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map.rs
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map.rs
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use std::fmt;
use std::iter::FromIterator;
use std::io;
#[cfg(feature = "mmap")]
use std::path::Path;
use automaton::{Automaton, AlwaysMatch};
use raw;
pub use raw::IndexedValue as IndexedValue;
pub use raw::IndexedValueWithState as IndexedValueWithState;
use stream::{IntoStreamer, Streamer};
use Result;
/// Map is a lexicographically ordered map from byte strings to integers.
///
/// A `Map` is constructed with the `MapBuilder` type. Alternatively, a `Map`
/// can be constructed in memory from a lexicographically ordered iterator
/// of key-value pairs (`Map::from_iter`).
///
/// A key feature of `Map` is that it can be serialized to disk compactly. Its
/// underlying representation is built such that the `Map` can be memory mapped
/// (`Map::from_path`) and searched without necessarily loading the entire
/// map into memory.
///
/// It supports most common operations associated with maps, such as key
/// lookup and search. It also supports set operations on its keys along with
/// the ability to specify how conflicting values are merged together. Maps
/// also support range queries and automata based searches (e.g. a regular
/// expression).
///
/// Maps are represented by a finite state transducer where inputs are the keys
/// and outputs are the values. As such, maps have the following invariants:
///
/// 1. Once constructed, a `Map` can never be modified.
/// 2. Maps must be constructed with lexicographically ordered byte sequences.
/// There is no restricting on the ordering of values.
///
/// # Differences with sets
///
/// Maps and sets are represented by the same underlying data structure: the
/// finite state transducer. The principal difference between them is that
/// sets always have their output values set to `0`. This has an impact on the
/// representation size and is reflected in the type system for convenience.
/// A secondary but subtle difference is that duplicate values can be added
/// to a set, but it is an error to do so with maps. That is, a set can have
/// the same key added sequentially, but a map can't.
///
/// # The future
///
/// It is regrettable that the output value is fixed to `u64`. Indeed, it is
/// not necessary, but it was a major simplification in the implementation.
/// In the future, the value type may become generic to an extent (outputs must
/// satisfy a basic algebra).
///
/// Keys will always be byte strings; however, we may grow more conveniences
/// around dealing with them (such as a serialization/deserialization step,
/// although it isn't clear where exactly this should live).
pub struct Map(raw::Fst);
impl Map {
/// Opens a map stored at the given file path via a memory map.
///
/// The map must have been written with a compatible finite state
/// transducer builder (`MapBuilder` qualifies). If the format is invalid
/// or if there is a mismatch between the API version of this library
/// and the map, then an error is returned.
///
/// This is unsafe because Rust programs cannot guarantee that memory
/// backed by a memory mapped file won't be mutably aliased. It is up to
/// the caller to enforce that the memory map is not modified while it is
/// opened.
#[cfg(feature = "mmap")]
pub unsafe fn from_path<P: AsRef<Path>>(path: P) -> Result<Self> {
raw::Fst::from_path(path).map(Map)
}
/// Creates a map from its representation as a raw byte sequence.
///
/// Note that this operation is very cheap (no allocations and no copies).
///
/// The map must have been written with a compatible finite state
/// transducer builder (`MapBuilder` qualifies). If the format is invalid
/// or if there is a mismatch between the API version of this library
/// and the map, then an error is returned.
pub fn from_bytes(bytes: Vec<u8>) -> Result<Self> {
raw::Fst::from_bytes(bytes).map(Map)
}
/// Create a `Map` from an iterator of lexicographically ordered byte
/// strings and associated values.
///
/// If the iterator does not yield unique keys in lexicographic order, then
/// an error is returned.
///
/// Note that this is a convenience function to build a map in memory.
/// To build a map that streams to an arbitrary `io::Write`, use
/// `MapBuilder`.
pub fn from_iter<K, I>(iter: I) -> Result<Self>
where K: AsRef<[u8]>, I: IntoIterator<Item=(K, u64)> {
let mut builder = MapBuilder::memory();
builder.extend_iter(iter)?;
Map::from_bytes(builder.into_inner()?)
}
/// Tests the membership of a single key.
