2 files changed, 598 insertions, 92 deletions

diff --git a/crates/ra_analysis/src/completion/completion_item.rs b/crates/ra_analysis/src/completion/completion_item.rs
new file mode 100644
index 000000000..d5d751759
--- /dev/null
+++ b/crates/ra_analysis/src/completion/completion_item.rs
@@ -0,0 +1,178 @@
+/// `CompletionItem` describes a single completion variant in the editor pop-up.
+/// It is basically a POD with various properties. To construct a
+/// `CompletionItem`, use `new` method and the `Builder` struct.
+#[derive(Debug)]
+pub struct CompletionItem {
+    label: String,
+    lookup: Option<String>,
+    snippet: Option<String>,
+    /// Used only internally in test, to check only specific kind of completion.
+    kind: CompletionKind,
+}
+
+pub enum InsertText {
+    PlainText { text: String },
+    Snippet { text: String },
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) enum CompletionKind {
+    /// Parser-based keyword completion.
+    Keyword,
+    /// Your usual "complete all valid identifiers".
+    Reference,
+    /// "Secret sauce" completions.
+    Magic,
+    Snippet,
+    Unspecified,
+}
+
+impl CompletionItem {
+    pub(crate) fn new(label: impl Into<String>) -> Builder {
+        let label = label.into();
+        Builder {
+            label,
+            lookup: None,
+            snippet: None,
+            kind: CompletionKind::Unspecified,
+        }
+    }
+    /// What user sees in pop-up in the UI.
+    pub fn label(&self) -> &str {
+        &self.label
+    }
+    /// What string is used for filtering.
+    pub fn lookup(&self) -> &str {
+        self.lookup
+            .as_ref()
+            .map(|it| it.as_str())
+            .unwrap_or(self.label())
+    }
+    /// What is inserted.
+    pub fn insert_text(&self) -> InsertText {
+        match &self.snippet {
+            None => InsertText::PlainText {
+                text: self.label.clone(),
+            },
+            Some(it) => InsertText::Snippet { text: it.clone() },
+        }
+    }
+}
+
+/// A helper to make `CompletionItem`s.
+#[must_use]
+pub(crate) struct Builder {
+    label: String,
+    lookup: Option<String>,
+    snippet: Option<String>,
+    kind: CompletionKind,
+}
+
+impl Builder {
+    pub(crate) fn add_to(self, acc: &mut Completions) {
+        acc.add(self.build())
+    }
+
+    pub(crate) fn build(self) -> CompletionItem {
+        CompletionItem {
+            label: self.label,
+            lookup: self.lookup,
+            snippet: self.snippet,
+            kind: self.kind,
+        }
+    }
+    pub(crate) fn lookup_by(mut self, lookup: impl Into<String>) -> Builder {
+        self.lookup = Some(lookup.into());
+        self
+    }
+    pub(crate) fn snippet(mut self, snippet: impl Into<String>) -> Builder {
+        self.snippet = Some(snippet.into());
+        self
+    }
+    pub(crate) fn kind(mut self, kind: CompletionKind) -> Builder {
+        self.kind = kind;
+        self
+    }
+}
+
+impl Into<CompletionItem> for Builder {
+    fn into(self) -> CompletionItem {
+        self.build()
+    }
+}
+
+/// Represents an in-progress set of completions being built.
+#[derive(Debug, Default)]
+pub(crate) struct Completions {
+    buf: Vec<CompletionItem>,
+}
+
+impl Completions {
+    pub(crate) fn add(&mut self, item: impl Into<CompletionItem>) {
+        self.buf.push(item.into())
+    }
+    pub(crate) fn add_all<I>(&mut self, items: I)
+    where
+        I: IntoIterator,
+        I::Item: Into<CompletionItem>,
+    {
+        items.into_iter().for_each(|item| self.add(item.into()))
+    }
+
+    #[cfg(test)]
+    pub(crate) fn assert_match(&self, expected: &str, kind: CompletionKind) {
+        let expected = normalize(expected);
+        let actual = self.debug_render(kind);
+        test_utils::assert_eq_text!(expected.as_str(), actual.as_str(),);
+
+        /// Normalize the textual representation of `Completions`:
+        /// replace `;` with newlines, normalize whitespace
+        fn normalize(expected: &str) -> String {
+            use ra_syntax::{tokenize, TextUnit, TextRange, SyntaxKind::SEMI};
+            let mut res = String::new();
+            for line in expected.trim().lines() {
+                let line = line.trim();
+                let mut start_offset: TextUnit = 0.into();
+                // Yep, we use rust tokenize in completion tests :-)
+                for token in tokenize(line) {
+                    let range = TextRange::offset_len(start_offset, token.len);
+                    start_offset += token.len;
+                    if token.kind == SEMI {
+                        res.push('\n');
+                    } else {
+                        res.push_str(&line[range]);
+                    }
+                }
+
+                res.push('\n');
+            }
+            res
+        }
+    }
+
+    #[cfg(test)]
+    fn debug_render(&self, kind: CompletionKind) -> String {
+        let mut res = String::new();
+        for c in self.buf.iter() {
+            if c.kind == kind {
+                if let Some(lookup) = &c.lookup {
+                    res.push_str(lookup);
+                    res.push_str(&format!(" {:?}", c.label));
+                } else {
+                    res.push_str(&c.label);
+                }
+                if let Some(snippet) = &c.snippet {
+                    res.push_str(&format!(" {:?}", snippet));
+                }
+                res.push('\n');
+            }
+        }
+        res
+    }
+}
+
+impl Into<Vec<CompletionItem>> for Completions {
+    fn into(self) -> Vec<CompletionItem> {
+        self.buf
+    }
+}
diff --git a/crates/ra_analysis/src/completion/reference_completion.rs b/crates/ra_analysis/src/completion/reference_completion.rs
index f483ed045..c2a650b6d 100644
--- a/crates/ra_analysis/src/completion/reference_completion.rs
+++ b/crates/ra_analysis/src/completion/reference_completion.rs
@@ -6,21 +6,19 @@ use ra_syntax::{
     ast::{self, LoopBodyOwner},
     SyntaxKind::*,
 };
-use     hir::{
-        self,
-        FnScopes,
-        Def,
-        Path,
+use hir::{
+    self,
+    FnScopes, Def, Path
 };
 
