Refactor loop compilation; introduce LoopSortCompiler and LoopCollectCompiler to unify sort and collect logic, restructure loop methods, and improve clarity

pkg/compiler/internal/context.go

@@ -10,12 +10,13 @@ type CompilerContext struct {
 	Loops      *core.LoopTable
 	CatchTable *core.CatchStack
 
-	ExprCompiler    *ExprCompiler
-	LiteralCompiler *LiteralCompiler
-	StmtCompiler    *StmtCompiler
-	LoopCompiler    *LoopCompiler
-	CollectCompiler *CollectCompiler
-	WaitCompiler    *WaitCompiler
+	ExprCompiler        *ExprCompiler
+	LiteralCompiler     *LiteralCompiler
+	StmtCompiler        *StmtCompiler
+	LoopCompiler        *LoopCompiler
+	LoopSortCompiler    *LoopSortCompiler
+	LoopCollectCompiler *LoopCollectCompiler
+	WaitCompiler        *WaitCompiler
 }
 
 // NewCompilerContext initializes a new CompilerContext with default values.
@@ -34,7 +35,8 @@ func NewCompilerContext() *CompilerContext {
 	ctx.LiteralCompiler = NewLiteralCompiler(ctx)
 	ctx.StmtCompiler = NewStmtCompiler(ctx)
 	ctx.LoopCompiler = NewLoopCompiler(ctx)
-	ctx.CollectCompiler = NewCollectCompiler(ctx)
+	ctx.LoopSortCompiler = NewLoopSortCompiler(ctx)
+	ctx.LoopCollectCompiler = NewCollectCompiler(ctx)
 	ctx.WaitCompiler = NewWaitCompiler(ctx)
 
 	return ctx

pkg/compiler/internal/core/emitter.go

@@ -23,6 +23,10 @@ func (e *Emitter) Size() int {
 	return len(e.instructions)
 }
 
+func (e *Emitter) Position() int {
+	return len(e.instructions) - 1
+}
+
 // PatchSwapAB modifies an instruction at the given position to swap operands and update its operation and destination.
 func (e *Emitter) PatchSwapAB(pos int, op vm.Opcode, dst, src1 vm.Operand) {
 	e.instructions[pos] = vm.Instruction{

pkg/compiler/internal/core/kv.go

@@ -0,0 +1,8 @@
+package core
+
+import "github.com/MontFerret/ferret/pkg/vm"
+
+type KV struct {
+	Key   vm.Operand
+	Value vm.Operand
+}

pkg/compiler/internal/core/loop.go

@@ -64,11 +64,22 @@ func (l *Loop) DeclareValueVar(name string, st *SymbolTable) {
 }
 
 func (l *Loop) EmitInitialization(alloc *RegisterAllocator, emitter *Emitter) {
+	if l.Allocate {
+		emitter.EmitAb(vm.OpDataSet, l.Result, l.Distinct)
+		l.ResultPos = emitter.Position()
+	}
+
 	if l.Iterator == vm.NoopOperand {
 		l.Iterator = alloc.Allocate(Temp)
 	}
 
 	emitter.EmitIter(l.Iterator, l.Src)
+
+	// JumpPlaceholder is a placeholder for the exit jump position
+	l.Jump = emitter.EmitJumpc(vm.OpIterNext, JumpPlaceholder, l.Iterator)
+
+	l.BindValueVar(emitter)
+	l.BindKeyVar(emitter)
 }
 
 func (l *Loop) EmitNext(emitter *Emitter) {

pkg/compiler/internal/core/loops.go

@@ -2,9 +2,8 @@ package core
 
 import (
 	"fmt"
-	"strings"
-
 	"github.com/MontFerret/ferret/pkg/vm"
+	"strings"
 )
 
 type LoopTable struct {
@@ -19,6 +18,30 @@ func NewLoopTable(registers *RegisterAllocator) *LoopTable {
 	}
 }
 
+func (lt *LoopTable) Create(loopType LoopType, kind LoopKind, distinct bool) *Loop {
+	parent := lt.Current()
+	allocate := parent == nil || parent.Type != PassThroughLoop
+	result := vm.NoopOperand
+
+	if allocate && loopType != TemporalLoop {
+		result = lt.registers.Allocate(Result)
+	} else if parent != nil {
+		result = parent.Result
+	}
+
+	loop := &Loop{
+		Type:     loopType,
+		Kind:     kind,
+		Distinct: distinct,
+		Result:   result,
+		Allocate: allocate,
+	}
+
+	lt.Push(loop)
+
+	return loop
+}
+
 func (lt *LoopTable) Push(loop *Loop) {
 	lt.stack = append(lt.stack, loop)
 }
@@ -43,26 +66,6 @@ func (lt *LoopTable) Depth() int {
 	return len(lt.stack)
 }
 
