Add support for Cairo language (#1193)

Author: ErikSchierboom

languages.json

@@ -192,6 +192,14 @@
       "multi_line_comments": [["{-", "-}"]],
       "extensions": ["cabal"]
     },
+    "Cairo": {
+      "line_comment": ["//"],
+      "extensions": ["cairo"],
+      "quotes": [
+        ["\\\"", "\\\""],
+        ["'", "'"]
+      ]
+    },
     "Cangjie": {
       "line_comment": ["//"],
       "multi_line_comments": [["/*", "*/"]],

tests/data/cairo.cairo

@@ -0,0 +1,51 @@
+//! 51 lines 32 code 13 comments 6 blanks
+//! ```rust
+//! fn main () {
+//!     // Comment
+//!
+//!     println!("Hello World!");
+//! }
+//! ```
+
+/// The main function
+fn main() {
+    let x: ByteArray = "\"/*##\"\"##\'\'";
+    // comment
+    loop {
+        if x.len() >= 2 && x[0] == '*' && x[1] == '/' { // found the */
+            break;
+        }
+    }
+}
+
+fn foo<T, +Drop<T>>(name: T) {
+    let this_ends = 'a "\'test/"*.';
+    call1();
+    call2();
+    let this_does_not =  // a // nested // comment " //
+    ///"*/another /*test
+    call3();
+//*/";
+}
+
+fn call1() {}
+fn call2() {}
+fn call3() {}
+
+fn foobar() {
+    let does_not_start: ByteArray =  // "
+    "until here,
+        test/*
+        test"; // a quote: "
+    let also_doesnt_start =
+        /// " */
+        'until here,
+        test,'; // another quote: "
+}
+
+fn foo2() {
+    let a = 4; // ///
+    let b = '5';
+    let c = 6; // ///
+}
+