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Boshen
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Oct 7, 2025
Reorder Kind enum to make all keywords truly contiguous, enabling a pure range check without additional OR clauses.
## Changes
**Enum Reordering**: Moved `True`, `False`, `Null` from the literals section (after punctuation) to immediately after `Yield`, making all keywords contiguous from `Await..=Null`.
**Before**:
```rust
pub fn is_any_keyword(self) -> bool {
matches!(self as u8, x if x >= Await as u8 && x <= Yield as u8)
|| matches!(self, True | False | Null) // Extra check needed!
}
```
**After**:
```rust
pub fn is_any_keyword(self) -> bool {
matches!(self as u8, x if x >= Await as u8 && x <= Null as u8) // Pure range check!
}
```
## Assembly Impact
### Before (range + OR)
```asm
; Range check for Await..=Yield
and w8, w0, #0xff
sub w8, w8, #5
cmp w8, #86
cset w9, lo
; Additional checks for True/False/Null
cmp w0, #168
ccmp w0, #171, #0, ne
cset w0, lo
orr w0, w9, w0 ; Combine results
```
**7 instructions**
### After (pure range)
```asm
and w8, w0, #0xff
sub w8, w8, #5
cmp w8, #89
cset w0, lo
```
**4 instructions** (43% reduction!)
## Why This Works
`True`, `False`, and `Null` are **both** keywords AND literals per ECMAScript spec:
- Keywords: Reserved words that cannot be used as identifiers
- Literals: Values with specific meanings
Grouping them with keywords is semantically correct and enables better optimization. The `is_literal()` function explicitly checks for these tokens, so their position in the enum doesn't affect correctness.
## Performance
- Called from `advance()` on **every token**
- **3 fewer instructions** on the hottest path
- **Simpler control flow** = better branch prediction
- **No OR operation** = faster execution
Added comprehensive tests including verification that True/False/Null work correctly as both keywords and literals.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
Boshen
added a commit
that referenced
this pull request
Oct 7, 2025
Reorder Kind enum to make all keywords truly contiguous, enabling a pure range check without additional OR clauses.
## Changes
**Enum Reordering**: Moved `True`, `False`, `Null` from the literals section (after punctuation) to immediately after `Yield`, making all keywords contiguous from `Await..=Null`.
**Before**:
```rust
pub fn is_any_keyword(self) -> bool {
matches!(self as u8, x if x >= Await as u8 && x <= Yield as u8)
|| matches!(self, True | False | Null) // Extra check needed!
}
```
**After**:
```rust
pub fn is_any_keyword(self) -> bool {
matches!(self as u8, x if x >= Await as u8 && x <= Null as u8) // Pure range check!
}
```
## Assembly Impact
### Before (range + OR)
```asm
; Range check for Await..=Yield
and w8, w0, #0xff
sub w8, w8, #5
cmp w8, #86
cset w9, lo
; Additional checks for True/False/Null
cmp w0, #168
ccmp w0, #171, #0, ne
cset w0, lo
orr w0, w9, w0 ; Combine results
```
**7 instructions**
### After (pure range)
```asm
and w8, w0, #0xff
sub w8, w8, #5
cmp w8, #89
cset w0, lo
```
**4 instructions** (43% reduction!)
## Why This Works
`True`, `False`, and `Null` are **both** keywords AND literals per ECMAScript spec:
- Keywords: Reserved words that cannot be used as identifiers
- Literals: Values with specific meanings
Grouping them with keywords is semantically correct and enables better optimization. The `is_literal()` function explicitly checks for these tokens, so their position in the enum doesn't affect correctness.
## Performance
- Called from `advance()` on **every token**
- **3 fewer instructions** on the hottest path
- **Simpler control flow** = better branch prediction
- **No OR operation** = faster execution
Added comprehensive tests including verification that True/False/Null work correctly as both keywords and literals.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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npx oxidation-compiler@latest lint libThis is amazing.