five/compiler/gengo/emit_stmt.go

// Copyright (c) 2026 Charles KWON OhJun (charleskwonohjun@gmail.com)
// All rights reserved.

// Statement emission for the Go code generator.
//
// Every PRG statement kind ultimately routes through emitStmt; this file
// holds emitStmt and every per-kind emitter it dispatches to:
//
//   - emitMidVarDecl / emitQOut / emitExprStmt / emitAssign /
//     emitCallAsStmt / emitMultiAssign / emitDefer — non-control-flow
//     statements.
//   - emitIf / emitDoWhile / emitFor / emitForEach / emitSwitch /
//     emitBeginSequence — control flow.
//
// A family of helper predicates (boolLiteralValue, hasRDDCommands,
// hasWorkareaChange, collectSymbols, collectReplaceFields,
// hasAppendInBody, bodyHasLoop, hasLoopStmt) supports hoisting and
// fast-path decisions inside the control-flow emitters; they live
// here rather than in gen_util.go because they're only used by
// statement emission.

package gengo

import (
	"five/compiler/ast"
	"five/compiler/token"
	"fmt"
	"strings"
)

// --- Statement emission ---

func (g *Generator) emitStmt(stmt ast.Stmt, locals localMap) {
	// Line hook — two variants:
	//   - Non-debug builds get DebugLineFast (inlineable, ~2 field
	//     writes) so error.log panic traces still carry a line number
	//     without the per-statement dispatch tax.
	//   - Debug builds get DebugLine, which additionally drives
	//     breakpoints, step mode, and the trace ring.
	if stmt.Pos().Line > 0 {
		if g.Debug {
			g.writeln(fmt.Sprintf("t.DebugLine(%q, %d)", g.file.Name, stmt.Pos().Line))
		} else {
			g.writeln(fmt.Sprintf("t.DebugLineFast(%q, %d)", g.file.Name, stmt.Pos().Line))
		}
	}

	switch s := stmt.(type) {
	case *ast.ReturnStmt:
		if len(s.Values) > 1 {
			// Multi-return: RETURN a, b, c → push array of values
			for _, v := range s.Values {
				g.emitExpr(v)
			}
			g.writeln(fmt.Sprintf("t.ArrayGen(%d)", len(s.Values)))
			g.writeln("t.RetValue()")
		} else if s.Value != nil {
			g.emitExpr(s.Value)
			g.writeln("t.RetValue()")
		} else {
			g.writeln("t.RetNil()")
		}
		g.writeln("return") // Go return to exit function immediately

	case *ast.QOutStmt:
		g.emitQOut(s, locals)

	case *ast.ExprStmt:
		g.emitExprStmt(s, locals)

	case *ast.IfStmt:
		g.emitIf(s, locals)

	case *ast.SwitchStmt:
		g.emitSwitch(s, locals)

	case *ast.DoWhileStmt:
		g.emitDoWhile(s, locals)

	case *ast.ForStmt:
		g.emitFor(s, locals)

	case *ast.ForEachStmt:
		g.emitForEach(s, locals)

	case *ast.ExitStmt:
		g.writeln("break")

	case *ast.LoopStmt:
		if g.curForLabel != "" {
			// Inside FOR..NEXT: goto label before increment (continue would skip it)
			g.writeln("goto " + g.curForLabel)
		} else {
			g.writeln("continue")
		}

	case *ast.MultiAssignStmt:
		g.emitMultiAssign(s, locals)

	case *ast.DeferStmt:
		g.emitDefer(s, locals)

	case *ast.VarDecl:
		// LOCAL in mid-function or PRIVATE/PUBLIC
		g.emitMidVarDecl(s, locals)

	// xBase commands — generate calls to hbrdd WorkAreaManager
	case *ast.UseCmd:
		g.emitUseCmd(s, locals)
	case *ast.GoCmd:
		g.emitGoCmd(s)
	case *ast.SkipCmd:
		g.emitSkipCmd(s, locals)
	case *ast.SeekCmd:
		g.emitSeekCmd(s, locals)
	case *ast.ReplaceCmd:
		g.emitReplaceCmd(s, locals)
	case *ast.AppendCmd:
		if g.hoistedFields != nil {
			// Use hoisted area variable
			g.writeln("if _rarea != nil { _rarea.Append() }")
		} else {
			g.writeln("{ _wa := t.WA.(*hbrdd.WorkAreaManager)")
			g.writeln("if _area := _wa.Current(); _area != nil { _area.Append() } }")
		}
	case *ast.DeleteCmd:
		if g.hoistedDW || g.hoistedFields != nil {
			g.writeln(fmt.Sprintf("if %s != nil { %s.Delete() }", g.hoistedAreaVar(), g.hoistedAreaVar()))
		} else {
			g.writeln("{ _wa := t.WA.(*hbrdd.WorkAreaManager)")
			g.writeln("if _area := _wa.Current(); _area != nil { _area.Delete() } }")
		}
	case *ast.SelectCmd:
		g.emitExpr(s.Area)
		g.writeln("{ _wa := t.WA.(*hbrdd.WorkAreaManager); _v := t.Pop2()")
		g.writeln("if _v.IsNumeric() { _wa.Select(int(_v.AsNumInt())) } else { _wa.Select(_v.AsString()) } }")
	case *ast.IndexCmd:
		g.writeln("{")
		g.indent++
		g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln("if area := wa.Current(); area != nil {")
		g.indent++
		g.writeln("if idx, ok := area.(hbrdd.Indexer); ok {")
		g.indent++
		keyStr := exprToString(s.KeyExpr)
		g.writeln(fmt.Sprintf("_keyExpr := %q", keyStr))

		// File expression: if it contains a function call, evaluate at
		// runtime — Harbour `INDEX ON ... TO ( cExpr )` semantics. Prior
		// behavior was static exprToString which serialized calls like
		// `Lower(cTable) + "_pk.ntx"` into the literal filename string.
		// Detect via containsCall; preserve static path for simple
		// `test.ntx` style identifiers.
		if containsCall(s.File) {
			g.emitExpr(s.File)
			g.writeln("_file := t.Pop2().AsString()")
		} else {
			fileStr := exprToString(s.File)
			g.writeln(fmt.Sprintf("_file := %q", fileStr))
		}
		forExpr := `""`
		if s.ForCond != nil {
			forExpr = fmt.Sprintf("%q", exprToString(s.ForCond))
		}

