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SSR: Refactor matching code.

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Mutable state is now stored in the enum Phase.
MatchState, since it now has no mutable state is renamed Matcher.
MatchInputs is merged into Matcher
This commit is contained in:
David Lattimore 2020-07-03 13:09:14 +10:00
parent 4a8679824b
commit 69051d2f9d
1 changed files with 75 additions and 80 deletions
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155
crates/ra_ssr/src/matching.rs
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@ -92,58 +92,52 @@ pub(crate) fn get_match(
sema: &Semantics<ra_ide_db::RootDatabase>,
) -> Result<Match, MatchFailed> {
record_match_fails_reasons_scope(debug_active, || {
MatchState::try_match(rule, code, restrict_range, sema)
Matcher::try_match(rule, code, restrict_range, sema)
})
}
/// Inputs to matching. This cannot be part of `MatchState`, since we mutate `MatchState` and in at
/// least one case need to hold a borrow of a placeholder from the input pattern while calling a
/// mutable `MatchState` method.
struct MatchInputs<'pattern> {
ssr_pattern: &'pattern SsrPattern,
}
/// State used while attempting to match our search pattern against a particular node of the AST.
struct MatchState<'db, 'sema> {
/// Checks if our search pattern matches a particular node of the AST.
struct Matcher<'db, 'sema> {
sema: &'sema Semantics<'db, ra_ide_db::RootDatabase>,
/// If any placeholders come from anywhere outside of this range, then the match will be
/// rejected.
restrict_range: Option<FileRange>,
/// The match that we're building. We do two passes for a successful match. On the first pass,
/// this is None so that we can avoid doing things like storing copies of what placeholders
/// matched to. If that pass succeeds, then we do a second pass where we collect those details.
/// This means that if we have a pattern like `$a.foo()` we won't do an insert into the
/// placeholders map for every single method call in the codebase. Instead we'll discard all the
/// method calls that aren't calls to `foo` on the first pass and only insert into the
/// placeholders map on the second pass. Likewise for ignored comments.
match_out: Option<Match>,
rule: &'sema SsrRule,
}
impl<'db, 'sema> MatchState<'db, 'sema> {
/// Which phase of matching we're currently performing. We do two phases because most attempted
/// matches will fail and it means we can defer more expensive checks to the second phase.
enum Phase<'a> {
/// On the first phase, we perform cheap checks. No state is mutated and nothing is recorded.
First,
/// On the second phase, we construct the `Match`. Things like what placeholders bind to is
/// recorded.
Second(&'a mut Match),
}
impl<'db, 'sema> Matcher<'db, 'sema> {
fn try_match(
rule: &SsrRule,
rule: &'sema SsrRule,
code: &SyntaxNode,
restrict_range: &Option<FileRange>,
sema: &'sema Semantics<'db, ra_ide_db::RootDatabase>,
) -> Result<Match, MatchFailed> {
let mut match_state =
MatchState { sema, restrict_range: restrict_range.clone(), match_out: None };
let match_inputs = MatchInputs { ssr_pattern: &rule.pattern };
let match_state = Matcher { sema, restrict_range: restrict_range.clone(), rule };
let pattern_tree = rule.pattern.tree_for_kind(code.kind())?;
// First pass at matching, where we check that node types and idents match.
match_state.attempt_match_node(&match_inputs, &pattern_tree, code)?;
match_state.attempt_match_node(&mut Phase::First, &pattern_tree, code)?;
match_state.validate_range(&sema.original_range(code))?;
match_state.match_out = Some(Match {
let mut the_match = Match {
range: sema.original_range(code),
matched_node: code.clone(),
placeholder_values: FxHashMap::default(),
ignored_comments: Vec::new(),
template: rule.template.clone(),
});
};
// Second matching pass, where we record placeholder matches, ignored comments and maybe do
// any other more expensive checks that we didn't want to do on the first pass.
match_state.attempt_match_node(&match_inputs, &pattern_tree, code)?;
Ok(match_state.match_out.unwrap())
match_state.attempt_match_node(&mut Phase::Second(&mut the_match), &pattern_tree, code)?;
Ok(the_match)
}
/// Checks that `range` is within the permitted range if any. This is applicable when we're
@ -161,27 +155,22 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
}
fn attempt_match_node(
&mut self,
match_inputs: &MatchInputs,
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
// Handle placeholders.
