2 files changed, 388 insertions, 6 deletions

diff --git a/crates/ra_ide_api/src/extend_selection.rs b/crates/ra_ide_api/src/extend_selection.rs
index d23290b74..63879a0b5 100644
--- a/crates/ra_ide_api/src/extend_selection.rs
+++ b/crates/ra_ide_api/src/extend_selection.rs
@@ -1,13 +1,378 @@
 use ra_db::SourceDatabase;
-use ra_syntax::AstNode;
-
-use crate::{
-    TextRange, FileRange,
-    db::RootDatabase,
+use ra_syntax::{
+    Direction, SyntaxNode, TextRange, TextUnit, AstNode,
+    algo::{find_covering_node, find_leaf_at_offset, LeafAtOffset},
+    SyntaxKind::*,
 };
 
+use crate::{FileRange, db::RootDatabase};
+
 // FIXME: restore macro support
 pub(crate) fn extend_selection(db: &RootDatabase, frange: FileRange) -> TextRange {
     let source_file = db.parse(frange.file_id);
-    ra_ide_api_light::extend_selection(source_file.syntax(), frange.range).unwrap_or(frange.range)
+    try_extend_selection(source_file.syntax(), frange.range).unwrap_or(frange.range)
+}
+
+fn try_extend_selection(root: &SyntaxNode, range: TextRange) -> Option<TextRange> {
+    let string_kinds = [COMMENT, STRING, RAW_STRING, BYTE_STRING, RAW_BYTE_STRING];
+    let list_kinds = [
+        FIELD_PAT_LIST,
+        MATCH_ARM_LIST,
+        NAMED_FIELD_DEF_LIST,
+        POS_FIELD_DEF_LIST,
+        NAMED_FIELD_LIST,
+        ENUM_VARIANT_LIST,
+        USE_TREE_LIST,
+        TYPE_PARAM_LIST,
+        TYPE_ARG_LIST,
+        PARAM_LIST,
+        ARG_LIST,
+        ARRAY_EXPR,
+    ];
+
+    if range.is_empty() {
+        let offset = range.start();
+        let mut leaves = find_leaf_at_offset(root, offset);
+        if leaves.clone().all(|it| it.kind() == WHITESPACE) {
+            return Some(extend_ws(root, leaves.next()?, offset));
+        }
+        let leaf_range = match leaves {
+            LeafAtOffset::None => return None,
+            LeafAtOffset::Single(l) => {
+                if string_kinds.contains(&l.kind()) {
+                    extend_single_word_in_comment_or_string(l, offset).unwrap_or_else(|| l.range())
+                } else {
+                    l.range()
+                }
+            }
+            LeafAtOffset::Between(l, r) => pick_best(l, r).range(),
+        };
+        return Some(leaf_range);
+    };
+    let node = find_covering_node(root, range);
+
+    // Using shallowest node with same range allows us to traverse siblings.
+    let node = node.ancestors().take_while(|n| n.range() == node.range()).last().unwrap();
+
+    if range == node.range() {
+        if string_kinds.contains(&node.kind()) {
+            if let Some(range) = extend_comments(node) {
+                return Some(range);
+            }
+        }
+
+        if node.parent().map(|n| list_kinds.contains(&n.kind())) == Some(true) {
+            if let Some(range) = extend_list_item(node) {
+                return Some(range);
+            }
+        }
+    }
+
+    match node.ancestors().skip_while(|n| n.range() == range).next() {
+        None => None,
+        Some(parent) => Some(parent.range()),
+    }
+}
+
+fn extend_single_word_in_comment_or_string(
+    leaf: &SyntaxNode,
+    offset: TextUnit,
+) -> Option<TextRange> {
+    let text: &str = leaf.leaf_text()?;
+    let cursor_position: u32 = (offset - leaf.range().start()).into();
+
+    let (before, after) = text.split_at(cursor_position as usize);
+
+    fn non_word_char(c: char) -> bool {
+        !(c.is_alphanumeric() || c == '_')
+    }
+
+    let start_idx = before.rfind(non_word_char)? as u32;
+    let end_idx = after.find(non_word_char).unwrap_or(after.len()) as u32;
+
+    let from: TextUnit = (start_idx + 1).into();
+    let to: TextUnit = (cursor_position + end_idx).into();
+
+    let range = TextRange::from_to(from, to);
+    if range.is_empty() {
+        None
+    } else {
+        Some(range + leaf.range().start())
+    }
+}
+
+fn extend_ws(root: &SyntaxNode, ws: &SyntaxNode, offset: TextUnit) -> TextRange {
+    let ws_text = ws.leaf_text().unwrap();
+    let suffix = TextRange::from_to(offset, ws.range().end()) - ws.range().start();
+    let prefix = TextRange::from_to(ws.range().start(), offset) - ws.range().start();
+    let ws_suffix = &ws_text.as_str()[suffix];
+    let ws_prefix = &ws_text.as_str()[prefix];
+    if ws_text.contains('\n') && !ws_suffix.contains('\n') {
+        if let Some(node) = ws.next_sibling() {
+            let start = match ws_prefix.rfind('\n') {
+                Some(idx) => ws.range().start() + TextUnit::from((idx + 1) as u32),
+                None => node.range().start(),
+            };
+            let end = if root.text().char_at(node.range().end()) == Some('\n') {
+                node.range().end() + TextUnit::of_char('\n')
+            } else {
+                node.range().end()
+            };
+            return TextRange::from_to(start, end);
+        }
+    }
+    ws.range()
+}
+
+fn pick_best<'a>(l: &'a SyntaxNode, r: &'a SyntaxNode) -> &'a SyntaxNode {
+    return if priority(r) > priority(l) { r } else { l };
+    fn priority(n: &SyntaxNode) -> usize {
+        match n.kind() {
+            WHITESPACE => 0,
+            IDENT | SELF_KW | SUPER_KW | CRATE_KW | LIFETIME => 2,
+            _ => 1,
+        }
+    }
+}
+
+/// Extend list item selection to include nearby comma and whitespace.
