Support Rust dependencies

tests/samples/codefiles/rust.rs

@@ -0,0 +1,21 @@
+extern crate proc_macro;
+extern crate phrases as sayings;
+extern crate syn;
+#[macro_use]
+extern crate quote;
+
+use sayings::japanese::greetings as ja_greetings;
+use sayings::japanese::farewells::*;
+use sayings::english::{self, greetings as en_greetings, farewells as en_farewells};
+
+extern "C" {
+    fn c_callback(n: c_int);
+}
+
+fn main() {
+    println!("Hello in English; {}", en_greetings::hello());
+    println!("And in Japanese: {}", ja_greetings::hello());
+    println!("Goodbye in English: {}", english::farewells::goodbye());
+    println!("Again: {}", en_farewells::goodbye());
+    println!("And in Japanese: {}", goodbye());
+}

tests/test_dependencies.py

@@ -435,3 +435,16 @@ class DependenciesTestCase(TestCase):
             expected_lines=14,
             entity='scala.scala',
         )
+
+    def test_rust_dependencies_detected(self):
+        self.shared(
+            expected_dependencies=[
+                'proc_macro',
+                'phrases',
+                'syn',
+                'quote',
+            ],
+            expected_language='Rust',
+            expected_lines=21,
+            entity='rust.rs',
+        )

wakatime/dependencies/rust.py

@@ -0,0 +1,54 @@
+# -*- coding: utf-8 -*-
+"""
+    wakatime.dependencies.rust
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Parse dependencies from Rust code.
+
+    :copyright: (c) 2018 Alan Hamlett.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from . import TokenParser
+
+
+class RustParser(TokenParser):
+    state = None
+
+    def parse(self):
+        for index, token, content in self.tokens:
+            self._process_token(token, content)
+        return self.dependencies
+
+    def _process_token(self, token, content):
+        if self.partial(token) == 'Keyword':
+            self._process_keyword(token, content)
+        elif self.partial(token) == 'Whitespace':
+            self._process_whitespace(token, content)
+        elif self.partial(token) == 'Name':
+            self._process_name(token, content)
+        else:
+            self._process_other(token, content)
+
+    def _process_keyword(self, token, content):
+        if self.state == 'extern' and content == 'crate':
+            self.state = 'extern crate'
+        else:
+            self.state = content
+
+    def _process_whitespace(self, token, content):
+        pass
+
+    def _process_name(self, token, content):
+        if self.state == 'extern crate':
+            self.append(self._format(content))
+        self.state = None
+
+    def _process_other(self, token, content):
+        self.state = None
+
+    def _format(self, content):
+        content = content.strip()
+        if content.startswith('"') or content.startswith("'"):
+            return None
+        return content