Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

14 files changed, 2157 insertions, 0 deletions

diff --git a/vendor/datafrog/.cargo-checksum.json b/vendor/datafrog/.cargo-checksum.json
new file mode 100644
index 000000000..80aa32c14
--- /dev/null
+++ b/vendor/datafrog/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"CODE_OF_CONDUCT.md":"edca092fde496419a9f1ba640048aa0270b62dfea576cd3175f0b53e3c230470","Cargo.toml":"c3a8ecf831d7985fafcb8e523fd2d1bf875297e1a11b750a28222793a42e0d4c","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"23f18e03dc49df91622fe2a76176497404e46ced8a715d9d2b67a7446571cca3","README.md":"60c181bf865b494df30968378509453719163f57a84f31a244fe69e62c342c5b","RELEASES.md":"a49128d725075bb614da3d53ea2aa2ab080bcb83ce46fc57655f6f6ecc9e2b74","examples/borrow_check.rs":"256857ed6609be8d1f3c8cf041ff8a1c0a884e8540f3156d2f3a2a2a9f73a05d","examples/graspan1.rs":"7d93ba71ff08a3667fea696d0a94e2c91e7514c304f2be8b088465cee17537fe","src/join.rs":"04eb29a02a1fd3ecf27d35a9eaabeec686bbfabdeafe13ad9ac98a622acb0f19","src/lib.rs":"7c95a63c237f48f986abd63ddfa4ed296bb5d280d245295d025fdf2f9744c2f3","src/map.rs":"93f1c7273fb67beb62a4b02201a6502bcaabf1e079aa7201a88d8e0aea6123e9","src/test.rs":"1eee5db2817a781cf8bf16744338b896252e400c150ae23ad87ce8c623acee69","src/treefrog.rs":"fe84a2bd2e36f1a48cb6b7e77a74addf218cfc881e9f6d4e7ceff4d8d97aa380"},"package":"a0afaad2b26fa326569eb264b1363e8ae3357618c43982b3f285f0774ce76b69"}
\ No newline at end of file
diff --git a/vendor/datafrog/CODE_OF_CONDUCT.md b/vendor/datafrog/CODE_OF_CONDUCT.md
new file mode 100644
index 000000000..d70b2b52a
--- /dev/null
+++ b/vendor/datafrog/CODE_OF_CONDUCT.md
@@ -0,0 +1,40 @@
+# The Rust Code of Conduct
+
+A version of this document [can be found online](https://www.rust-lang.org/conduct.html).
+
+## Conduct
+
+**Contact**: [rust-mods@rust-lang.org](mailto:rust-mods@rust-lang.org)
+
+* We are committed to providing a friendly, safe and welcoming environment for all, regardless of level of experience, gender identity and expression, sexual orientation, disability, personal appearance, body size, race, ethnicity, age, religion, nationality, or other similar characteristic.
+* On IRC, please avoid using overtly sexual nicknames or other nicknames that might detract from a friendly, safe and welcoming environment for all.
+* Please be kind and courteous. There's no need to be mean or rude.
+* Respect that people have differences of opinion and that every design or implementation choice carries a trade-off and numerous costs. There is seldom a right answer.
+* Please keep unstructured critique to a minimum. If you have solid ideas you want to experiment with, make a fork and see how it works.
+* We will exclude you from interaction if you insult, demean or harass anyone. That is not welcome behavior. We interpret the term "harassment" as including the definition in the <a href="http://citizencodeofconduct.org/">Citizen Code of Conduct</a>; if you have any lack of clarity about what might be included in that concept, please read their definition. In particular, we don't tolerate behavior that excludes people in socially marginalized groups.
+* Private harassment is also unacceptable. No matter who you are, if you feel you have been or are being harassed or made uncomfortable by a community member, please contact one of the channel ops or any of the [Rust moderation team][mod_team] immediately. Whether you're a regular contributor or a newcomer, we care about making this community a safe place for you and we've got your back.
+* Likewise any spamming, trolling, flaming, baiting or other attention-stealing behavior is not welcome.
+
+## Moderation
+
+
+These are the policies for upholding our community's standards of conduct. If you feel that a thread needs moderation, please contact the [Rust moderation team][mod_team].
+
+1. Remarks that violate the Rust standards of conduct, including hateful, hurtful, oppressive, or exclusionary remarks, are not allowed. (Cursing is allowed, but never targeting another user, and never in a hateful manner.)
+2. Remarks that moderators find inappropriate, whether listed in the code of conduct or not, are also not allowed.
+3. Moderators will first respond to such remarks with a warning.
+4. If the warning is unheeded, the user will be "kicked," i.e., kicked out of the communication channel to cool off.
+5. If the user comes back and continues to make trouble, they will be banned, i.e., indefinitely excluded.
+6. Moderators may choose at their discretion to un-ban the user if it was a first offense and they offer the offended party a genuine apology.
+7. If a moderator bans someone and you think it was unjustified, please take it up with that moderator, or with a different moderator, **in private**. Complaints about bans in-channel are not allowed.
+8. Moderators are held to a higher standard than other community members. If a moderator creates an inappropriate situation, they should expect less leeway than others.
+
+In the Rust community we strive to go the extra step to look out for each other. Don't just aim to be technically unimpeachable, try to be your best self. In particular, avoid flirting with offensive or sensitive issues, particularly if they're off-topic; this all too often leads to unnecessary fights, hurt feelings, and damaged trust; worse, it can drive people away from the community entirely.
+
+And if someone takes issue with something you said or did, resist the urge to be defensive. Just stop doing what it was they complained about and apologize. Even if you feel you were misinterpreted or unfairly accused, chances are good there was something you could've communicated better — remember that it's your responsibility to make your fellow Rustaceans comfortable. Everyone wants to get along and we are all here first and foremost because we want to talk about cool technology. You will find that people will be eager to assume good intent and forgive as long as you earn their trust.
+
+The enforcement policies listed above apply to all official Rust venues; including official IRC channels (#rust, #rust-internals, #rust-tools, #rust-libs, #rustc, #rust-beginners, #rust-docs, #rust-community, #rust-lang, and #cargo); GitHub repositories under rust-lang, rust-lang-nursery, and rust-lang-deprecated; and all forums under rust-lang.org (users.rust-lang.org, internals.rust-lang.org). For other projects adopting the Rust Code of Conduct, please contact the maintainers of those projects for enforcement. If you wish to use this code of conduct for your own project, consider explicitly mentioning your moderation policy or making a copy with your own moderation policy so as to avoid confusion.
+
+*Adapted from the [Node.js Policy on Trolling](http://blog.izs.me/post/30036893703/policy-on-trolling) as well as the [Contributor Covenant v1.3.0](https://www.contributor-covenant.org/version/1/3/0/).*
+
+[mod_team]: https://www.rust-lang.org/team.html#Moderation-team
diff --git a/vendor/datafrog/Cargo.toml b/vendor/datafrog/Cargo.toml
new file mode 100644
index 000000000..71bccdded
--- /dev/null
+++ b/vendor/datafrog/Cargo.toml
@@ -0,0 +1,29 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g. crates.io) dependencies
+#
+# If you believe there's an error in this file please file an
+# issue against the rust-lang/cargo repository. If you're
+# editing this file be aware that the upstream Cargo.toml
+# will likely look very different (and much more reasonable)
+
+[package]
+edition = "2018"
+name = "datafrog"
+version = "2.0.1"
+authors = ["Frank McSherry <fmcsherry@me.com>", "The Rust Project Developers", "Datafrog Developers"]
+description = "Lightweight Datalog engine intended to be embedded in other Rust programs"
+readme = "README.md"
+keywords = ["datalog", "analysis"]
+license = "Apache-2.0/MIT"
+repository = "https://github.com/rust-lang-nursery/datafrog"
+[dev-dependencies.proptest]
+version = "0.8.7"
+[badges.is-it-maintained-issue-resolution]
+repository = "https://github.com/rust-lang-nursery/datafrog"
+
+[badges.is-it-maintained-open-issues]
+repository = "https://github.com/rust-lang-nursery/datafrog"
diff --git a/vendor/datafrog/LICENSE-APACHE b/vendor/datafrog/LICENSE-APACHE
new file mode 100644
index 000000000..16fe87b06
--- /dev/null
+++ b/vendor/datafrog/LICENSE-APACHE
@@ -0,0 +1,201 @@
+                              Apache License
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diff --git a/vendor/datafrog/LICENSE-MIT b/vendor/datafrog/LICENSE-MIT
new file mode 100644
index 000000000..31aa79387
--- /dev/null
+++ b/vendor/datafrog/LICENSE-MIT
@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/vendor/datafrog/README.md b/vendor/datafrog/README.md
new file mode 100644
index 000000000..948358410
--- /dev/null
+++ b/vendor/datafrog/README.md
@@ -0,0 +1,44 @@
+# datafrog
+
+Datafrog is a lightweight Datalog engine intended to be embedded in other Rust programs.
+
+Datafrog has no runtime, and relies on you to build and repeatedly apply the update rules.
+It tries to help you do this correctly. As an example, here is how you might write a reachability
+query using Datafrog (minus the part where we populate the `nodes` and `edges` initial relations).
+
+```rust
+extern crate datafrog;
+use datafrog::Iteration;
+
+fn main() {
+
+    // Create a new iteration context, ...
+    let mut iteration = Iteration::new();
+
+    // .. some variables, ..
+    let nodes_var = iteration.variable::<(u32,u32)>("nodes");
+    let edges_var = iteration.variable::<(u32,u32)>("edges");
+
+    // .. load them with some initial values, ..
+    nodes_var.insert(nodes.into());
+    edges_var.insert(edges.into());
+
+    // .. and then start iterating rules!
