ripgrep/crates/searcher/src/lib.rs

/*!
This crate provides an implementation of line oriented search, with optional
support for multi-line search.

# Brief overview

The principle type in this crate is a [`Searcher`], which can be configured
and built by a [`SearcherBuilder`]. A `Searcher` is responsible for reading
bytes from a source (e.g., a file), executing a search of those bytes using
a `Matcher` (e.g., a regex) and then reporting the results of that search to
a [`Sink`] (e.g., stdout). The `Searcher` itself is principally responsible
for managing the consumption of bytes from a source and applying a `Matcher`
over those bytes in an efficient way. The `Searcher` is also responsible for
inverting a search, counting lines, reporting contextual lines, detecting
binary data and even deciding whether or not to use memory maps.

A `Matcher` (which is defined in the
[`grep-matcher`](https://crates.io/crates/grep-matcher) crate) is a trait
for describing the lowest levels of pattern search in a generic way. The
interface itself is very similar to the interface of a regular expression.
For example, the [`grep-regex`](https://crates.io/crates/grep-regex)
crate provides an implementation of the `Matcher` trait using Rust's
[`regex`](https://crates.io/crates/regex) crate.

Finally, a `Sink` describes how callers receive search results producer by a
`Searcher`. This includes routines that are called at the beginning and end of
a search, in addition to routines that are called when matching or contextual
lines are found by the `Searcher`. Implementations of `Sink` can be trivially
simple, or extraordinarily complex, such as the `Standard` printer found in
the [`grep-printer`](https://crates.io/crates/grep-printer) crate, which
effectively implements grep-like output. This crate also provides convenience
`Sink` implementations in the [`sinks`] sub-module for easy searching with
closures.

# Example

This example shows how to execute the searcher and read the search results
using the [`UTF8`](sinks::UTF8) implementation of `Sink`.

```
use {
    grep_matcher::Matcher,
    grep_regex::RegexMatcher,
    grep_searcher::Searcher,
    grep_searcher::sinks::UTF8,
};

const SHERLOCK: &'static [u8] = b"\
For the Doctor Watsons of this world, as opposed to the Sherlock
Holmeses, success in the province of detective work must always
be, to a very large extent, the result of luck. Sherlock Holmes
can extract a clew from a wisp of straw or a flake of cigar ash;
but Doctor Watson has to have it taken out for him and dusted,
and exhibited clearly, with a label attached.
";

let matcher = RegexMatcher::new(r"Doctor \w+")?;
let mut matches: Vec<(u64, String)> = vec![];
Searcher::new().search_slice(&matcher, SHERLOCK, UTF8(|lnum, line| {
    // We are guaranteed to find a match, so the unwrap is OK.
    let mymatch = matcher.find(line.as_bytes())?.unwrap();
    matches.push((lnum, line[mymatch].to_string()));
    Ok(true)
}))?;

assert_eq!(matches.len(), 2);
assert_eq!(
    matches[0],
    (1, "Doctor Watsons".to_string())
);
assert_eq!(
    matches[1],
    (5, "Doctor Watson".to_string())
);

# Ok::<(), Box<dyn std::error::Error>>(())
```

See also `examples/search-stdin.rs` from the root of this crate's directory
to see a similar example that accepts a pattern on the command line and
searches stdin.
*/

#![deny(missing_docs)]

pub use crate::{
    lines::{LineIter, LineStep},
    searcher::{
        BinaryDetection, ConfigError, Encoding, MmapChoice, Searcher,
        SearcherBuilder,
    },
    sink::{
        sinks, Sink, SinkContext, SinkContextKind, SinkError, SinkFinish,
        SinkMatch,
    },
};

#[macro_use]
mod macros;

mod line_buffer;
mod lines;
mod searcher;
mod sink;
#[cfg(test)]
mod testutil;