if let Some(placeholder) =
match_inputs.get_placeholder(&SyntaxElement::Node(pattern.clone()))
{
if let Some(placeholder) = self.get_placeholder(&SyntaxElement::Node(pattern.clone())) {
for constraint in &placeholder.constraints {
self.check_constraint(constraint, code)?;
}
if self.match_out.is_none() {
return Ok(());
}
let original_range = self.sema.original_range(code);
// We validated the range for the node when we started the match, so the placeholder
// probably can't fail range validation, but just to be safe...
self.validate_range(&original_range)?;
if let Some(match_out) = &mut self.match_out {
match_out.placeholder_values.insert(
if let Phase::Second(matches_out) = phase {
let original_range = self.sema.original_range(code);
// We validated the range for the node when we started the match, so the placeholder
// probably can't fail range validation, but just to be safe...
self.validate_range(&original_range)?;
matches_out.placeholder_values.insert(
Var(placeholder.ident.to_string()),
PlaceholderMatch::new(code, original_range),
);
@ -190,41 +179,47 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
}
// Non-placeholders.
if pattern.kind() != code.kind() {
fail_match!("Pattern had a {:?}, code had {:?}", pattern.kind(), code.kind());
fail_match!(
"Pattern had a `{}` ({:?}), code had `{}` ({:?})",
pattern.text(),
pattern.kind(),
code.text(),
code.kind()
);
}
// Some kinds of nodes have special handling. For everything else, we fall back to default
// matching.
match code.kind() {
SyntaxKind::RECORD_FIELD_LIST => {
self.attempt_match_record_field_list(match_inputs, pattern, code)
self.attempt_match_record_field_list(phase, pattern, code)
}
SyntaxKind::TOKEN_TREE => self.attempt_match_token_tree(match_inputs, pattern, code),
_ => self.attempt_match_node_children(match_inputs, pattern, code),
SyntaxKind::TOKEN_TREE => self.attempt_match_token_tree(phase, pattern, code),
_ => self.attempt_match_node_children(phase, pattern, code),
}
}
fn attempt_match_node_children(
&mut self,
match_inputs: &MatchInputs,
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
self.attempt_match_sequences(
match_inputs,
phase,
PatternIterator::new(pattern),
code.children_with_tokens(),
)
}
fn attempt_match_sequences(
&mut self,
match_inputs: &MatchInputs,
&self,
phase: &mut Phase,
pattern_it: PatternIterator,
mut code_it: SyntaxElementChildren,
) -> Result<(), MatchFailed> {
let mut pattern_it = pattern_it.peekable();
loop {
match self.next_non_trivial(&mut code_it) {
match phase.next_non_trivial(&mut code_it) {
None => {
if let Some(p) = pattern_it.next() {
fail_match!("Part of the pattern was unmatched: {:?}", p);
@ -232,11 +227,11 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
return Ok(());
}
Some(SyntaxElement::Token(c)) => {
self.attempt_match_token(&mut pattern_it, &c)?;
self.attempt_match_token(phase, &mut pattern_it, &c)?;
}
Some(SyntaxElement::Node(c)) => match pattern_it.next() {
Some(SyntaxElement::Node(p)) => {
self.attempt_match_node(match_inputs, &p, &c)?;
self.attempt_match_node(phase, &p, &c)?;
}
Some(p) => fail_match!("Pattern wanted '{}', code has {}", p, c.text()),
None => fail_match!("Pattern reached end, code has {}", c.text()),
@ -246,11 +241,12 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
}
fn attempt_match_token(
&mut self,
&self,
phase: &mut Phase,
pattern: &mut Peekable<PatternIterator>,
code: &ra_syntax::SyntaxToken,
) -> Result<(), MatchFailed> {
self.record_ignored_comments(code);
phase.record_ignored_comments(code);
// Ignore whitespace and comments.
if code.kind().is_trivia() {
return Ok(());
@ -317,8 +313,8 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
/// We want to allow the records to match in any order, so we have special matching logic for
/// them.
fn attempt_match_record_field_list(
&mut self,
match_inputs: &MatchInputs,
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
@ -334,11 +330,11 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
for p in pattern.children_with_tokens() {
if let SyntaxElement::Node(p) = p {
if let Some(name_element) = p.first_child_or_token() {
if match_inputs.get_placeholder(&name_element).is_some() {
if self.get_placeholder(&name_element).is_some() {
// If the pattern is using placeholders for field names then order
// independence doesn't make sense. Fall back to regular ordered
// matching.
