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Unroll switch range case if range has only one number.

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This commit is contained in:
Stephen Chung
2021-12-22 10:48:19 +08:00
parent 7ff50451cc
commit 1c50efbac8
2 changed files with 47 additions and 21 deletions
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30
src/parser.rs
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@@ -15,7 +15,7 @@ use crate::tokenizer::{
};
use crate::types::dynamic::AccessMode;
use crate::{
calc_fn_hash, calc_qualified_fn_hash, calc_qualified_var_hash, Engine, ExclusiveRange,
calc_fn_hash, calc_qualified_fn_hash, calc_qualified_var_hash, Dynamic, Engine, ExclusiveRange,
Identifier, ImmutableString, InclusiveRange, LexError, ParseError, ParseErrorType, Position,
Scope, Shared, StaticVec, AST, INT,
};
@@ -1095,7 +1095,29 @@ fn parse_switch(
def_stmt = match (hash, range) {
(None, Some(range)) => {
ranges.push((range.0, range.1, range.2, condition, stmt.into()));
let is_empty = if range.2 {
(range.0..=range.1).is_empty()
} else {
(range.0..range.1).is_empty()
};
if !is_empty {
match (range.1.checked_sub(range.0), range.2) {
// Unroll single range
(Some(1), false) | (Some(0), true) => {
let value = Dynamic::from_int(range.0);
let hasher = &mut get_hasher();
value.hash(hasher);
let hash = hasher.finish();
if !table.contains_key(&hash) {
table.insert(hash, (condition.clone(), stmt.into()).into());
}
}
// Other range
_ => ranges.push((range.0, range.1, range.2, condition, stmt.into())),
}
}
None
}
(Some(hash), None) => {
@@ -1103,9 +1125,7 @@ fn parse_switch(
None
}
(None, None) => Some(stmt.into()),
(Some(_), Some(_)) => {
unreachable!("cannot have both a hash and a range in a `switch` statement")
}
_ => unreachable!("both hash and range in `switch` statement case"),
};
match input.peek().expect(NEVER_ENDS) {