+fn extend_list_item(node: &SyntaxNode) -> Option<TextRange> {
+    fn is_single_line_ws(node: &SyntaxNode) -> bool {
+        node.kind() == WHITESPACE && !node.leaf_text().unwrap().contains('\n')
+    }
+
+    fn nearby_comma(node: &SyntaxNode, dir: Direction) -> Option<&SyntaxNode> {
+        node.siblings(dir)
+            .skip(1)
+            .skip_while(|node| is_single_line_ws(node))
+            .next()
+            .filter(|node| node.kind() == COMMA)
+    }
+
+    if let Some(comma_node) = nearby_comma(node, Direction::Prev) {
+        return Some(TextRange::from_to(comma_node.range().start(), node.range().end()));
+    }
+
+    if let Some(comma_node) = nearby_comma(node, Direction::Next) {
+        // Include any following whitespace when comma if after list item.
+        let final_node = comma_node
+            .siblings(Direction::Next)
+            .skip(1)
+            .next()
+            .filter(|node| is_single_line_ws(node))
+            .unwrap_or(comma_node);
+
+        return Some(TextRange::from_to(node.range().start(), final_node.range().end()));
+    }
+
+    return None;
+}
+
+fn extend_comments(node: &SyntaxNode) -> Option<TextRange> {
+    let prev = adj_comments(node, Direction::Prev);
+    let next = adj_comments(node, Direction::Next);
+    if prev != next {
+        Some(TextRange::from_to(prev.range().start(), next.range().end()))
+    } else {
+        None
+    }
+}
+
+fn adj_comments(node: &SyntaxNode, dir: Direction) -> &SyntaxNode {
+    let mut res = node;
+    for node in node.siblings(dir) {
+        match node.kind() {
+            COMMENT => res = node,
+            WHITESPACE if !node.leaf_text().unwrap().as_str().contains("\n\n") => (),
+            _ => break,
+        }
+    }
+    res
+}
+
+#[cfg(test)]
+mod tests {
+    use ra_syntax::{SourceFile, AstNode};
+    use test_utils::extract_offset;
+
+    use super::*;
+
+    fn do_check(before: &str, afters: &[&str]) {
+        let (cursor, before) = extract_offset(before);
+        let file = SourceFile::parse(&before);
+        let mut range = TextRange::offset_len(cursor, 0.into());
+        for &after in afters {
+            range = try_extend_selection(file.syntax(), range).unwrap();
+            let actual = &before[range];
+            assert_eq!(after, actual);
+        }
+    }
+
+    #[test]
+    fn test_extend_selection_arith() {
+        do_check(r#"fn foo() { <|>1 + 1 }"#, &["1", "1 + 1", "{ 1 + 1 }"]);
+    }
+
+    #[test]
+    fn test_extend_selection_list() {
+        do_check(r#"fn foo(<|>x: i32) {}"#, &["x", "x: i32"]);
+        do_check(r#"fn foo(<|>x: i32, y: i32) {}"#, &["x", "x: i32", "x: i32, "]);
+        do_check(r#"fn foo(<|>x: i32,y: i32) {}"#, &["x", "x: i32", "x: i32,"]);
+        do_check(r#"fn foo(x: i32, <|>y: i32) {}"#, &["y", "y: i32", ", y: i32"]);
+        do_check(r#"fn foo(x: i32, <|>y: i32, ) {}"#, &["y", "y: i32", ", y: i32"]);
+        do_check(r#"fn foo(x: i32,<|>y: i32) {}"#, &["y", "y: i32", ",y: i32"]);
+
+        do_check(r#"const FOO: [usize; 2] = [ 22<|> , 33];"#, &["22", "22 , "]);
+        do_check(r#"const FOO: [usize; 2] = [ 22 , 33<|>];"#, &["33", ", 33"]);
+        do_check(r#"const FOO: [usize; 2] = [ 22 , 33<|> ,];"#, &["33", ", 33"]);
+
+        do_check(
+            r#"
+const FOO: [usize; 2] = [
+    22,
+    <|>33,
+]"#,
+            &["33", "33,"],
+        );
+
+        do_check(
+            r#"
+const FOO: [usize; 2] = [
+    22
+    , 33<|>,
+]"#,
+            &["33", ", 33"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_start_of_the_line() {
