1 files changed, 281 insertions, 0 deletions

diff --git a/crates/ra_ide_api_light/src/extend_selection.rs b/crates/ra_ide_api_light/src/extend_selection.rs
new file mode 100644
index 000000000..08cae5a51
--- /dev/null
+++ b/crates/ra_ide_api_light/src/extend_selection.rs
@@ -0,0 +1,281 @@
+use ra_syntax::{
+    Direction, SyntaxNode, TextRange, TextUnit,
+    algo::{find_covering_node, find_leaf_at_offset, LeafAtOffset},
+    SyntaxKind::*,
+};
+
+pub fn extend_selection(root: &SyntaxNode, range: TextRange) -> Option<TextRange> {
+    let string_kinds = [COMMENT, STRING, RAW_STRING, BYTE_STRING, RAW_BYTE_STRING];
+    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);
+    if string_kinds.contains(&node.kind()) && range == node.range() {
+        if let Some(range) = extend_comments(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,
+        }
+    }
+}
+
+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 = 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_start_of_the_lind() {
+        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() {\""],
+        );
+    }
+}