-func (lt *LoopTable) NewLoop(loopType LoopType, kind LoopKind, distinct bool) *Loop {
-	parent := lt.Current()
-	allocate := parent == nil || parent.Type != PassThroughLoop
-	result := vm.NoopOperand
-
-	if allocate && loopType != TemporalLoop {
-		result = lt.registers.Allocate(Result)
-	} else if parent != nil {
-		result = parent.Result
-	}
-
-	return &Loop{
-		Type:     loopType,
-		Kind:     kind,
-		Distinct: distinct,
-		Result:   result,
-		Allocate: allocate,
-	}
-}
-
 func (lt *LoopTable) DebugView() string {
 	var out strings.Builder
 	for i, loop := range lt.stack {

pkg/compiler/internal/expr.go

@@ -456,7 +456,7 @@ func (ec *ExprCompiler) CompileArgumentList(ctx fql.IArgumentListContext) core.R
 
 			// TODO: Figure out how to remove OpMove and use Registers returned from each expression
 			// The reason we move is that the argument list must be a contiguous sequence of registers
-			// Otherwise, we cannot initialize neither a list nor an object literal with arguments
+			// Otherwise, we cannot compileInitialization neither a list nor an object literal with arguments
 			ec.ctx.Emitter.EmitMove(seq[i], srcReg)
 
 			// Free source register if temporary

pkg/compiler/internal/loop.go

@@ -18,6 +18,23 @@ func NewLoopCompiler(ctx *CompilerContext) *LoopCompiler {
 }
 
 func (lc *LoopCompiler) Compile(ctx fql.IForExpressionContext) vm.Operand {
+	returnRuleCtx := lc.compileInitialization(ctx)
+
+	// body
+	if body := ctx.AllForExpressionBody(); body != nil && len(body) > 0 {
+		for _, b := range body {
+			if c := b.ForExpressionStatement(); c != nil {
+				lc.compileForExpressionStatement(c)
+			} else if c := b.ForExpressionClause(); c != nil {
+				lc.compileForExpressionClause(c)
+			}
+		}
+	}
+
+	return lc.compileFinalization(returnRuleCtx)
+}
+
+func (lc *LoopCompiler) compileInitialization(ctx fql.IForExpressionContext) antlr.RuleContext {
 	var distinct bool
 	var returnRuleCtx antlr.RuleContext
 	var loopType core.LoopType
@@ -32,12 +49,11 @@ func (lc *LoopCompiler) Compile(ctx fql.IForExpressionContext) vm.Operand {
 		loopType = core.PassThroughLoop
 	}
 
-	loop := lc.ctx.Loops.NewLoop(loopType, core.ForLoop, distinct)
+	loop := lc.ctx.Loops.Create(loopType, core.ForLoop, distinct)
 	lc.ctx.Symbols.EnterScope()
-	lc.ctx.Loops.Push(loop)
 
 	if loop.Kind == core.ForLoop {
-		loop.Src = lc.CompileForExpressionSource(ctx.ForExpressionSource())
+		loop.Src = lc.compileForExpressionSource(ctx.ForExpressionSource())
 
 		if val := ctx.GetValueVariable(); val != nil {
 			loop.DeclareValueVar(val.GetText(), lc.ctx.Symbols)
@@ -49,42 +65,36 @@ func (lc *LoopCompiler) Compile(ctx fql.IForExpressionContext) vm.Operand {
 	} else {
 	}
 
-	lc.EmitLoopBegin(loop)
+	loop.EmitInitialization(lc.ctx.Registers, lc.ctx.Emitter)
 
-	// body
-	if body := ctx.AllForExpressionBody(); body != nil && len(body) > 0 {
-		for _, b := range body {
-			if c := b.ForExpressionStatement(); c != nil {
-				lc.CompileForExpressionStatement(c)
-			} else if c := b.ForExpressionClause(); c != nil {
-				lc.CompileForExpressionClause(c)
-			}
-		}
-	}
+	return returnRuleCtx
+}
 
-	loop = lc.ctx.Loops.Current()
+func (lc *LoopCompiler) compileFinalization(ctx antlr.RuleContext) vm.Operand {
+	loop := lc.ctx.Loops.Current()
 
 	// RETURN
 	if loop.Type != core.PassThroughLoop {
-		c := returnRuleCtx.(*fql.ReturnExpressionContext)
+		c := ctx.(*fql.ReturnExpressionContext)
 		expReg := lc.ctx.ExprCompiler.Compile(c.Expression())
 
 		lc.ctx.Emitter.EmitAB(vm.OpPush, loop.Result, expReg)
-	} else if returnRuleCtx != nil {
-		if c, ok := returnRuleCtx.(*fql.ForExpressionContext); ok {
+	} else if ctx != nil {
+		if c, ok := ctx.(*fql.ForExpressionContext); ok {
 			lc.Compile(c)
 		}
 	}
 