 use crate::{
     db::RootDatabase,
-    completion::CompletionItem,
+    completion::{CompletionItem, Completions, CompletionKind::*},
     Cancelable
 };
 
 pub(super) fn completions(
-    acc: &mut Vec<CompletionItem>,
+    acc: &mut Completions,
     db: &RootDatabase,
     module: &hir::Module,
     file: &SourceFileNode,
@@ -41,25 +39,23 @@ pub(super) fn completions(
             }
 
             let module_scope = module.scope(db)?;
-            acc.extend(
-                module_scope
-                    .entries()
-                    .filter(|(_name, res)| {
-                        // Don't expose this item
-                        match res.import {
-                            None => true,
-                            Some(import) => {
-                                let range = import.range(db, module.source().file_id());
-                                !range.is_subrange(&name_ref.syntax().range())
-                            }
+            module_scope
+                .entries()
+                .filter(|(_name, res)| {
+                    // Don't expose this item
+                    match res.import {
+                        None => true,
+                        Some(import) => {
+                            let range = import.range(db, module.source().file_id());
+                            !range.is_subrange(&name_ref.syntax().range())
                         }
-                    })
-                    .map(|(name, _res)| CompletionItem {
-                        label: name.to_string(),
-                        lookup: None,
-                        snippet: None,
-                    }),
-            );
+                    }
+                })
+                .for_each(|(name, _res)| {
+                    CompletionItem::new(name.to_string())
+                        .kind(Reference)
+                        .add_to(acc)
+                });
         }
         NameRefKind::Path(path) => complete_path(acc, db, module, path)?,
         NameRefKind::BareIdentInMod => {
@@ -125,30 +121,24 @@ fn classify_name_ref(name_ref: ast::NameRef) -> Option<NameRefKind> {
     None
 }
 