+    while iteration.changed() {
+        // nodes(a,c)  <-  nodes(a,b), edges(b,c)
+        nodes_var.from_join(&nodes_var, &edges_var, |_b, &a, &c| (c,a));
+    }
+
+    // extract the final results.
+    let reachable: Vec<(u32,u32)> = variable.complete();
+}
+```
+
+If you'd like to read more about how it works, check out [this blog post](https://github.com/frankmcsherry/blog/blob/master/posts/2018-05-19.md).
+
+## Authorship
+
+Datafrog was initially developed by [Frank McSherry][fmc] and was
+later transferred to the rust-lang-nursery organization. Thanks Frank!
+
+[fmc]: https://github.com/frankmcsherry
diff --git a/vendor/datafrog/RELEASES.md b/vendor/datafrog/RELEASES.md
new file mode 100644
index 000000000..7d666f620
--- /dev/null
+++ b/vendor/datafrog/RELEASES.md
@@ -0,0 +1,26 @@
+# 2.0.1
+
+- Work around a rustdoc ICE (#24)
+
+# 2.0.0
+
+- Breaking changes:
+  - leapjoin now takes a tuple of leapers, and not a `&mut` slice:
+    - `from_leapjoin(&input, &mut [&mut foo.extend_with(...), ..], ..)` becomes
+      `from_leapjoin(&input, (foo.extend_with(...), ..), ..)`
+    - if there is only one leaper, no tuple is needed
+  - `Relation::from` now requires a vector, not an iterator; use
+    `Relation::from_iter` instead
+- Changed the API to permit using `Relation` and `Variable` more interchangeably,
+  and added a number of operations to construct relations directly, like `Relation::from_join`
+- Extended leapfrog triejoin with new operations (`PrefixFilter` and `ValueFilter`)
+
+# 1.0.0
+
+- Added leapfrog triejoin (#11).
+- Have badges and repo links now!
+- Minor performance improvements (#13).
+
+# 0.1.0
+
+- Initial release.
diff --git a/vendor/datafrog/examples/borrow_check.rs b/vendor/datafrog/examples/borrow_check.rs
new file mode 100644
index 000000000..8f2197aef
--- /dev/null
+++ b/vendor/datafrog/examples/borrow_check.rs
@@ -0,0 +1,115 @@
+extern crate datafrog;
+use datafrog::Iteration;
+
+type Region = u32;
+type Borrow = u32;
+type Point = u32;
+
+fn main() {
+    let subset = {
+        // Create a new iteration context, ...
+        let mut iteration1 = Iteration::new();
+
+        // .. some variables, ..
+        let subset = iteration1.variable::<(Region, Region, Point)>("subset");
+
+        // different indices for `subset`.
+        let subset_r1p = iteration1.variable::<((Region, Point), Region)>("subset_r1p");
+        let subset_r2p = iteration1.variable::<((Region, Point), Region)>("subset_r2p");
+        let subset_p = iteration1.variable::<(Point, (Region, Region))>("subset_p");
+
+        // temporaries as we perform a multi-way join.
+        let subset_1 = iteration1.variable::<((Region, Point), Region)>("subset_1");
+        let subset_2 = iteration1.variable::<((Region, Point), Region)>("subset_2");
+
+        let region_live_at = iteration1.variable::<((Region, Point), ())>("region_live_at");
+        let cfg_edge_p = iteration1.variable::<(Point, Point)>("cfg_edge_p");
+
+        // load initial facts.
+        subset.insert(Vec::new().into());
+        region_live_at.insert(Vec::new().into());
+        cfg_edge_p.insert(Vec::new().into());
+
+        // .. and then start iterating rules!
+        while iteration1.changed() {
+            // remap fields to re-index by keys.
+            subset_r1p.from_map(&subset, |&(r1, r2, p)| ((r1, p), r2));
+            subset_r2p.from_map(&subset, |&(r1, r2, p)| ((r2, p), r1));
+            subset_p.from_map(&subset, |&(r1, r2, p)| (p, (r1, r2)));
+
+            // R0: subset(R1, R2, P) :- outlives(R1, R2, P).
+            // Already loaded; outlives is static.
+
+            // R1: subset(R1, R3, P) :-
+            //   subset(R1, R2, P),
+            //   subset(R2, R3, P).
+            subset.from_join(&subset_r2p, &subset_r1p, |&(_r2, p), &r1, &r3| (r1, r3, p));
+
+            // R2: subset(R1, R2, Q) :-
+            //   subset(R1, R2, P),
+            //   cfg_edge(P, Q),
+            //   region_live_at(R1, Q),
+            //   region_live_at(R2, Q).
+
+            subset_1.from_join(&subset_p, &cfg_edge_p, |&_p, &(r1, r2), &q| ((r1, q), r2));
+            subset_2.from_join(&subset_1, &region_live_at, |&(r1, q), &r2, &()| {
+                ((r2, q), r1)
+            });
+            subset.from_join(&subset_2, &region_live_at, |&(r2, q), &r1, &()| (r1, r2, q));
+        }
+
+        subset_r1p.complete()
+    };
+
+    let _requires = {
+        // Create a new iteration context, ...
+        let mut iteration2 = Iteration::new();
+
+        // .. some variables, ..
+        let requires = iteration2.variable::<(Region, Borrow, Point)>("requires");
+        requires.insert(Vec::new().into());
+
+        let requires_rp = iteration2.variable::<((Region, Point), Borrow)>("requires_rp");
+        let requires_bp = iteration2.variable::<((Borrow, Point), Region)>("requires_bp");
+
+        let requires_1 = iteration2.variable::<(Point, (Borrow, Region))>("requires_1");
+        let requires_2 = iteration2.variable::<((Region, Point), Borrow)>("requires_2");
+
+        let subset_r1p = iteration2.variable::<((Region, Point), Region)>("subset_r1p");
+        subset_r1p.insert(subset);
+
+        let killed = Vec::new().into();
+        let region_live_at = iteration2.variable::<((Region, Point), ())>("region_live_at");
+        let cfg_edge_p = iteration2.variable::<(Point, Point)>("cfg_edge_p");
+
+        // .. and then start iterating rules!
+        while iteration2.changed() {
+            requires_rp.from_map(&requires, |&(r, b, p)| ((r, p), b));
+            requires_bp.from_map(&requires, |&(r, b, p)| ((b, p), r));
+
+            // requires(R, B, P) :- borrow_region(R, B, P).
+            // Already loaded; borrow_region is static.
+
+            // requires(R2, B, P) :-
+            //   requires(R1, B, P),
+            //   subset(R1, R2, P).
+            requires.from_join(&requires_rp, &subset_r1p, |&(_r1, p), &b, &r2| (r2, b, p));
+
+            // requires(R, B, Q) :-
+            //   requires(R, B, P),
+            //   !killed(B, P),
+            //   cfg_edge(P, Q),
+            //   (region_live_at(R, Q); universal_region(R)).
+
+            requires_1.from_antijoin(&requires_bp, &killed, |&(b, p), &r| (p, (b, r)));
+            requires_2.from_join(&requires_1, &cfg_edge_p, |&_p, &(b, r), &q| ((r, q), b));
+            requires.from_join(&requires_2, &region_live_at, |&(r, q), &b, &()| (r, b, q));
+        }
+
+        requires.complete()
+    };
+
+    // borrow_live_at(B, P) :- requires(R, B, P), region_live_at(R, P)
+
+    // borrow_live_at(B, P) :- requires(R, B, P), universal_region(R).
+}
diff --git a/vendor/datafrog/examples/graspan1.rs b/vendor/datafrog/examples/graspan1.rs
new file mode 100644
index 000000000..31225b11d
--- /dev/null
+++ b/vendor/datafrog/examples/graspan1.rs
@@ -0,0 +1,62 @@
+extern crate datafrog;
+use datafrog::Iteration;
+
+fn main() {
+    let timer = ::std::time::Instant::now();
+
+    // Make space for input data.
+    let mut nodes = Vec::new();
+    let mut edges = Vec::new();
+
+    // Read input data from a handy file.
+    use std::fs::File;
+    use std::io::{BufRead, BufReader};
+
+    let filename = std::env::args().nth(1).unwrap();
+    let file = BufReader::new(File::open(filename).unwrap());
+    for readline in file.lines() {
+        let line = readline.expect("read error");
+        if !line.is_empty() && !line.starts_with('#') {
+            let mut elts = line[..].split_whitespace();
+            let src: u32 = elts.next().unwrap().parse().expect("malformed src");
+            let dst: u32 = elts.next().unwrap().parse().expect("malformed dst");
+            let typ: &str = elts.next().unwrap();
+            match typ {
+                "n" => {
+                    nodes.push((dst, src));
+                }
+                "e" => {
+                    edges.push((src, dst));
+                }
+                unk => panic!("unknown type: {}", unk),
+            }
+        }
+    }
+
+    println!("{:?}\tData loaded", timer.elapsed());
+
+    // Create a new iteration context, ...
+    let mut iteration = Iteration::new();
+
+    // .. some variables, ..
+    let variable1 = iteration.variable::<(u32, u32)>("nodes");
+    let variable2 = iteration.variable::<(u32, u32)>("edges");
+
+    // .. load them with some initial values, ..
+    variable1.insert(nodes.into());
+    variable2.insert(edges.into());
+
+    // .. and then start iterating rules!
+    while iteration.changed() {
+        // N(a,c) <-  N(a,b), E(b,c)
+        variable1.from_join(&variable1, &variable2, |_b, &a, &c| (c, a));
+    }
+
+    let reachable = variable1.complete();
+
+    println!(
+        "{:?}\tComputation complete (nodes_final: {})",
+        timer.elapsed(),
+        reachable.len()
+    );
+}
diff --git a/vendor/datafrog/src/join.rs b/vendor/datafrog/src/join.rs
new file mode 100644
index 000000000..94270af77
--- /dev/null
+++ b/vendor/datafrog/src/join.rs
@@ -0,0 +1,180 @@
+//! Join functionality.