+        do_check(
+            r#"
+impl S {
+<|>    fn foo() {
+
+    }
+}"#,
+            &["    fn foo() {\n\n    }\n"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_doc_comments() {
+        do_check(
+            r#"
+struct A;
+
+/// bla
+/// bla
+struct B {
+    <|>
+}
+            "#,
+            &["\n    \n", "{\n    \n}", "/// bla\n/// bla\nstruct B {\n    \n}"],
+        )
+    }
+
+    #[test]
+    fn test_extend_selection_comments() {
+        do_check(
+            r#"
+fn bar(){}
+
+// fn foo() {
+// 1 + <|>1
+// }
+
+// fn foo(){}
+    "#,
+            &["1", "// 1 + 1", "// fn foo() {\n// 1 + 1\n// }"],
+        );
+
+        do_check(
+            r#"
+// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+// pub enum Direction {
+//  <|>   Next,
+//     Prev
+// }
+"#,
+            &[
+                "//     Next,",
+                "// #[derive(Debug, Clone, Copy, PartialEq, Eq)]\n// pub enum Direction {\n//     Next,\n//     Prev\n// }",
+            ],
+        );
+
+        do_check(
+            r#"
+/*
+foo
+_bar1<|>*/
+    "#,
+            &["_bar1", "/*\nfoo\n_bar1*/"],
+        );
+
+        do_check(
+            r#"
+//!<|>foo_2 bar
+    "#,
+            &["foo_2", "//!foo_2 bar"],
+        );
+
+        do_check(
+            r#"
+/<|>/foo bar
+    "#,
+            &["//foo bar"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_prefer_idents() {
+        do_check(
+            r#"
+fn main() { foo<|>+bar;}
+    "#,
+            &["foo", "foo+bar"],
+        );
+        do_check(
+            r#"
+fn main() { foo+<|>bar;}
+    "#,
+            &["bar", "foo+bar"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_prefer_lifetimes() {
+        do_check(r#"fn foo<<|>'a>() {}"#, &["'a", "<'a>"]);
+        do_check(r#"fn foo<'a<|>>() {}"#, &["'a", "<'a>"]);
+    }
+
+    #[test]
+    fn test_extend_selection_select_first_word() {
+        do_check(r#"// foo bar b<|>az quxx"#, &["baz", "// foo bar baz quxx"]);
+        do_check(
+            r#"
+impl S {
+    fn foo() {
+        // hel<|>lo world
+    }
+}
+        "#,
+            &["hello", "// hello world"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_string() {
+        do_check(
+            r#"
+fn bar(){}
+
+" fn f<|>oo() {"
+    "#,
+            &["foo", "\" fn foo() {\""],
+        );
+    }
 }
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index b8a4adbce..81ca57035 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -211,6 +211,23 @@ pub struct Analysis {
 // API, the API should in theory be usable as a library, or via a different
 // protocol.
 impl Analysis {
+    // Creates an analysis instance for a single file, without any extenal
+    // dependencies, stdlib support or ability to apply changes. See
+    // `AnalysisHost` for creating a fully-featured analysis.
+    pub fn from_single_file(text: String) -> (Analysis, FileId) {
+        let mut host = AnalysisHost::default();
+        let source_root = SourceRootId(0);
+        let mut change = AnalysisChange::new();
+        change.add_root(source_root, true);
+        let mut crate_graph = CrateGraph::default();
+        let file_id = FileId(0);
+        crate_graph.add_crate_root(file_id, Edition::Edition2018);
+        change.add_file(source_root, file_id, "main.rs".into(), Arc::new(text));
+        change.set_crate_graph(crate_graph);
+        host.apply_change(change);
+        (host.analysis(), file_id)
+    }
+
     /// Debug info about the current state of the analysis
     pub fn status(&self) -> String {
         status::status(&*self.db)