///
/// # Example
///
/// ```rust
/// use fst::Map;
///
/// let map = Map::from_iter(vec![("a", 1), ("b", 2), ("c", 3)]).unwrap();
///
/// assert_eq!(map.contains_key("b"), true);
/// assert_eq!(map.contains_key("z"), false);
/// ```
pub fn contains_key<K: AsRef<[u8]>>(&self, key: K) -> bool {
self.0.contains_key(key)
}
/// Retrieves the value associated with a key.
///
/// If the key does not exist, then `None` is returned.
///
/// # Example
///
/// ```rust
/// use fst::Map;
///
/// let map = Map::from_iter(vec![("a", 1), ("b", 2), ("c", 3)]).unwrap();
///
/// assert_eq!(map.get("b"), Some(2));
/// assert_eq!(map.get("z"), None);
/// ```
pub fn get<K: AsRef<[u8]>>(&self, key: K) -> Option<u64> {
self.0.get(key).map(|output| output.value())
}
/// Return a lexicographically ordered stream of all key-value pairs in
/// this map.
///
/// While this is a stream, it does require heap space proportional to the
/// longest key in the map.
///
/// If the map is memory mapped, then no further heap space is needed.
/// Note though that your operating system may fill your page cache
/// (which will cause the resident memory usage of the process to go up
/// correspondingly).
///
/// # Example
///
/// Since streams are not iterators, the traditional `for` loop cannot be
/// used. `while let` is useful instead:
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map};
///
/// let map = Map::from_iter(vec![("a", 1), ("b", 2), ("c", 3)]).unwrap();
/// let mut stream = map.stream();
///
/// let mut kvs = vec![];
/// while let Some((k, v)) = stream.next() {
/// kvs.push((k.to_vec(), v));
/// }
/// assert_eq!(kvs, vec![
/// (b"a".to_vec(), 1),
/// (b"b".to_vec(), 2),
/// (b"c".to_vec(), 3),
/// ]);
/// ```
pub fn stream(&self) -> Stream {
Stream(self.0.stream())
}
/// Return a lexicographically ordered stream of all keys in this map.
///
/// Memory requirements are the same as described on `Map::stream`.
///
/// # Example
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map};
///
/// let map = Map::from_iter(vec![("a", 1), ("b", 2), ("c", 3)]).unwrap();
/// let mut stream = map.keys();
///
/// let mut keys = vec![];
/// while let Some(k) = stream.next() {
/// keys.push(k.to_vec());
/// }
/// assert_eq!(keys, vec![b"a", b"b", b"c"]);
/// ```
pub fn keys(&self) -> Keys {
Keys(self.0.stream())
}
/// Return a stream of all values in this map ordered lexicographically
/// by each value's corresponding key.
///
/// Memory requirements are the same as described on `Map::stream`.
///
/// # Example
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map};
///
/// let map = Map::from_iter(vec![("a", 1), ("b", 2), ("c", 3)]).unwrap();
/// let mut stream = map.values();
///
/// let mut values = vec![];
/// while let Some(v) = stream.next() {
/// values.push(v);
/// }
/// assert_eq!(values, vec![1, 2, 3]);
/// ```
pub fn values(&self) -> Values {
Values(self.0.stream())
}
/// Return a builder for range queries.
///
/// A range query returns a subset of key-value pairs in this map in a
/// range given in lexicographic order.
///
/// Memory requirements are the same as described on `Map::stream`.
/// Notably, only the keys in the range are read; keys outside the range
/// are not.
///
/// # Example
///
/// Returns only the key-value pairs in the range given.
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map};
///
/// let map = Map::from_iter(vec![
/// ("a", 1), ("b", 2), ("c", 3), ("d", 4), ("e", 5),
/// ]).unwrap();
/// let mut stream = map.range().ge("b").lt("e").into_stream();
///
/// let mut kvs = vec![];
/// while let Some((k, v)) = stream.next() {
/// kvs.push((k.to_vec(), v));
/// }
/// assert_eq!(kvs, vec![
/// (b"b".to_vec(), 2),
/// (b"c".to_vec(), 3),
/// (b"d".to_vec(), 4),
/// ]);
/// ```
pub fn range(&self) -> StreamBuilder {
StreamBuilder(self.0.range())
}
/// Executes an automaton on the keys of this map.
///
/// Note that this returns a `StreamBuilder`, which can be used to
/// add a range query to the search (see the `range` method).
///
/// Memory requirements are the same as described on `Map::stream`.