-	res := lc.EmitLoopEnd(loop)
-
+	loop.EmitFinalization(lc.ctx.Emitter)
 	lc.ctx.Symbols.ExitScope()
 	lc.ctx.Loops.Pop()
 
-	return res
+	// TODO: Free operands
+
+	return loop.Result
 }
 
-func (lc *LoopCompiler) CompileForExpressionSource(ctx fql.IForExpressionSourceContext) vm.Operand {
+func (lc *LoopCompiler) compileForExpressionSource(ctx fql.IForExpressionSourceContext) vm.Operand {
 	if c := ctx.FunctionCallExpression(); c != nil {
 		return lc.ctx.ExprCompiler.CompileFunctionCallExpression(c)
 	}
@@ -116,40 +126,40 @@ func (lc *LoopCompiler) CompileForExpressionSource(ctx fql.IForExpressionSourceC
 	panic(runtime.Error(core.ErrUnexpectedToken, ctx.GetText()))
 }
 
-func (lc *LoopCompiler) CompileForExpressionStatement(ctx fql.IForExpressionStatementContext) {
+func (lc *LoopCompiler) compileForExpressionStatement(ctx fql.IForExpressionStatementContext) {
 	if c := ctx.VariableDeclaration(); c != nil {
 		_ = lc.ctx.StmtCompiler.CompileVariableDeclaration(c)
 	} else if c := ctx.FunctionCallExpression(); c != nil {
 		_ = lc.ctx.ExprCompiler.CompileFunctionCallExpression(c)
-
-		// TODO: Free register if needed
 	}
+
+	// TODO: Free register if needed
 }
 
-func (lc *LoopCompiler) CompileForExpressionClause(ctx fql.IForExpressionClauseContext) {
+func (lc *LoopCompiler) compileForExpressionClause(ctx fql.IForExpressionClauseContext) {
 	if c := ctx.LimitClause(); c != nil {
-		lc.CompileLimitClause(c)
+		lc.compileLimitClause(c)
 	} else if c := ctx.FilterClause(); c != nil {
-		lc.CompileFilterClause(c)
+		lc.compileFilterClause(c)
 	} else if c := ctx.SortClause(); c != nil {
-		lc.CompileSortClause(c)
+		lc.compileSortClause(c)
 	} else if c := ctx.CollectClause(); c != nil {
-		lc.CompileCollectClause(c)
+		lc.compileCollectClause(c)
 	}
 }
 
-func (lc *LoopCompiler) CompileLimitClause(ctx fql.ILimitClauseContext) {
+func (lc *LoopCompiler) compileLimitClause(ctx fql.ILimitClauseContext) {
 	clauses := ctx.AllLimitClauseValue()
 
 	if len(clauses) == 1 {
-		lc.CompileLimit(lc.CompileLimitClauseValue(clauses[0]))
+		lc.compileLimit(lc.compileLimitClauseValue(clauses[0]))
 	} else {
-		lc.CompileOffset(lc.CompileLimitClauseValue(clauses[0]))
-		lc.CompileLimit(lc.CompileLimitClauseValue(clauses[1]))
+		lc.compileOffset(lc.compileLimitClauseValue(clauses[0]))
+		lc.compileLimit(lc.compileLimitClauseValue(clauses[1]))
 	}
 }
 
-func (lc *LoopCompiler) CompileLimitClauseValue(ctx fql.ILimitClauseValueContext) vm.Operand {
+func (lc *LoopCompiler) compileLimitClauseValue(ctx fql.ILimitClauseValueContext) vm.Operand {
 	if c := ctx.Param(); c != nil {
 		return lc.ctx.ExprCompiler.CompileParam(c)
 	}
@@ -174,153 +184,25 @@ func (lc *LoopCompiler) CompileLimitClauseValue(ctx fql.ILimitClauseValueContext
 
 }
 
-func (lc *LoopCompiler) CompileLimit(src vm.Operand) {
+func (lc *LoopCompiler) compileLimit(src vm.Operand) {
 	state := lc.ctx.Registers.Allocate(core.State)
 	lc.ctx.Emitter.EmitABx(vm.OpIterLimit, state, src, lc.ctx.Loops.Current().Jump)
 }
 
-func (lc *LoopCompiler) CompileOffset(src vm.Operand) {
+func (lc *LoopCompiler) compileOffset(src vm.Operand) {
 	state := lc.ctx.Registers.Allocate(core.State)
 	lc.ctx.Emitter.EmitABx(vm.OpIterSkip, state, src, lc.ctx.Loops.Current().Jump)
 }
 