+
+use super::{Relation, Variable};
+use std::cell::Ref;
+use std::ops::Deref;
+
+/// Implements `join`. Note that `input1` must be a variable, but
+/// `input2` can be either a variable or a relation. This is necessary
+/// because relations have no "recent" tuples, so the fn would be a
+/// guaranteed no-op if both arguments were relations.  See also
+/// `join_into_relation`.
+pub(crate) fn join_into<'me, Key: Ord, Val1: Ord, Val2: Ord, Result: Ord>(
+    input1: &Variable<(Key, Val1)>,
+    input2: impl JoinInput<'me, (Key, Val2)>,
+    output: &Variable<Result>,
+    mut logic: impl FnMut(&Key, &Val1, &Val2) -> Result,
+) {
+    let mut results = Vec::new();
+
+    let recent1 = input1.recent();
+    let recent2 = input2.recent();
+
+    {
+        // scoped to let `closure` drop borrow of `results`.
+
+        let mut closure = |k: &Key, v1: &Val1, v2: &Val2| results.push(logic(k, v1, v2));
+
+        for batch2 in input2.stable().iter() {
+            join_helper(&recent1, &batch2, &mut closure);
+        }
+
+        for batch1 in input1.stable().iter() {
+            join_helper(&batch1, &recent2, &mut closure);
+        }
+
+        join_helper(&recent1, &recent2, &mut closure);
+    }
+
+    output.insert(Relation::from_vec(results));
+}
+
+/// Join, but for two relations.
+pub(crate) fn join_into_relation<'me, Key: Ord, Val1: Ord, Val2: Ord, Result: Ord>(
+    input1: &Relation<(Key, Val1)>,
+    input2: &Relation<(Key, Val2)>,
+    mut logic: impl FnMut(&Key, &Val1, &Val2) -> Result,
+) -> Relation<Result> {
+    let mut results = Vec::new();
+
+    join_helper(&input1.elements, &input2.elements, |k, v1, v2| {
+        results.push(logic(k, v1, v2));
+    });
+
+    Relation::from_vec(results)
+}
+
+/// Moves all recent tuples from `input1` that are not present in `input2` into `output`.
+pub(crate) fn antijoin<'me, Key: Ord, Val: Ord, Result: Ord>(
+    input1: impl JoinInput<'me, (Key, Val)>,
+    input2: &Relation<Key>,
+    mut logic: impl FnMut(&Key, &Val) -> Result,
+) -> Relation<Result> {
+    let mut tuples2 = &input2[..];
+
+    let results = input1
+        .recent()
+        .iter()
+        .filter(|(ref key, _)| {
+            tuples2 = gallop(tuples2, |k| k < key);
+            tuples2.first() != Some(key)
+        })
+        .map(|(ref key, ref val)| logic(key, val))
+        .collect::<Vec<_>>();
+
+    Relation::from_vec(results)
+}
+
+fn join_helper<K: Ord, V1, V2>(
+    mut slice1: &[(K, V1)],
+    mut slice2: &[(K, V2)],
+    mut result: impl FnMut(&K, &V1, &V2),
+) {
+    while !slice1.is_empty() && !slice2.is_empty() {
+        use std::cmp::Ordering;
+
+        // If the keys match produce tuples, else advance the smaller key until they might.
+        match slice1[0].0.cmp(&slice2[0].0) {
+            Ordering::Less => {
+                slice1 = gallop(slice1, |x| x.0 < slice2[0].0);
+            }
+            Ordering::Equal => {
+                // Determine the number of matching keys in each slice.
+                let count1 = slice1.iter().take_while(|x| x.0 == slice1[0].0).count();
+                let count2 = slice2.iter().take_while(|x| x.0 == slice2[0].0).count();
+
+                // Produce results from the cross-product of matches.
+                for index1 in 0..count1 {
+                    for s2 in slice2[..count2].iter() {
+                        result(&slice1[0].0, &slice1[index1].1, &s2.1);
+                    }
+                }
+
+                // Advance slices past this key.
+                slice1 = &slice1[count1..];
+                slice2 = &slice2[count2..];
+            }
+            Ordering::Greater => {
+                slice2 = gallop(slice2, |x| x.0 < slice1[0].0);
+            }
+        }
+    }
+}
+
+pub(crate) fn gallop<T>(mut slice: &[T], mut cmp: impl FnMut(&T) -> bool) -> &[T] {
+    // if empty slice, or already >= element, return
+    if !slice.is_empty() && cmp(&slice[0]) {
+        let mut step = 1;
+        while step < slice.len() && cmp(&slice[step]) {
+            slice = &slice[step..];
+            step <<= 1;
+        }
+
+        step >>= 1;
+        while step > 0 {
+            if step < slice.len() && cmp(&slice[step]) {
+                slice = &slice[step..];
+            }
+            step >>= 1;
+        }
+
+        slice = &slice[1..]; // advance one, as we always stayed < value
+    }
+
+    slice
+}
+
+/// An input that can be used with `from_join`; either a `Variable` or a `Relation`.
+pub trait JoinInput<'me, Tuple: Ord>: Copy {
+    /// If we are on iteration N of the loop, these are the tuples
+    /// added on iteration N-1. (For a `Relation`, this is always an
+    /// empty slice.)
+    type RecentTuples: Deref<Target = [Tuple]>;
+
+    /// If we are on iteration N of the loop, these are the tuples
+    /// added on iteration N - 2 or before. (For a `Relation`, this is
+    /// just `self`.)
+    type StableTuples: Deref<Target = [Relation<Tuple>]>;
+
+    /// Get the set of recent tuples.
+    fn recent(self) -> Self::RecentTuples;
+
+    /// Get the set of stable tuples.
+    fn stable(self) -> Self::StableTuples;
+}
+
+impl<'me, Tuple: Ord> JoinInput<'me, Tuple> for &'me Variable<Tuple> {
+    type RecentTuples = Ref<'me, [Tuple]>;
+    type StableTuples = Ref<'me, [Relation<Tuple>]>;
+
+    fn recent(self) -> Self::RecentTuples {
+        Ref::map(self.recent.borrow(), |r| &r.elements[..])
+    }
+
+    fn stable(self) -> Self::StableTuples {
+        Ref::map(self.stable.borrow(), |v| &v[..])
+    }
+}
+
+impl<'me, Tuple: Ord> JoinInput<'me, Tuple> for &'me Relation<Tuple> {
+    type RecentTuples = &'me [Tuple];
+    type StableTuples = &'me [Relation<Tuple>];
+
+    fn recent(self) -> Self::RecentTuples {
+        &[]
+    }
+
+    fn stable(self) -> Self::StableTuples {
+        std::slice::from_ref(self)
+    }
+}
diff --git a/vendor/datafrog/src/lib.rs b/vendor/datafrog/src/lib.rs
new file mode 100644
index 000000000..d2f93239e
--- /dev/null
+++ b/vendor/datafrog/src/lib.rs
@@ -0,0 +1,567 @@
+//! A lightweight Datalog engine in Rust
+//!
+//! The intended design is that one has static `Relation` types that are sets
+//! of tuples, and `Variable` types that represent monotonically increasing
+//! sets of tuples.
+//!
+//! The types are mostly wrappers around `Vec<Tuple>` indicating sorted-ness,
+//! and the intent is that this code can be dropped in the middle of an otherwise
+//! normal Rust program, run to completion, and then the results extracted as
+//! vectors again.
+
+#![forbid(missing_docs)]
+
+use std::cell::RefCell;
+use std::cmp::Ordering;
+use std::iter::FromIterator;
+use std::rc::Rc;
+
+mod join;
+mod map;
+mod test;
+mod treefrog;
+pub use crate::join::JoinInput;
+pub use crate::treefrog::{
+    extend_anti::ExtendAnti,
+    extend_with::ExtendWith,
+    filter_anti::FilterAnti,
+    filter_with::FilterWith,
+    filters::{PrefixFilter, ValueFilter},
+    Leaper, Leapers, RelationLeaper,
+};
+
+/// A static, ordered list of key-value pairs.
+///
+/// A relation represents a fixed set of key-value pairs. In many places in a
+/// Datalog computation we want to be sure that certain relations are not able
+/// to vary (for example, in antijoins).
+#[derive(Clone)]
+pub struct Relation<Tuple: Ord> {
+    /// Sorted list of distinct tuples.
+    pub elements: Vec<Tuple>,
+}
+
+impl<Tuple: Ord> Relation<Tuple> {
+    /// Merges two relations into their union.
+    pub fn merge(self, other: Self) -> Self {
+        let Relation {
+            elements: mut elements1,
+        } = self;
+        let Relation {
+            elements: mut elements2,
+        } = other;
+
+        // If one of the element lists is zero-length, we don't need to do any work
+        if elements1.is_empty() {
+            return Relation {
+                elements: elements2,
+            };
+        }
+
+        if elements2.is_empty() {
+            return Relation {
+                elements: elements1,
+            };
+        }
+
+        // Make sure that elements1 starts with the lower element
+        // Will not panic since both collections must have at least 1 element at this point
+        if elements1[0] > elements2[0] {
+            std::mem::swap(&mut elements1, &mut elements2);
+        }
+
+        // Fast path for when all the new elements are after the exiting ones
+        if elements1[elements1.len() - 1] < elements2[0] {
+            elements1.extend(elements2.into_iter());
+            // println!("fast path");
+            return Relation {
+                elements: elements1,
+            };
+        }
+
+        let mut elements = Vec::with_capacity(elements1.len() + elements2.len());
+        let mut elements1 = elements1.drain(..);
+        let mut elements2 = elements2.drain(..).peekable();
+
+        elements.push(elements1.next().unwrap());
+        if elements.first() == elements2.peek() {
+            elements2.next();
+        }
+
+        for elem in elements1 {
+            while elements2.peek().map(|x| x.cmp(&elem)) == Some(Ordering::Less) {
+                elements.push(elements2.next().unwrap());
+            }
+            if elements2.peek().map(|x| x.cmp(&elem)) == Some(Ordering::Equal) {
+                elements2.next();
+            }
+            elements.push(elem);
+        }
+
+        // Finish draining second list
+        elements.extend(elements2);
+
+        Relation { elements }
+    }
+
+    /// Creates a `Relation` from the elements of the `iterator`.
