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Do insertion lookahead in algo::diff

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This commit is contained in:
Lukas Wirth 2020-10-26 15:40:08 +01:00
parent 1a84cadc88
commit 750ab54573
2 changed files with 139 additions and 59 deletions
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2
crates/ide/src/diagnostics.rs
View file

@ -613,7 +613,7 @@ fn main() {
pub struct Foo { pub a: i32, pub b: i32 }
"#,
r#"
fn some(, b: ()} {}
fn some(, b: ()) {}
fn items() {}
fn here() {}

194
crates/syntax/src/algo.rs
View file

@ -137,7 +137,7 @@ impl TreeDiff {
}
}
/// Finds minimal the diff, which, applied to `from`, will result in `to`.
/// Finds a (potentially minimal) diff, which, applied to `from`, will result in `to`.
///
/// Specifically, returns a structure that consists of a replacements, insertions and deletions
/// such that applying this map on `from` will result in `to`.
@ -151,7 +151,6 @@ pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
};
let (from, to) = (from.clone().into(), to.clone().into());
// FIXME: this is horrible inefficient. I bet there's a cool algorithm to diff trees properly.
if !syntax_element_eq(&from, &to) {
go(&mut diff, from, to);
}
@ -169,6 +168,7 @@ pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
}
}
// FIXME: this is horrible inefficient. I bet there's a cool algorithm to diff trees properly.
fn go(diff: &mut TreeDiff, lhs: SyntaxElement, rhs: SyntaxElement) {
let (lhs, rhs) = match lhs.as_node().zip(rhs.as_node()) {
Some((lhs, rhs)) => (lhs, rhs),
@ -179,6 +179,8 @@ pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
}
};
let mut look_ahead_scratch = Vec::default();
let mut rhs_children = rhs.children_with_tokens();
let mut lhs_children = lhs.children_with_tokens();
let mut last_lhs = None;
@ -204,7 +206,31 @@ pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
diff.deletions.push(element);
}
(Some(ref lhs_ele), Some(ref rhs_ele)) if syntax_element_eq(lhs_ele, rhs_ele) => {}
(Some(lhs_ele), Some(rhs_ele)) => go(diff, lhs_ele, rhs_ele),
(Some(lhs_ele), Some(rhs_ele)) => {
// nodes differ, look for lhs_ele in rhs, if its found we can mark everything up
// until that element as insertions. This is important to keep the diff minimal
// in regards to insertions that have been actually done, this is important for
// use insertions as we do not want to replace the entire module node.
look_ahead_scratch.push(rhs_ele.clone());
let mut rhs_children_clone = rhs_children.clone();
let mut insert = false;
while let Some(rhs_child) = rhs_children_clone.next() {
if syntax_element_eq(&lhs_ele, &rhs_child) {
mark::hit!(diff_insertions);
insert = true;
break;
} else {
look_ahead_scratch.push(rhs_child);
}
}
let drain = look_ahead_scratch.drain(..);
if let Some(prev) = last_lhs.clone().filter(|_| insert) {
diff.insertions.entry(prev).or_insert_with(Vec::new).extend(drain);
rhs_children = rhs_children_clone;
} else {
go(diff, lhs_ele, rhs_ele)
}
}
}
last_lhs = lhs_child.or(last_lhs);
}
@ -292,7 +318,6 @@ fn _replace_children(