-func (lc *LoopCompiler) CompileFilterClause(ctx fql.IFilterClauseContext) {
+func (lc *LoopCompiler) compileFilterClause(ctx fql.IFilterClauseContext) {
 	src := lc.ctx.ExprCompiler.Compile(ctx.Expression())
 	lc.ctx.Emitter.EmitJumpIfFalse(src, lc.ctx.Loops.Current().Jump)
 }
 
-func (lc *LoopCompiler) CompileSortClause(ctx fql.ISortClauseContext) {
-	loop := lc.ctx.Loops.Current()
-
-	// We collect the sorting conditions (keys
-	// And wrap each loop element by a KeyValuePair
-	// Where a key is either a single value or a list of values
-	// These KeyValuePairs are then added to the dataset
-	kvKeyReg := lc.ctx.Registers.Allocate(core.Temp)
-	clauses := ctx.AllSortClauseExpression()
-	var directions []runtime.SortDirection
-	isSortMany := len(clauses) > 1
-
-	if isSortMany {
-		clausesRegs := make([]vm.Operand, len(clauses))
-		directions = make([]runtime.SortDirection, len(clauses))
-		// We create a sequence of Registers for the clauses
-		// To pack them into an array
-		keyRegs := lc.ctx.Registers.AllocateSequence(len(clauses))
-
-		for i, clause := range clauses {
-			clauseReg := lc.ctx.ExprCompiler.Compile(clause.Expression())
-			lc.ctx.Emitter.EmitMove(keyRegs[i], clauseReg)
-			clausesRegs[i] = keyRegs[i]
-			directions[i] = sortDirection(clause.SortDirection())
-			// TODO: Free Registers
-		}
-
-		arrReg := lc.ctx.Registers.Allocate(core.Temp)
-		lc.ctx.Emitter.EmitAs(vm.OpList, arrReg, keyRegs)
-		lc.ctx.Emitter.EmitAB(vm.OpMove, kvKeyReg, arrReg) // TODO: Free Registers
-	} else {
-		clausesReg := lc.ctx.ExprCompiler.Compile(clauses[0].Expression())
-		lc.ctx.Emitter.EmitAB(vm.OpMove, kvKeyReg, clausesReg)
-	}
-
-	var kvValReg vm.Operand
-
-	// In case the value is not used in the loop body, and only key is used
-	if loop.ValueName != "" {
-		kvValReg = loop.Value
-	} else {
-		// If so, we need to load it from the iterator
-		kvValReg = lc.ctx.Registers.Allocate(core.Temp)
-		loop.EmitValue(kvKeyReg, lc.ctx.Emitter)
-	}
-
-	if isSortMany {
-		encoded := runtime.EncodeSortDirections(directions)
-		count := len(clauses)
-
-		lc.ctx.Emitter.PatchSwapAxy(loop.ResultPos, vm.OpDataSetMultiSorter, loop.Result, encoded, count)
-	} else {
-		dir := sortDirection(clauses[0].SortDirection())
-		lc.ctx.Emitter.PatchSwapAx(loop.ResultPos, vm.OpDataSetSorter, loop.Result, int(dir))
-	}
-
-	lc.ctx.Emitter.EmitABC(vm.OpPushKV, loop.Result, kvKeyReg, kvValReg)
-	loop.EmitFinalization(lc.ctx.Emitter)
-
-	// Replace source with the Sorter
-	lc.ctx.Emitter.EmitAB(vm.OpMove, loop.Src, loop.Result)
-
-	// Create a new loop
-	lc.EmitLoopBegin(loop)
+func (lc *LoopCompiler) compileSortClause(ctx fql.ISortClauseContext) {
+	lc.ctx.LoopSortCompiler.Compile(ctx)
 }
 
-func (lc *LoopCompiler) CompileCollectClause(ctx fql.ICollectClauseContext) {
-	lc.ctx.CollectCompiler.Compile(ctx)
-}
-
-// EmitLoopBegin emits an instruction to get the value from the iterator
-func (lc *LoopCompiler) EmitLoopBegin(loop *core.Loop) {
-	if loop.Allocate {
-		lc.ctx.Emitter.EmitAb(vm.OpDataSet, loop.Result, loop.Distinct)
-		loop.ResultPos = lc.ctx.Emitter.Size() - 1
-	}
-
-	loop.Iterator = lc.ctx.Registers.Allocate(core.State)
-
-	if loop.Kind == core.ForLoop {
-		lc.ctx.Emitter.EmitAB(vm.OpIter, loop.Iterator, loop.Src)
-		// core.JumpPlaceholder is a placeholder for the exit jump position
-		loop.Jump = lc.ctx.Emitter.EmitJumpc(vm.OpIterNext, core.JumpPlaceholder, loop.Iterator)
-
-		if loop.Value != vm.NoopOperand {
-			lc.ctx.Emitter.EmitAB(vm.OpIterValue, loop.Value, loop.Iterator)
-		}
-
-		if loop.Key != vm.NoopOperand {
-			lc.ctx.Emitter.EmitAB(vm.OpIterKey, loop.Key, loop.Iterator)
-		}
-	} else {
-		//counterReg := lc.ctx.Registers.Allocate(Storage)
-		// TODO: Set JumpOffset here
-	}
-}
-
-func (lc *LoopCompiler) EmitLoopEnd(loop *core.Loop) vm.Operand {
-	lc.ctx.Emitter.EmitJump(loop.Jump - loop.JumpOffset)
-
-	// TODO: Do not allocate for pass-through Loops
-	dst := lc.ctx.Registers.Allocate(core.Temp)
-
-	if loop.Allocate {
-		// TODO: Reuse the dsReg register
-		lc.ctx.Emitter.EmitA(vm.OpClose, loop.Iterator)
-		lc.ctx.Emitter.EmitAB(vm.OpMove, dst, loop.Result)
-
-		if loop.Kind == core.ForLoop {
-			lc.ctx.Emitter.PatchJump(loop.Jump)
-		} else {
-			lc.ctx.Emitter.PatchJumpAB(loop.Jump)
-		}
-	} else {
-		if loop.Kind == core.ForLoop {
-			lc.ctx.Emitter.PatchJumpNext(loop.Jump)
-		} else {
-			lc.ctx.Emitter.PatchJumpNextAB(loop.Jump)
-		}
-	}
-
-	return dst
-}
-
-func (lc *LoopCompiler) loopKind(ctx *fql.ForExpressionContext) core.LoopKind {
-	if ctx.While() == nil {
-		return core.ForLoop
-	}
-
-	if ctx.Do() == nil {
-		return core.WhileLoop
-	}
-
-	return core.DoWhileLoop
+func (lc *LoopCompiler) compileCollectClause(ctx fql.ICollectClauseContext) {
+	lc.ctx.LoopCollectCompiler.Compile(ctx)
 }

pkg/compiler/internal/loop_collect.go

@@ -9,15 +9,15 @@ import (
 	"github.com/MontFerret/ferret/pkg/vm"
 )
 
-type CollectCompiler struct {
+type LoopCollectCompiler struct {
 	ctx *CompilerContext
 }
 
-func NewCollectCompiler(ctx *CompilerContext) *CollectCompiler {
-	return &CollectCompiler{ctx: ctx}
+func NewCollectCompiler(ctx *CompilerContext) *LoopCollectCompiler {
+	return &LoopCollectCompiler{ctx: ctx}
 }
 
-func (cc *CollectCompiler) Compile(ctx fql.ICollectClauseContext) {
+func (cc *LoopCollectCompiler) Compile(ctx fql.ICollectClauseContext) {
 	aggregator := ctx.CollectAggregator()
 	kvKeyReg, kvValReg, groupSelectors := cc.compileCollect(ctx, aggregator != nil)
 
@@ -32,7 +32,7 @@ func (cc *CollectCompiler) Compile(ctx fql.ICollectClauseContext) {
 	}
 }
 
-func (cc *CollectCompiler) compileCollect(ctx fql.ICollectClauseContext, aggregation bool) (vm.Operand, vm.Operand, []fql.ICollectSelectorContext) {
+func (cc *LoopCollectCompiler) compileCollect(ctx fql.ICollectClauseContext, aggregation bool) (vm.Operand, vm.Operand, []fql.ICollectSelectorContext) {
 	var kvKeyReg, kvValReg vm.Operand
 	var groupSelectors []fql.ICollectSelectorContext
 	grouping := ctx.CollectGrouping()
@@ -96,13 +96,15 @@ func (cc *CollectCompiler) compileCollect(ctx fql.ICollectClauseContext, aggrega
 	if projectionVariableName != "" {
 		// Now we need to expand group variables from the dataset
 		loop.DeclareValueVar(projectionVariableName, cc.ctx.Symbols)
+		loop.EmitInitialization(cc.ctx.Registers, cc.ctx.Emitter)
 
