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Avoid using fall-through in get_changed_ranges

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Also, clean up the that function a bit and add a few comments.
This commit is contained in:
Max Brunsfeld 2019-02-06 10:23:23 -08:00
parent a8cc082ce2
commit b925f6e136
1 changed files with 56 additions and 34 deletions
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90
lib/src/get_changed_ranges.c
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@ -288,30 +288,32 @@ typedef enum {
} IteratorComparison;
IteratorComparison iterator_compare(const Iterator *old_iter, const Iterator *new_iter) {
Subtree old_tree = NULL_SUBTREE, new_tree = NULL_SUBTREE;
uint32_t old_start = 0, new_start = 0;
TSSymbol old_alias_symbol = 0, new_alias_symbol = 0;
Subtree old_tree = NULL_SUBTREE;
Subtree new_tree = NULL_SUBTREE;
uint32_t old_start = 0;
uint32_t new_start = 0;
TSSymbol old_alias_symbol = 0;
TSSymbol new_alias_symbol = 0;
iterator_get_visible_state(old_iter, &old_tree, &old_alias_symbol, &old_start);
iterator_get_visible_state(new_iter, &new_tree, &new_alias_symbol, &new_start);
if (!old_tree.ptr && !new_tree.ptr) return IteratorMatches;
if (!old_tree.ptr || !new_tree.ptr) return IteratorDiffers;
if (old_alias_symbol == new_alias_symbol) {
if (old_start == new_start) {
if (!ts_subtree_has_changes(old_tree) &&
ts_subtree_symbol(old_tree) == ts_subtree_symbol(new_tree) &&
ts_subtree_symbol(old_tree) != ts_builtin_sym_error &&
ts_subtree_size(old_tree).bytes == ts_subtree_size(new_tree).bytes &&
ts_subtree_parse_state(old_tree) != TS_TREE_STATE_NONE &&
ts_subtree_parse_state(new_tree) != TS_TREE_STATE_NONE &&
(ts_subtree_parse_state(old_tree) == ERROR_STATE) ==
(ts_subtree_parse_state(new_tree) == ERROR_STATE)) {
return IteratorMatches;
}
}
if (ts_subtree_symbol(old_tree) == ts_subtree_symbol(new_tree)) {
if (
old_alias_symbol == new_alias_symbol &&
ts_subtree_symbol(old_tree) == ts_subtree_symbol(new_tree)
) {
if (old_start == new_start &&
!ts_subtree_has_changes(old_tree) &&
ts_subtree_symbol(old_tree) != ts_builtin_sym_error &&
ts_subtree_size(old_tree).bytes == ts_subtree_size(new_tree).bytes &&
ts_subtree_parse_state(old_tree) != TS_TREE_STATE_NONE &&
ts_subtree_parse_state(new_tree) != TS_TREE_STATE_NONE &&
(ts_subtree_parse_state(old_tree) == ERROR_STATE) ==
(ts_subtree_parse_state(new_tree) == ERROR_STATE)) {
return IteratorMatches;
} else {
return IteratorMayDiffer;
}
}
@ -366,21 +368,31 @@ unsigned ts_subtree_get_changed_ranges(const Subtree *old_tree, const Subtree *n
puts("");
#endif
// Compare the old and new subtrees.
IteratorComparison comparison = iterator_compare(&old_iter, &new_iter);
// Even if the two subtrees appear to be identical, they could differ
// internally if they contain a range of text that was previously
// excluded from the parse, and is now included, or vice-versa.
if (comparison == IteratorMatches && ts_range_array_intersects(
included_range_differences,
included_range_difference_index,
position.bytes,
iterator_end_position(&old_iter).bytes
)) {
comparison = IteratorMayDiffer;
}
bool is_changed = false;
switch (iterator_compare(&old_iter, &new_iter)) {
switch (comparison) {
// If the subtrees are definitely identical, move to the end
// of both subtrees.
case IteratorMatches:
next_position = iterator_end_position(&old_iter);
if (ts_range_array_intersects(
included_range_differences,
included_range_difference_index,
position.bytes, next_position.bytes
)) {
next_position = position;
__attribute__ ((fallthrough));
} else {
break;
}
break;
// If the subtrees might differ internally, descend into both
// subtrees, finding the first child that spans the current position.
case IteratorMayDiffer:
if (iterator_descend(&old_iter, position.bytes)) {
if (!iterator_descend(&new_iter, position.bytes)) {
@ -398,6 +410,8 @@ unsigned ts_subtree_get_changed_ranges(const Subtree *old_tree, const Subtree *n
}
break;
// If the subtrees are different, record a change and then move
// to the end of both subtrees.
case IteratorDiffers:
is_changed = true;
next_position = length_min(
@ -407,19 +421,23 @@ unsigned ts_subtree_get_changed_ranges(const Subtree *old_tree, const Subtree *n
break;
}
// Ensure that both iterators are caught up to the current position.
while (
!iterator_done(&old_iter) &&
iterator_end_position(&old_iter).bytes <= next_position.bytes
) iterator_advance(&old_iter);
while (
!iterator_done(&new_iter) &&
iterator_end_position(&new_iter).bytes <= next_position.bytes
) iterator_advance(&new_iter);
while (old_iter.visible_depth > new_iter.visible_depth) iterator_ascend(&old_iter);
while (new_iter.visible_depth > old_iter.visible_depth) iterator_ascend(&new_iter);
// Ensure that both iterators are at the same depth in the tree.
while (old_iter.visible_depth > new_iter.visible_depth) {
iterator_ascend(&old_iter);
}
while (new_iter.visible_depth > old_iter.visible_depth) {
iterator_ascend(&new_iter);
}
if (is_changed) {
#ifdef DEBUG_GET_CHANGED_RANGES
@ -435,8 +453,12 @@ unsigned ts_subtree_get_changed_ranges(const Subtree *old_tree, const Subtree *n
position = next_position;
// Keep track of the current position in the included range differences
// array in order to avoid scanning the entire array on each iteration.
while (included_range_difference_index < included_range_differences->size) {
const TSRange *range = &included_range_differences->contents[included_range_difference_index];
const TSRange *range = &included_range_differences->contents[
included_range_difference_index
];
if (range->end_byte <= position.bytes) {
included_range_difference_index++;
} else {