libripgrep: initial commit introducing libripgrep

libripgrep is not any one library, but rather, a collection of libraries
that roughly separate the following key distinct phases in a grep
implementation:

  1. Pattern matching (e.g., by a regex engine).
  2. Searching a file using a pattern matcher.
  3. Printing results.

Ultimately, both (1) and (3) are defined by de-coupled interfaces, of
which there may be multiple implementations. Namely, (1) is satisfied by
the `Matcher` trait in the `grep-matcher` crate and (3) is satisfied by
the `Sink` trait in the `grep2` crate. The searcher (2) ties everything
together and finds results using a matcher and reports those results
using a `Sink` implementation.

Closes #162

grep-printer/src/lib.rs

@@ -0,0 +1,106 @@
+/*!
+This crate provides featureful and fast printers that interoperate with the
+[`grep-searcher`](https://docs.rs/grep-searcher)
+crate.
+
+# Brief overview
+
+The [`Standard`](struct.Standard.html) printer shows results in a human
+readable format, and is modeled after the formats used by standard grep-like
+tools. Features include, but are not limited to, cross platform terminal
+coloring, search & replace, multi-line result handling and reporting summary
+statistics.
+
+The [`JSON`](struct.JSON.html) printer shows results in a machine readable
+format. To facilitate a stream of search results, the format uses
+[JSON Lines](http://jsonlines.org/)
+by emitting a series of messages as search results are found.
+
+The [`Summary`](struct.Summary.html) printer shows *aggregate* results for a
+single search in a human readable format, and is modeled after similar formats
+found in standard grep-like tools. This printer is useful for showing the total
+number of matches and/or printing file paths that either contain or don't
+contain matches.
+
+# Example
+
+This example shows how to create a "standard" printer and execute a search.
+
+```
+extern crate grep_regex;
+extern crate grep_printer;
+extern crate grep_searcher;
+
+use std::error::Error;
+
+use grep_regex::RegexMatcher;
+use grep_printer::Standard;
+use grep_searcher::Searcher;
+
+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.
+";
+
+# fn main() { example().unwrap(); }
+fn example() -> Result<(), Box<Error>> {
+    let matcher = RegexMatcher::new(r"Sherlock")?;
+    let mut printer = Standard::new_no_color(vec![]);
+    Searcher::new().search_slice(&matcher, SHERLOCK, printer.sink(&matcher))?;
+
+    // into_inner gives us back the underlying writer we provided to
+    // new_no_color, which is wrapped in a termcolor::NoColor. Thus, a second
+    // into_inner gives us back the actual buffer.
+    let output = String::from_utf8(printer.into_inner().into_inner())?;
+    let expected = "\
+1:For the Doctor Watsons of this world, as opposed to the Sherlock
+3:be, to a very large extent, the result of luck. Sherlock Holmes
+";
+    assert_eq!(output, expected);
+    Ok(())
+}
+```
+*/
+
+#![deny(missing_docs)]
+
+#[cfg(feature = "serde1")]
+extern crate base64;
+extern crate grep_matcher;
+#[cfg(test)]
+extern crate grep_regex;
+extern crate grep_searcher;
+#[cfg(feature = "serde1")]
+extern crate serde;
+#[cfg(feature = "serde1")]
+#[macro_use]
+extern crate serde_derive;
+#[cfg(feature = "serde1")]
+extern crate serde_json;
+extern crate termcolor;
+
+pub use color::{ColorError, ColorSpecs, UserColorSpec};
+#[cfg(feature = "serde1")]
+pub use json::{JSON, JSONBuilder, JSONSink};
+pub use standard::{Standard, StandardBuilder, StandardSink};
+pub use stats::Stats;
+pub use summary::{Summary, SummaryBuilder, SummaryKind, SummarySink};
+pub use util::PrinterPath;
+
+#[macro_use]
+mod macros;
+
+mod color;
+mod counter;
+#[cfg(feature = "serde1")]
+mod json;
+#[cfg(feature = "serde1")]
+mod jsont;
+mod standard;
+mod stats;
+mod summary;
+mod util;