		// Emit compiled key evaluator as Go closure.
		// This inlines the AST of the key expression into native Go code,
		// eliminating per-record MacroEval string parsing + symbol lookup.
		// In INDEX context, bare identifiers are FIELD names (not locals).
		g.writeln("_keyFunc := func() hbrt.Value {")
		g.indent++
		g.emitIndexKeyExpr(s.KeyExpr)
		g.writeln("return t.Pop2()")
		g.indent--
		g.writeln("}")

		// Emit compiled FOR evaluator when the source has a FOR clause.
		// Mirrors _keyFunc — zero runtime parsing, field-name identifier
		// context, closure captures the Thread.
		forFuncRef := "nil"
		if s.ForCond != nil {
			g.writeln("_forFunc := func() bool {")
			g.indent++
			g.emitIndexKeyExpr(s.ForCond)
			g.writeln("return t.Pop2().AsBool()")
			g.indent--
			g.writeln("}")
			forFuncRef = "_forFunc"
		}

		// Still set MacroEval fallback for evalKeyExprInner (used for keyLen sampling)
		g.writeln("dbf.KeyEvalFunc = func(expr string) hbrt.Value { return t.MacroEval(expr) }")
		g.writeln(fmt.Sprintf("idx.OrderCreate(hbrdd.OrderCreateParams{KeyExpr: _keyExpr, FilePath: _file, ForExpr: %s, TagName: %q, Unique: %v, Descending: %v, KeyFunc: _keyFunc, ForFunc: %s})",
			forExpr, s.TagName, s.Unique, s.Descending, forFuncRef))
		g.writeln("dbf.KeyEvalFunc = nil")
		g.indent--
		g.writeln("}")
		g.indent--
		g.writeln("}")
		g.indent--
		g.writeln("}")
	case *ast.SetCmd:
		upper := strings.ToUpper(s.Setting)

		// Boolean SET toggles — call RTL Set function, no workarea needed
		setFuncMap := map[string]string{
			"DELETED":   "SETDELETED",
			"EXACT":     "SETEXACT",
			"SOFTSEEK":  "SETSOFTSEEK",
			"EXCLUSIVE": "SETEXCLUSIVE",
			"FIXED":     "SETFIXED",
			"CANCEL":    "SETCANCEL",
			"BELL":      "SETBELL",
			"CONFIRM":   "SETCONFIRM",
			"INSERT":    "SETINSERT",
			"ESCAPE":    "SETESCAPE",
			"WRAP":      "SETWRAP",
		}
		if funcName, ok := setFuncMap[upper]; ok {
			onOff := strings.ToUpper(s.Extra)
			if onOff == "ON" || onOff == "OFF" {
				val := "true"
				if onOff == "OFF" {
					val = "false"
				}
				g.emitPushSymbol(funcName)
				g.writeln("t.PushNil()")
				g.writeln(fmt.Sprintf("t.PushBool(%s)", val))
				g.writeln("t.Do(1)")
			}
			break
		}

		// Value SET commands — SET DATE/DECIMALS/EPOCH TO expr
		valueFuncMap := map[string]string{
			"DATE":     "__SETDATEFORMAT",
			"DECIMALS": "SETDECIMALS",
			"EPOCH":    "SETEPOCH",
		}
		if funcName, ok := valueFuncMap[upper]; ok && s.Expr != nil {
			g.emitPushSymbol(funcName)
			g.writeln("t.PushNil()")
			g.emitExpr(s.Expr)
			g.writeln("t.Do(1)")
			break
		}

		// Workarea-specific SET commands
		g.writeln("{")
		g.indent++
		g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln("if area := wa.Current(); area != nil {")
		g.indent++
		switch upper {
		case "FILTER":
			if s.Expr != nil {
				g.emitExpr(s.Expr)
				g.writeln(`area.SetFilter(t.Pop2().AsString(), nil)`)
			} else {
				g.writeln("area.ClearFilter()")
			}
		case "ORDER":
			if s.Expr != nil {
				g.writeln("if idx, ok := area.(hbrdd.Indexer); ok {")
				g.indent++
				g.emitExpr(s.Expr)
				g.writeln(`{ _ov := t.Pop2(); var _os string; if _ov.IsNumeric() { _os = hbrt.NtoS(_ov.AsNumInt()) } else { _os = _ov.AsString() }; idx.OrderListFocus(_os) }`)
				g.indent--
				g.writeln("}")
			}
		case "INDEX":
			if s.Expr != nil {
				fileStr := exprToString(s.Expr)
				g.writeln("if idx, ok := area.(hbrdd.Indexer); ok {")
				g.indent++
				if fileStr != "" {
					// SET INDEX TO a, b, c — split comma-separated file names
					// and call OrderListAdd for each. Harbour loads all NTX
					// files into the active index list.
					clean := fileStr
					if len(clean) >= 2 && clean[0] == '"' && clean[len(clean)-1] == '"' {
						clean = clean[1 : len(clean)-1]
					}
					parts := strings.Split(clean, ",")
					for _, p := range parts {
						p = strings.TrimSpace(p)
						if p != "" {
							g.writeln(fmt.Sprintf(`idx.OrderListAdd(%q)`, p))
						}
					}
				} else {
					g.emitExpr(s.Expr)
					g.writeln(`idx.OrderListAdd(t.Pop2().AsString())`)
				}
				g.indent--
				g.writeln("}")
			} else {
				g.writeln("if idx, ok := area.(hbrdd.Indexer); ok { idx.OrderListClear() }")
			}
		default:
			g.writeln(fmt.Sprintf("// SET %s: not yet implemented", upper))
		}
		g.indent--
		g.writeln("}")
		g.indent--
		g.writeln("}")

	case *ast.SeqStmt:
		g.emitBeginSequence(s, locals)

