Add language support for Ada

Implement support in difftastic for the Ada programming language
using the treesitter grammar provided in 'briot/tree-sitter-ada'.

Language detection depends on the following suffixes:

    * adb
    * ads
    * ada

The presence of the alire TOML file (alire.toml) is also used as
a heuristic.

build.rs

@@ -90,6 +90,11 @@ impl TreeSitterParser {
 
 fn main() {
     let parsers = vec![
+        TreeSitterParser {
+            name: "tree-sitter-ada",
+            src_dir: "vendored_parsers/tree-sitter-ada-src",
+            extra_files: vec![],
+        },
         TreeSitterParser {
             name: "tree-sitter-bash",
             src_dir: "vendored_parsers/tree-sitter-bash-src",

manual/src/languages_supported.md

@@ -8,6 +8,7 @@ with `difft --list-languages`.
 
 | Language        | Parser Used                                                                                                                                                    |
 |-----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Ada             | [tree-sitter/tree-sitter-ada](https://github.com/briot/tree-sitter-ada)                                                                                        |
 | Bash            | [tree-sitter/tree-sitter-bash](https://github.com/tree-sitter/tree-sitter-bash)                                                                                |
 | C               | [tree-sitter/tree-sitter-c](https://github.com/tree-sitter/tree-sitter-c)                                                                                      |
 | C++             | [tree-sitter/tree-sitter-cpp](https://github.com/tree-sitter/tree-sitter-cpp)                                                                                  |

src/parse/guess_language.rs

@@ -18,6 +18,7 @@ use std::{borrow::Borrow, ffi::OsStr, path::Path};
 /// corresponding tree-sitter parser.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Language {
+    Ada,
     Bash,
     C,
     Clojure,
@@ -74,6 +75,7 @@ pub enum Language {
 /// The language name shown to the user.
 pub fn language_name(language: Language) -> &'static str {
     match language {
+        Ada => "Ada",
         Bash => "Bash",
         C => "C",
         Clojure => "Clojure",
@@ -132,6 +134,12 @@ use Language::*;
 
 /// Which file extensions are associated with which languages.
 pub const LANG_EXTENSIONS: &[(Language, &[&str])] = &[
+    (
+        Ada,
+        &[
+            "ada", "adb", "ads"
+        ],
+    ),
     (
         Bash,
         &[
@@ -224,6 +232,7 @@ pub const LANG_EXTENSIONS: &[(Language, &[&str])] = &[
 
 /// Which file names are associated with which languages.
 pub const LANG_FILE_NAMES: &[(Language, &[&str])] = &[
+    (Ada, &["alire.toml"]),
     (
         Bash,
         &[
@@ -349,6 +358,7 @@ fn from_emacs_mode_header(src: &str) -> Option<Language> {
             _ => "".into(),
         };
         let lang = match mode_name.to_ascii_lowercase().trim().borrow() {
+            "ada" => Some(Ada),
             "c" => Some(C),
             "clojure" => Some(Clojure),
             "csharp" => Some(CSharp),

src/parse/tree_sitter_parser.rs

@@ -63,6 +63,7 @@ pub struct TreeSitterConfig {
 }
 
 extern "C" {
+    fn tree_sitter_ada() -> ts::Language;
     fn tree_sitter_bash() -> ts::Language;
     fn tree_sitter_c() -> ts::Language;
     fn tree_sitter_c_sharp() -> ts::Language;
@@ -128,6 +129,20 @@ const OCAML_ATOM_NODES: [&str; 6] = [
 pub fn from_language(language: guess::Language) -> TreeSitterConfig {
     use guess::Language::*;
     match language {
+        Ada => {
+            let language = unsafe { tree_sitter_ada() };
+            TreeSitterConfig {
+                language,
+                atom_nodes: vec!["string_literal", "character_literal"].into_iter().collect(),
+                delimiter_tokens: vec![("(", ")"), ("[", "]")],
+                highlight_query: ts::Query::new(
+                    language,
+                    include_str!("../../vendored_parsers/highlights/ada.scm"),
+                )
+                .unwrap(),
+                sub_languages: vec![],
+            }
+        }
         Bash => {
             let language = unsafe { tree_sitter_bash() };
             TreeSitterConfig {