129 lines
4.4 KiB
Markdown
129 lines
4.4 KiB
Markdown
# Phase 182-1: JsonParser Simple Loops Design Memo
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## Overview
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Phase 182 implements three simple JsonParser loops using existing P2/P1 JoinIR patterns.
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This follows Phase 181's design investigation.
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## Target Loops (3)
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### 1. _parse_number (P2 Break)
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- **Loop condition**: `p < s.length()` (LoopParam only)
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- **Carriers**: `p`, `num_str` (2 carriers)
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- **Control flow**: `break` on `digit_pos < 0`
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- **Pattern**: P2 Break
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- **JoinIR support**: ✅ Existing P2 lowerer sufficient
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- **AST characteristics**:
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- Single break point
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- No continue
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- No nested control flow
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- Carriers updated unconditionally before break check
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### 2. _atoi (P2 Break)
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- **Loop condition**: `i < n` (LoopParam + OuterLocal)
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- **Carriers**: `v`, `i` (2 carriers)
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- **Control flow**: `break` on `ch < "0" || ch > "9"` + `pos < 0`
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- **Pattern**: P2 Break
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- **JoinIR support**: ✅ Existing P2 lowerer sufficient
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- **AST characteristics**:
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- Multiple break conditions (combined with OR)
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- No continue
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- No nested control flow
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- Carriers updated before and after break check
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### 3. _match_literal (P1 Simple)
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- **Loop condition**: `i < len` (LoopParam + OuterLocal)
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- **Carriers**: `i` (1 carrier)
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- **Control flow**: `return` (early exit)
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- **Pattern**: P1 Simple
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- **JoinIR support**: ✅ Existing P1 lowerer sufficient
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- **AST characteristics**:
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- No break/continue
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- Early return instead
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- Single carrier increment
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- Simple conditional logic
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## Pipeline Integration Strategy
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### Existing Infrastructure (Reuse)
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- **PatternPipelineContext**: Already handles P1/P2 detection
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- **build_pattern_context()**: Existing logic sufficient
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- **P1 lowerer**: `lower_simple_while_minimal()` ready
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- **P2 lowerer**: `lower_loop_with_break_minimal()` ready
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- **LoopFeatures**: Shape detection already identifies P1/P2
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### Minimal Additions Required
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1. **Routing whitelist**: Ensure 3 functions are in JOINIR_TARGETS
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2. **LoopUpdateAnalyzer**: May need to skip string-heavy operations (gradual enablement)
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3. **Tracing**: Use NYASH_JOINIR_STRUCTURE_ONLY=1 for verification
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### NOT Required
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- ❌ New pattern types
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- ❌ New lowerer functions
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- ❌ Special carrier handling
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- ❌ Custom PHI generation
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## Verification Plan
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### Phase 182-2: Routing Check
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```bash
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# Verify functions are in whitelist
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grep -E "(_parse_number|_atoi|_match_literal)" \
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src/mir/builder/control_flow/joinir/routing.rs
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```
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### Phase 182-3: Pattern Detection Tracing
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```bash
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# Verify correct pattern routing
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NYASH_JOINIR_STRUCTURE_ONLY=1 NYASH_JOINIR_DEBUG=1 \
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./target/release/hakorune apps/selfhost-runtime/jsonparser.hako 2>&1 | \
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grep -E "(pattern|route|_parse_number|_atoi|_match)"
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```
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Expected output:
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- `_parse_number` → [trace:pattern] route: Pattern2_Break MATCHED
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- `_atoi` → [trace:pattern] route: Pattern2_Break MATCHED
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- `_match_literal` → [trace:pattern] route: Pattern1_Minimal MATCHED
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- No `[joinir/freeze]` errors
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### Phase 182-5: Representative Tests
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Create 3 minimal test files:
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1. `local_tests/test_jsonparser_parse_number_min.hako` - number parsing
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2. `local_tests/test_jsonparser_atoi_min.hako` - string to integer
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3. `local_tests/test_jsonparser_match_literal_min.hako` - literal matching
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Success criteria:
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- ✅ RC = 0 (normal exit)
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- ✅ Output matches expected values
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- ✅ No `[joinir/freeze]` errors
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- ✅ Same results as Rust JsonParser
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## Implementation Notes
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### Design Principles
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1. **Fit into existing framework** - Don't add special cases
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2. **Minimal additions** - Only adjust filters if necessary
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3. **Gradual enablement** - String operations can be phased in
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4. **Reuse pattern pipeline** - PatternPipelineContext handles everything
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### Potential Issues
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- **String operations**: May need LoopUpdateAnalyzer filtering
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- **Carrier complexity**: P2 has 2 carriers, but existing code handles this
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- **Break conditions**: Multiple conditions in _atoi, but OR combination is standard
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### Success Metrics
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- All 3 loops route to correct patterns (P2/P1)
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- No new special-case code required
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- Tests pass with NYASH_JOINIR_CORE=1
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- Performance comparable to existing patterns
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## Next Steps (Phase 183+)
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- _parse_array (P4 Continue candidate)
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- _parse_object (P4 Continue candidate)
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- Complex nested loops (future phases)
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## References
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- Phase 170: Loop header PHI design
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- Phase 181: JsonParser loop analysis
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- Pattern detection: `src/mir/builder/control_flow/joinir/patterns/detection.rs`
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- P1/P2 lowerers: `src/mir/builder/control_flow/joinir/patterns/pattern{1,2}_*.rs`
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