	case *ast.AtSayCmd:
		g.emitAtSayCmd(s)
	case *ast.AtGetCmd:
		g.emitAtGetCmd(s, locals)
	case *ast.AtSayGetCmd:
		g.emitAtSayGetCmd(s, locals)
	case *ast.ReadCmd:
		g.emitReadCmd(s, locals)

	default:
		g.writeln(fmt.Sprintf("// WARN: unhandled statement type %T — skipped", stmt))
	}
}

func (g *Generator) emitMidVarDecl(s *ast.VarDecl, locals localMap) {
	for _, v := range s.Vars {
		idx, found := locals[strings.ToUpper(v.Name)]
		if !found {
			maxIdx := 0
			for _, i := range locals {
				if i > maxIdx {
					maxIdx = i
				}
			}
			idx = maxIdx + 1
			locals[strings.ToUpper(v.Name)] = idx
		}
		if v.Init != nil {
			if _, isConst := g.constLocals[strings.ToUpper(v.Name)]; !isConst {
				g.emitExpr(v.Init)
				g.writeln(fmt.Sprintf("t.PopLocalFast(%d)", idx))
			}
		}
	}
}

func (g *Generator) emitQOut(s *ast.QOutStmt, locals localMap) {
	sym := "QOUT"
	if s.IsQQ {
		sym = "QQOUT"
	}
	g.emitPushSymbol(sym)
	g.writeln("t.PushNil()")
	for _, expr := range s.Exprs {
		g.emitExpr(expr)
	}
	g.writeln(fmt.Sprintf("t.Function(%d)", len(s.Exprs)))
}

func (g *Generator) emitExprStmt(s *ast.ExprStmt, locals localMap) {
	// Check if it's an assignment
	if assign, ok := s.X.(*ast.AssignExpr); ok {
		g.emitAssign(assign, locals)
		return
	}
	// Check if it's a function call (discard result)
	if call, ok := s.X.(*ast.CallExpr); ok {
		g.emitCallAsStmt(call, locals)
		return
	}
	// Bare identifier as statement (e.g., CLS, CLEAR) — treat as zero-arg function call
	if ident, ok := s.X.(*ast.IdentExpr); ok {
		if _, found := locals[strings.ToUpper(ident.Name)]; !found {
			g.emitPushSymbol(strings.ToUpper(ident.Name))
			g.writeln("t.PushNil()")
			g.writeln("t.Do(0)")
			return
		}
	}
	// Postfix ++/--
	if pf, ok := s.X.(*ast.PostfixExpr); ok {
		// Local variable: n++
		if ident, ok := pf.X.(*ast.IdentExpr); ok {
			upper := strings.ToUpper(ident.Name)
			if idx, found := locals[upper]; found {
				if pf.Op == token.INC {
					g.writeln(fmt.Sprintf("t.LocalAddInt(%d, 1)", idx))
				} else {
					g.writeln(fmt.Sprintf("t.LocalAddInt(%d, -1)", idx))
				}
				return
			}
			// STATIC variable: s_nPass++
			if goVar, found := g.staticVars[upper]; found {
				delta := "1"
				if pf.Op == token.DEC {
					delta = "-1"
				}
				g.writeln(fmt.Sprintf("{ _v := %s.AsNumInt() + %s; %s = hbrt.MakeInt(int(_v)) }", goVar, delta, goVar))
				return
			}
		}
		// Self field: ::field++
		if send, ok := pf.X.(*ast.SendExpr); ok {
			if _, isSelf := send.Object.(*ast.SelfExpr); isSelf {
				fieldName := strings.ToUpper(send.Method)
				g.writeln(fmt.Sprintf("t.PushSelfField(%q)", fieldName))
				if pf.Op == token.INC {
					g.writeln("t.PushInt(1)")
					g.writeln("t.Plus()")
				} else {
					g.writeln("t.PushInt(1)")
					g.writeln("t.Minus()")
				}
				g.writeln(fmt.Sprintf("t.SetSelfField(%q)", fieldName))
				return
			}
		}
	}
	// General expression (result on stack, pop it)
	g.emitExpr(s.X)
	g.writeln("t.Pop()")
}

func (g *Generator) emitAssign(a *ast.AssignExpr, locals localMap) {
	// Check for arr[idx] := value (array index assignment)
	if idx, ok := a.Left.(*ast.IndexExpr); ok {
		if a.Op == token.ASSIGN {
			g.emitExpr(idx.X)      // array
			g.emitExpr(idx.Index)  // index
			g.emitExpr(a.Right)    // value
			g.writeln("t.ArrayPop()") // set array[index] = value
			return
		}
	}

	// Check for obj:field := value (object field assignment)
	if send, ok := a.Left.(*ast.SendExpr); ok {
		_, isSelf := send.Object.(*ast.SelfExpr)

		if isSelf {
			fieldName := strings.ToUpper(send.Method)
			switch a.Op {
			case token.ASSIGN:
				g.emitExpr(a.Right)
				g.writeln(fmt.Sprintf("t.SetSelfField(%q)", fieldName))
			case token.PLUSEQ:
				g.writeln(fmt.Sprintf("t.PushSelfField(%q)", fieldName))
				g.emitExpr(a.Right)
				g.writeln("t.Plus()")
				g.writeln(fmt.Sprintf("t.SetSelfField(%q)", fieldName))
			case token.MINUSEQ:
				g.writeln(fmt.Sprintf("t.PushSelfField(%q)", fieldName))
				g.emitExpr(a.Right)
				g.writeln("t.Minus()")
				g.writeln(fmt.Sprintf("t.SetSelfField(%q)", fieldName))
			case token.STAREQ:
				g.writeln(fmt.Sprintf("t.PushSelfField(%q)", fieldName))
				g.emitExpr(a.Right)
				g.writeln("t.Mult()")
				g.writeln(fmt.Sprintf("t.SetSelfField(%q)", fieldName))
			case token.SLASHEQ:
				g.writeln(fmt.Sprintf("t.PushSelfField(%q)", fieldName))
				g.emitExpr(a.Right)
				g.writeln("t.Divide()")
				g.writeln(fmt.Sprintf("t.SetSelfField(%q)", fieldName))
			default:
				g.emitExpr(a.Right)
				g.writeln(fmt.Sprintf("t.SetSelfField(%q)", fieldName))
			}
			return
		}

		// Non-self: obj:field := value → obj:_FIELD(value)
		if a.Op == token.ASSIGN {
			g.emitExpr(send.Object)
			g.emitExpr(a.Right)
			g.writeln(fmt.Sprintf("t.Send(%q, 1)", "_"+strings.ToUpper(send.Method)))
			g.writeln("t.Pop() // discard setter result")
			return
		}
	}

	// Check for alias->field := value (FIELD->NAME := value)
	if aliasExpr, ok := a.Left.(*ast.AliasExpr); ok {
		if aliasIdent, ok2 := aliasExpr.Alias.(*ast.IdentExpr); ok2 {
			if fieldIdent, ok3 := aliasExpr.Field.(*ast.IdentExpr); ok3 {
				upper := strings.ToUpper(aliasIdent.Name)
				// `M->name := v` / `MEMVAR->name := v` are memvar writes,
				// not workarea field writes.
				if upper == "M" || upper == "MEMVAR" {
					g.emitExpr(a.Right)
					g.writeln(fmt.Sprintf(`t.PopMemvar(%q)`, fieldIdent.Name))
					return
				}
				g.emitExpr(a.Right)
				g.writeln(fmt.Sprintf(`{ _wa := t.WA.(*hbrdd.WorkAreaManager); _wa.SetAliasField(%q, %q, t.Pop2()) }`, aliasIdent.Name, fieldIdent.Name))
				return
			}
		}
	}

	if ident, ok := a.Left.(*ast.IdentExpr); ok {
		if idx, found := locals[strings.ToUpper(ident.Name)]; found {
			switch a.Op {
			case token.ASSIGN:
				// Peephole: `x := x + <expr>` / `x := x - <expr>` →
				// LocalAdd. Same result as `x += <expr>` but lets the
				// PRG side use the explicit form without penalty.
				if be, ok := a.Right.(*ast.BinaryExpr); ok &&
					(be.Op == token.PLUS || be.Op == token.MINUS) {
					if lid, isIdent := be.Left.(*ast.IdentExpr); isIdent {
						if selfIdx, found := locals[strings.ToUpper(lid.Name)]; found && selfIdx == idx {
							g.emitExpr(be.Right)
							if be.Op == token.MINUS {
								g.writeln("t.Negate()")
							}
							g.writeln(fmt.Sprintf("t.LocalAdd(%d)", idx))
							return
						}
					}
				}
				g.emitExpr(a.Right)
				g.writeln(fmt.Sprintf("t.PopLocalFast(%d)", idx))
			case token.PLUSEQ:
				g.emitExpr(a.Right)
				g.writeln(fmt.Sprintf("t.LocalAdd(%d)", idx))
			case token.MINUSEQ:
				g.emitExpr(a.Right)
				g.writeln("t.Negate()")
				g.writeln(fmt.Sprintf("t.LocalAdd(%d)", idx))
			default:
				// General compound: push local, push right, op, pop local
				g.writeln(fmt.Sprintf("t.PushLocalFast(%d)", idx))
				g.emitExpr(a.Right)
				g.emitBinaryOp(a.Op)
				g.writeln(fmt.Sprintf("t.PopLocalFast(%d)", idx))
			}
			return
		}
		// Check module-level or function-level STATIC variable
		upper := strings.ToUpper(ident.Name)
		if goVar, found := g.staticVars[upper]; found {
			switch a.Op {
			case token.ASSIGN:
				g.emitExpr(a.Right)
				g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
			case token.PLUSEQ:
				g.writeln(fmt.Sprintf("t.PushValue(%s)", goVar))
				g.emitExpr(a.Right)
				g.writeln("t.Plus()")
				g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
			case token.MINUSEQ:
				g.writeln(fmt.Sprintf("t.PushValue(%s)", goVar))
				g.emitExpr(a.Right)
				g.writeln("t.Minus()")
				g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
			case token.STAREQ:
				g.writeln(fmt.Sprintf("t.PushValue(%s)", goVar))
				g.emitExpr(a.Right)
				g.writeln("t.Mult()")
				g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
			case token.SLASHEQ:
				g.writeln(fmt.Sprintf("t.PushValue(%s)", goVar))
				g.emitExpr(a.Right)
				g.writeln("t.Divide()")
				g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
			default:
				g.writeln(fmt.Sprintf("t.PushValue(%s)", goVar))
				g.emitExpr(a.Right)
				g.emitBinaryOp(a.Op)
				g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
			}
			return
		}
	}
	// Fallback: general assignment via stack
	g.emitExpr(a.Right)
	g.writeln("// WARN: complex assignment target — simplified")
	g.writeln("t.Pop()")
}

func (g *Generator) emitCallAsStmt(call *ast.CallExpr, locals localMap) {
	if ident, ok := call.Func.(*ast.IdentExpr); ok {
		g.emitPushSymbol(strings.ToUpper(ident.Name))
	} else {
		g.emitExpr(call.Func)
	}
	g.writeln("t.PushNil()")
	for _, arg := range call.Args {
		g.emitExpr(arg)
	}
	g.writeln(fmt.Sprintf("t.Do(%d)", len(call.Args)))
}

// boolLiteralValue returns (value, true) if e reduces to a .T./.F.
// literal at compile time. Sees through an outer `.NOT.` so expressions
// like `!.F.` also collapse. Used by emitIf to skip dead branches and
// by the AND/OR short-circuit emitter.
func boolLiteralValue(e ast.Expr) (bool, bool) {
	if u, ok := e.(*ast.UnaryExpr); ok && u.Op == token.NOT {
		if v, ok := boolLiteralValue(u.X); ok {
			return !v, true
		}
		return false, false
	}
	lit, ok := e.(*ast.LiteralExpr)
	if !ok {
		return false, false
	}
	switch lit.Kind {
	case token.TRUE:
		return true, true
	case token.FALSE:
		return false, true
	}
	return false, false
}

func (g *Generator) emitIf(s *ast.IfStmt, locals localMap) {
	// Dead-branch elimination for literal conditions. An IF .T. collapses
	// to its body; an IF .F. collapses to its first live ELSEIF/ELSE.
	// We resolve the main Cond here and recurse on the remainder if it
	// turns into a new IF chain.
	if v, ok := boolLiteralValue(s.Cond); ok {
		if v {
			for _, stmt := range s.Body {
				g.emitStmt(stmt, locals)
			}
			return
		}
		// IF .F. — scan ElseIfs for first non-.F. branch.
		for i, ei := range s.ElseIfs {
			if v2, ok2 := boolLiteralValue(ei.Cond); ok2 {
				if v2 {
					for _, stmt := range ei.Body {
						g.emitStmt(stmt, locals)
					}
					return
				}
				continue // ELSEIF .F. — dead, skip
			}
			// Non-literal ELSEIF becomes the new IF head.
			newIf := &ast.IfStmt{
				IfPos:    ei.ElseIfPos,
				Cond:     ei.Cond,
				Body:     ei.Body,
				ElseIfs:  s.ElseIfs[i+1:],
				ElseBody: s.ElseBody,
			}
			g.emitIf(newIf, locals)
			return
		}
		// All ElseIfs were .F. — only ELSE body remains.
		for _, stmt := range s.ElseBody {
			g.emitStmt(stmt, locals)
		}
		return
	}

	// Main cond is dynamic. Still filter dead ELSEIFs (.F. removed;
	// an ELSEIF .T. truncates the chain and becomes the ELSE).
	elseIfs := s.ElseIfs
	elseBody := s.ElseBody
	if len(elseIfs) > 0 {
		filtered := make([]*ast.ElseIfClause, 0, len(elseIfs))
		for _, ei := range elseIfs {
			if v, ok := boolLiteralValue(ei.Cond); ok {
				if v {
					// ELSEIF .T. — chain stops here; body becomes ELSE.
					elseBody = ei.Body
					elseIfs = filtered
					goto emit
				}
				continue // ELSEIF .F. — dead
			}
			filtered = append(filtered, ei)
		}
		elseIfs = filtered
	}

emit:
	g.emitExpr(s.Cond)
	g.writeln("if t.PopLogical() {")
	g.indent++
	for _, stmt := range s.Body {
		g.emitStmt(stmt, locals)
	}
	g.indent--

	for _, ei := range elseIfs {
		g.writeIndent()
		g.write("} else {\n")
		g.indent++
		g.emitExpr(ei.Cond)
		g.writeln("if t.PopLogical() {")
		g.indent++
		for _, stmt := range ei.Body {
			g.emitStmt(stmt, locals)
		}
		g.indent--
	}

	if len(elseBody) > 0 {
		g.writeln("} else {")
		g.indent++
		for _, stmt := range elseBody {
			g.emitStmt(stmt, locals)
		}
		g.indent--
	}

	g.writeln("}")

	// Close nested elseif braces
	for range elseIfs {
		g.writeln("}")
	}
}

func (g *Generator) emitDoWhile(s *ast.DoWhileStmt, locals localMap) {
	// DO WHILE .F. — body is unreachable; emit nothing.
	if v, ok := boolLiteralValue(s.Cond); ok && !v {
		return
	}

	// Detect RDD commands in body for WA hoisting
	hasRDD := hasRDDCommands(s.Body)
	safeToHoist := hasRDD && !hasWorkareaChange(s.Body)

	if safeToHoist && g.hoistedFields == nil {
		g.writeln("{")
		g.indent++
		g.writeln("_dwa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln("_darea := _dwa.Current()")
		g.hoistedDW = true
	}

	g.writeln("for {")
	g.indent++
	// DO WHILE .T. — the idiomatic infinite loop. Skip the per-iteration
	// PushBool/PopLogical; exit only through EXIT / LOOP / RETURN.
	if v, ok := boolLiteralValue(s.Cond); !ok || !v {
		g.emitExpr(s.Cond)
		g.writeln("if !t.PopLogical() { break }")
	}
	for _, stmt := range s.Body {
		g.emitStmt(stmt, locals)
	}
	g.indent--
	g.writeln("}")

	if safeToHoist && g.hoistedDW {
		g.hoistedDW = false
		g.indent--
		g.writeln("}")
	}
}

// hasRDDCommands checks if any statement is an RDD operation.
func hasRDDCommands(stmts []ast.Stmt) bool {
	for _, s := range stmts {
		switch s.(type) {
		case *ast.SkipCmd, *ast.GoCmd, *ast.SeekCmd,
			*ast.ReplaceCmd, *ast.AppendCmd, *ast.DeleteCmd:
			return true
		}
	}
	return false
}

// hasWorkareaChange checks for USE/SELECT that would invalidate cached area.
func hasWorkareaChange(stmts []ast.Stmt) bool {
	for _, s := range stmts {
		switch v := s.(type) {
		case *ast.UseCmd, *ast.SelectCmd:
			return true
		case *ast.IfStmt:
			if hasWorkareaChange(v.Body) || hasWorkareaChange(v.ElseBody) {
				return true
			}
		case *ast.DoWhileStmt:
			if hasWorkareaChange(v.Body) {
				return true
			}
		}
	}
	return false
}

// collectSymbols scans AST for all symbol names referenced by function calls.
// Returns unique names for hoisting FindSymbol to function prologue.
func collectSymbols(stmts []ast.Stmt) []string {
	seen := map[string]bool{}
	var names []string
	var walk func([]ast.Stmt)
	var walkExpr func(ast.Expr)

	walkExpr = func(e ast.Expr) {
		if e == nil {
			return
		}
		switch v := e.(type) {
		case *ast.CallExpr:
			if ident, ok := v.Func.(*ast.IdentExpr); ok {
				name := strings.ToUpper(ident.Name)
				if !seen[name] {
					seen[name] = true
					names = append(names, name)
				}
			}
			for _, a := range v.Args {
				walkExpr(a)
			}
		case *ast.BinaryExpr:
			walkExpr(v.Left)
			walkExpr(v.Right)
		case *ast.UnaryExpr:
			walkExpr(v.X)
		}
	}

	walk = func(stmts []ast.Stmt) {
		for _, s := range stmts {
			switch v := s.(type) {
			case *ast.ExprStmt:
				walkExpr(v.X)
			case *ast.ReturnStmt:
				if v.Value != nil {
					walkExpr(v.Value)
				}
			case *ast.IfStmt:
				walkExpr(v.Cond)
				walk(v.Body)
				walk(v.ElseBody)
			case *ast.ForStmt:
				walk(v.Body)
			case *ast.ForEachStmt:
				walk(v.Body)
			case *ast.DoWhileStmt:
				walkExpr(v.Cond)
				walk(v.Body)
			case *ast.SeqStmt:
				walk(v.Body)
				walk(v.RecoverBody)
			case *ast.SwitchStmt:
				for _, c := range v.Cases {
					walk(c.Body)
				}
			}
		}
	}

	walk(stmts)
	return names
}

// collectReplaceFields scans statements for REPLACE field names.
// Returns nil if unsafe to hoist (USE/SELECT/CLOSE found).
func collectReplaceFields(stmts []ast.Stmt) []string {
	seen := map[string]bool{}
	var fields []string
	for _, s := range stmts {
		switch v := s.(type) {
		case *ast.ReplaceCmd:
			for _, rf := range v.Fields {
				if ident, ok := rf.Field.(*ast.IdentExpr); ok {
					name := ident.Name
					if !seen[name] {
						seen[name] = true
						fields = append(fields, name)
					}
				}
			}
		case *ast.UseCmd, *ast.SelectCmd:
			return nil // workarea may change — unsafe to hoist
		case *ast.IfStmt:
			// Check nested blocks
			if sub := collectReplaceFields(v.Body); sub == nil {
				return nil
			}
			if sub := collectReplaceFields(v.ElseBody); sub == nil {
				return nil
			}
		case *ast.DoWhileStmt:
			if sub := collectReplaceFields(v.Body); sub == nil {
				return nil
			}
		}
	}
	return fields
}

// hasAppendInBody checks if any APPEND command exists in the statements.
func hasAppendInBody(stmts []ast.Stmt) bool {
	for _, s := range stmts {
		if _, ok := s.(*ast.AppendCmd); ok {
			return true
		}
	}
	return false
}

func (g *Generator) emitFor(s *ast.ForStmt, locals localMap) {
	idx, found := locals[strings.ToUpper(s.Var)]
	if !found {
		g.writeln("// ERROR: FOR variable not found in locals")
		return
	}

	// i := start
	g.emitExpr(s.Start)
	g.writeln(fmt.Sprintf("t.PopLocalFast(%d)", idx))

	// Detect step direction for comparison
	isNegStep := false
	if s.Step != nil {
		if lit, ok := s.Step.(*ast.LiteralExpr); ok {
			if lit.Kind == token.INT && len(lit.Value) > 0 && lit.Value[0] == '-' {
				isNegStep = true
			}
		}
		if un, ok := s.Step.(*ast.UnaryExpr); ok && un.Op == token.MINUS {
			isNegStep = true
		}
	}

	// Optimization: hoist WA/FieldIndex lookups outside FOR loop
	// if body contains REPLACE and no USE/SELECT (safe to cache).
	rddFields := collectReplaceFields(s.Body)
	hoistRDD := len(rddFields) > 0 && hasAppendInBody(s.Body)

	if hoistRDD {
		g.writeln("{")
		g.indent++
		g.writeln("_rwa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln("_rarea := _rwa.Current()")
		g.writeln("var _rdbf *dbf.DBFArea")
		g.writeln("if _rarea != nil { _rdbf, _ = _rarea.(*dbf.DBFArea) }")
		// Pre-compute field indexes
		for i, fname := range rddFields {
			g.writeln(fmt.Sprintf("var _rfi%d int = -1", i))
			g.writeln(fmt.Sprintf("if _rdbf != nil { _rfi%d = _rdbf.FieldIndex(%q) }", i, fname))
		}
		g.hoistedFields = rddFields // store for emitReplaceCmdHoisted
	}

	g.writeln("for {")
	g.indent++

	// Comparison: fused opcode when limit is literal int (most common).
	// Also see through const-propagated LOCALs: `LOCAL n := 100; FOR i := 1
	// TO n` should hit the same fast path as a bare literal.
	toLit, _ := s.To.(*ast.LiteralExpr)
	if toLit == nil {
		if id, ok := s.To.(*ast.IdentExpr); ok {
			if l, ok2 := g.constLocals[strings.ToUpper(id.Name)]; ok2 {
				toLit = l
			}
		}
	}
	if lit := toLit; lit != nil && lit.Kind == token.INT {
		if isNegStep {
			g.writeln(fmt.Sprintf("if !t.LocalGreaterEqualInt(%d, %s) { break }", idx, lit.Value))
		} else {
			g.writeln(fmt.Sprintf("if !t.LocalLessEqualInt(%d, %s) { break }", idx, lit.Value))
		}
	} else {
		// General case: stack-based comparison
		g.writeln(fmt.Sprintf("t.PushLocalFast(%d)", idx))
		g.emitExpr(s.To)
		if isNegStep {
			g.writeln("t.GreaterEqual()")
		} else {
			g.writeln("t.LessEqual()")
		}
		g.writeln("if !t.PopLogical() { break }")
	}

	// Track FOR loop depth so LOOP can use goto instead of continue.
	// Only emit label if LOOP is present in the body (Go rejects unused labels).
	hasLoop := bodyHasLoop(s.Body)
	forLabel := ""
	prevForLabel := g.curForLabel
	if hasLoop {
		forLabel = fmt.Sprintf("_for_next_%d", g.forLabelSeq)
		g.forLabelSeq++
		g.curForLabel = forLabel
	} else {
		g.curForLabel = ""
	}

	// body
	for _, stmt := range s.Body {
		g.emitStmt(stmt, locals)
	}

	// Label for LOOP to jump to (skipping continue which would miss increment)
	if hasLoop {
		g.writeln(forLabel + ":")
	}

