rustdoc-search: parse and search with ML-style HOF

Option::map, for example, looks like this:

    option<t>, (t -> u) -> option<u>

This syntax searches all of the HOFs in Rust: traits Fn, FnOnce,
and FnMut, and bare fn primitives.

2 files changed, 378 insertions, 2 deletions

diff --git a/tests/rustdoc-js-std/parser-errors.js b/tests/rustdoc-js-std/parser-errors.js
index 16d171260da..8efb81841d4 100644
--- a/tests/rustdoc-js-std/parser-errors.js
+++ b/tests/rustdoc-js-std/parser-errors.js
@@ -114,7 +114,7 @@ const PARSED = [
         original: "(p -> p",
         returned: [],
         userQuery: "(p -> p",
-        error: "Unexpected `-` after `(`",
+        error: "Unclosed `(`",
     },
     {
         query: "::a::b",
@@ -330,7 +330,7 @@ const PARSED = [
         original: 'a<->',
         returned: [],
         userQuery: 'a<->',
-        error: 'Unexpected `-` after `<`',
+        error: 'Unclosed `<`',
     },
     {
         query: "a<a>:",
diff --git a/tests/rustdoc-js-std/parser-hof.js b/tests/rustdoc-js-std/parser-hof.js
new file mode 100644
index 00000000000..331c516e047
--- /dev/null
+++ b/tests/rustdoc-js-std/parser-hof.js
@@ -0,0 +1,376 @@
+const PARSED = [
+    {
+        query: "(-> F<P>)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [],
+            bindings: [
+                [
+                    "output",
+                    [{
+                        name: "f",
+                        fullPath: ["f"],
+                        pathWithoutLast: [],
+                        pathLast: "f",
+                        generics: [
+                            {
+                                name: "p",
+                                fullPath: ["p"],
+                                pathWithoutLast: [],
+                                pathLast: "p",
+                                generics: [],
+                            },
+                        ],
+                        typeFilter: -1,
+                    }],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(-> F<P>)",
+        returned: [],
+        userQuery: "(-> f<p>)",
+        error: null,
+    },
+    {
+        query: "(-> P)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [],
+            bindings: [
+                [
+                    "output",
+                    [{
+                        name: "p",
+                        fullPath: ["p"],
+                        pathWithoutLast: [],
+                        pathLast: "p",
+                        generics: [],
+                        typeFilter: -1,
+                    }],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(-> P)",
+        returned: [],
+        userQuery: "(-> p)",
+        error: null,
+    },
+    {
+        query: "(->,a)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [],
+            bindings: [
+                [
+                    "output",
+                    [{
+                        name: "a",
+                        fullPath: ["a"],
+                        pathWithoutLast: [],
+                        pathLast: "a",
+                        generics: [],
+                        typeFilter: -1,
+                    }],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(->,a)",
+        returned: [],
+        userQuery: "(->,a)",
+        error: null,
+    },
+    {
+        query: "(F<P> ->)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [{
+                name: "f",
+                fullPath: ["f"],
+                pathWithoutLast: [],
+                pathLast: "f",
+                generics: [
+                    {
+                        name: "p",
+                        fullPath: ["p"],
+                        pathWithoutLast: [],
+                        pathLast: "p",
+                        generics: [],
+                    },
+                ],
+                typeFilter: -1,
+            }],
+            bindings: [
+                [
+                    "output",
+                    [],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(F<P> ->)",
+        returned: [],
+        userQuery: "(f<p> ->)",
+        error: null,
+    },
+    {
+        query: "(P ->)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [{
+                name: "p",
+                fullPath: ["p"],
+                pathWithoutLast: [],
+                pathLast: "p",
+                generics: [],
+                typeFilter: -1,
+            }],
+            bindings: [
+                [
+                    "output",
+                    [],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(P ->)",
+        returned: [],
+        userQuery: "(p ->)",
+        error: null,
+    },
+    {
+        query: "(,a->)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [{
+                name: "a",
+                fullPath: ["a"],
+                pathWithoutLast: [],
+                pathLast: "a",
+                generics: [],
+                typeFilter: -1,
+            }],
+            bindings: [
+                [
+                    "output",
+                    [],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(,a->)",
+        returned: [],
+        userQuery: "(,a->)",
+        error: null,
+    },
