1 files changed, 196 insertions, 0 deletions
diff --git a/support/texlab/src/features/completion/import.rs b/support/texlab/src/features/completion/import.rs
new file mode 100644
index 0000000000..ac5f2e6e40
--- /dev/null
+++ b/support/texlab/src/features/completion/import.rs
@@ -0,0 +1,196 @@
+use cancellation::CancellationToken;
+use cstree::TextRange;
+use lsp_types::CompletionParams;
+use rustc_hash::FxHashSet;
+use smol_str::SmolStr;
+
+use crate::{
+    component_db::COMPONENT_DATABASE,
+    features::cursor::CursorContext,
+    syntax::{latex, CstNode},
+};
+
+use super::types::{InternalCompletionItem, InternalCompletionItemData};
+
+pub fn complete_imports<'a>(
+    context: &'a CursorContext<CompletionParams>,
+    items: &mut Vec<InternalCompletionItem<'a>>,
+    cancellation_token: &CancellationToken,
+) -> Option<()> {
+    let token = context.cursor.as_latex()?;
+    let range = if token.kind() == latex::WORD {
+        token.text_range()
+    } else {
+        TextRange::empty(context.offset)
+    };
+
+    let group = latex::CurlyGroupWordList::cast(token.parent())
+        .filter(|group| context.is_inside_latex_curly(group))?;
+
+    let (extension, mut factory): (
+        &str,
+        Box<dyn FnMut(SmolStr) -> InternalCompletionItemData<'a>>,
+    ) = match group.syntax().parent()?.kind() {
+        latex::PACKAGE_INCLUDE => (
+            "sty",
+            Box::new(|name| InternalCompletionItemData::Package { name }),
+        ),
+        latex::CLASS_INCLUDE => (
+            "cls",
+            Box::new(|name| InternalCompletionItemData::Class { name }),
+        ),
+        _ => return None,
+    };
+
+    let mut file_names = FxHashSet::default();
+    for file_name in COMPONENT_DATABASE
+        .components
+        .iter()
+        .flat_map(|comp| comp.file_names.iter())
+        .filter(|file_name| file_name.ends_with(extension))
+    {
+        cancellation_token.result().ok()?;
+        file_names.insert(file_name);
+        let stem = &file_name[0..file_name.len() - 4];
+        let data = factory(stem.into());
+        let item = InternalCompletionItem::new(range, data);
+        items.push(item);
+    }
+
+    let resolver = context.request.context.resolver.lock().unwrap();
+    for file_name in resolver
+        .files_by_name
+        .keys()
+        .filter(|file_name| file_name.ends_with(extension) && !file_names.contains(file_name))
+    {
+        cancellation_token.result().ok()?;
+
+        let stem = &file_name[0..file_name.len() - 4];
+        let data = factory(stem.into());
+        let item = InternalCompletionItem::new(range, data);
+        items.push(item);
+    }
+
+    Some(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::features::testing::FeatureTester;
+
+    use super::*;
+
+    #[test]
+    fn test_empty_latex_document() {
+        let request = FeatureTester::builder()
+            .files(vec![("main.tex", "")])
+            .main("main.tex")
+            .line(0)
+            .character(0)
+            .build()
+            .completion();
+
+        let context = CursorContext::new(request);
+        let mut actual_items = Vec::new();
+        complete_imports(&context, &mut actual_items, CancellationToken::none());
+
+        assert!(actual_items.is_empty());
+    }
+
+    #[test]
+    fn test_empty_bibtex_document() {
+        let request = FeatureTester::builder()
+            .files(vec![("main.bib", "")])
+            .main("main.bib")
+            .line(0)
+            .character(0)
+            .build()
+            .completion();
+
+        let context = CursorContext::new(request);
+        let mut actual_items = Vec::new();
+        complete_imports(&context, &mut actual_items, CancellationToken::none());
+
+        assert!(actual_items.is_empty());
+    }
+
+    #[test]
+    fn test_latex_simple_package() {
+        let request = FeatureTester::builder()
+            .files(vec![("main.tex", "\\usepackage{}")])
+            .main("main.tex")
+            .line(0)
+            .character(12)
+            .build()
+            .completion();
+
+        let context = CursorContext::new(request);
+        let mut actual_items = Vec::new();
+        complete_imports(&context, &mut actual_items, CancellationToken::none());
+
+        assert!(!actual_items.is_empty());
+        for item in actual_items {
+            assert_eq!(item.range, TextRange::new(12.into(), 12.into()));
+        }
+    }
+
+    #[test]
+    fn test_latex_open_brace_package() {
+        let request = FeatureTester::builder()
+            .files(vec![("main.tex", "\\usepackage{ \\foo")])
+            .main("main.tex")
+            .line(0)
+            .character(12)
+            .build()
+            .completion();
+
+        let context = CursorContext::new(request);
+        let mut actual_items = Vec::new();
+        complete_imports(&context, &mut actual_items, CancellationToken::none());
+
+        assert!(!actual_items.is_empty());
+        for item in actual_items {
+            assert_eq!(item.range, TextRange::new(12.into(), 12.into()));
+        }
+    }
+
+    #[test]
+    fn test_latex_simple_class() {
+        let request = FeatureTester::builder()
+            .files(vec![("main.tex", "\\documentclass{}")])
+            .main("main.tex")
+            .line(0)
+            .character(15)
+            .build()
+            .completion();
+
+        let context = CursorContext::new(request);
+        let mut actual_items = Vec::new();
+        complete_imports(&context, &mut actual_items, CancellationToken::none());
+
+        assert!(!actual_items.is_empty());
+        for item in actual_items {
+            assert_eq!(item.range, TextRange::new(15.into(), 15.into()));
+        }
+    }
+
+    #[test]
+    fn test_latex_open_brace_class() {
+        let request = FeatureTester::builder()
+            .files(vec![("main.tex", "\\documentclass{ \\foo")])
+            .main("main.tex")
+            .line(0)
+            .character(15)
+            .build()
+            .completion();
+
+        let context = CursorContext::new(request);
+        let mut actual_items = Vec::new();
+        complete_imports(&context, &mut actual_items, CancellationToken::none());
+
+        assert!(!actual_items.is_empty());
+        for item in actual_items {
+            assert_eq!(item.range, TextRange::new(15.into(), 15.into()));
+        }
+    }
+}