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Implement single-char state transitions using a static array and for loop

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This reduces compile time, compared to generating many individual if statements.
This commit is contained in:
Max Brunsfeld 2024-04-12 14:34:03 -07:00
parent 3210c7e21f
commit 7ec40b0ab4
2 changed files with 51 additions and 3 deletions
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43
cli/src/generate/render.rs
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@ -704,7 +704,44 @@ impl Generator {
let mut large_set = CharacterSet::empty();
let mut ruled_out_chars = CharacterSet::empty();
for (chars, action) in state.advance_actions {
// The transitions in a lex state are sorted with the single-character
// transitions first. If there are many single-character transitions,
// then implement them using an array of (lookahead character, state)
// pairs, instead of individual if statements, in order to reduce compile
// time.
let mut leading_simple_transition_count = 0;
let mut leading_simple_transition_character_count = 0;
for (chars, action) in &state.advance_actions {
if action.in_main_token
&& chars
.ranges()
.all(|r| r.start() == r.end() && *r.start() as u32 <= u16::MAX as u32)
{
leading_simple_transition_count += 1;
leading_simple_transition_character_count += chars.range_count();
} else {
break;
}
}
if leading_simple_transition_character_count >= 8 {
add_line!(self, "ADVANCE_MAP(");
indent!(self);
for (chars, action) in &state.advance_actions[0..leading_simple_transition_count] {
for range in chars.ranges() {
add_whitespace!(self);
self.add_character(*range.start());
add!(self, ", {},\n", action.state);
}
ruled_out_chars = ruled_out_chars.add(chars);
}
dedent!(self);
add_line!(self, ");");
} else {
leading_simple_transition_count = 0;
}
for (chars, action) in &state.advance_actions[leading_simple_transition_count..] {
add_whitespace!(self);
// The lex state's advance actions are represented with disjoint
@ -749,7 +786,7 @@ impl Generator {
// Add this transition's character set to the set of ruled out characters,
// which don't need to be checked for subsequent transitions in this state.
ruled_out_chars = ruled_out_chars.add(&chars);
ruled_out_chars = ruled_out_chars.add(chars);
let mut large_char_set_ix = None;
let mut asserted_chars = simplified_chars;
@ -823,7 +860,7 @@ impl Generator {
add!(self, ") ");
}
self.add_advance_action(&action);
self.add_advance_action(action);
add!(self, "\n");
}