+    ///
+    /// Same as the `from_iter` method from `std::iter::FromIterator` trait.
+    pub fn from_iter<I>(iterator: I) -> Self
+    where
+        I: IntoIterator<Item = Tuple>,
+    {
+        iterator.into_iter().collect()
+    }
+
+    /// Creates a `Relation` using the `leapjoin` logic;
+    /// see [`Variable::from_leapjoin`]
+    pub fn from_leapjoin<'leap, SourceTuple: Ord, Val: Ord + 'leap>(
+        source: &Relation<SourceTuple>,
+        leapers: impl Leapers<'leap, SourceTuple, Val>,
+        logic: impl FnMut(&SourceTuple, &Val) -> Tuple,
+    ) -> Self {
+        treefrog::leapjoin(&source.elements, leapers, logic)
+    }
+
+    /// Creates a `Relation` by joining the values from `input1` and
+    /// `input2` and then applying `logic`. Like
+    /// [`Variable::from_join`] except for use where the inputs are
+    /// not varying across iterations.
+    pub fn from_join<Key: Ord, Val1: Ord, Val2: Ord>(
+        input1: &Relation<(Key, Val1)>,
+        input2: &Relation<(Key, Val2)>,
+        logic: impl FnMut(&Key, &Val1, &Val2) -> Tuple,
+    ) -> Self {
+        join::join_into_relation(input1, input2, logic)
+    }
+
+    /// Creates a `Relation` by removing all values from `input1` that
+    /// share a key with `input2`, and then transforming the resulting
+    /// tuples with the `logic` closure. Like
+    /// [`Variable::from_antijoin`] except for use where the inputs
+    /// are not varying across iterations.
+    pub fn from_antijoin<Key: Ord, Val1: Ord>(
+        input1: &Relation<(Key, Val1)>,
+        input2: &Relation<Key>,
+        logic: impl FnMut(&Key, &Val1) -> Tuple,
+    ) -> Self {
+        join::antijoin(input1, input2, logic)
+    }
+
+    /// Construct a new relation by mapping another one. Equivalent to
+    /// creating an iterator but perhaps more convenient. Analogous to
+    /// `Variable::from_map`.
+    pub fn from_map<T2: Ord>(input: &Relation<T2>, logic: impl FnMut(&T2) -> Tuple) -> Self {
+        input.iter().map(logic).collect()
+    }
+
+    /// Creates a `Relation` from a vector of tuples.
+    pub fn from_vec(mut elements: Vec<Tuple>) -> Self {
+        elements.sort();
+        elements.dedup();
+        Relation { elements }
+    }
+}
+
+impl<Tuple: Ord> From<Vec<Tuple>> for Relation<Tuple> {
+    fn from(iterator: Vec<Tuple>) -> Self {
+        Self::from_vec(iterator)
+    }
+}
+
+impl<Tuple: Ord> FromIterator<Tuple> for Relation<Tuple> {
+    fn from_iter<I>(iterator: I) -> Self
+    where
+        I: IntoIterator<Item = Tuple>,
+    {
+        Relation::from_vec(iterator.into_iter().collect())
+    }
+}
+
+impl<'tuple, Tuple: 'tuple + Copy + Ord> FromIterator<&'tuple Tuple> for Relation<Tuple> {
+    fn from_iter<I>(iterator: I) -> Self
+    where
+        I: IntoIterator<Item = &'tuple Tuple>,
+    {
+        Relation::from_vec(iterator.into_iter().cloned().collect())
+    }
+}
+
+impl<Tuple: Ord> std::ops::Deref for Relation<Tuple> {
+    type Target = [Tuple];
+    fn deref(&self) -> &Self::Target {
+        &self.elements[..]
+    }
+}
+
+/// An iterative context for recursive evaluation.
+///
+/// An `Iteration` tracks monotonic variables, and monitors their progress.
+/// It can inform the user if they have ceased changing, at which point the
+/// computation should be done.
+pub struct Iteration {
+    variables: Vec<Box<dyn VariableTrait>>,
+}
+
+impl Iteration {
+    /// Create a new iterative context.
+    pub fn new() -> Self {
+        Iteration {
+            variables: Vec::new(),
+        }
+    }
+    /// Reports whether any of the monitored variables have changed since
+    /// the most recent call.
+    pub fn changed(&mut self) -> bool {
+        let mut result = false;
+        for variable in self.variables.iter_mut() {
+            if variable.changed() {
+                result = true;
+            }
+        }
+        result
+    }
+    /// Creates a new named variable associated with the iterative context.
+    pub fn variable<Tuple: Ord + 'static>(&mut self, name: &str) -> Variable<Tuple> {
+        let variable = Variable::new(name);
+        self.variables.push(Box::new(variable.clone()));
+        variable
+    }
+    /// Creates a new named variable associated with the iterative context.
+    ///
+    /// This variable will not be maintained distinctly, and may advertise tuples as
+    /// recent multiple times (perhaps unboundedly many times).
+    pub fn variable_indistinct<Tuple: Ord + 'static>(&mut self, name: &str) -> Variable<Tuple> {
+        let mut variable = Variable::new(name);
+        variable.distinct = false;
+        self.variables.push(Box::new(variable.clone()));
+        variable
+    }
+}
+
+/// A type that can report on whether it has changed.
+trait VariableTrait {
+    /// Reports whether the variable has changed since it was last asked.
+    fn changed(&mut self) -> bool;
+}
+
+/// An monotonically increasing set of `Tuple`s.
+///
+/// There are three stages in the lifecycle of a tuple:
+///
+///   1. A tuple is added to `self.to_add`, but is not yet visible externally.
+///   2. Newly added tuples are then promoted to `self.recent` for one iteration.
+///   3. After one iteration, recent tuples are moved to `self.tuples` for posterity.
+///
+/// Each time `self.changed()` is called, the `recent` relation is folded into `tuples`,
+/// and the `to_add` relations are merged, potentially deduplicated against `tuples`, and
+/// then made  `recent`. This way, across calls to `changed()` all added tuples are in
+/// `recent` at least once and eventually all are in `tuples`.
+///
+/// A `Variable` may optionally be instructed not to de-duplicate its tuples, for reasons
+/// of performance. Such a variable cannot be relied on to terminate iterative computation,
+/// and it is important that any cycle of derivations have at least one de-duplicating
+/// variable on it.
+pub struct Variable<Tuple: Ord> {
+    /// Should the variable be maintained distinctly.
+    distinct: bool,
+    /// A useful name for the variable.
+    name: String,
+    /// A list of relations whose union are the accepted tuples.
+    pub stable: Rc<RefCell<Vec<Relation<Tuple>>>>,
+    /// A list of recent tuples, still to be processed.
+    pub recent: Rc<RefCell<Relation<Tuple>>>,
+    /// A list of future tuples, to be introduced.
+    to_add: Rc<RefCell<Vec<Relation<Tuple>>>>,
+}
+
+// Operator implementations.
+impl<Tuple: Ord> Variable<Tuple> {
+    /// Adds tuples that result from joining `input1` and `input2` --
+    /// each of the inputs must be a set of (Key, Value) tuples. Both
+    /// `input1` and `input2` must have the same type of key (`K`) but
+    /// they can have distinct value types (`V1` and `V2`
+    /// respectively). The `logic` closure will be invoked for each
+    /// key that appears in both inputs; it is also given the two
+    /// values, and from those it should construct the resulting
+    /// value.
+    ///
+    /// Note that `input1` must be a variable, but `input2` can be a
+    /// relation or a variable. Therefore, you cannot join two
+    /// relations with this method. This is not because the result
+    /// would be wrong, but because it would be inefficient: the
+    /// result from such a join cannot vary across iterations (as
+    /// relations are fixed), so you should prefer to invoke `insert`
+    /// on a relation created by `Relation::from_join` instead.
+    ///
+    /// # Examples
+    ///
+    /// This example starts a collection with the pairs (x, x+1) and (x+1, x) for x in 0 .. 10.
+    /// It then adds pairs (y, z) for which (x, y) and (x, z) are present. Because the initial
+    /// pairs are symmetric, this should result in all pairs (x, y) for x and y in 0 .. 11.
+    ///
+    /// ```
+    /// use datafrog::{Iteration, Relation};
+    ///
+    /// let mut iteration = Iteration::new();
+    /// let variable = iteration.variable::<(usize, usize)>("source");
+    /// variable.extend((0 .. 10).map(|x| (x, x + 1)));
+    /// variable.extend((0 .. 10).map(|x| (x + 1, x)));
+    ///
+    /// while iteration.changed() {
+    ///     variable.from_join(&variable, &variable, |&key, &val1, &val2| (val1, val2));
+    /// }
+    ///
+    /// let result = variable.complete();
+    /// assert_eq!(result.len(), 121);
+    /// ```
+    pub fn from_join<'me, K: Ord, V1: Ord, V2: Ord>(
+        &self,
+        input1: &'me Variable<(K, V1)>,
+        input2: impl JoinInput<'me, (K, V2)>,
+        logic: impl FnMut(&K, &V1, &V2) -> Tuple,
+    ) {
+        join::join_into(input1, input2, self, logic)
+    }
+
+    /// Adds tuples from `input1` whose key is not present in `input2`.