	// i += step (default 1)
	if s.Step != nil {
		g.emitExpr(s.Step)
		g.writeln(fmt.Sprintf("t.LocalAdd(%d)", idx))
	} else {
		g.writeln(fmt.Sprintf("t.LocalAddInt(%d, 1)", idx))
	}

	g.curForLabel = prevForLabel
	g.indent--
	g.writeln("}")

	// Close hoisting block
	if hoistRDD {
		g.hoistedFields = nil
		g.indent--
		g.writeln("}")
	}
}

// bodyHasLoop checks if any statement in the body is a LOOP.
// Only checks the immediate level — LOOP inside nested FOR/DO WHILE is irrelevant.
func bodyHasLoop(stmts []ast.Stmt) bool {
	for _, s := range stmts {
		if hasLoopStmt(s) {
			return true
		}
	}
	return false
}

func hasLoopStmt(s ast.Stmt) bool {
	switch s := s.(type) {
	case *ast.LoopStmt:
		return true
	case *ast.IfStmt:
		for _, st := range s.Body {
			if hasLoopStmt(st) {
				return true
			}
		}
		for _, ei := range s.ElseIfs {
			for _, st := range ei.Body {
				if hasLoopStmt(st) {
					return true
				}
			}
		}
		for _, st := range s.ElseBody {
			if hasLoopStmt(st) {
				return true
			}
		}
	case *ast.SeqStmt:
		for _, st := range s.Body {
			if hasLoopStmt(st) {
				return true
			}
		}
		for _, st := range s.RecoverBody {
			if hasLoopStmt(st) {
				return true
			}
		}
	case *ast.SwitchStmt:
		for _, c := range s.Cases {
			for _, st := range c.Body {
				if hasLoopStmt(st) {
					return true
				}
			}
		}
		for _, st := range s.Otherwise {
			if hasLoopStmt(st) {
				return true
			}
		}
	// Do NOT recurse into ForStmt/DoWhileStmt — nested LOOP is for the inner loop
	}
	return false
}


func (g *Generator) emitSwitch(s *ast.SwitchStmt, locals localMap) {
	// Wrap the whole thing in a one-iteration `for` so:
	//   1. `_sw` stays scoped to the switch.
	//   2. `EXIT` inside a CASE emits `break` and targets this loop,
	//      matching Harbour SWITCH semantics (EXIT terminates SWITCH).
	//   3. Empty SWITCH (`SWITCH x ENDSWITCH`, common in conditional-
	//      compile test files) stays valid Go.
	g.writeln("for {")
	g.indent++
	g.emitExpr(s.Expr)
	g.writeln("_sw := t.Pop2()")
	g.writeln("_ = _sw") // silence unused-var warning when no cases reference it
	// Use the runtime's type-aware Equal() instead of coercing to
	// NumInt. The AsNumInt() path broke every non-numeric SWITCH
	// (strings, dates, logicals): "ABC".AsNumInt() returns 0, so
	// `SWITCH cType CASE "C"` folded every arm to the same false.
	// Each CASE emits an independent `if !_swHit { push _sw; push
	// caseVal; t.Equal(); if t.PopLogical() { body; _swHit = true } }`
	// block so the stack is balanced even when a body executes EXIT /
	// RETURN mid-case.
	first := true
	for _, c := range s.Cases {
		if first {
			g.writeln("_swHit := false")
			first = false
		}
		g.writeln("if !_swHit {")
		g.indent++
		g.writeln("t.PushValue(_sw)")
		g.emitExpr(c.Value)
		g.writeln("t.Equal()")
		g.writeln("if t.PopLogical() {")
		g.indent++
		g.writeln("_swHit = true")
		for _, stmt := range c.Body {
			g.emitStmt(stmt, locals)
		}
		g.indent--
		g.writeln("}")
		g.indent--
		g.writeln("}")
	}
	if len(s.Otherwise) > 0 {
		if first {
			// No CASE arms — emit the OTHERWISE body as-is.
			for _, stmt := range s.Otherwise {
				g.emitStmt(stmt, locals)
			}
		} else {
			g.writeln("if !_swHit {")
			g.indent++
			for _, stmt := range s.Otherwise {
				g.emitStmt(stmt, locals)
			}
			g.indent--
			g.writeln("}")
		}
	}
	if !first {
		g.writeln("_ = _swHit") // guard against bodies that never read it
	}
	// Always break out of our one-iteration `for` wrapper, regardless
	// of which (or no) case ran.
	g.writeln("break")
	g.indent--
	g.writeln("}")
}

func (g *Generator) emitBeginSequence(s *ast.SeqStmt, locals localMap) {
	// BEGIN SEQUENCE → Go's panic/recover.
	// Catches both *HbError (runtime errors) and BreakValue (Break() calls).
	// BreakValue is defined in hbrtl, but we detect it via duck typing
	// to avoid import cycles.
	g.writeln("{ // BEGIN SEQUENCE")
	g.indent++
	g.writeln("_seqErr := func() (_recoverVal interface{}) {")
	g.indent++
	g.writeln("defer func() {")
	g.indent++
	g.writeln("if r := recover(); r != nil {")
	g.indent++
	g.writeln("_recoverVal = r")
	g.indent--
	g.writeln("}")
	g.indent--
	g.writeln("}()")

	// Body
	for _, stmt := range s.Body {
		g.emitStmt(stmt, locals)
	}

	g.writeln("return nil")
	g.indent--
	g.writeln("}()")