-fn complete_fn(name_ref: ast::NameRef, scopes: &FnScopes, acc: &mut Vec<CompletionItem>) {
+fn complete_fn(name_ref: ast::NameRef, scopes: &FnScopes, acc: &mut Completions) {
     let mut shadowed = FxHashSet::default();
-    acc.extend(
-        scopes
-            .scope_chain(name_ref.syntax())
-            .flat_map(|scope| scopes.entries(scope).iter())
-            .filter(|entry| shadowed.insert(entry.name()))
-            .map(|entry| CompletionItem {
-                label: entry.name().to_string(),
-                lookup: None,
-                snippet: None,
-            }),
-    );
+    scopes
+        .scope_chain(name_ref.syntax())
+        .flat_map(|scope| scopes.entries(scope).iter())
+        .filter(|entry| shadowed.insert(entry.name()))
+        .for_each(|entry| {
+            CompletionItem::new(entry.name().to_string())
+                .kind(Reference)
+                .add_to(acc)
+        });
     if scopes.self_param.is_some() {
-        acc.push(CompletionItem {
-            label: "self".to_string(),
-            lookup: None,
-            snippet: None,
-        })
+        CompletionItem::new("self").kind(Reference).add_to(acc);
     }
 }
 
 fn complete_path(
-    acc: &mut Vec<CompletionItem>,
+    acc: &mut Completions,
     db: &RootDatabase,
     module: &hir::Module,
     mut path: Path,
@@ -166,58 +156,56 @@ fn complete_path(
         _ => return Ok(()),
     };
     let module_scope = target_module.scope(db)?;
-    let completions = module_scope.entries().map(|(name, _res)| CompletionItem {
-        label: name.to_string(),
-        lookup: None,
-        snippet: None,
+    module_scope.entries().for_each(|(name, _res)| {
+        CompletionItem::new(name.to_string())
+            .kind(Reference)
+            .add_to(acc)
     });
-    acc.extend(completions);
     Ok(())
 }
 
-fn complete_mod_item_snippets(acc: &mut Vec<CompletionItem>) {
-    acc.push(CompletionItem {
-        label: "Test function".to_string(),
-        lookup: Some("tfn".to_string()),
-        snippet: Some(
-            "#[test]\n\
-             fn ${1:feature}() {\n\
-             $0\n\
-             }"
-            .to_string(),
-        ),
-    });
-    acc.push(CompletionItem {
-        label: "pub(crate)".to_string(),
-        lookup: None,
-        snippet: Some("pub(crate) $0".to_string()),
-    })
+fn complete_mod_item_snippets(acc: &mut Completions) {
+    CompletionItem::new("Test function")
+        .lookup_by("tfn")
+        .snippet(
+            "\
+#[test]
+fn ${1:feature}() {
+    $0
+}",
+        )
+        .kind(Snippet)
+        .add_to(acc);
+    CompletionItem::new("pub(crate)")
+        .snippet("pub(crate) $0")
+        .kind(Snippet)
+        .add_to(acc);
 }
 
 fn complete_expr_keywords(
     file: &SourceFileNode,
     fn_def: ast::FnDef,
     name_ref: ast::NameRef,
-    acc: &mut Vec<CompletionItem>,
+    acc: &mut Completions,
 ) {
-    acc.push(keyword("if", "if $0 {}"));
-    acc.push(keyword("match", "match $0 {}"));
-    acc.push(keyword("while", "while $0 {}"));
-    acc.push(keyword("loop", "loop {$0}"));
+    acc.add(keyword("if", "if $0 {}"));
+    acc.add(keyword("match", "match $0 {}"));
+    acc.add(keyword("while", "while $0 {}"));
+    acc.add(keyword("loop", "loop {$0}"));
 
     if let Some(off) = name_ref.syntax().range().start().checked_sub(2.into()) {
         if let Some(if_expr) = find_node_at_offset::<ast::IfExpr>(file.syntax(), off) {
             if if_expr.syntax().range().end() < name_ref.syntax().range().start() {
-                acc.push(keyword("else", "else {$0}"));
-                acc.push(keyword("else if", "else if $0 {}"));
+                acc.add(keyword("else", "else {$0}"));
+                acc.add(keyword("else if", "else if $0 {}"));
             }
         }
     }
     if is_in_loop_body(name_ref) {
-        acc.push(keyword("continue", "continue"));
-        acc.push(keyword("break", "break"));
+        acc.add(keyword("continue", "continue"));
+        acc.add(keyword("break", "break"));
     }
-    acc.extend(complete_return(fn_def, name_ref));
+    acc.add_all(complete_return(fn_def, name_ref));
 }
 
 fn is_in_loop_body(name_ref: ast::NameRef) -> bool {
@@ -272,23 +260,363 @@ fn complete_return(fn_def: ast::FnDef, name_ref: ast::NameRef) -> Option<Complet
     Some(keyword("return", snip))
 }
 