#[derive(Debug, PartialEq, Eq, Hash)]
enum InsertPos {
FirstChildOf(SyntaxNode),
// Before(SyntaxElement),
After(SyntaxElement),
}
@ -602,31 +627,6 @@ mod tests {
);
}
#[test]
fn insert() {
mark::check!(diff_insert);
check_diff(
r#"use foo;"#,
r#"use foo;
use bar;"#,
expect![[r#"
insertions:
Line 0: Node(USE@0..8)
-> "\n"
-> use bar;
replacements:
deletions:
"#]],
);
}
#[test]
fn replace_parent() {
mark::check!(diff_replace_parent);
@ -650,7 +650,92 @@ use bar;"#,
}
#[test]
fn delete() {
fn insert_last() {
mark::check!(diff_insert);
check_diff(
r#"
use foo;
use bar;"#,
r#"
use foo;
use bar;
use baz;"#,
expect![[r#"
insertions:
Line 2: Node(USE@10..18)
-> "\n"
-> use baz;
replacements:
deletions:
"#]],
);
}
#[test]
fn insert_middle() {
check_diff(
r#"
use foo;
use baz;"#,
r#"
use foo;
use bar;
use baz;"#,
expect![[r#"
insertions:
Line 2: Token(WHITESPACE@9..10 "\n")
-> use bar;
-> "\n"
replacements:
deletions:
"#]],
)
}
#[test]
fn insert_first() {
check_diff(
r#"
use bar;
use baz;"#,
r#"
use foo;
use bar;
use baz;"#,
expect![[r#"
insertions:
Line 0: Token(WHITESPACE@0..1 "\n")
-> use foo;
-> "\n"
replacements:
deletions:
"#]],
)
}
#[test]
fn delete_last() {
mark::check!(diff_delete);
check_diff(
r#"use foo;
@ -674,52 +759,50 @@ use bar;"#,
}
#[test]
fn insert_use() {
fn delete_middle() {
mark::check!(diff_insertions);
check_diff(
r#"
use expect_test::{expect, Expect};
use crate::AstNode;
"#,
r#"
use expect_test::{expect, Expect};
use text_edit::TextEdit;
use crate::AstNode;
"#,
r#"
use expect_test::{expect, Expect};
use crate::AstNode;
"#,
expect![[r#"
insertions:
Line 4: Token(WHITESPACE@56..57 "\n")
Line 1: Node(USE@1..35)
-> "\n\n"
-> use crate::AstNode;
-> "\n"
replacements:
Line 2: Token(WHITESPACE@35..37 "\n\n") -> "\n"
Line 4: Token(CRATE_KW@41..46 "crate") -> text_edit
Line 4: Token(IDENT@48..55 "AstNode") -> TextEdit
Line 4: Token(WHITESPACE@56..57 "\n") -> "\n\n"
deletions:
Line 2: use text_edit::TextEdit;
Line 3: "\n\n"
Line 4: use crate::AstNode;
Line 5: "\n"
"#]],
)
}
#[test]
fn remove_use() {
fn delete_first() {
check_diff(
r#"
use expect_test::{expect, Expect};
use text_edit::TextEdit;
use crate::AstNode;
"#,
r#"
use expect_test::{expect, Expect};
use crate::AstNode;
"#,
expect![[r#"
@ -729,15 +812,14 @@ use crate::AstNode;
replacements:
Line 2: Token(WHITESPACE@35..36 "\n") -> "\n\n"
Line 3: Node(NAME_REF@40..49) -> crate
Line 3: Token(IDENT@51..59 "TextEdit") -> AstNode
Line 3: Token(WHITESPACE@60..62 "\n\n") -> "\n"
Line 2: Node(NAME_REF@5..14) -> crate
Line 2: Token(IDENT@16..24 "TextEdit") -> AstNode
Line 2: Token(WHITESPACE@25..27 "\n\n") -> "\n"
deletions:
Line 4: use crate::AstNode;
Line 5: "\n"
Line 3: use crate::AstNode;
Line 4: "\n"
"#]],
)
}
@ -814,17 +896,15 @@ fn main() {
_ => return,
}
-> ;
Line 5: Token(R_CURLY@64..65 "}")
Line 3: Node(IF_EXPR@17..63)
-> "\n "
-> }
-> foo(x);
replacements:
Line 3: Token(IF_KW@17..19 "if") -> let
Line 3: Token(LET_KW@20..23 "let") -> x
Line 3: Node(BLOCK_EXPR@40..63) -> =
Line 5: Token(WHITESPACE@63..64 "\n") -> "\n "
Line 5: Token(R_CURLY@64..65 "}") -> foo(x);
deletions: