Expose Five's existing FRB bytecode compiler for single-expression
compilation, enabling prepared-statement-style caching in dynamic
query engines (FiveSql2, scripting layers, rule engines).
1. genpc.CompileExpr(ast.Expr) *hbrt.PcodeFunc
- New public API that compiles a single expression to a
standalone pcode function
- Reuses genpc's mature emitExpr (no new emit logic)
- ExecPcode manages the frame around the generated code
2. hbrtl.PcCompile(cPrgExpr) -> pFunc
- RTL entry point for runtime compilation
- Wraps the expression in a FUNCTION stub, uses the full PRG
parser pipeline (pp + parser + genpc), extracts the compiled
pcode function, returns it as an opaque pointer
- Callers pay parse+compile cost ONCE per expression
3. hbrtl.PcEval(pFunc) -> xValue
- RTL entry point for runtime execution
- Calls hbrt.ExecPcode; the pcode's RetValue opcode sets retVal,
which our EndProc preserves as PcEval's return value
- ~1.2x slower than direct FieldGet (pcode interpreter overhead),
but eliminates AST tree-walk per row for complex expressions
Usage (FiveSql2 hot path, planned):
pc := PcCompile("FieldGet(4) > 50000") // parse+compile once
WHILE !Eof()
IF PcEval(pc) // ~10us per row
AAdd(aRows, ...)
ENDIF
dbSkip()
ENDDO
Benchmark (50k records, WHERE salary > 50000):
Raw FieldGet: 7.9 ms (baseline)
FieldPos+Get: 10.2 ms (with O(1) FieldPos cache)
PcEval bytecode: 10.1 ms (interpreted bytecode)
MacroEval: parse+eval per row — orders of magnitude slower
Tests:
go test ./... ALL PASS (14 packages)
FiveSql2 43/43 100%
compat_harbour 51/51
PcCompile/PcEval verified on 50k-row scan
FiveSql2 engine integration deferred — requires careful PRG-level
refactoring to thread pcode pointers through the plan structure.
The Go-level infrastructure is now in place for that work.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Two SQLite-style optimizations for RDD and SQL workloads:
1. FieldPos() O(1) column binding cache
Before: FieldPos(name) linear scan — O(n) per call with string
comparison. In SQL engines that call FieldPos per row per
column, this is hundreds of thousands of calls.
After: DBFArea builds a map[UPPER(name)]→pos on first lookup.
All subsequent lookups are O(1) hash. SQLite calls this
"column affinity binding" — positions resolved at prepare,
not per row.
Implementation:
- hbrdd/dbf/dbf.go: DBFArea.FieldPosCache(name) method
- hbrtl/procinfo.go: FieldPos RTL uses fieldPosCacher interface
- Lazy init: only pays for tables that get queried
2. hbrdd import auto-detection for function-call style PRGs
Before: compiler only added hbrdd import when PRG used xBase commands
(USE, SKIP, INDEX...). Pure function-call style like
`dbUseArea(.T.,,"t")`, `FieldPut(1, val)` was missed —
generated Go failed to compile ("undefined: hbrdd").
After: scanStmtsForXBase walks ExprStmt bodies too, detecting
CallExpr to any of the ~40 xBase RTL function names.
FIELD->NAME alias expressions also trigger the import.
Resolves: small PRGs that use only dbUseArea/FieldGet/FieldPut.
Benchmark notes (50k records):
Raw RDD scan: 7 ms (baseline)
FiveSql2 SELECT WHERE: 157 ms (unchanged — bottleneck is
not FieldPos, it's PRG-level
expression tree walk per row)
compat_harbour 51/51: PASS
FiveSql2 43/43: 100%
The FieldPos cache helps heavy field-name-based code paths but the
primary FiveSql2 bottleneck is the PRG interpreter walking expression
ASTs per row (needs bytecode compilation to close the gap).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Eliminate MacroEval overhead for INDEX ON with UDF/complex expressions.
Before: gengo passed KeyExpr as a string → indexer called MacroEval()
per record (50k × string parse + symbol lookup + function call).
After: gengo emits a Go closure (_keyFunc) that inlines the AST of
the key expression as direct Go code. The indexer calls the
closure directly — zero string parsing, zero runtime symbol
lookup for the hot loop.
Three code paths in the closure, depending on expression type:
1. UDF call: FindSymbol("FULLNAME") + Function(0)
(symbol lookup once per closure creation, not per record)
2. Field reference: GetValue(fieldIndex) inline
(no MacroEval, no FIELD-> alias resolution)
3. UPPER/LOWER(expr): strings.ToUpper/Lower inline
(no RTL function call overhead)
Architecture (Go compiler design principle):
Compile time knows the AST → emit native code.
Don't serialize to string → re-parse at runtime 50k times.
Benchmark (50k records, 3 UDF indexes):
before after Harbour ratio
3 UDF INDEX 163.0ms 60.0ms 55.0ms Five/HB = 1.09x
SEEK 10k 7.6ms 7.6ms 14.0ms Five 1.8x faster
SCAN 50k 3.4ms 3.4ms 4.0ms Five 15% faster
TOTAL 233.0ms 130.0ms 147.0ms Five 12% faster overall
UDF INDEX build went from 3x SLOWER than Harbour to nearly EQUAL.
SEEK/SCAN remain faster than Harbour (mmap + NTX optimizations).
Changes:
hbrdd/driver.go KeyFunc field in OrderCreateParams
hbrdd/dbf/indexer.go compiled path using KeyFunc before MacroEval fallback
compiler/gengo/gengo.go emitIndexKeyExpr: field-aware AST→Go emitter
for INDEX ON key expressions
Correctness: Harbour vs Five UDF diff = 0 (25-line output match)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
All 3 remaining known constraints resolved. CLAUDE.md now shows zero.
1. CDX compound index WRITE support (was read-only)
New file: hbrdd/cdx/build.go (~400 LOC)
- CreateOrAddTag() builds Harbour-compatible CDX files
- Bit-packed leaf pages (RecBits/DupBits/TrlBits compression)
- Interior nodes with big-endian RecNo/ChildPage
- Compound root directory (structural B-tree of tag names)
- Append-safe: preserves existing tags when adding new ones
- Linked leaf pages (LeftPtr/RightPtr for sequential scan)
Pipeline: INDEX ON expr TAG tagname TO file
- ast.IndexCmd gains TagName field
- Parser captures TAG name (was discarded)
- gengo passes TagName to OrderCreateParams
- indexer.go routes to cdx.CreateOrAddTag when TAG specified
Verified: 3 tags (BYNAME/BYCITY/BYAGE), OrdSetFocus by name,
SEEK, GoTop/GoBottom, close+reopen with SET INDEX TO
2. {||} empty code block parsing in function arguments
Parser's parseArrayOrBlock() called parseExpr() unconditionally
after closing |, failing when body was empty ({||}).
Fix: check for RBRACE after closing | and emit NIL literal body.
{=>} empty hash already worked.
3. Semicolon IF...ENDIF — already worked (removed from constraints)
Tests:
go test ./... 14 packages ALL PASS
FiveSql2 43/43 100%
compat_harbour 51/51
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Before: `STATIC n := 0` inside a FUNCTION caused "local variable
index out of range: 0" panic. The gengo code generator only handled
module-level STATIC (file scope) but silently ignored function-level
STATIC declarations.
After: Function-level STATIC variables are emitted as Go package-level
vars with function-name prefixed names (e.g., `static_COUNTER_N`),
registered in staticVars map during function emission, and cleaned up
after the function to prevent name collisions.
Also fixes compound assignment (+=, -=, *=, /=) on STATIC variables,
which previously only handled simple assignment (:=).
FUNCTION Counter()
STATIC n := 0 // persists across calls
n++ // n++ already worked (postfix handler)
n += 10 // was broken, now works
RETURN n
Verified:
Counter() → 1, 2, 3 (n++)
CountA() → 10, 20, 30 (n += 10, separate scope)
CountB() → 101, 102, 103 (n += 1, init 100, separate scope)
go test ./... 14 packages OK
FiveSql2 43/43 100%
compat_harbour 51/51
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Release-blocking compatibility issues discovered during the 258-test
pre-release validation suite (100 syntax + 44 RDD + 114 RTL).
1. PCount() always returned 0 in PRG code
Root cause: ParamCount() returned t.pendingParams, which is
overwritten by every nested Function() call. By the time the
PCount() RTL's Frame() executes, pendingParams is already 0.
Fix: Frame() now stores pendingParams in frame.paramCount.
PCount() RTL uses CallerParamCount() which reads callSP-2
(the PRG caller's frame), while RTL functions still use
ParamCount() (reads pendingParams before their own Frame).
Verified: PCount(1,2,3)=3, PCount(1)=1, PCount()=0
2. Break("string") panicked instead of being caught by RECOVER USING
Root cause: Generated SEQUENCE code only caught *HbError panics.
Break() panics with BreakValue (a different type), which fell
through to EndProc's "runtime error" message and re-panic.
Fix (two parts):
a) gengo emitBeginSequence: recover closure now catches any
panic (interface{}), then dispatches via type switch:
- *HbError → extract .Error() string
- hasValue interface (BreakValue) → extract .GetValue()
- other → static "error" string
b) hbrtl/error.go: BreakValue gets GetValue() method for
duck-type detection without import cycles
c) hbrt/thread.go EndProc: BreakValue type name check added
so it re-panics silently (no stderr noise)
3. SET INDEX TO a, b, c only opened the last file
Root cause: Parser's parseSet() called parseExpr() once for
INDEX setting, stopping at the first comma. Remaining file
names were consumed by the "eat rest of line" loop.
Fix: Parser now collects comma-separated identifiers into a
single string literal "a,b,c". gengo splits on comma and
calls OrderListAdd() for each file.
Verified: SET INDEX TO si_name, si_city → OrdCount=2
All tests pass:
go test ./... 14 packages OK
FiveSql2 43/43 100%
compat_harbour 51/51
Syntax test 100/100
RDD test 44/44
RTL test 114/114
Windows cross-compile OK
Linux cross-compile OK
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Replaces the FLOCK/DBRLOCK/DBRUNLOCK no-op stubs with actual
fcntl(F_SETLK) byte-range advisory locks, matching Harbour's
hb_fsLockLarge implementation.
Before: rtlDbRLock always returned .T. regardless of contention.
Multi-process writers could silently corrupt records.
After: Non-blocking POSIX byte-range locks per file descriptor.
Cross-process exclusion verified by a subprocess-spawning
Go test that witnesses BUSY vs OK transitions.
New files:
hbrdd/dbf/locks_posix.go fcntl F_WRLCK/F_UNLCK wrappers
hbrdd/dbf/locks_windows.go stub (TODO: LockFileEx)
hbrdd/dbf/lock_multi_test.go cross-process verification
docs/gap-analysis.md honest Harbour parity assessment
Modified:
hbrdd/dbf/dbf.go
- DBFArea gains fileLocked bool + lockedRecs map
- Close() calls releaseAllLocks() before dropping the fd
hbrtl/database.go
- rtlDbRLock / rtlDbRUnlock now delegate to DBFArea.LockRecord /
UnlockRecord instead of returning fixed .T./NIL
- New rtlFLock / rtlDbUnlock for FLOCK() / DBUNLOCK()
hbrtl/register.go
- FLOCK and DBUNLOCK symbols registered (were missing entirely)
compiler/analyzer/analyzer.go
- FLOCK / DBUNLOCK added to RTL known-function set
Lock region layout (non-overlapping on purpose):
FLOCK region [0, HeaderLen+1)
Record N region [RecordOffset(N), RecordLen)
So a workarea can hold FLOCK and multiple DBRLOCK simultaneously
on the same fd without conflict.
Design rationale (captured in locks_posix.go header):
* POSIX fcntl, not flock(2) — byte-range + NFS-safe
* Non-blocking F_SETLK — matches Clipper FLOCK() → .F. semantics
* Released explicitly on Close to avoid workarea-sharing races
* Windows falls back to no-op (TODO: LockFileEx)
Verification:
go test ./hbrdd/dbf/ -run TestFLockBlocksAcrossProcesses PASS
go test ./hbrdd/dbf/ -run TestRLockBlocksAcrossProcesses PASS
go test ./... ALL PASS
FiveSql2 43/43 100%
compat_harbour 51/51 100%
The gap-analysis doc (docs/gap-analysis.md) is a running inventory
of what works vs what's still missing vs Harbour 3.2, written for
users evaluating Five for production — not a sales pitch.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Five RDD engine now matches Harbour DBFNTX and DBFCDX byte-for-byte
in ordering, seek, navigation, and field access. Verified against
Harbour 3.2.0dev with a 281-line comparison test covering:
- Natural/NAME/CITY/AGE/SALARY/UPPER ordering
- SEEK (exact/not-found), GoTop/GoBottom per order
- DELETE/RECALL with SET DELETED
- CDX compound index read with 5 tags (BYNAME, BYCITY, BYAGE, BYSAL, BYUNAME)
- Reverse traversal
Fixes:
1. FIELD->NAME returned NIL
GetAliasField returned interface{} but runtime expected hbrt.Value,
so the type assertion in PushAliasField failed and pushed NIL.
- workarea.go: change return type to hbrt.Value, handle FIELD/_FIELD
as current-workarea alias, add SetAliasField
- gengo.go: emit SetAliasField() for alias->field := value in both
statement and expression contexts
2. OrdSetFocus(n) silently switched to natural order
v.AsString() returns "" for a numeric Value, so OrderListFocus("")
set current=-1.
- indexrtl.go: convert numeric param via fmt.Sprintf("%d", ...)
3. CDX compound tag order mismatched Harbour
Five decoded the structural B-tree which is alphabetical, but
Harbour sorts tags by TagBlock (file offset = creation order).
- cdx/cdx.go: sort tagEntries by offset ascending after decoding,
matching hb_cdxIndexLoadAvailTags in dbfcdx1.c
4. OutStd()/OutErr() not registered — caused panic on call
- hbrtl/console.go: add rtlOutStd/rtlOutErr implementations
- hbrtl/register.go: register OUTSTD and OUTERR
- analyzer.go: add OUTSTD/OUTERR to RTL known-functions
5. FIELD keyword triggered "undeclared variable" warnings
- analyzer.go: add FIELD, _FIELD, M, MEMVAR as builtin constants
Tests:
go test ./... — ALL PASS (17 packages)
FiveSql2 43/43 — 100%
compat_harbour 51/51 — 100%
Harbour diff — 0 lines differ (281-line comparison)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Register all 479 RTL functions from hbrtl/register.go (was ~60)
- Recognize module-level STATIC variables across all functions
- Declare RECOVER USING variables in analyzer scope
- Register code block parameters ({|x,y| ...}) as declared
- 2-pass multi-file build: collect cross-file function names before analysis
- Add QUIT, ERRORLEVEL, ALTSRC to builtin constants
All 3 test suites pass with 0 warnings:
go test ./... — ALL PASS
FiveSql2 43/43 — 100%
compat_harbour 51/51 — 100%
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
From senior Go developer review:
C7 CRITICAL: pagePool data race (ntx.go)
- Moved global pagePool[8] + pagePoolIdx into per-Index struct
- Eliminates race condition across goroutines using separate indexes
C8 CRITICAL: Page.data dangling pointer after remap (ntx.go)
- remapFile() now clears pagePool data slices (pointed into old mmap)
- Prevents segfault from stale mmap references
C4 HIGH: pop() bounds check restored (thread.go)
- Removed performance optimization that eliminated underflow detection
- Stack underflow now produces clear error instead of index -1 panic
C1 HIGH: intExpLen overflow on MinInt64 (value.go)
- Added special case: MinInt64 returns 20 (length of -9223372036854775808)
- Prevents -v overflow in negation
C11 CRITICAL: GoTo ReadAt error handling (dbf.go)
- ReadAt failure now returns error and sets EOF
- Previously silently used stale record buffer (data corruption risk)
C14 HIGH: LEN() inline missing Hash case (gengo.go)
- Added _v.IsHash() → len(Keys) branch
C15 HIGH: EMPTY() inline missing Date case (gengo.go)
- Added _v.IsDate() && _v.AsJulian() == 0 check
82/82 stress PASS. 14 packages ALL PASS.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
DO WHILE optimization:
- Detect RDD commands in body (SKIP/GO/SEEK/REPLACE/DELETE)
- If no USE/SELECT (safe), hoist _dwa/_darea before loop
- SKIP/GO/SEEK/DELETE inside loop use cached area variable
- Eliminates WA lookup + Current() per iteration
SEEK optimization:
- Use hoisted area when inside DO WHILE or FOR hoist context
- Eliminates WA lookup per SEEK call in tight loops
DELETE optimization:
- Use hoisted area when available
All commands now check g.hoistedDW || g.hoistedFields:
- GO TOP/BOTTOM/n → cached area
- SKIP n → cached area
- SEEK key → cached area + Indexer check
- DELETE → cached area
- APPEND → cached area (FOR loop)
- REPLACE → cached _rdbf + _rfiN (FOR loop)
82/82 stress PASS. 14 packages ALL PASS.
CDX SCOPE: 12ms (Harbour 4ms = 3x)
NTX SCAN: 24ms (Harbour 5ms = 4.8x)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
When FOR body contains APPEND+REPLACE and no USE/SELECT:
- Hoist WorkAreaManager, Current(), *dbf.DBFArea outside loop
- Pre-compute FieldIndex for all REPLACE fields once
- REPLACE inside loop uses cached _rdbf and _rfiN variables
- APPEND inside loop uses cached _rarea (no WA lookup per iter)
Safety: collectReplaceFields returns nil if USE/SELECT found in body
(workarea may change → cannot safely cache). Falls back to normal emit.
10K APPEND benchmark: 28ms (Harbour 27ms — essentially equal!)
82/82 stress test PASS. 14 packages ALL PASS.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
NTX 3-level tree (build.go):
- Hybrid approach: bulk build for ≤2 levels, insertKeyBTree for 3+
- rebuildWithInsert: creates proper B-tree via per-key insertion
- 5000-key test: Count=5000 Found=5000 (was 5004/4868)
CDX SET INDEX TO (gengo.go):
- Strip surrounding quotes from string literal in OrderListAdd
- Was: idx.OrderListAdd("\"path\"") → file not found
- Now: idx.OrderListAdd("path") → correct
All tests:
- 14 packages ALL PASS
- 82/82 NTX stress test
- 18/18 CDX cross-read
- 50K benchmark: all counts correct
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
1. SOFTSEEK: use idx.CurRecNo() for positioning (was checking recNo > 0)
- SEEK with SET SOFTSEEK ON now positions at next higher key
- SEEK command reads SET SOFTSEEK at runtime (was compile-time only)
- rtlDbSeek defaults to GetSetSoftSeek() when no explicit param
2. SET DELETED ON + INDEX: SkipIndexed skips deleted records
- GoTopIndexed: skip deleted record at top position
- SkipIndexed: inner loop continues past deleted records
3. Compound key (CITY+NAME): field name TrimSpace before lookup
- evalKeyExprInner: TrimSpace on fieldName after FIELD-> strip
- Fixed "CITY " != "CITY" mismatch from + operator splitting
4. SET INDEX TO filename: treated as string, not variable
- gengo uses exprToString for SET INDEX TO (was emitExpr)
- Prevents identifier being resolved as local variable
5. hasXBaseCommands: recursive scan into nested blocks
- BEGIN SEQUENCE, IF, FOR, DO WHILE, SWITCH bodies now scanned
- Fixes missing hbrdd import for DB commands inside blocks
Thorough test: 77 items (14 sections) covering exact/partial/soft seek,
SET DELETED, duplicate keys, numeric keys, compound keys, empty/single
table, state consistency, order switching, full traversal — all identical.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Core change:
- dbf.KeyEvalFunc: global callback set by gengo before OrderCreate
- evalKeyExprInner default case: calls KeyEvalFunc for unknown functions
- Final fallback: any unresolvable expression → KeyEvalFunc → MacroEval
- valueToKeyBytes: converts MacroEval result to index key bytes
- gengo: sets dbf.KeyEvalFunc = t.MacroEval before OrderCreate, clears after
Examples that now work:
INDEX ON MyFunc(FIELD->NAME) TO idx // UDF in key expression
INDEX ON CityKey(FIELD->CITY, NAME) TO idx // multi-param UDF
INDEX ON Left(MyFunc(NAME), 15) TO idx // nested built-in + UDF
Also fixed:
- SET ORDER TO n: int→string via hbrt.NtoS (was empty string)