///
/// # Example
///
/// An implementation of regular expressions for `Automaton` is available
/// in the `fst-regex` crate, which can be used to search maps.
///
/// ```rust
/// extern crate fst;
/// extern crate fst_regex;
///
/// use std::error::Error;
///
/// use fst::{IntoStreamer, Streamer, Map};
/// use fst_regex::Regex;
///
/// # fn main() { example().unwrap(); }
/// fn example() -> Result<(), Box<Error>> {
/// let map = Map::from_iter(vec![
/// ("foo", 1), ("foo1", 2), ("foo2", 3), ("foo3", 4), ("foobar", 5),
/// ]).unwrap();
///
/// let re = Regex::new("f[a-z]+3?").unwrap();
/// let mut stream = map.search(&re).into_stream();
///
/// let mut kvs = vec![];
/// while let Some((k, v)) = stream.next() {
/// kvs.push((k.to_vec(), v));
/// }
/// assert_eq!(kvs, vec![
/// (b"foo".to_vec(), 1),
/// (b"foo3".to_vec(), 4),
/// (b"foobar".to_vec(), 5),
/// ]);
///
/// Ok(())
/// }
/// ```
pub fn search<A: Automaton>(&self, aut: A) -> StreamBuilder<A> {
StreamBuilder(self.0.search(aut))
}
/// Returns the number of elements in this map.
pub fn len(&self) -> usize {
self.0.len()
}
/// Returns true if and only if this map is empty.
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Creates a new map operation with this map added to it.
///
/// The `OpBuilder` type can be used to add additional map streams
/// and perform set operations like union, intersection, difference and
/// symmetric difference on the keys of the map. These set operations also
/// allow one to specify how conflicting values are merged in the stream.
///
/// # Example
///
/// This example demonstrates a union on multiple map streams. Notice that
/// the stream returned from the union is not a sequence of key-value
/// pairs, but rather a sequence of keys associated with one or more
/// values. Namely, a key is associated with each value associated with
/// that same key in the all of the streams.
///
/// ```rust
/// use fst::{Streamer, Map};
/// use fst::map::IndexedValue;
///
/// let map1 = Map::from_iter(vec![
/// ("a", 1), ("b", 2), ("c", 3),
/// ]).unwrap();
/// let map2 = Map::from_iter(vec![
/// ("a", 10), ("y", 11), ("z", 12),
/// ]).unwrap();
///
/// let mut union = map1.op().add(&map2).union();
///
/// let mut kvs = vec![];
/// while let Some((k, vs)) = union.next() {
/// kvs.push((k.to_vec(), vs.to_vec()));
/// }
/// assert_eq!(kvs, vec![
/// (b"a".to_vec(), vec![
/// IndexedValue { index: 0, value: 1 },
/// IndexedValue { index: 1, value: 10 },
/// ]),
/// (b"b".to_vec(), vec![IndexedValue { index: 0, value: 2 }]),
/// (b"c".to_vec(), vec![IndexedValue { index: 0, value: 3 }]),
/// (b"y".to_vec(), vec![IndexedValue { index: 1, value: 11 }]),
/// (b"z".to_vec(), vec![IndexedValue { index: 1, value: 12 }]),
/// ]);
/// ```
pub fn op(&self) -> OpBuilder {
OpBuilder::new().add(self)
}
/// Returns a reference to the underlying raw finite state transducer.
pub fn as_fst(&self) -> &raw::Fst {
&self.0
}
}
impl fmt::Debug for Map {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Map([")?;
let mut stream = self.stream();
let mut first = true;
while let Some((k, v)) = stream.next() {
if !first {
write!(f, ", ")?;
}
first = false;
write!(f, "({}, {})", String::from_utf8_lossy(k), v)?;
}
write!(f, "])")
}
}
// Construct a map from an Fst object.
impl From<raw::Fst> for Map {
fn from(fst: raw::Fst) -> Map {
Map(fst)
}
}
/// Returns the underlying finite state transducer.
impl AsRef<raw::Fst> for Map {
fn as_ref(&self) -> &raw::Fst {
&self.0
}
}
impl<'m, 'a> IntoStreamer<'a> for &'m Map {
type Item = (&'a [u8], u64);
type Into = Stream<'m>;
fn into_stream(self) -> Self::Into {
Stream(self.0.stream())
}
}
/// A builder for creating a map.
