Self, F, N>

where Self: Sized, F: FnMut(&[Self::Item; N]) -> R,

🔬This is a nightly-only experimental API. (iter_map_windows)

Calls the given function f for each contiguous window of size N over self and returns an iterator over the outputs of f. Like slice::windows(), the windows during mapping overlap as well.

fn fuse(self) -> Fuse<Self>

where Self: Sized,

Creates an iterator which ends after the first None.

fn inspect<F>(self, f: F) -> Inspect<Self, F>

where Self: Sized, F: FnMut(&Self::Item),

Does something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Borrows an iterator, rather than consuming it.

fn collect<B>(self) -> B

where B: FromIterator<Self::Item>, Self: Sized,

Transforms an iterator into a collection.

fn collect_into<E>(self, collection: &mut E) -> &mut E

where E: Extend<Self::Item>, Self: Sized,

🔬This is a nightly-only experimental API. (iter_collect_into)

Collects all the items from an iterator into a collection.

fn partition<B, F>(self, f: F) -> (B, B)

where Self: Sized, B: Default + Extend<Self::Item>, F: FnMut(&Self::Item) -> bool,

Consumes an iterator, creating two collections from it.

fn partition_in_place<'a, T, P>(self, predicate: P) -> usize

where T: 'a, Self: Sized + DoubleEndedIterator<Item = &'a mut T>, P: FnMut(&T) -> bool,

🔬This is a nightly-only experimental API. (iter_partition_in_place)

Reorders the elements of this iterator in-place according to the given predicate, such that all those that return true precede all those that return false. Returns the number of true elements found.

fn is_partitioned<P>(self, predicate: P) -> bool

where Self: Sized, P: FnMut(Self::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_is_partitioned)

Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R

where Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Output = B>,

An iterator method that applies a function as long as it returns successfully, producing a single, final value.

fn try_for_each<F, R>(&mut self, f: F) -> R

where Self: Sized, F: FnMut(Self::Item) -> R, R: Try<Output = ()>,

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

fn fold<B, F>(self, init: B, f: F) -> B

where Self: Sized, F: FnMut(B, Self::Item) -> B,

Folds every element into an accumulator by applying an operation, returning the final result.

fn reduce<F>(self, f: F) -> Option<Self::Item>

where Self: Sized, F: FnMut(Self::Item, Self::Item) -> Self::Item,

Reduces the elements to a single one, by repeatedly applying a reducing operation.

fn try_reduce<R>( &mut self, f: impl FnMut(Self::Item, Self::Item) -> R, ) -> <<R as Try>::Residual as Residual<Option<<R as Try>::Output>>>::TryType

where Self: Sized, R: Try<Output = Self::Item>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (iterator_try_reduce)

Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately.

fn all<F>(&mut self, f: F) -> bool

where Self: Sized, F: FnMut(Self::Item) -> bool,

Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> bool

where Self: Sized, F: FnMut(Self::Item) -> bool,

Tests if any element of the iterator matches a predicate.

fn find<P>(&mut self, predicate: P) -> Option<Self::Item>

where Self: Sized, P: FnMut(&Self::Item) -> bool,

Searches for an element of an iterator that satisfies a predicate.

fn find_map<B, F>(&mut self, f: F) -> Option<B>

where Self: Sized, F: FnMut(Self::Item) -> Option<B>,

Applies function to the elements of iterator and returns the first non-none result.

fn try_find<R>( &mut self, f: impl FnMut(&Self::Item) -> R, ) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryType

where Self: Sized, R: Try<Output = bool>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (try_find)

Applies function to the elements of iterator and returns the first true result or the first error.

fn position<P>(&mut self, predicate: P) -> Option<usize>

where Self: Sized, P: FnMut(Self::Item) -> bool,

Searches for an element in an iterator, returning its index.

fn rposition<P>(&mut self, predicate: P) -> Option<usize>

where P: FnMut(Self::Item) -> bool, Self: Sized + ExactSizeIterator + DoubleEndedIterator,

Searches for an element in an iterator from the right, returning its index.

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item>

where B: Ord, Self: Sized, F: FnMut(&Self::Item) -> B,

Returns the element that gives the maximum value from the specified function.

fn max_by<F>(self, compare: F) -> Option<Self::Item>

where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the maximum value with respect to the specified comparison function.

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item>

where B: Ord, Self: Sized, F: FnMut(&Self::Item) -> B,

Returns the element that gives the minimum value from the specified function.

fn min_by<F>(self, compare: F) -> Option<Self::Item>

where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the minimum value with respect to the specified comparison function.

fn rev(self) -> Rev<Self>

where Self: Sized + DoubleEndedIterator,

Reverses an iterator’s direction.

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB)

where FromA: Default + Extend<A>, FromB: Default + Extend<B>, Self: Sized + Iterator<Item = (A, B)>,

Converts an iterator of pairs into a pair of containers.

fn copied<'a, T>(self) -> Copied<Self>

where T: 'a + Copy, Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which copies all of its elements.

fn cloned<'a, T>(self) -> Cloned<Self>

where T: 'a + Clone, Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which clones all of its elements.

fn cycle(self) -> Cycle<Self>

where Self: Sized + Clone,

Repeats an iterator endlessly.

fn array_chunks<const N: usize>(self) -> ArrayChunks<Self, N>

where Self: Sized,

🔬This is a nightly-only experimental API. (iter_array_chunks)

Returns an iterator over N elements of the iterator at a time.

fn sum<S>(self) -> S

where Self: Sized, S: Sum<Self::Item>,

Sums the elements of an iterator.

fn product<P>(self) -> P

where Self: Sized, P: Product<Self::Item>,

Iterates over the entire iterator, multiplying all the elements

fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering

where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,

🔬This is a nightly-only experimental API. (iter_order_by)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn partial_cmp<I>(self, other: I) -> Option<Ordering>

where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Lexicographically compares the PartialOrd elements of this Iterator with those of another. The comparison works like short-circuit evaluation, returning a result without comparing the remaining elements. As soon as an order can be determined, the evaluation stops and a result is returned.

fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering>

where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,

🔬This is a nightly-only experimental API. (iter_order_by)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn eq<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialEq<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are equal to those of another.

fn eq_by<I, F>(self, other: I, eq: F) -> bool

where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_order_by)

Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function.

fn ne<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialEq<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are not equal to those of another.

fn lt<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically less than those of another.

fn le<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically less or equal to those of another.

fn gt<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically greater than those of another.

fn ge<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.

fn is_sorted_by<F>(self, compare: F) -> bool

where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> bool,

Checks if the elements of this iterator are sorted using the given comparator function.

fn is_sorted_by_key<F, K>(self, f: F) -> bool

where Self: Sized, F: FnMut(Self::Item) -> K, K: PartialOrd,

Checks if the elements of this iterator are sorted using the given key extraction function.

impl<'i, R: PartialEq> PartialEq for Pairs<'i, R>

fn eq(&self, other: &Pairs<'i, R>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'i, R: Eq> Eq for Pairs<'i, R>