- CDX compound leaf decoder: proper bit-packed tag name extraction
- CDX compound recNo = direct byte offset (not page number)
All existing tests pass, NTX 47/47 + CDX 20/20 Harbour compat maintained.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
CDX Integration:
- IndexEngine interface: common for NTX Index and CDX Tag
- OrderListAdd: auto-detects .cdx/.ntx extension, opens CDX tags
- decodeCompoundLeaf: proper bit-packed tag directory decoding
(was stub falling through to scanCompoundLeaves with wrong names)
- CDX Tag: added KeyLen(), KeyExpr(), ForExpr(), IsDescending(), Close()
- CDX compound recNo = direct byte offset (not page number)
ORDSCOPE:
- SetScope/ClearScope/SetScopeTop/SetScopeBottom on DBFArea
- GoTopIndexed: seeks to scopeTop, validates within scopeBottom
- GoBottomIndexed: seeks to scopeBottom boundary
- SkipIndexed: stops at scope boundaries (top and bottom)
- OrdScope RTL function registered (nScope: 0=TOP, 1=BOTTOM)
- scopeKeyFromValue: converts Value to padded key bytes
Index Order Management:
- OrderListFocus: handles numeric order ("2" → order 2)
- SET ORDER TO n: gengo emits hbrt.NtoS for int-to-string conversion
- IndexOrd/OrdCount/OrdName/OrdKey: real implementations (were stubs)
- OrderCount/CurrentOrder/OrderName/OrderKeyExpr accessors on DBFArea
- ClearScope on order switch (prevents stale scope)
Cross-read test: Harbour-created CDX → Five reads, 20/20 items match:
NAME/CITY/ID seek, ORDSCOPE count, GoTop/GoBottom all identical
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Bug 1: FIELD->NAME in INDEX ON expression
- evalKeyExprInner: strip FIELD->/alias-> prefix before field lookup
- exprToString: handle AliasExpr (FIELD->NAME → "FIELD->NAME")
Bug 2: AsNumInt() on Double returned IEEE 754 raw bits
- Value.AsNumInt(): check tDouble and convert via Float64frombits
- Fixed array index crash when index is result of % modulo
Bug 3: PACK/ZAP crash with open indexes
- OrderListRebuild: fully implemented (was TODO stub)
Saves index info, closes all, sets idxState=nil, recreates
- OrderCreate: set current=-1 during key evaluation (natural GoTo)
- PACK/ZAP: save/restore idxState, rebuild after operation
- Register __DBPACK, __DBZAP, DBRECALL symbol aliases
Harbour vs Five: 45/47 match (96%), 2 diffs are duplicate-key sort order
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- skipFilter: skip deleted records in GoTop/GoBottom/Skip when SET DELETED ON
- hbrdd.IsSetDeleted callback: avoids circular import hbrdd→hbrtl
- Parser: capture ON/OFF for boolean SET commands (DELETED, EXACT, SOFTSEEK, etc.)
- Parser: capture TO expr for SET DATE/DECIMALS/EPOCH
- Gengo: emit proper t.Do() calls for 11 SET toggles + 3 value SETs
- stmtSet: was stub (skipToEOL), now calls parseSet()
- RTL: register 11 SET toggle functions (SETDELETED, SETEXACT, etc.)
- RTL: DBLOCATE/DBCONTINUE for sequential search
- RTL: DBSETFILTER/DBCLEARFILTER/DBFILTER
- PadL/PadR: support 3rd param fill character
- Area interface: added SetFound, SetLocate, LocateBlock, filter methods
- MemRDD: implements new Area interface methods
- Comprehensive PRG test: test_search.prg (7 test suites all pass)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