///
/// This is not your average everyday builder. It has two important qualities
/// that make it a bit unique from what you might expect:
///
/// 1. All keys must be added in lexicographic order. Adding a key out of order
/// will result in an error. Additionally, adding a duplicate key will also
/// result in an error. That is, once a key is associated with a value,
/// that association can never be modified or deleted.
/// 2. The representation of a map is streamed to *any* `io::Write` as it is
/// built. For an in memory representation, this can be a `Vec<u8>`.
///
/// Point (2) is especially important because it means that a map can be
/// constructed *without storing the entire map in memory*. Namely, since it
/// works with any `io::Write`, it can be streamed directly to a file.
///
/// With that said, the builder does use memory, but **memory usage is bounded
/// to a constant size**. The amount of memory used trades off with the
/// compression ratio. Currently, the implementation hard codes this trade off
/// which can result in about 5-20MB of heap usage during construction. (N.B.
/// Guaranteeing a maximal compression ratio requires memory proportional to
/// the size of the map, which defeats some of the benefit of streaming
/// it to disk. In practice, a small bounded amount of memory achieves
/// close-to-minimal compression ratios.)
///
/// The algorithmic complexity of map construction is `O(n)` where `n` is the
/// number of elements added to the map.
///
/// # Example: build in memory
///
/// This shows how to use the builder to construct a map in memory. Note that
/// `Map::from_iter` provides a convenience function that achieves this same
/// goal without needing to explicitly use `MapBuilder`.
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map, MapBuilder};
///
/// let mut build = MapBuilder::memory();
/// build.insert("bruce", 1).unwrap();
/// build.insert("clarence", 2).unwrap();
/// build.insert("stevie", 3).unwrap();
///
/// // You could also call `finish()` here, but since we're building the map in
/// // memory, there would be no way to get the `Vec<u8>` back.
/// let bytes = build.into_inner().unwrap();
///
/// // At this point, the map has been constructed, but here's how to read it.
/// let map = Map::from_bytes(bytes).unwrap();
/// let mut stream = map.into_stream();
/// let mut kvs = vec![];
/// while let Some((k, v)) = stream.next() {
/// kvs.push((k.to_vec(), v));
/// }
/// assert_eq!(kvs, vec![
/// (b"bruce".to_vec(), 1),
/// (b"clarence".to_vec(), 2),
/// (b"stevie".to_vec(), 3),
/// ]);
/// ```
///
/// # Example: stream to file
///
/// This shows how to do stream construction of a map to a file.
///
/// ```rust,no_run
/// use std::fs::File;
/// use std::io;
///
/// use fst::{IntoStreamer, Streamer, Map, MapBuilder};
///
/// let mut wtr = io::BufWriter::new(File::create("map.fst").unwrap());
/// let mut build = MapBuilder::new(wtr).unwrap();
/// build.insert("bruce", 1).unwrap();
/// build.insert("clarence", 2).unwrap();
/// build.insert("stevie", 3).unwrap();
///
/// // If you want the writer back, then call `into_inner`. Otherwise, this
/// // will finish construction and call `flush`.
/// build.finish().unwrap();
///
/// // At this point, the map has been constructed, but here's how to read it.
/// let map = unsafe { Map::from_path("map.fst").unwrap() };
/// let mut stream = map.into_stream();
/// let mut kvs = vec![];
/// while let Some((k, v)) = stream.next() {
/// kvs.push((k.to_vec(), v));
/// }
/// assert_eq!(kvs, vec![
/// (b"bruce".to_vec(), 1),
/// (b"clarence".to_vec(), 2),
/// (b"stevie".to_vec(), 3),
/// ]);
/// ```
pub struct MapBuilder<W>(raw::Builder<W>);
impl MapBuilder<Vec<u8>> {
/// Create a builder that builds a map in memory.
pub fn memory() -> Self {
MapBuilder(raw::Builder::memory())
}
}
impl<W: io::Write> MapBuilder<W> {
/// Create a builder that builds a map by writing it to `wtr` in a
/// streaming fashion.
pub fn new(wtr: W) -> Result<MapBuilder<W>> {
raw::Builder::new_type(wtr, 0).map(MapBuilder)
}
/// Insert a new key-value pair into the map.
///
/// Keys must be convertible to byte strings. Values must be a `u64`, which
/// is a restriction of the current implementation of finite state
/// transducers. (Values may one day be expanded to other types.)