+    {
+        query: "(aaaaa->a)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [{
+                name: "aaaaa",
+                fullPath: ["aaaaa"],
+                pathWithoutLast: [],
+                pathLast: "aaaaa",
+                generics: [],
+                typeFilter: -1,
+            }],
+            bindings: [
+                [
+                    "output",
+                    [{
+                        name: "a",
+                        fullPath: ["a"],
+                        pathWithoutLast: [],
+                        pathLast: "a",
+                        generics: [],
+                        typeFilter: -1,
+                    }],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(aaaaa->a)",
+        returned: [],
+        userQuery: "(aaaaa->a)",
+        error: null,
+    },
+    {
+        query: "(aaaaa, b -> a)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [
+                {
+                    name: "aaaaa",
+                    fullPath: ["aaaaa"],
+                    pathWithoutLast: [],
+                    pathLast: "aaaaa",
+                    generics: [],
+                    typeFilter: -1,
+                },
+                {
+                    name: "b",
+                    fullPath: ["b"],
+                    pathWithoutLast: [],
+                    pathLast: "b",
+                    generics: [],
+                    typeFilter: -1,
+                },
+            ],
+            bindings: [
+                [
+                    "output",
+                    [{
+                        name: "a",
+                        fullPath: ["a"],
+                        pathWithoutLast: [],
+                        pathLast: "a",
+                        generics: [],
+                        typeFilter: -1,
+                    }],
+                ],
+            ],
+            typeFilter: -1,
+        }],
+        foundElems: 1,
+        original: "(aaaaa, b -> a)",
+        returned: [],
+        userQuery: "(aaaaa, b -> a)",
+        error: null,
+    },
+    {
+        query: "primitive:(aaaaa, b -> a)",
+        elems: [{
+            name: "->",
+            fullPath: ["->"],
+            pathWithoutLast: [],
+            pathLast: "->",
+            generics: [
+                {
+                    name: "aaaaa",
+                    fullPath: ["aaaaa"],
+                    pathWithoutLast: [],
+                    pathLast: "aaaaa",
+                    generics: [],
+                    typeFilter: -1,
+                },
+                {
+                    name: "b",
+                    fullPath: ["b"],
+                    pathWithoutLast: [],
+                    pathLast: "b",
+                    generics: [],
+                    typeFilter: -1,
+                },
+            ],
+            bindings: [
+                [
+                    "output",
+                    [{
+                        name: "a",
+                        fullPath: ["a"],
+                        pathWithoutLast: [],
+                        pathLast: "a",
+                        generics: [],
+                        typeFilter: -1,
+                    }],
+                ],
+            ],
+            typeFilter: 1,
+        }],
+        foundElems: 1,
+        original: "primitive:(aaaaa, b -> a)",
+        returned: [],
+        userQuery: "primitive:(aaaaa, b -> a)",
+        error: null,
+    },
+    {
+        query: "x, trait:(aaaaa, b -> a)",
+        elems: [
+            {
+                name: "x",
+                fullPath: ["x"],
+                pathWithoutLast: [],
+                pathLast: "x",
+                generics: [],
+                typeFilter: -1,
+            },
+            {
+                name: "->",
+                fullPath: ["->"],
+                pathWithoutLast: [],
+                pathLast: "->",
+                generics: [
+                    {
+                        name: "aaaaa",
+                        fullPath: ["aaaaa"],
+                        pathWithoutLast: [],
+                        pathLast: "aaaaa",
+                        generics: [],
+                        typeFilter: -1,
+                    },
+                    {
+                        name: "b",
+                        fullPath: ["b"],
+                        pathWithoutLast: [],
+                        pathLast: "b",
+                        generics: [],
+                        typeFilter: -1,
+                    },
+                ],
+                bindings: [
+                    [
+                        "output",
+                        [{
+                            name: "a",
+                            fullPath: ["a"],
+                            pathWithoutLast: [],
+                            pathLast: "a",
+                            generics: [],
+                            typeFilter: -1,
+                        }],
+                    ],
+                ],
+                typeFilter: 10,
+            }
+        ],
+        foundElems: 2,
+        original: "x, trait:(aaaaa, b -> a)",
+        returned: [],
+        userQuery: "x, trait:(aaaaa, b -> a)",
+        error: null,
+    },
+];