return self.attempt_match_node_children(match_inputs, pattern, code);
return self.attempt_match_node_children(phase, pattern, code);
}
if let Some(ident) = only_ident(name_element) {
let code_record = fields_by_name.remove(ident.text()).ok_or_else(|| {
@ -347,7 +343,7 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
ident
)
})?;
self.attempt_match_node(match_inputs, &p, &code_record)?;
self.attempt_match_node(phase, &p, &code_record)?;
}
}
}
@ -367,16 +363,15 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
/// pattern matches the macro invocation. For matches within the macro call, we'll already have
/// expanded the macro.
fn attempt_match_token_tree(
&mut self,
match_inputs: &MatchInputs,
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &ra_syntax::SyntaxNode,
) -> Result<(), MatchFailed> {
let mut pattern = PatternIterator::new(pattern).peekable();
let mut children = code.children_with_tokens();
while let Some(child) = children.next() {
if let Some(placeholder) = pattern.peek().and_then(|p| match_inputs.get_placeholder(p))
{
if let Some(placeholder) = pattern.peek().and_then(|p| self.get_placeholder(p)) {
pattern.next();
let next_pattern_token = pattern
.peek()
@ -402,7 +397,7 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
if Some(first_token.to_string()) == next_pattern_token {
if let Some(SyntaxElement::Node(p)) = pattern.next() {
// We have a subtree that starts with the next token in our pattern.
self.attempt_match_token_tree(match_inputs, &p, &n)?;
self.attempt_match_token_tree(phase, &p, &n)?;
break;
}
}
@ -411,7 +406,7 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
};
last_matched_token = next;
}
if let Some(match_out) = &mut self.match_out {
if let Phase::Second(match_out) = phase {
match_out.placeholder_values.insert(
Var(placeholder.ident.to_string()),
PlaceholderMatch::from_range(FileRange {
@ -427,11 +422,11 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
// Match literal (non-placeholder) tokens.
match child {
SyntaxElement::Token(token) => {
self.attempt_match_token(&mut pattern, &token)?;
self.attempt_match_token(phase, &mut pattern, &token)?;
}
SyntaxElement::Node(node) => match pattern.next() {
Some(SyntaxElement::Node(p)) => {
self.attempt_match_token_tree(match_inputs, &p, &node)?;
self.attempt_match_token_tree(phase, &p, &node)?;
}
Some(SyntaxElement::Token(p)) => fail_match!(
"Pattern has token '{}', code has subtree '{}'",
@ -448,6 +443,13 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
Ok(())
}
fn get_placeholder(&self, element: &SyntaxElement) -> Option<&Placeholder> {
only_ident(element.clone())
.and_then(|ident| self.rule.pattern.placeholders_by_stand_in.get(ident.text()))
}
}
impl Phase<'_> {
fn next_non_trivial(&mut self, code_it: &mut SyntaxElementChildren) -> Option<SyntaxElement> {
loop {
let c = code_it.next();
@ -463,7 +465,7 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
fn record_ignored_comments(&mut self, token: &SyntaxToken) {
if token.kind() == SyntaxKind::COMMENT {
if let Some(match_out) = &mut self.match_out {
if let Phase::Second(match_out) = self {
if let Some(comment) = ast::Comment::cast(token.clone()) {
match_out.ignored_comments.push(comment);
}
@ -472,13 +474,6 @@ impl<'db, 'sema> MatchState<'db, 'sema> {
}
}
impl MatchInputs<'_> {
fn get_placeholder(&self, element: &SyntaxElement) -> Option<&Placeholder> {
only_ident(element.clone())
.and_then(|ident| self.ssr_pattern.placeholders_by_stand_in.get(ident.text()))
}
}
fn is_closing_token(kind: SyntaxKind) -> bool {
kind == SyntaxKind::R_PAREN || kind == SyntaxKind::R_CURLY || kind == SyntaxKind::R_BRACK
}
@ -596,12 +591,12 @@ impl PatternIterator {
#[cfg(test)]
mod tests {
use super::*;
use crate::MatchFinder;
use crate::{MatchFinder, SsrRule};
#[test]
fn parse_match_replace() {
let rule: SsrRule = "foo($x) ==>> bar($x)".parse().unwrap();
let input = "fn main() { foo(1+2); }";
let input = "fn foo() {} fn main() { foo(1+2); }";
use ra_db::fixture::WithFixture;
let (db, file_id) = ra_ide_db::RootDatabase::with_single_file(input);
@ -623,6 +618,6 @@ mod tests {
let edit = crate::replacing::matches_to_edit(&matches, input);
let mut after = input.to_string();
edit.apply(&mut after);
assert_eq!(after, "fn main() { bar(1+2); }");
assert_eq!(after, "fn foo() {} fn main() { bar(1+2); }");
}
}