///
/// If a key is inserted that is less than or equal to any previous key
/// added, then an error is returned. Similarly, if there was a problem
/// writing to the underlying writer, an error is returned.
pub fn insert<K: AsRef<[u8]>>(&mut self, key: K, val: u64) -> Result<()> {
self.0.insert(key, val)
}
/// Calls insert on each item in the iterator.
///
/// If an error occurred while adding an element, processing is stopped
/// and the error is returned.
///
/// If a key is inserted that is less than or equal to any previous key
/// added, then an error is returned. Similarly, if there was a problem
/// writing to the underlying writer, an error is returned.
pub fn extend_iter<K, I>(&mut self, iter: I) -> Result<()>
where K: AsRef<[u8]>, I: IntoIterator<Item=(K, u64)> {
self.0.extend_iter(iter.into_iter()
.map(|(k, v)| (k, raw::Output::new(v))))
}
/// Calls insert on each item in the stream.
///
/// Note that unlike `extend_iter`, this is not generic on the items in
/// the stream.
///
/// If a key is inserted that is less than or equal to any previous key
/// added, then an error is returned. Similarly, if there was a problem
/// writing to the underlying writer, an error is returned.
pub fn extend_stream<'f, I, S>(&mut self, stream: I) -> Result<()>
where I: for<'a> IntoStreamer<'a, Into=S, Item=(&'a [u8], u64)>,
S: 'f + for<'a> Streamer<'a, Item=(&'a [u8], u64)> {
self.0.extend_stream(StreamOutput(stream.into_stream()))
}
/// Finishes the construction of the map and flushes the underlying
/// writer. After completion, the data written to `W` may be read using
/// one of `Map`'s constructor methods.
pub fn finish(self) -> Result<()> {
self.0.finish()
}
/// Just like `finish`, except it returns the underlying writer after
/// flushing it.
pub fn into_inner(self) -> Result<W> {
self.0.into_inner()
}
/// Gets a reference to the underlying writer.
pub fn get_ref(&self) -> &W {
self.0.get_ref()
}
/// Returns the number of bytes written to the underlying writer
pub fn bytes_written(&self) -> u64 {
self.0.bytes_written()
}
}
/// A lexicographically ordered stream of key-value pairs from a map.
///
/// The `A` type parameter corresponds to an optional automaton to filter
/// the stream. By default, no filtering is done.
///
/// The `'m` lifetime parameter refers to the lifetime of the underlying map.
pub struct Stream<'m, A=AlwaysMatch>(raw::Stream<'m, A>) where A: Automaton;
impl<'a, 'm, A: Automaton> Streamer<'a> for Stream<'m, A> {
type Item = (&'a [u8], u64);
fn next(&'a mut self) -> Option<Self::Item> {
self.0.next().map(|(key, out)| (key, out.value()))
}
}
impl<'m, A: Automaton> Stream<'m, A> {
/// Convert this stream into a vector of byte strings and outputs.
///
/// Note that this creates a new allocation for every key in the stream.
pub fn into_byte_vec(self) -> Vec<(Vec<u8>, u64)> {
self.0.into_byte_vec()
}
/// Convert this stream into a vector of Unicode strings and outputs.
///
/// If any key is not valid UTF-8, then iteration on the stream is stopped
/// and a UTF-8 decoding error is returned.
///
/// Note that this creates a new allocation for every key in the stream.
pub fn into_str_vec(self) -> Result<Vec<(String, u64)>> {
self.0.into_str_vec()
}
/// Convert this stream into a vector of byte strings.
///
/// Note that this creates a new allocation for every key in the stream.
pub fn into_byte_keys(self) -> Vec<Vec<u8>> {
self.0.into_byte_keys()
}
/// Convert this stream into a vector of Unicode strings.
///
/// If any key is not valid UTF-8, then iteration on the stream is stopped
/// and a UTF-8 decoding error is returned.
///
/// Note that this creates a new allocation for every key in the stream.
pub fn into_str_keys(self) -> Result<Vec<String>> {
self.0.into_str_keys()
}
/// Convert this stream into a vector of outputs.
pub fn into_values(self) -> Vec<u64> {
self.0.into_values()
}
}
/// A lexicographically ordered stream of key-value from a map
/// along with the states of the automaton.
///
/// The `Stream` type is based on the `StreamWithState`.
pub struct StreamWithState<'m, A=AlwaysMatch>(raw::StreamWithState<'m, A>) where A: Automaton;
impl<'a, 'm, A: 'a> Streamer<'a> for StreamWithState<'m, A>
where
A: Automaton,
A::State: Clone
{
type Item = (&'a [u8], u64, A::State);
fn next(&'a mut self) -> Option<Self::Item> {
self.0.next().map(|(key, out, state)| (key, out.value(), state))
}
}
/// A lexicographically ordered stream of keys from a map.
///
/// The `'m` lifetime parameter refers to the lifetime of the underlying map.
pub struct Keys<'m>(raw::Stream<'m>);
impl<'a, 'm> Streamer<'a> for Keys<'m> {
type Item = &'a [u8];
fn next(&'a mut self) -> Option<Self::Item> {
self.0.next().map(|(key, _)| key)
}
}
/// A stream of values from a map, lexicographically ordered by each value's
/// corresponding key.
///
/// The `'m` lifetime parameter refers to the lifetime of the underlying map.
pub struct Values<'m>(raw::Stream<'m>);
impl<'a, 'm> Streamer<'a> for Values<'m> {
type Item = u64;
fn next(&'a mut self) -> Option<Self::Item> {
self.0.next().map(|(_, out)| out.value())
}
}
/// A builder for constructing range queries on streams.
///
/// Once all bounds are set, one should call `into_stream` to get a
/// `Stream`.
///
/// Bounds are not additive. That is, if `ge` is called twice on the same
/// builder, then the second setting wins.
///
/// The `A` type parameter corresponds to an optional automaton to filter
/// the stream. By default, no filtering is done.
///
/// The `'m` lifetime parameter refers to the lifetime of the underlying map.
pub struct StreamBuilder<'m, A=AlwaysMatch>(raw::StreamBuilder<'m, A>);
impl<'m, A> StreamBuilder<'m, A> {
/// Specify a greater-than-or-equal-to bound.
pub fn ge<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamBuilder(self.0.ge(bound))
}
/// Specify a greater-than bound.
pub fn gt<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamBuilder(self.0.gt(bound))
}
/// Specify a less-than-or-equal-to bound.
pub fn le<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamBuilder(self.0.le(bound))
}
/// Specify a less-than bound.
pub fn lt<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamBuilder(self.0.lt(bound))
}
/// Return this builder and gives the automaton states
/// along with the results.
pub fn with_state(self) -> StreamWithStateBuilder<'m, A> {
StreamWithStateBuilder(self.0.with_state())
}
}
impl<'m, 'a, A: Automaton> IntoStreamer<'a> for StreamBuilder<'m, A> {
type Item = (&'a [u8], u64);
type Into = Stream<'m, A>;
fn into_stream(self) -> Self::Into {
Stream(self.0.into_stream())
}
}
/// A builder for constructing range queries of streams
/// that returns results along with automaton states.
///
/// Once all bounds are set, one should call `into_stream` to get a
/// `StreamWithState`.
///
/// Bounds are not additive. That is, if `ge` is called twice on the same
/// builder, then the second setting wins.
///
/// The `A` type parameter corresponds to an optional automaton to filter
/// the stream. By default, no filtering is done.
///
/// The `'m` lifetime parameter refers to the lifetime of the underlying map.
pub struct StreamWithStateBuilder<'m, A=AlwaysMatch>(raw::StreamWithStateBuilder<'m, A>);
impl<'m, A> StreamWithStateBuilder<'m, A> {
/// Specify a greater-than-or-equal-to bound.
pub fn ge<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamWithStateBuilder(self.0.ge(bound))
}
/// Specify a greater-than bound.
pub fn gt<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamWithStateBuilder(self.0.gt(bound))
}
/// Specify a less-than-or-equal-to bound.
pub fn le<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamWithStateBuilder(self.0.le(bound))
}
/// Specify a less-than bound.
pub fn lt<T: AsRef<[u8]>>(self, bound: T) -> Self {
StreamWithStateBuilder(self.0.lt(bound))
}
}
impl<'m, 'a, A: 'a> IntoStreamer<'a> for StreamWithStateBuilder<'m, A>
where
A: Automaton,
A::State: Clone
{
type Item = (&'a [u8], u64, A::State);
type Into = StreamWithState<'m, A>;
fn into_stream(self) -> Self::Into {
StreamWithState(self.0.into_stream())
}
}
/// A builder for collecting map streams on which to perform set operations
/// on the keys of maps.