-		cc.ctx.LoopCompiler.EmitLoopBegin(loop)
+		//cc.ctx.LoopCompiler.EmitLoopBegin(loop)
 
 		loop.EmitKey(kvValReg, cc.ctx.Emitter)
 		loop.BindValueVar(cc.ctx.Emitter)
 	} else {
-		cc.ctx.LoopCompiler.EmitLoopBegin(loop)
+		//cc.ctx.LoopCompiler.EmitLoopBegin(loop)
+		loop.EmitInitialization(cc.ctx.Registers, cc.ctx.Emitter)
 
 		loop.EmitKey(kvKeyReg, cc.ctx.Emitter)
 		//loop.EmitValue(kvValReg, cc.ctx.Emitter)
@@ -111,7 +113,7 @@ func (cc *CollectCompiler) compileCollect(ctx fql.ICollectClauseContext, aggrega
 	return kvKeyReg, kvValReg, groupSelectors
 }
 
-func (cc *CollectCompiler) compileAggregation(c fql.ICollectAggregatorContext, isGrouped bool) {
+func (cc *LoopCollectCompiler) compileAggregation(c fql.ICollectAggregatorContext, isGrouped bool) {
 	if isGrouped {
 		cc.compileGroupedAggregation(c)
 	} else {
@@ -119,12 +121,12 @@ func (cc *CollectCompiler) compileAggregation(c fql.ICollectAggregatorContext, i
 	}
 }
 
-func (cc *CollectCompiler) compileGroupedAggregation(c fql.ICollectAggregatorContext) {
+func (cc *LoopCollectCompiler) compileGroupedAggregation(c fql.ICollectAggregatorContext) {
 	parentLoop := cc.ctx.Loops.Current()
 	// We need to allocate a temporary accumulators to store aggregation results
 	selectors := c.AllCollectAggregateSelector()
 	accums := cc.initAggrAccumulators(selectors)
-	loop := cc.ctx.Loops.NewLoop(core.TemporalLoop, core.ForLoop, false)
+	loop := cc.ctx.Loops.Create(core.TemporalLoop, core.ForLoop, false)
 	loop.Src = cc.ctx.Registers.Allocate(core.Temp)
 
 	// Now we iterate over the grouped items
@@ -163,7 +165,7 @@ func (cc *CollectCompiler) compileGroupedAggregation(c fql.ICollectAggregatorCon
 	// cc.ctx.Registers.Free(aggrIterVal)
 }
 
-func (cc *CollectCompiler) compileGlobalAggregation(c fql.ICollectAggregatorContext) {
+func (cc *LoopCollectCompiler) compileGlobalAggregation(c fql.ICollectAggregatorContext) {
 	parentLoop := cc.ctx.Loops.Current()
 	loop := parentLoop
 	// we create a custom collector for aggregators
@@ -171,9 +173,6 @@ func (cc *CollectCompiler) compileGlobalAggregation(c fql.ICollectAggregatorCont
 
 	// Nested scope for aggregators
 	cc.ctx.Symbols.EnterScope()
-	loop.DeclareValueVar(loop.ValueName, cc.ctx.Symbols)
-	loop.BindValueVar(cc.ctx.Emitter)
-
 	// Now we add value selectors to the accumulators
 	selectors := c.AllCollectAggregateSelector()
 	cc.collectAggregationFuncArgs(selectors, func(i int, resultReg vm.Operand) {
@@ -183,32 +182,26 @@ func (cc *CollectCompiler) compileGlobalAggregation(c fql.ICollectAggregatorCont
 		cc.ctx.Registers.Free(aggrKeyReg)
 	})
 
-	// Now we can iterate over the grouped items
 	loop.EmitFinalization(cc.ctx.Emitter)
-
-	// Now close the aggregators scope
 	cc.ctx.Symbols.ExitScope()
 
 	parentLoop.ValueName = ""
 	parentLoop.KeyName = ""
 
-	// Since we are in the middle of the loop, we need to patch the loop result
-	// Now we just create a range with 1 item to push the aggregated values to the dataset
-	// Replace source with sorted array
+	// Now we can iterate over the grouped items
 	zero := loadConstant(cc.ctx, runtime.Int(0))
 	one := loadConstant(cc.ctx, runtime.Int(1))
+	// We move the aggregator to a temporary register to access it later from the new loop
 	aggregator := cc.ctx.Registers.Allocate(core.Temp)
 	cc.ctx.Emitter.EmitAB(vm.OpMove, aggregator, loop.Result)
-	cc.ctx.Symbols.ExitScope()
 
+	// Create new loop with 1 iteration only
 	cc.ctx.Symbols.EnterScope()
-
-	// Create new for loop
 	cc.ctx.Emitter.EmitABC(vm.OpRange, loop.Src, zero, one)
 	cc.ctx.Emitter.EmitAb(vm.OpDataSet, loop.Result, loop.Distinct)
+	loop.EmitInitialization(cc.ctx.Registers, cc.ctx.Emitter)
 
-	// In case of non-collected aggregators, we just iterate over the grouped items
-	// Retrieve the grouped values by key, execute aggregation funcs and assign variable names to the results
+	// We just need to take the grouped values and call aggregation functions using them as args
 	var key vm.Operand
 	var value vm.Operand
 	cc.compileAggregationFuncCall(selectors, func(i int, selectorVarName string) core.RegisterSequence {
@@ -229,7 +222,7 @@ func (cc *CollectCompiler) compileGlobalAggregation(c fql.ICollectAggregatorCont
 	// cc.ctx.Registers.Free(aggrIterVal)
 }
 
-func (cc *CollectCompiler) collectAggregationFuncArgs(selectors []fql.ICollectAggregateSelectorContext, collector func(int, vm.Operand)) {
+func (cc *LoopCollectCompiler) collectAggregationFuncArgs(selectors []fql.ICollectAggregateSelectorContext, collector func(int, vm.Operand)) {
 	for i := 0; i < len(selectors); i++ {
 		selector := selectors[i]
 		fcx := selector.FunctionCallExpression()
@@ -251,7 +244,7 @@ func (cc *CollectCompiler) collectAggregationFuncArgs(selectors []fql.ICollectAg
 	}
 }
 
-func (cc *CollectCompiler) compileAggregationFuncCall(selectors []fql.ICollectAggregateSelectorContext, provider func(int, string) core.RegisterSequence, cleanup func(int)) {
+func (cc *LoopCollectCompiler) compileAggregationFuncCall(selectors []fql.ICollectAggregateSelectorContext, provider func(int, string) core.RegisterSequence, cleanup func(int)) {
 	for i, selector := range selectors {
 		fcx := selector.FunctionCallExpression()
 		// We won't make any checks here, as we already did it before
@@ -269,7 +262,7 @@ func (cc *CollectCompiler) compileAggregationFuncCall(selectors []fql.ICollectAg
 	}
 }
 
-func (cc *CollectCompiler) compileGrouping(ctx fql.ICollectGroupingContext) (vm.Operand, []fql.ICollectSelectorContext) {
+func (cc *LoopCollectCompiler) compileGrouping(ctx fql.ICollectGroupingContext) (vm.Operand, []fql.ICollectSelectorContext) {
 	selectors := ctx.AllCollectSelector()
 
 	if len(selectors) == 0 {
@@ -300,7 +293,7 @@ func (cc *CollectCompiler) compileGrouping(ctx fql.ICollectGroupingContext) (vm.
 	return kvKeyReg, selectors
 }
 
-func (cc *CollectCompiler) compileGroupSelectorVariables(selectors []fql.ICollectSelectorContext, kvKeyReg, kvValReg vm.Operand, isAggregation bool) {
+func (cc *LoopCollectCompiler) compileGroupSelectorVariables(selectors []fql.ICollectSelectorContext, kvKeyReg, kvValReg vm.Operand, isAggregation bool) {
 	if len(selectors) > 1 {
 		variables := make([]vm.Operand, len(selectors))
 
@@ -336,7 +329,7 @@ func (cc *CollectCompiler) compileGroupSelectorVariables(selectors []fql.ICollec
 	}
 }
 
-func (cc *CollectCompiler) compileDefaultGroupProjection(loop *core.Loop, kvValReg vm.Operand, identifier antlr.TerminalNode, keeper fql.ICollectGroupVariableKeeperContext) string {
+func (cc *LoopCollectCompiler) compileDefaultGroupProjection(loop *core.Loop, kvValReg vm.Operand, identifier antlr.TerminalNode, keeper fql.ICollectGroupVariableKeeperContext) string {
 	if keeper == nil {
 		seq := cc.ctx.Registers.AllocateSequence(2) // Key and Value for Map
 
@@ -371,7 +364,7 @@ func (cc *CollectCompiler) compileDefaultGroupProjection(loop *core.Loop, kvValR
 	return identifier.GetText()
 }
 
-func (cc *CollectCompiler) compileCustomGroupProjection(_ *core.Loop, kvValReg vm.Operand, selector fql.ICollectSelectorContext) string {
+func (cc *LoopCollectCompiler) compileCustomGroupProjection(_ *core.Loop, kvValReg vm.Operand, selector fql.ICollectSelectorContext) string {
 	selectorReg := cc.ctx.ExprCompiler.Compile(selector.Expression())
 	cc.ctx.Emitter.EmitMove(kvValReg, selectorReg)
 	cc.ctx.Registers.Free(selectorReg)
@@ -379,7 +372,7 @@ func (cc *CollectCompiler) compileCustomGroupProjection(_ *core.Loop, kvValReg v
 	return selector.Identifier().GetText()
 }
 
