traxys/tree-sitter
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

CLI: Account for field names when comparing parse items

Browse source
This commit is contained in:
Max Brunsfeld 2019-03-29 12:13:24 -07:00
parent 1e64985f1f
commit 9bdac0e693
1 changed files with 26 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

29
cli/src/generate/build_tables/item.rs
View file

@ -25,6 +25,10 @@ lazy_static! {
};
}
// Because tokens are represented as small (~400 max) unsigned integers,
// sets of tokens can be efficiently represented as bit vectors with each
// index correspoding to a token, and each value representing whether or not
// the token is present in the set.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub(crate) struct TokenSet {
terminal_bits: SmallBitVec,
@ -394,8 +398,20 @@ impl<'a> Hash for ParseItem<'a> {
hasher.write_usize(self.production.steps.len());
hasher.write_i32(self.precedence());
self.associativity().hash(hasher);
// When comparing two parse items, the symbols that were already consumed by
// both items don't matter. Take for example these two items:
// X -> a b • c
// X -> a d • c
// These two items can be considered equivalent, for the purposes of parse
// table generation, because they entail the same actions. However, if the
// productions have different aliases or field names, they *cannot* be
// treated as equivalent, because those details are ultimately stored as
// attributes of the `REDUCE` action that will be performed when the item
// is finished.
for step in &self.production.steps[0..self.step_index as usize] {
step.alias.hash(hasher);
step.field_name.hash(hasher);
}
for step in &self.production.steps[self.step_index as usize..] {
step.hash(hasher);
@ -416,14 +432,17 @@ impl<'a> PartialEq for ParseItem<'a> {
}
for (i, step) in self.production.steps.iter().enumerate() {
// See the previous comment (in the `Hash::hash` impl) regarding comparisons
// of parse items' already-completed steps.
if i < self.step_index as usize {
if step.alias != other.production.steps[i].alias {
return false;
}
} else {
if *step != other.production.steps[i] {
if step.field_name != other.production.steps[i].field_name {
return false;
}
} else if *step != other.production.steps[i] {
return false;
}
}
@ -465,8 +484,12 @@ impl<'a> Ord for ParseItem<'a> {
return o;
}
for (i, step) in self.production.steps.iter().enumerate() {
// See the previous comment (in the `Hash::hash` impl) regarding comparisons
// of parse items' already-completed steps.
let o = if i < self.step_index as usize {
step.alias.cmp(&other.production.steps[i].alias)
step.alias
.cmp(&other.production.steps[i].alias)
.then_with(|| step.field_name.cmp(&other.production.steps[i].field_name))
} else {
step.cmp(&other.production.steps[i])
};