-fn keyword(kw: &str, snip: &str) -> CompletionItem {
-    CompletionItem {
-        label: kw.to_string(),
-        lookup: None,
-        snippet: Some(snip.to_string()),
-    }
+fn keyword(kw: &str, snippet: &str) -> CompletionItem {
+    CompletionItem::new(kw)
+        .kind(Keyword)
+        .snippet(snippet)
+        .build()
 }
 
-fn complete_expr_snippets(acc: &mut Vec<CompletionItem>) {
-    acc.push(CompletionItem {
-        label: "pd".to_string(),
-        lookup: None,
-        snippet: Some("eprintln!(\"$0 = {:?}\", $0);".to_string()),
-    });
-    acc.push(CompletionItem {
-        label: "ppd".to_string(),
-        lookup: None,
-        snippet: Some("eprintln!(\"$0 = {:#?}\", $0);".to_string()),
-    });
+fn complete_expr_snippets(acc: &mut Completions) {
+    CompletionItem::new("pd")
+        .snippet("eprintln!(\"$0 = {:?}\", $0);")
+        .kind(Snippet)
+        .add_to(acc);
+    CompletionItem::new("ppd")
+        .snippet("eprintln!(\"$0 = {:#?}\", $0);")
+        .kind(Snippet)
+        .add_to(acc);
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::{CompletionKind, check_completion};
+
+    fn check_reference_completion(code: &str, expected_completions: &str) {
+        check_completion(code, expected_completions, CompletionKind::Reference);
+    }
+
+    fn check_keyword_completion(code: &str, expected_completions: &str) {
+        check_completion(code, expected_completions, CompletionKind::Keyword);
+    }
+
+    fn check_snippet_completion(code: &str, expected_completions: &str) {
+        check_completion(code, expected_completions, CompletionKind::Snippet);
+    }
+
+    #[test]
+    fn test_completion_let_scope() {
+        check_reference_completion(
+            r"
+            fn quux(x: i32) {
+                let y = 92;
+                1 + <|>;
+                let z = ();
+            }
+            ",
+            "y;x;quux",
+        );
+    }
+
+    #[test]
+    fn test_completion_if_let_scope() {
+        check_reference_completion(
+            r"
+            fn quux() {
+                if let Some(x) = foo() {
+                    let y = 92;
+                };
+                if let Some(a) = bar() {
+                    let b = 62;
+                    1 + <|>
+                }
+            }
+            ",
+            "b;a;quux",
+        );
+    }
+
+    #[test]
+    fn test_completion_for_scope() {
+        check_reference_completion(
+            r"
+            fn quux() {
+                for x in &[1, 2, 3] {
+                    <|>
+                }
+            }
+            ",
+            "x;quux",
+        );
+    }
+
+    #[test]
+    fn test_completion_mod_scope() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            enum Baz {}
+            fn quux() {
+                <|>
+            }
+            ",
+            "quux;Foo;Baz",
+        );
+    }
+
+    #[test]
+    fn test_completion_mod_scope_no_self_use() {
+        check_reference_completion(
+            r"
+            use foo<|>;
+            ",
+            "",
+        );
+    }
+
+    #[test]
+    fn test_completion_self_path() {
+        check_reference_completion(
+            r"
+            use self::m::<|>;
+
+            mod m {
+                struct Bar;
+            }
+            ",
+            "Bar",
+        );
+    }
+
+    #[test]
+    fn test_completion_mod_scope_nested() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            mod m {
+                struct Bar;
+                fn quux() { <|> }
+            }
+            ",
+            "quux;Bar",
+        );
+    }
+
+    #[test]
+    fn test_complete_type() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            fn x() -> <|>
+            ",
+            "Foo;x",
+        )
+    }
+
+    #[test]
+    fn test_complete_shadowing() {
+        check_reference_completion(
+            r"
+            fn foo() -> {
+                let bar = 92;
+                {
+                    let bar = 62;
+                    <|>
+                }
+            }
+            ",
+            "bar;foo",
+        )
+    }
+
+    #[test]
+    fn test_complete_self() {
+        check_reference_completion(r"impl S { fn foo(&self) { <|> } }", "self")
+    }
+
+    #[test]
