Provide completion for citations

Cargo.toml

@@ -28,6 +28,7 @@ clap = "2.33"
 indoc = "0.3.1"
 regex = "1.1.6"
 url = "1.7.2"
+url_serde = "0.2.0"
 path-clean = "0.1.0"
 itertools = "0.8.0"
 walkdir = "2"

src/completion/factory.rs

@@ -1,4 +1,4 @@
-use lsp_types::{CompletionItem, CompletionItemKind, InsertTextFormat};
+use lsp_types::{CompletionItem, CompletionItemKind, InsertTextFormat, Uri};
 use serde::{Deserialize, Serialize};
 use std::borrow::Cow;
 use std::path::Path;
@@ -20,7 +20,7 @@ impl LatexComponentId {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy, Serialize, Deserialize)]
+#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize)]
 pub enum CompletionItemData {
     Snippet,
     Command,
@@ -36,7 +36,11 @@ pub enum CompletionItemData {
     Class,
     EntryKind,
     FieldName,
-    Citation,
+    Citation {
+        #[serde(with = "url_serde")]
+        uri: Uri,
+        key: String,
+    },
     CommandSymbol,
     ArgumentSymbol,
 }
@@ -157,3 +161,12 @@ pub fn create_class(name: Cow<'static, str>) -> CompletionItem {
         ..CompletionItem::default()
     }
 }
+
+pub fn create_citation(uri: Uri, key: String) -> CompletionItem {
+    CompletionItem {
+        label: Cow::from(key.clone()),
+        kind: Some(CompletionItemKind::Field),
+        data: Some(CompletionItemData::Citation { uri, key }.into()),
+        ..CompletionItem::default()
+    }
+}

src/completion/latex/citation.rs

@@ -0,0 +1,85 @@
+use crate::completion::factory;
+use crate::completion::latex::combinators::LatexCombinators;
+use crate::feature::FeatureRequest;
+use crate::syntax::bibtex::BibtexDeclaration;
+use crate::syntax::latex::CITATION_COMMANDS;
+use crate::workspace::SyntaxTree;
+use lsp_types::{CompletionItem, CompletionParams};
+
+pub struct LatexCitationCompletionProvider;
+
+impl LatexCitationCompletionProvider {
+    pub async fn execute(request: &FeatureRequest<CompletionParams>) -> Vec<CompletionItem> {
+        await!(LatexCombinators::argument(
+            request,
+            CITATION_COMMANDS,
+            0,
+            async move |_| {
+                let mut items = Vec::new();
+                for document in &request.related_documents {
+                    if let SyntaxTree::Bibtex(tree) = &document.tree {
+                        for declaration in &tree.root.children {
+                            if let BibtexDeclaration::Entry(entry) = declaration {
+                                if let Some(key) = &entry.key {
+                                    items.push(factory::create_citation(
+                                        document.uri.clone(),
+                                        key.text().to_owned(),
+                                    ));
+                                }
+                            }
+                        }
+                    }
+                }
+                items
+            }
+        ))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::completion::latex::data::types::LatexComponentDatabase;
+    use crate::feature::FeatureSpec;
+    use crate::test_feature;
+    use lsp_types::Position;
+
+    #[test]
+    fn test_inside_cite() {
+        let items = test_feature!(
+            LatexCitationCompletionProvider,
+            FeatureSpec {
+                files: vec![
+                    FeatureSpec::file("foo.tex", "\\addbibresource{bar.bib}\n\\cite{}"),
+                    FeatureSpec::file("bar.bib", "@article{foo,}"),
+                    FeatureSpec::file("baz.bib", "@article{bar,}")
+                ],
+                main_file: "foo.tex",
+                position: Position::new(1, 6),
+                new_name: "",
+                component_database: LatexComponentDatabase::default(),
+            }
+        );
+        assert_eq!(items.len(), 1);
+        assert_eq!("foo", items[0].label);
+    }
+
+    #[test]
+    fn test_outside_cite() {
+        let items = test_feature!(
+            LatexCitationCompletionProvider,
+            FeatureSpec {
+                files: vec![
+                    FeatureSpec::file("foo.tex", "\\addbibresource{bar.bib}\n\\cite{}"),
+                    FeatureSpec::file("bar.bib", "@article{foo,}"),
+                    FeatureSpec::file("baz.bib", "@article{bar,}")
+                ],
+                main_file: "foo.tex",
+                position: Position::new(1, 7),
+                new_name: "",
+                component_database: LatexComponentDatabase::default(),
+            }
+        );
+        assert_eq!(items, Vec::new());
+    }
+}

src/completion/latex/mod.rs

@@ -1,4 +1,5 @@
 pub mod begin_command;
+pub mod citation;
 pub mod color;
 pub mod color_model;
 mod combinators;

src/completion/latex/user_command.rs

@@ -28,7 +28,10 @@ impl LatexUserCommandCompletionProvider {
                             .map(|command| &command.name.text()[1..])
                             .unique()
                             .map(|name| {
-                                factory::create_command(Cow::from(name.to_owned()), &LatexComponentId::Unknown)
+                                factory::create_command(
+                                    Cow::from(name.to_owned()),
+                                    &LatexComponentId::Unknown,
+                                )
                             })
                             .for_each(|item| items.push(item));
                     }

src/completion/mod.rs

@@ -3,6 +3,7 @@ pub mod latex;
 mod quality;
 
 use self::latex::begin_command::LatexBeginCommandCompletionProvider;
+use self::latex::citation::LatexCitationCompletionProvider;
 use self::latex::color::LatexColorCompletionProvider;
 use self::latex::color_model::LatexColorModelCompletionProvider;
 use self::latex::include::LatexIncludeCompletionProvider;
@@ -36,6 +37,7 @@ impl CompletionProvider {
                     LatexColorCompletionProvider,
                     LatexColorModelCompletionProvider,
                     LatexLabelCompletionProvider,
+                    LatexCitationCompletionProvider,
                     LatexIncludeCompletionProvider,
                     LatexBeginCommandCompletionProvider,
                     LatexTikzCommandCompletionProvider,