///
/// Set operations include intersection, union, difference and symmetric
/// difference. The result of each set operation is itself a stream that emits
/// pairs of keys and a sequence of each occurrence of that key in the
/// participating streams. This information allows one to perform set
/// operations on maps and customize how conflicting output values are handled.
///
/// All set operations work efficiently on an arbitrary number of
/// streams with memory proportional to the number of streams.
///
/// The algorithmic complexity of all set operations is `O(n1 + n2 + n3 + ...)`
/// where `n1, n2, n3, ...` correspond to the number of elements in each
/// stream.
///
/// The `'m` lifetime parameter refers to the lifetime of the underlying set.
pub struct OpBuilder<'m>(raw::OpBuilder<'m>);
impl<'m> OpBuilder<'m> {
/// Create a new set operation builder.
pub fn new() -> Self {
OpBuilder(raw::OpBuilder::new())
}
/// Add a stream to this set operation.
///
/// This is useful for a chaining style pattern, e.g.,
/// `builder.add(stream1).add(stream2).union()`.
///
/// The stream must emit a lexicographically ordered sequence of key-value
/// pairs.
pub fn add<I, S>(mut self, streamable: I) -> Self
where I: for<'a> IntoStreamer<'a, Into=S, Item=(&'a [u8], u64)>,
S: 'm + for<'a> Streamer<'a, Item=(&'a [u8], u64)> {
self.push(streamable);
self
}
/// Add a stream to this set operation.
///
/// The stream must emit a lexicographically ordered sequence of key-value
/// pairs.
pub fn push<I, S>(&mut self, streamable: I)
where I: for<'a> IntoStreamer<'a, Into=S, Item=(&'a [u8], u64)>,
S: 'm + for<'a> Streamer<'a, Item=(&'a [u8], u64)> {
self.0.push(StreamOutput(streamable.into_stream()));
}
/// Performs a union operation on all streams that have been added.
///
/// Note that this returns a stream of `(&[u8], &[IndexedValue])`. The
/// first element of the tuple is the byte string key. The second element
/// of the tuple is a list of all occurrences of that key in participating
/// streams. The `IndexedValue` contains an index and the value associated
/// with that key in that stream. The index uniquely identifies each
/// stream, which is an integer that is auto-incremented when a stream
/// is added to this operation (starting at `0`).
///
/// # Example
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map};
/// use fst::map::IndexedValue;
///
/// let map1 = Map::from_iter(vec![
/// ("a", 1), ("b", 2), ("c", 3),
/// ]).unwrap();
/// let map2 = Map::from_iter(vec![
/// ("a", 11), ("y", 12), ("z", 13),
/// ]).unwrap();
///
/// let mut union = map1.op().add(&map2).union();
///
/// let mut kvs = vec![];
/// while let Some((k, vs)) = union.next() {
/// kvs.push((k.to_vec(), vs.to_vec()));
/// }
/// assert_eq!(kvs, vec![
/// (b"a".to_vec(), vec![
/// IndexedValue { index: 0, value: 1 },
/// IndexedValue { index: 1, value: 11 },
/// ]),
/// (b"b".to_vec(), vec![IndexedValue { index: 0, value: 2 }]),
/// (b"c".to_vec(), vec![IndexedValue { index: 0, value: 3 }]),
/// (b"y".to_vec(), vec![IndexedValue { index: 1, value: 12 }]),
/// (b"z".to_vec(), vec![IndexedValue { index: 1, value: 13 }]),
/// ]);
/// ```
pub fn union(self) -> Union<'m> {
Union(self.0.union())
}
/// Performs an intersection operation on all streams that have been added.
///
/// Note that this returns a stream of `(&[u8], &[IndexedValue])`. The
/// first element of the tuple is the byte string key. The second element
/// of the tuple is a list of all occurrences of that key in participating
/// streams. The `IndexedValue` contains an index and the value associated
/// with that key in that stream. The index uniquely identifies each
/// stream, which is an integer that is auto-incremented when a stream
/// is added to this operation (starting at `0`).