	// RECOVER
	if len(s.RecoverBody) > 0 {
		g.writeln("if _seqErr != nil {")
		g.indent++
		if s.RecoverVar != "" {
			if idx, found := locals[strings.ToUpper(s.RecoverVar)]; found {
				// Extract the value from the recovered panic:
				//   *HbError → error description string
				//   BreakValue (has .Value field) → the Break() argument
				//   other → string representation
				g.writeln(fmt.Sprintf(`{ // RECOVER USING %s`, s.RecoverVar))
				g.indent++
				g.writeln(`switch _sv := _seqErr.(type) {`)
				g.writeln(`case *hbrt.HbError:`)
				g.writeln(fmt.Sprintf(`  t.SetLocalFast(%d, hbrt.MakeString(_sv.Error()))`, idx))
				g.writeln(`default:`)
				// For BreakValue, use reflection-free approach: check if
				// the type has a Value field via a local interface.
				g.writeln(`  type hasValue interface{ GetValue() hbrt.Value }`)
				g.writeln(`  if bv, ok := _sv.(hasValue); ok {`)
				g.writeln(fmt.Sprintf(`    t.SetLocalFast(%d, bv.GetValue())`, idx))
				g.writeln(`  } else {`)
				g.writeln(fmt.Sprintf(`    t.SetLocalFast(%d, hbrt.MakeString("error"))`, idx))
				g.writeln(`  }`)
				g.writeln(`}`)
				g.indent--
				g.writeln(`}`)
			}
		}
		for _, stmt := range s.RecoverBody {
			g.emitStmt(stmt, locals)
		}
		g.indent--
		g.writeln("}")
	} else {
		g.writeln("_ = _seqErr")
	}

	g.indent--
	g.writeln("} // END SEQUENCE")
}

func (g *Generator) emitForEach(s *ast.ForEachStmt, locals localMap) {
	varIdx, found := locals[strings.ToUpper(s.Var)]
	if !found {
		g.writeln("// ERROR: FOR EACH variable not in locals")
		return
	}

	// Evaluate collection once; the emitted loop dispatches on the
	// runtime type so the same FOR EACH works for arrays, hashes, and
	// strings (Harbour semantics). Hash iteration yields values — the
	// user can get at keys via hb_HKeys(h) before the loop. String
	// iteration walks byte-by-byte, matching Harbour's "character"
	// enumeration via single-byte sub-strings.
	g.emitExpr(s.Collection)
	g.writeln("{ _feArr := t.Pop2()")

	// Array branch — the common case, kept as-is for zero overhead
	// when the collection is an array.
	g.writeln("if _feArr.IsArray() {")
	g.indent++
	g.writeln("_feItems := _feArr.AsArray().Items")
	g.writeln("for _feI := 0; _feI < len(_feItems); _feI++ {")
	g.indent++
	g.writeln(fmt.Sprintf("t.SetLocalFast(%d, _feItems[_feI])", varIdx))
	for _, stmt := range s.Body {
		g.emitStmt(stmt, locals)
	}
	g.indent--
	g.writeln("}")
	g.indent--
	// Hash branch — iterate values in insertion order. HbHash keeps
	// Keys/Values parallel slices in insertion order (see hash_helpers.go
	// appendPair); the Order slice is only populated by a handful of
	// Go-RTL builders and is empty for hash literals / hb_Hash(), so we
	// walk Values directly.
	g.writeln("} else if _feArr.IsHash() {")
	g.indent++
	g.writeln("_feH := _feArr.AsHash()")
	g.writeln("for _feI := 0; _feI < len(_feH.Values); _feI++ {")
	g.indent++
	g.writeln(fmt.Sprintf("t.SetLocalFast(%d, _feH.Values[_feI])", varIdx))
	for _, stmt := range s.Body {
		g.emitStmt(stmt, locals)
	}
	g.indent--
	g.writeln("}")
	g.indent--
	// String branch — iterate bytes as single-character substrings.
	g.writeln("} else if _feArr.IsString() {")
	g.indent++
	g.writeln("_feStr := _feArr.AsString()")
	g.writeln("for _feI := 0; _feI < len(_feStr); _feI++ {")
	g.indent++
	g.writeln(fmt.Sprintf("t.SetLocalFast(%d, hbrt.MakeString(string(_feStr[_feI])))", varIdx))
	for _, stmt := range s.Body {
		g.emitStmt(stmt, locals)
	}
	g.indent--
	g.writeln("}")
	g.indent--
	g.writeln("} }")
}

// --- Expression emission ---
// Each emitExpr leaves one value on the stack.

// emitMultiAssign: a, b := Func()  or  a, b := x, y
func (g *Generator) emitMultiAssign(s *ast.MultiAssignStmt, locals localMap) {
	if len(s.Values) == 1 {
		// Single RHS: a, b := Func() → call function, unpack array result
		g.emitExpr(s.Values[0])
		g.writeln("{")
		g.indent++
		g.writeln("_mr := t.Pop2()")
		g.writeln("if _mr.IsArray() {")
		g.indent++
		g.writeln("_arr := _mr.AsArray()")
		for i, name := range s.Targets {
			if name == "_" {
				continue
			}
			idx := locals[strings.ToUpper(name)]
			if idx > 0 {
				g.writeln(fmt.Sprintf("if %d < len(_arr.Items) { t.SetLocalFast(%d, _arr.Items[%d]) }", i, idx, i))
			}
		}
		g.indent--
		g.writeln("} else {")
		g.indent++
		// Not array — assign first target, rest get NIL
		if s.Targets[0] != "_" {
			idx := locals[strings.ToUpper(s.Targets[0])]
			if idx > 0 {
				g.writeln(fmt.Sprintf("t.SetLocalFast(%d, _mr)", idx))
			}
		}
		g.indent--
		g.writeln("}")
		g.indent--
		g.writeln("}")
	} else {
		// Multiple RHS: a, b := x, y (parallel assign)
		// Evaluate all RHS first, then assign
		for i, val := range s.Values {
			g.emitExpr(val)
			g.writeln(fmt.Sprintf("_mv%d := t.Pop2()", i))
		}
		for i, name := range s.Targets {
			if name == "_" || i >= len(s.Values) {
				continue
			}
			idx := locals[strings.ToUpper(name)]
			if idx > 0 {
				g.writeln(fmt.Sprintf("t.SetLocalFast(%d, _mv%d)", idx, i))
			}
		}
	}
}

// emitDefer: DEFER expr → Go defer
func (g *Generator) emitDefer(s *ast.DeferStmt, locals localMap) {
	g.writeln("defer func() {")
	g.indent++
	g.emitExpr(s.Call)
	g.writeln("t.Pop() // discard defer result")
	g.indent--
	g.writeln("}()")
}