+    ///
+    /// Note that `input1` must be a variable: if you have a relation
+    /// instead, you can use `Relation::from_antijoin` and then
+    /// `Variable::insert`.  Note that the result will not vary during
+    /// the iteration.
+    ///
+    /// # Examples
+    ///
+    /// This example starts a collection with the pairs (x, x+1) for x in 0 .. 10. It then
+    /// adds any pairs (x+1,x) for which x is not a multiple of three. That excludes four
+    /// pairs (for 0, 3, 6, and 9) which should leave us with 16 total pairs.
+    ///
+    /// ```
+    /// use datafrog::{Iteration, Relation};
+    ///
+    /// let mut iteration = Iteration::new();
+    /// let variable = iteration.variable::<(usize, usize)>("source");
+    /// variable.extend((0 .. 10).map(|x| (x, x + 1)));
+    ///
+    /// let relation: Relation<_> = (0 .. 10).filter(|x| x % 3 == 0).collect();
+    ///
+    /// while iteration.changed() {
+    ///     variable.from_antijoin(&variable, &relation, |&key, &val| (val, key));
+    /// }
+    ///
+    /// let result = variable.complete();
+    /// assert_eq!(result.len(), 16);
+    /// ```
+    pub fn from_antijoin<K: Ord, V: Ord>(
+        &self,
+        input1: &Variable<(K, V)>,
+        input2: &Relation<K>,
+        logic: impl FnMut(&K, &V) -> Tuple,
+    ) {
+        self.insert(join::antijoin(input1, input2, logic))
+    }
+
+    /// Adds tuples that result from mapping `input`.
+    ///
+    /// # Examples
+    ///
+    /// This example starts a collection with the pairs (x, x) for x in 0 .. 10. It then
+    /// repeatedly adds any pairs (x, z) for (x, y) in the collection, where z is the Collatz
+    /// step for y: it is y/2 if y is even, and 3*y + 1 if y is odd. This produces all of the
+    /// pairs (x, y) where x visits y as part of its Collatz journey.
+    ///
+    /// ```
+    /// use datafrog::{Iteration, Relation};
+    ///
+    /// let mut iteration = Iteration::new();
+    /// let variable = iteration.variable::<(usize, usize)>("source");
+    /// variable.extend((0 .. 10).map(|x| (x, x)));
+    ///
+    /// while iteration.changed() {
+    ///     variable.from_map(&variable, |&(key, val)|
+    ///         if val % 2 == 0 {
+    ///             (key, val/2)
+    ///         }
+    ///         else {
+    ///             (key, 3*val + 1)
+    ///         });
+    /// }
+    ///
+    /// let result = variable.complete();
+    /// assert_eq!(result.len(), 74);
+    /// ```
+    pub fn from_map<T2: Ord>(&self, input: &Variable<T2>, logic: impl FnMut(&T2) -> Tuple) {
+        map::map_into(input, self, logic)
+    }
+
+    /// Adds tuples that result from combining `source` with the
+    /// relations given in `leapers`. This operation is very flexible
+    /// and can be used to do a combination of joins and anti-joins.
+    /// The main limitation is that the things being combined must
+    /// consist of one dynamic variable (`source`) and then several
+    /// fixed relations (`leapers`).
+    ///
+    /// The idea is as follows:
+    ///
+    /// - You will be inserting new tuples that result from joining (and anti-joining)
+    ///   some dynamic variable `source` of source tuples (`SourceTuple`)
+    ///   with some set of values (of type `Val`).
+    /// - You provide these values by combining `source` with a set of leapers
+    ///   `leapers`, each of which is derived from a fixed relation. The `leapers`
+    ///   should be either a single leaper (of suitable type) or else a tuple of leapers.
+    ///   You can create a leaper in one of two ways:
+    ///   - Extension: In this case, you have a relation of type `(K, Val)` for some
+    ///     type `K`. You provide a closure that maps from `SourceTuple` to the key
+    ///     `K`. If you use `relation.extend_with`, then any `Val` values the
+    ///     relation provides will be added to the set of values; if you use
+    ///     `extend_anti`, then the `Val` values will be removed.
+    ///   - Filtering: In this case, you have a relation of type `K` for some
+    ///     type `K` and you provide a closure that maps from `SourceTuple` to
+    ///     the key `K`. Filters don't provide values but they remove source
+    ///     tuples.
+    /// - Finally, you get a callback `logic` that accepts each `(SourceTuple, Val)`
+    ///   that was successfully joined (and not filtered) and which maps to the
+    ///   type of this variable.
+    pub fn from_leapjoin<'leap, SourceTuple: Ord, Val: Ord + 'leap>(
+        &self,
+        source: &Variable<SourceTuple>,
+        leapers: impl Leapers<'leap, SourceTuple, Val>,
+        logic: impl FnMut(&SourceTuple, &Val) -> Tuple,
+    ) {
+        self.insert(treefrog::leapjoin(&source.recent.borrow(), leapers, logic));
+    }
+}
+
+impl<Tuple: Ord> Clone for Variable<Tuple> {
+    fn clone(&self) -> Self {
+        Variable {
+            distinct: self.distinct,
+            name: self.name.clone(),
+            stable: self.stable.clone(),
+            recent: self.recent.clone(),
+            to_add: self.to_add.clone(),
+        }
+    }
+}
+
+impl<Tuple: Ord> Variable<Tuple> {
+    fn new(name: &str) -> Self {
+        Variable {
+            distinct: true,
+            name: name.to_string(),
+            stable: Rc::new(RefCell::new(Vec::new())),
+            recent: Rc::new(RefCell::new(Vec::new().into())),
+            to_add: Rc::new(RefCell::new(Vec::new())),
+        }
+    }
+
+    /// Inserts a relation into the variable.
+    ///
+    /// This is most commonly used to load initial values into a variable.
+    /// it is not obvious that it should be commonly used otherwise, but
+    /// it should not be harmful.
+    pub fn insert(&self, relation: Relation<Tuple>) {
+        if !relation.is_empty() {
+            self.to_add.borrow_mut().push(relation);
+        }
+    }
+
+    /// Extend the variable with values from the iterator.
+    ///
+    /// This is most commonly used to load initial values into a variable.
+    /// it is not obvious that it should be commonly used otherwise, but
+    /// it should not be harmful.
+    pub fn extend<T>(&self, iterator: impl IntoIterator<Item = T>)
+    where
+        Relation<Tuple>: FromIterator<T>,
+    {
+        self.insert(iterator.into_iter().collect());
+    }
+
+    /// Consumes the variable and returns a relation.
+    ///
+    /// This method removes the ability for the variable to develop, and
+    /// flattens all internal tuples down to one relation. The method
+    /// asserts that iteration has completed, in that `self.recent` and
+    /// `self.to_add` should both be empty.
+    pub fn complete(self) -> Relation<Tuple> {
+        assert!(self.recent.borrow().is_empty());
+        assert!(self.to_add.borrow().is_empty());
+        let mut result: Relation<Tuple> = Vec::new().into();
+        while let Some(batch) = self.stable.borrow_mut().pop() {
+            result = result.merge(batch);
+        }
+        result
+    }
+}
+
+impl<Tuple: Ord> VariableTrait for Variable<Tuple> {
+    fn changed(&mut self) -> bool {
+        // 1. Merge self.recent into self.stable.
+        if !self.recent.borrow().is_empty() {
+            let mut recent =
+                ::std::mem::replace(&mut (*self.recent.borrow_mut()), Vec::new().into());
+            while self
+                .stable
+                .borrow()
+                .last()
+                .map(|x| x.len() <= 2 * recent.len())
+                == Some(true)
+            {
+                let last = self.stable.borrow_mut().pop().unwrap();
+                recent = recent.merge(last);
+            }
+            self.stable.borrow_mut().push(recent);
+        }
+
+        // 2. Move self.to_add into self.recent.
+        let to_add = self.to_add.borrow_mut().pop();
+        if let Some(mut to_add) = to_add {
+            while let Some(to_add_more) = self.to_add.borrow_mut().pop() {
+                to_add = to_add.merge(to_add_more);
+            }
+            // 2b. Restrict `to_add` to tuples not in `self.stable`.
+            if self.distinct {
+                for batch in self.stable.borrow().iter() {
+                    let mut slice = &batch[..];
+                    // Only gallop if the slice is relatively large.
+                    if slice.len() > 4 * to_add.elements.len() {
+                        to_add.elements.retain(|x| {
+                            slice = join::gallop(slice, |y| y < x);
+                            slice.is_empty() || &slice[0] != x
+                        });
+                    } else {
+                        to_add.elements.retain(|x| {
+                            while !slice.is_empty() && &slice[0] < x {
+                                slice = &slice[1..];
+                            }
+                            slice.is_empty() || &slice[0] != x
+                        });
+                    }
+                }
+            }
+            *self.recent.borrow_mut() = to_add;
+        }
+
+        // let mut total = 0;
+        // for tuple in self.stable.borrow().iter() {
+        //     total += tuple.len();
+        // }
+
+        // println!("Variable\t{}\t{}\t{}", self.name, total, self.recent.borrow().len());
+
+        !self.recent.borrow().is_empty()
+    }
+}
+
+// impl<Tuple: Ord> Drop for Variable<Tuple> {
+//     fn drop(&mut self) {
+//         let mut total = 0;
+//         for batch in self.stable.borrow().iter() {
+//             total += batch.len();
+//         }
+//         println!("FINAL: {:?}\t{:?}", self.name, total);
+//     }
+// }
diff --git a/vendor/datafrog/src/map.rs b/vendor/datafrog/src/map.rs
new file mode 100644
index 000000000..1a8c10128
--- /dev/null
+++ b/vendor/datafrog/src/map.rs
@@ -0,0 +1,13 @@
+//! Map functionality.