///
/// # Example
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map};
/// use fst::map::IndexedValue;
///
/// let map1 = Map::from_iter(vec![
/// ("a", 1), ("b", 2), ("c", 3),
/// ]).unwrap();
/// let map2 = Map::from_iter(vec![
/// ("a", 11), ("y", 12), ("z", 13),
/// ]).unwrap();
///
/// let mut intersection = map1.op().add(&map2).intersection();
///
/// let mut kvs = vec![];
/// while let Some((k, vs)) = intersection.next() {
/// kvs.push((k.to_vec(), vs.to_vec()));
/// }
/// assert_eq!(kvs, vec![
/// (b"a".to_vec(), vec![
/// IndexedValue { index: 0, value: 1 },
/// IndexedValue { index: 1, value: 11 },
/// ]),
/// ]);
/// ```
pub fn intersection(self) -> Intersection<'m> {
Intersection(self.0.intersection())
}
/// Performs a difference operation with respect to the first stream added.
/// That is, this returns a stream of all elements in the first stream
/// that don't exist in any other stream that has been added.
///
/// Note that this returns a stream of `(&[u8], &[IndexedValue])`. The
/// first element of the tuple is the byte string key. The second element
/// of the tuple is a list of all occurrences of that key in participating
/// streams. The `IndexedValue` contains an index and the value associated
/// with that key in that stream. The index uniquely identifies each
/// stream, which is an integer that is auto-incremented when a stream
/// is added to this operation (starting at `0`).
///
/// # Example
///
/// ```rust
/// use fst::{Streamer, Map};
/// use fst::map::IndexedValue;
///
/// let map1 = Map::from_iter(vec![
/// ("a", 1), ("b", 2), ("c", 3),
/// ]).unwrap();
/// let map2 = Map::from_iter(vec![
/// ("a", 11), ("y", 12), ("z", 13),
/// ]).unwrap();
///
/// let mut difference = map1.op().add(&map2).difference();
///
/// let mut kvs = vec![];
/// while let Some((k, vs)) = difference.next() {
/// kvs.push((k.to_vec(), vs.to_vec()));
/// }
/// assert_eq!(kvs, vec![
/// (b"b".to_vec(), vec![IndexedValue { index: 0, value: 2 }]),
/// (b"c".to_vec(), vec![IndexedValue { index: 0, value: 3 }]),
/// ]);
/// ```
pub fn difference(self) -> Difference<'m> {
Difference(self.0.difference())
}
/// Performs a symmetric difference operation on all of the streams that
/// have been added.
///
/// When there are only two streams, then the keys returned correspond to
/// keys that are in either stream but *not* in both streams.
///
/// More generally, for any number of streams, keys that occur in an odd
/// number of streams are returned.
///
/// Note that this returns a stream of `(&[u8], &[IndexedValue])`. The
/// first element of the tuple is the byte string key. The second element
/// of the tuple is a list of all occurrences of that key in participating
/// streams. The `IndexedValue` contains an index and the value associated
/// with that key in that stream. The index uniquely identifies each
/// stream, which is an integer that is auto-incremented when a stream
/// is added to this operation (starting at `0`).
///
/// # Example
///
/// ```rust
/// use fst::{IntoStreamer, Streamer, Map};
/// use fst::map::IndexedValue;
///
/// let map1 = Map::from_iter(vec![
/// ("a", 1), ("b", 2), ("c", 3),
/// ]).unwrap();
/// let map2 = Map::from_iter(vec![
/// ("a", 11), ("y", 12), ("z", 13),
/// ]).unwrap();
///
/// let mut sym_difference = map1.op().add(&map2).symmetric_difference();
///
/// let mut kvs = vec![];
/// while let Some((k, vs)) = sym_difference.next() {
/// kvs.push((k.to_vec(), vs.to_vec()));
/// }
/// assert_eq!(kvs, vec![
/// (b"b".to_vec(), vec![IndexedValue { index: 0, value: 2 }]),
/// (b"c".to_vec(), vec![IndexedValue { index: 0, value: 3 }]),
/// (b"y".to_vec(), vec![IndexedValue { index: 1, value: 12 }]),
/// (b"z".to_vec(), vec![IndexedValue { index: 1, value: 13 }]),
/// ]);
/// ```
pub fn symmetric_difference(self) -> SymmetricDifference<'m> {
SymmetricDifference(self.0.symmetric_difference())
}