+    fn test_complete_crate_path() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            struct Spam;
+            //- /foo.rs
+            use crate::Sp<|>
+            ",
+            "Spam;foo",
+        );
+    }
+
+    #[test]
+    fn test_complete_crate_path_with_braces() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            struct Spam;
+            //- /foo.rs
+            use crate::{Sp<|>};
+            ",
+            "Spam;foo",
+        );
+    }
+
+    #[test]
+    fn test_complete_crate_path_in_nested_tree() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            pub mod bar {
+                pub mod baz {
+                    pub struct Spam;
+                }
+            }
+            //- /foo.rs
+            use crate::{bar::{baz::Sp<|>}};
+            ",
+            "Spam",
+        );
+    }
+
+    #[test]
+    fn test_completion_kewords() {
+        check_keyword_completion(
+            r"
+            fn quux() {
+                <|>
+            }
+            ",
+            r#"
+            if "if $0 {}"
+            match "match $0 {}"
+            while "while $0 {}"
+            loop "loop {$0}"
+            return "return"
+            "#,
+        );
+    }
+
+    #[test]
+    fn test_completion_else() {
+        check_keyword_completion(
+            r"
+            fn quux() {
+                if true {
+                    ()
+                } <|>
+            }
+            ",
+            r#"
+            if "if $0 {}"
+            match "match $0 {}"
+            while "while $0 {}"
+            loop "loop {$0}"
+            else "else {$0}"
+            else if "else if $0 {}"
+            return "return"
+            "#,
+        );
+    }
+
+    #[test]
+    fn test_completion_return_value() {
+        check_keyword_completion(
+            r"
+            fn quux() -> i32 {
+                <|>
+                92
+            }
+            ",
+            r#"
+            if "if $0 {}"
+            match "match $0 {}"
+            while "while $0 {}"
+            loop "loop {$0}"
+            return "return $0;"
+            "#,
+        );
+        check_keyword_completion(
+            r"
+            fn quux() {
+                <|>
+                92
+            }
+            ",
+            r#"
+            if "if $0 {}"
+            match "match $0 {}"
+            while "while $0 {}"
+            loop "loop {$0}"
+            return "return;"
+            "#,
+        );
+    }
+
+    #[test]
+    fn test_completion_return_no_stmt() {
+        check_keyword_completion(
+            r"
+            fn quux() -> i32 {
+                match () {
+                    () => <|>
+                }
+            }
+            ",
+            r#"
+            if "if $0 {}"
+            match "match $0 {}"
+            while "while $0 {}"
+            loop "loop {$0}"
+            return "return $0"
+            "#,
+        );
+    }
+
+    #[test]
+    fn test_continue_break_completion() {
+        check_keyword_completion(
+            r"
+            fn quux() -> i32 {
+                loop { <|> }
+            }
+            ",
+            r#"
+            if "if $0 {}"
+            match "match $0 {}"
+            while "while $0 {}"
+            loop "loop {$0}"
+            continue "continue"
+            break "break"
+            return "return $0"
+            "#,
+        );
+        check_keyword_completion(
+            r"
+            fn quux() -> i32 {
+                loop { || { <|> } }
+            }
+            ",
+            r#"
+            if "if $0 {}"
+            match "match $0 {}"
+            while "while $0 {}"
+            loop "loop {$0}"
+            return "return $0"
+            "#,
+        );
+    }
+
+    #[test]
+    fn test_item_snippets() {
+        // check_snippet_completion(r"
+        //     <|>
+        //     ",
+        //     r##"[CompletionItem { label: "Test function", lookup: None, snippet: Some("#[test]\nfn test_${1:feature}() {\n$0\n}"##,
+        // );
+        check_snippet_completion(
+            r"
+            #[cfg(test)]
+            mod tests {
+                <|>
+            }
+            ",
+            r##"
+            tfn "Test function" "#[test]\nfn ${1:feature}() {\n    $0\n}"
+            pub(crate) "pub(crate) $0"
+        "##,
+        );
+    }
+
 }