+
+use super::{Relation, Variable};
+
+pub(crate) fn map_into<T1: Ord, T2: Ord>(
+    input: &Variable<T1>,
+    output: &Variable<T2>,
+    logic: impl FnMut(&T1) -> T2,
+) {
+    let results: Vec<T2> = input.recent.borrow().iter().map(logic).collect();
+
+    output.insert(Relation::from_vec(results));
+}
diff --git a/vendor/datafrog/src/test.rs b/vendor/datafrog/src/test.rs
new file mode 100644
index 000000000..9d5af3561
--- /dev/null
+++ b/vendor/datafrog/src/test.rs
@@ -0,0 +1,195 @@
+#![cfg(test)]
+
+use crate::Iteration;
+use crate::Relation;
+use crate::RelationLeaper;
+use proptest::prelude::*;
+use proptest::{proptest, proptest_helper};
+
+fn inputs() -> impl Strategy<Value = Vec<(u32, u32)>> {
+    prop::collection::vec((0_u32..100, 0_u32..100), 1..500)
+}
+
+/// The original way to use datafrog -- computes reachable nodes from a set of edges
+fn reachable_with_var_join(edges: &[(u32, u32)]) -> Relation<(u32, u32)> {
+    let edges: Relation<_> = edges.iter().collect();
+    let mut iteration = Iteration::new();
+
+    let edges_by_successor = iteration.variable::<(u32, u32)>("edges_invert");
+    edges_by_successor.extend(edges.iter().map(|&(n1, n2)| (n2, n1)));
+
+    let reachable = iteration.variable::<(u32, u32)>("reachable");
+    reachable.insert(edges);
+
+    while iteration.changed() {
+        // reachable(N1, N3) :- edges(N1, N2), reachable(N2, N3).
+        reachable.from_join(&reachable, &edges_by_successor, |&_, &n3, &n1| (n1, n3));
+    }
+
+    reachable.complete()
+}
+
+/// Like `reachable`, but using a relation as an input to `from_join`
+fn reachable_with_relation_join(edges: &[(u32, u32)]) -> Relation<(u32, u32)> {
+    let edges: Relation<_> = edges.iter().collect();
+    let mut iteration = Iteration::new();
+
+    // NB. Changed from `reachable_with_var_join`:
+    let edges_by_successor: Relation<_> = edges.iter().map(|&(n1, n2)| (n2, n1)).collect();
+
+    let reachable = iteration.variable::<(u32, u32)>("reachable");
+    reachable.insert(edges);
+
+    while iteration.changed() {
+        // reachable(N1, N3) :- edges(N1, N2), reachable(N2, N3).
+        reachable.from_join(&reachable, &edges_by_successor, |&_, &n3, &n1| (n1, n3));
+    }
+
+    reachable.complete()
+}
+
+fn reachable_with_leapfrog(edges: &[(u32, u32)]) -> Relation<(u32, u32)> {
+    let edges: Relation<_> = edges.iter().collect();
+    let mut iteration = Iteration::new();
+
+    let edges_by_successor: Relation<_> = edges.iter().map(|&(n1, n2)| (n2, n1)).collect();
+
+    let reachable = iteration.variable::<(u32, u32)>("reachable");
+    reachable.insert(edges);
+
+    while iteration.changed() {
+        // reachable(N1, N3) :- edges(N1, N2), reachable(N2, N3).
+        reachable.from_leapjoin(
+            &reachable,
+            edges_by_successor.extend_with(|&(n2, _)| n2),
+            |&(_, n3), &n1| (n1, n3),
+        );
+    }
+
+    reachable.complete()
+}
+
+/// Computes a join where the values are summed -- uses iteration
+/// variables (the original datafrog technique).
+fn sum_join_via_var(
+    input1_slice: &[(u32, u32)],
+    input2_slice: &[(u32, u32)],
+) -> Relation<(u32, u32)> {
+    let mut iteration = Iteration::new();
+
+    let input1 = iteration.variable::<(u32, u32)>("input1");
+    input1.extend(input1_slice);
+
+    let input2 = iteration.variable::<(u32, u32)>("input1");
+    input2.extend(input2_slice);
+
+    let output = iteration.variable::<(u32, u32)>("output");
+
+    while iteration.changed() {
+        // output(K1, V1 * 100 + V2) :- input1(K1, V1), input2(K1, V2).
+        output.from_join(&input1, &input2, |&k1, &v1, &v2| (k1, v1 * 100 + v2));
+    }
+
+    output.complete()
+}
+
+/// Computes a join where the values are summed -- uses iteration
+/// variables (the original datafrog technique).
+fn sum_join_via_relation(
+    input1_slice: &[(u32, u32)],
+    input2_slice: &[(u32, u32)],
+) -> Relation<(u32, u32)> {
+    let input1: Relation<_> = input1_slice.iter().collect();
+    let input2: Relation<_> = input2_slice.iter().collect();
+    Relation::from_join(&input1, &input2, |&k1, &v1, &v2| (k1, v1 * 100 + v2))
+}
+
+proptest! {
+    #[test]
+    fn reachable_leapfrog_vs_var_join(edges in inputs()) {
+        let reachable1 = reachable_with_var_join(&edges);
+        let reachable2 = reachable_with_leapfrog(&edges);
+        assert_eq!(reachable1.elements, reachable2.elements);
+    }
+
+    #[test]
+    fn reachable_rel_join_vs_var_join(edges in inputs()) {
+        let reachable1 = reachable_with_var_join(&edges);
+        let reachable2 = reachable_with_relation_join(&edges);
+        assert_eq!(reachable1.elements, reachable2.elements);
+    }
+
+    #[test]
+    fn sum_join_from_var_vs_rel((set1, set2) in (inputs(), inputs())) {
+        let output1 = sum_join_via_var(&set1, &set2);
+        let output2 = sum_join_via_relation(&set1, &set2);
+        assert_eq!(output1.elements, output2.elements);
+    }
+
+    /// Test the behavior of `filter_anti` used on its own in a
+    /// leapjoin -- effectively it becomes an "intersection"
+    /// operation.
+    #[test]
+    fn filter_with_on_its_own((set1, set2) in (inputs(), inputs())) {
+        let input1: Relation<(u32, u32)> = set1.iter().collect();
+        let input2: Relation<(u32, u32)> = set2.iter().collect();
+        let intersection1 = Relation::from_leapjoin(
+            &input1,
+            input2.filter_with(|&tuple| tuple),
+            |&tuple, &()| tuple,
+        );
+
+        let intersection2: Relation<(u32, u32)> = input1.elements.iter()
+            .filter(|t| input2.elements.binary_search(&t).is_ok())
+            .collect();
+
+        assert_eq!(intersection1.elements, intersection2.elements);
+    }
+
+    /// Test the behavior of `filter_anti` used on its own in a
+    /// leapjoin -- effectively it becomes a "set minus" operation.
+    #[test]
+    fn filter_anti_on_its_own((set1, set2) in (inputs(), inputs())) {
+        let input1: Relation<(u32, u32)> = set1.iter().collect();
+        let input2: Relation<(u32, u32)> = set2.iter().collect();
+
+        let difference1 = Relation::from_leapjoin(
+            &input1,
+            input2.filter_anti(|&tuple| tuple),
+            |&tuple, &()| tuple,
+        );
+
+        let difference2: Relation<(u32, u32)> = input1.elements.iter()
+            .filter(|t| input2.elements.binary_search(&t).is_err())
+            .collect();
+
+        assert_eq!(difference1.elements, difference2.elements);
+    }
+}
+
+/// Test that `from_leapjoin` matches against the tuples from an
+/// `extend` that precedes first iteration.
+///
+/// This was always true, but wasn't immediately obvious to me until I
+/// re-read the code more carefully. -nikomatsakis
+#[test]
+fn leapjoin_from_extend() {
+    let doubles: Relation<(u32, u32)> = (0..10).map(|i| (i, i * 2)).collect();
+
+    let mut iteration = Iteration::new();
+
+    let variable = iteration.variable::<(u32, u32)>("variable");
+    variable.extend(Some((2, 2)));
+
+    while iteration.changed() {
+        variable.from_leapjoin(
+            &variable,
+            doubles.extend_with(|&(i, _)| i),
+            |&(i, _), &j| (i, j),
+        );
+    }
+
+    let variable = variable.complete();
+
+    assert_eq!(variable.elements, vec![(2, 2), (2, 4)]);
+}
diff --git a/vendor/datafrog/src/treefrog.rs b/vendor/datafrog/src/treefrog.rs
new file mode 100644
index 000000000..2ad238fd0
--- /dev/null
+++ b/vendor/datafrog/src/treefrog.rs
@@ -0,0 +1,661 @@
+//! Join functionality.
+
+use super::Relation;
+
+/// Performs treefrog leapjoin using a list of leapers.
+pub(crate) fn leapjoin<'leap, Tuple: Ord, Val: Ord + 'leap, Result: Ord>(
+    source: &[Tuple],
+    mut leapers: impl Leapers<'leap, Tuple, Val>,
+    mut logic: impl FnMut(&Tuple, &Val) -> Result,
+) -> Relation<Result> {
+    let mut result = Vec::new(); // temp output storage.
+    let mut values = Vec::new(); // temp value storage.
+
+    for tuple in source {
+        // Determine which leaper would propose the fewest values.
+        let mut min_index = usize::max_value();
+        let mut min_count = usize::max_value();
+        leapers.for_each_count(tuple, |index, count| {
+            if min_count > count {
+                min_count = count;
+                min_index = index;
+            }
+        });
+
+        // We had best have at least one relation restricting values.
+        assert!(min_count < usize::max_value());
+
+        // If there are values to propose:
+        if min_count > 0 {
+            // Push the values that `min_index` "proposes" into `values`.
+            leapers.propose(tuple, min_index, &mut values);
+
+            // Give other leapers a chance to remove values from
+            // anti-joins or filters.
+            leapers.intersect(tuple, min_index, &mut values);
+
+            // Push remaining items into result.
+            for val in values.drain(..) {
+                result.push(logic(tuple, val));
+            }
+        }
+    }
+
+    Relation::from_vec(result)
+}
+
+/// Implemented for a tuple of leapers
+pub trait Leapers<'leap, Tuple, Val> {
+    /// Internal method:
+    fn for_each_count(&mut self, tuple: &Tuple, op: impl FnMut(usize, usize));
+
+    /// Internal method:
+    fn propose(&mut self, tuple: &Tuple, min_index: usize, values: &mut Vec<&'leap Val>);
+
+    /// Internal method:
+    fn intersect(&mut self, tuple: &Tuple, min_index: usize, values: &mut Vec<&'leap Val>);
+}
+
+macro_rules! tuple_leapers {
+    ($($Ty:ident)*) => {
+        #[allow(unused_assignments, non_snake_case)]
+        impl<'leap, Tuple, Val, $($Ty),*> Leapers<'leap, Tuple, Val> for ($($Ty,)*)
+        where
+            $($Ty: Leaper<'leap, Tuple, Val>,)*
+        {
+            fn for_each_count(&mut self, tuple: &Tuple, mut op: impl FnMut(usize, usize)) {
+                let ($($Ty,)*) = self;
+                let mut index = 0;
+                $(
+                    let count = $Ty.count(tuple);
+                    op(index, count);
+                    index += 1;
+                )*
+            }
+
+            fn propose(&mut self, tuple: &Tuple, min_index: usize, values: &mut Vec<&'leap Val>) {
+                let ($($Ty,)*) = self;
+                let mut index = 0;
+                $(
+                    if min_index == index {
+                        return $Ty.propose(tuple, values);
+                    }
+                    index += 1;
+                )*
+                    panic!("no match found for min_index={}", min_index);
+            }
+
+            fn intersect(&mut self, tuple: &Tuple, min_index: usize, values: &mut Vec<&'leap Val>) {
+                let ($($Ty,)*) = self;
+                let mut index = 0;
+                $(
+                    if min_index != index {
+                        $Ty.intersect(tuple, values);
+                    }
+                    index += 1;
+                )*
+            }
+        }
+    }
+}
+
+tuple_leapers!(A B);
+tuple_leapers!(A B C);
+tuple_leapers!(A B C D);
+tuple_leapers!(A B C D E);
+tuple_leapers!(A B C D E F);
+tuple_leapers!(A B C D E F G);
+
+/// Methods to support treefrog leapjoin.
+pub trait Leaper<'leap, Tuple, Val> {
+    /// Estimates the number of proposed values.
+    fn count(&mut self, prefix: &Tuple) -> usize;
+    /// Populates `values` with proposed values.
+    fn propose(&mut self, prefix: &Tuple, values: &mut Vec<&'leap Val>);
+    /// Restricts `values` to proposed values.
+    fn intersect(&mut self, prefix: &Tuple, values: &mut Vec<&'leap Val>);
+}
+
+pub(crate) mod filters {
+    use super::Leaper;
+    use super::Leapers;
+
+    /// A treefrog leaper that tests each of the tuples from the main
+    /// input (the "prefix"). Use like `PrefixFilter::from(|tuple|
+    /// ...)`; if the closure returns true, then the tuple is
+    /// retained, else it will be ignored. This leaper can be used in
+    /// isolation in which case it just acts like a filter on the
+    /// input (the "proposed value" will be `()` type).
+    pub struct PrefixFilter<Tuple, Func: Fn(&Tuple) -> bool> {
+        phantom: ::std::marker::PhantomData<Tuple>,
+        predicate: Func,
+    }
+
+    impl<'leap, Tuple, Func> PrefixFilter<Tuple, Func>
+    where
+        Func: Fn(&Tuple) -> bool,
+    {
+        /// Creates a new filter based on the prefix
+        pub fn from(predicate: Func) -> Self {
+            PrefixFilter {
+                phantom: ::std::marker::PhantomData,
+                predicate,
+            }
+        }
+    }
+
+    impl<'leap, Tuple, Val, Func> Leaper<'leap, Tuple, Val> for PrefixFilter<Tuple, Func>
+    where
+        Func: Fn(&Tuple) -> bool,
+    {
+        /// Estimates the number of proposed values.
+        fn count(&mut self, prefix: &Tuple) -> usize {
+            if (self.predicate)(prefix) {
+                usize::max_value()
+            } else {
+                0
+            }
+        }
+        /// Populates `values` with proposed values.
+        fn propose(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val>) {
+            panic!("PrefixFilter::propose(): variable apparently unbound");
+        }
+        /// Restricts `values` to proposed values.
+        fn intersect(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val>) {
+            // We can only be here if we returned max_value() above.
+        }
+    }
+
+    impl<'leap, Tuple, Func> Leapers<'leap, Tuple, ()> for PrefixFilter<Tuple, Func>
+    where
+        Func: Fn(&Tuple) -> bool,
+    {
+        fn for_each_count(&mut self, tuple: &Tuple, mut op: impl FnMut(usize, usize)) {
+            if <Self as Leaper<'_, Tuple, ()>>::count(self, tuple) == 0 {
+                op(0, 0)
+            } else {
+                // we will "propose" the `()` value if the predicate applies
+                op(0, 1)
+            }
+        }
+
+        fn propose(&mut self, _: &Tuple, min_index: usize, values: &mut Vec<&'leap ()>) {
+            assert_eq!(min_index, 0);
+            values.push(&());
+        }
+
+        fn intersect(&mut self, _: &Tuple, min_index: usize, values: &mut Vec<&'leap ()>) {
+            assert_eq!(min_index, 0);
+            assert_eq!(values.len(), 1);
+        }
+    }
+
+    /// A treefrog leaper based on a predicate of prefix and value.
+    /// Use like `ValueFilter::from(|tuple, value| ...)`. The closure
+    /// should return true if `value` ought to be retained. The
+    /// `value` will be a value proposed elsewhere by an `extend_with`
+    /// leaper.
+    ///
+    /// This leaper cannot be used in isolation, it must be combined
+    /// with other leapers.
+    pub struct ValueFilter<Tuple, Val, Func: Fn(&Tuple, &Val) -> bool> {
+        phantom: ::std::marker::PhantomData<(Tuple, Val)>,
+        predicate: Func,
+    }
+
+    impl<'leap, Tuple, Val, Func> ValueFilter<Tuple, Val, Func>
+    where
+        Func: Fn(&Tuple, &Val) -> bool,
+    {
+        /// Creates a new filter based on the prefix
+        pub fn from(predicate: Func) -> Self {
+            ValueFilter {
+                phantom: ::std::marker::PhantomData,
+                predicate,
+            }
+        }
+    }
+
+    impl<'leap, Tuple, Val, Func> Leaper<'leap, Tuple, Val> for ValueFilter<Tuple, Val, Func>
+    where
+        Func: Fn(&Tuple, &Val) -> bool,
+    {
+        /// Estimates the number of proposed values.
+        fn count(&mut self, _prefix: &Tuple) -> usize {
+            usize::max_value()
+        }
+        /// Populates `values` with proposed values.
+        fn propose(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val>) {
+            panic!("PrefixFilter::propose(): variable apparently unbound");
+        }
+        /// Restricts `values` to proposed values.
+        fn intersect(&mut self, prefix: &Tuple, values: &mut Vec<&'leap Val>) {
+            values.retain(|val| (self.predicate)(prefix, val));
+        }
+    }
+
+}
+
+/// Extension method for relations.
+pub trait RelationLeaper<Key: Ord, Val: Ord> {
+    /// Extend with `Val` using the elements of the relation.
+    fn extend_with<'leap, Tuple: Ord, Func: Fn(&Tuple) -> Key>(
+        &'leap self,
+        key_func: Func,
+    ) -> extend_with::ExtendWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap;
+    /// Extend with `Val` using the complement of the relation.
+    fn extend_anti<'leap, Tuple: Ord, Func: Fn(&Tuple) -> Key>(
+        &'leap self,
+        key_func: Func,
+    ) -> extend_anti::ExtendAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap;
+    /// Extend with any value if tuple is present in relation.
+    fn filter_with<'leap, Tuple: Ord, Func: Fn(&Tuple) -> (Key, Val)>(
+        &'leap self,
+        key_func: Func,
+    ) -> filter_with::FilterWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap;
+    /// Extend with any value if tuple is absent from relation.
+    fn filter_anti<'leap, Tuple: Ord, Func: Fn(&Tuple) -> (Key, Val)>(
+        &'leap self,
+        key_func: Func,
+    ) -> filter_anti::FilterAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap;
+}
+
+impl<Key: Ord, Val: Ord> RelationLeaper<Key, Val> for Relation<(Key, Val)> {
+    fn extend_with<'leap, Tuple: Ord, Func: Fn(&Tuple) -> Key>(
+        &'leap self,
+        key_func: Func,
+    ) -> extend_with::ExtendWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap,
+    {
+        extend_with::ExtendWith::from(self, key_func)
+    }
+    fn extend_anti<'leap, Tuple: Ord, Func: Fn(&Tuple) -> Key>(
+        &'leap self,
+        key_func: Func,
+    ) -> extend_anti::ExtendAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap,
+    {
+        extend_anti::ExtendAnti::from(self, key_func)
+    }
+    fn filter_with<'leap, Tuple: Ord, Func: Fn(&Tuple) -> (Key, Val)>(
+        &'leap self,
+        key_func: Func,
+    ) -> filter_with::FilterWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap,
+    {
+        filter_with::FilterWith::from(self, key_func)
+    }
+    fn filter_anti<'leap, Tuple: Ord, Func: Fn(&Tuple) -> (Key, Val)>(
+        &'leap self,
+        key_func: Func,
+    ) -> filter_anti::FilterAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: 'leap,
+        Val: 'leap,
+    {
+        filter_anti::FilterAnti::from(self, key_func)
+    }
+}
+
+pub(crate) mod extend_with {
+    use super::{binary_search, Leaper, Leapers, Relation};
+    use crate::join::gallop;
+
+    /// Wraps a Relation<Tuple> as a leaper.
+    pub struct ExtendWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> Key,
+    {
+        relation: &'leap Relation<(Key, Val)>,
+        start: usize,
+        end: usize,
+        key_func: Func,
+        phantom: ::std::marker::PhantomData<Tuple>,
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> ExtendWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> Key,
+    {
+        /// Constructs a ExtendWith from a relation and key and value function.
+        pub fn from(relation: &'leap Relation<(Key, Val)>, key_func: Func) -> Self {
+            ExtendWith {
+                relation,
+                start: 0,
+                end: 0,
+                key_func,
+                phantom: ::std::marker::PhantomData,
+            }
+        }
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> Leaper<'leap, Tuple, Val>
+        for ExtendWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> Key,
+    {
+        fn count(&mut self, prefix: &Tuple) -> usize {
+            let key = (self.key_func)(prefix);
+            self.start = binary_search(&self.relation[..], |x| &x.0 < &key);
+            let slice1 = &self.relation[self.start..];
+            let slice2 = gallop(slice1, |x| &x.0 <= &key);
+            self.end = self.relation.len() - slice2.len();
+            slice1.len() - slice2.len()
+        }
+        fn propose(&mut self, _prefix: &Tuple, values: &mut Vec<&'leap Val>) {
+            let slice = &self.relation[self.start..self.end];
+            values.extend(slice.iter().map(|&(_, ref val)| val));
+        }
+        fn intersect(&mut self, _prefix: &Tuple, values: &mut Vec<&'leap Val>) {
+            let mut slice = &self.relation[self.start..self.end];
+            values.retain(|v| {
+                slice = gallop(slice, |kv| &kv.1 < v);
+                slice.get(0).map(|kv| &kv.1) == Some(v)
+            });
+        }
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> Leapers<'leap, Tuple, Val>
+        for ExtendWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> Key,
+    {
+        fn for_each_count(&mut self, tuple: &Tuple, mut op: impl FnMut(usize, usize)) {
+            op(0, self.count(tuple))
+        }
+
+        fn propose(&mut self, tuple: &Tuple, min_index: usize, values: &mut Vec<&'leap Val>) {
+            assert_eq!(min_index, 0);
+            Leaper::propose(self, tuple, values);
+        }
+
+        fn intersect(&mut self, _: &Tuple, min_index: usize, _: &mut Vec<&'leap Val>) {
+            assert_eq!(min_index, 0);
+        }
+    }
+}
+
+pub(crate) mod extend_anti {
+    use super::{binary_search, Leaper, Relation};
+    use crate::join::gallop;
+
+    /// Wraps a Relation<Tuple> as a leaper.
+    pub struct ExtendAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> Key,
+    {
+        relation: &'leap Relation<(Key, Val)>,
+        key_func: Func,
+        phantom: ::std::marker::PhantomData<Tuple>,
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> ExtendAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> Key,
+    {
+        /// Constructs a ExtendAnti from a relation and key and value function.
+        pub fn from(relation: &'leap Relation<(Key, Val)>, key_func: Func) -> Self {
+            ExtendAnti {
+                relation,
+                key_func,
+                phantom: ::std::marker::PhantomData,
+            }
+        }
+    }
+
+    impl<'leap, Key: Ord, Val: Ord + 'leap, Tuple: Ord, Func> Leaper<'leap, Tuple, Val>
+        for ExtendAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> Key,
+    {
+        fn count(&mut self, _prefix: &Tuple) -> usize {
+            usize::max_value()
+        }
+        fn propose(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val>) {
+            panic!("ExtendAnti::propose(): variable apparently unbound.");
+        }
+        fn intersect(&mut self, prefix: &Tuple, values: &mut Vec<&'leap Val>) {
+            let key = (self.key_func)(prefix);
+            let start = binary_search(&self.relation[..], |x| &x.0 < &key);
+            let slice1 = &self.relation[start..];
+            let slice2 = gallop(slice1, |x| &x.0 <= &key);
+            let mut slice = &slice1[..(slice1.len() - slice2.len())];
+            if !slice.is_empty() {
+                values.retain(|v| {
+                    slice = gallop(slice, |kv| &kv.1 < v);
+                    slice.get(0).map(|kv| &kv.1) != Some(v)
+                });
+            }
+        }
+    }
+}
+
+pub(crate) mod filter_with {
+
+    use super::{Leaper, Leapers, Relation};
+
+    /// Wraps a Relation<Tuple> as a leaper.
+    pub struct FilterWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        relation: &'leap Relation<(Key, Val)>,
+        key_func: Func,
+        phantom: ::std::marker::PhantomData<Tuple>,
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> FilterWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        /// Constructs a FilterWith from a relation and key and value function.
+        pub fn from(relation: &'leap Relation<(Key, Val)>, key_func: Func) -> Self {
+            FilterWith {
+                relation,
+                key_func,
+                phantom: ::std::marker::PhantomData,
+            }
+        }
+    }
+
+    impl<'leap, Key, Val, Val2, Tuple, Func> Leaper<'leap, Tuple, Val2>
+        for FilterWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        fn count(&mut self, prefix: &Tuple) -> usize {
+            let key_val = (self.key_func)(prefix);
+            if self.relation.binary_search(&key_val).is_ok() {
+                usize::max_value()
+            } else {
+                0
+            }
+        }
+        fn propose(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val2>) {
+            panic!("FilterWith::propose(): variable apparently unbound.");
+        }
+        fn intersect(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val2>) {
+            // Only here because we didn't return zero above, right?
+        }
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> Leapers<'leap, Tuple, ()>
+        for FilterWith<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        fn for_each_count(&mut self, tuple: &Tuple, mut op: impl FnMut(usize, usize)) {
+            if <Self as Leaper<Tuple, ()>>::count(self, tuple) == 0 {
+                op(0, 0)
+            } else {
+                op(0, 1)
+            }
+        }
+
+        fn propose(&mut self, _: &Tuple, min_index: usize, values: &mut Vec<&'leap ()>) {
+            assert_eq!(min_index, 0);
+            values.push(&());
+        }
+
+        fn intersect(&mut self, _: &Tuple, min_index: usize, values: &mut Vec<&'leap ()>) {
+            assert_eq!(min_index, 0);
+            assert_eq!(values.len(), 1);
+        }
+    }
+}
+
+pub(crate) mod filter_anti {
+
+    use super::{Leaper, Leapers, Relation};
+
+    /// Wraps a Relation<Tuple> as a leaper.
+    pub struct FilterAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        relation: &'leap Relation<(Key, Val)>,
+        key_func: Func,
+        phantom: ::std::marker::PhantomData<Tuple>,
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> FilterAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        /// Constructs a FilterAnti from a relation and key and value function.
+        pub fn from(relation: &'leap Relation<(Key, Val)>, key_func: Func) -> Self {
+            FilterAnti {
+                relation,
+                key_func,
+                phantom: ::std::marker::PhantomData,
+            }
+        }
+    }
+
+    impl<'leap, Key: Ord, Val: Ord + 'leap, Val2, Tuple: Ord, Func> Leaper<'leap, Tuple, Val2>
+        for FilterAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        fn count(&mut self, prefix: &Tuple) -> usize {
+            let key_val = (self.key_func)(prefix);
+            if self.relation.binary_search(&key_val).is_ok() {
+                0
+            } else {
+                usize::max_value()
+            }
+        }
+        fn propose(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val2>) {
+            panic!("FilterAnti::propose(): variable apparently unbound.");
+        }
+        fn intersect(&mut self, _prefix: &Tuple, _values: &mut Vec<&'leap Val2>) {
+            // Only here because we didn't return zero above, right?
+        }
+    }
+
+    impl<'leap, Key, Val, Tuple, Func> Leapers<'leap, Tuple, ()>
+        for FilterAnti<'leap, Key, Val, Tuple, Func>
+    where
+        Key: Ord + 'leap,
+        Val: Ord + 'leap,
+        Tuple: Ord,
+        Func: Fn(&Tuple) -> (Key, Val),
+    {
+        fn for_each_count(&mut self, tuple: &Tuple, mut op: impl FnMut(usize, usize)) {
+            if <Self as Leaper<Tuple, ()>>::count(self, tuple) == 0 {
+                op(0, 0)
+            } else {
+                op(0, 1)
+            }
+        }
+
+        fn propose(&mut self, _: &Tuple, min_index: usize, values: &mut Vec<&'leap ()>) {
+            // We only get here if `tuple` is *not* a member of `self.relation`
+            assert_eq!(min_index, 0);
+            values.push(&());
+        }
+
+        fn intersect(&mut self, _: &Tuple, min_index: usize, values: &mut Vec<&'leap ()>) {
+            // We only get here if `tuple` is not a member of `self.relation`
+            assert_eq!(min_index, 0);
+            assert_eq!(values.len(), 1);
+        }
+    }
+}
+
+fn binary_search<T>(slice: &[T], mut cmp: impl FnMut(&T) -> bool) -> usize {
+    // we maintain the invariant that `lo` many elements of `slice` satisfy `cmp`.
+    // `hi` is maintained at the first element we know does not satisfy `cmp`.
+
+    let mut hi = slice.len();
+    let mut lo = 0;
+    while lo < hi {
+        let mid = lo + (hi - lo) / 2;
+        if cmp(&slice[mid]) {
+            lo = mid + 1;
+        } else {
+            hi = mid;
+        }
+    }
+    lo
+}