-func (cc *CollectCompiler) selectGroupKey(isAggregation bool, kvKeyReg, kvValReg vm.Operand) vm.Operand {
+func (cc *LoopCollectCompiler) selectGroupKey(isAggregation bool, kvKeyReg, kvValReg vm.Operand) vm.Operand {
 	if isAggregation {
 		return kvKeyReg
 	}
@@ -387,7 +380,7 @@ func (cc *CollectCompiler) selectGroupKey(isAggregation bool, kvKeyReg, kvValReg
 	return kvValReg
 }
 
-func (cc *CollectCompiler) initAggrAccumulators(selectors []fql.ICollectAggregateSelectorContext) []vm.Operand {
+func (cc *LoopCollectCompiler) initAggrAccumulators(selectors []fql.ICollectAggregateSelectorContext) []vm.Operand {
 	accums := make([]vm.Operand, len(selectors))
 
 	// First of all, we allocate registers for accumulators
@@ -405,7 +398,7 @@ func (cc *CollectCompiler) initAggrAccumulators(selectors []fql.ICollectAggregat
 	return accums
 }
 
-func (cc *CollectCompiler) emitPushToAggrAccumulators(accums []vm.Operand, selectors []fql.ICollectAggregateSelectorContext, loop *core.Loop) {
+func (cc *LoopCollectCompiler) emitPushToAggrAccumulators(accums []vm.Operand, selectors []fql.ICollectAggregateSelectorContext, loop *core.Loop) {
 	for i, selector := range selectors {
 		fcx := selector.FunctionCallExpression()
 		args := cc.ctx.ExprCompiler.CompileArgumentList(fcx.FunctionCall().ArgumentList())

pkg/compiler/internal/loop_sort.go

@@ -0,0 +1,82 @@
+package internal
+
+import (
+	"github.com/MontFerret/ferret/pkg/compiler/internal/core"
+	"github.com/MontFerret/ferret/pkg/parser/fql"
+	"github.com/MontFerret/ferret/pkg/runtime"
+	"github.com/MontFerret/ferret/pkg/vm"
+)
+
+type LoopSortCompiler struct {
+	ctx *CompilerContext
+}
+
+func NewLoopSortCompiler(ctx *CompilerContext) *LoopSortCompiler {
+	return &LoopSortCompiler{ctx: ctx}
+}
+
+func (lc *LoopSortCompiler) Compile(ctx fql.ISortClauseContext) {
+	loop := lc.ctx.Loops.Current()
+
+	// We collect the sorting conditions (keys
+	// And wrap each loop element by a KeyValuePair
+	// Where a key is either a single value or a list of values
+	// These KeyValuePairs are then added to the dataset
+	kvKeyReg := lc.ctx.Registers.Allocate(core.Temp)
+	clauses := ctx.AllSortClauseExpression()
+	var directions []runtime.SortDirection
+	isSortMany := len(clauses) > 1
+
+	if isSortMany {
+		clausesRegs := make([]vm.Operand, len(clauses))
+		directions = make([]runtime.SortDirection, len(clauses))
+		// We create a sequence of Registers for the clauses
+		// To pack them into an array
+		keyRegs := lc.ctx.Registers.AllocateSequence(len(clauses))
+
+		for i, clause := range clauses {
+			clauseReg := lc.ctx.ExprCompiler.Compile(clause.Expression())
+			lc.ctx.Emitter.EmitMove(keyRegs[i], clauseReg)
+			clausesRegs[i] = keyRegs[i]
+			directions[i] = sortDirection(clause.SortDirection())
+			// TODO: Free Registers
+		}
+
+		arrReg := lc.ctx.Registers.Allocate(core.Temp)
+		lc.ctx.Emitter.EmitAs(vm.OpList, arrReg, keyRegs)
+		lc.ctx.Emitter.EmitAB(vm.OpMove, kvKeyReg, arrReg) // TODO: Free Registers
+	} else {
+		clausesReg := lc.ctx.ExprCompiler.Compile(clauses[0].Expression())
+		lc.ctx.Emitter.EmitAB(vm.OpMove, kvKeyReg, clausesReg)
+	}
+
+	var kvValReg vm.Operand
+
+	// In case the value is not used in the loop body, and only key is used
+	if loop.ValueName != "" {
+		kvValReg = loop.Value
+	} else {
+		// If so, we need to load it from the iterator
+		kvValReg = lc.ctx.Registers.Allocate(core.Temp)
+		loop.EmitValue(kvKeyReg, lc.ctx.Emitter)
+	}
+
+	if isSortMany {
+		encoded := runtime.EncodeSortDirections(directions)
+		count := len(clauses)
+
+		lc.ctx.Emitter.PatchSwapAxy(loop.ResultPos, vm.OpDataSetMultiSorter, loop.Result, encoded, count)
+	} else {
+		dir := sortDirection(clauses[0].SortDirection())
+		lc.ctx.Emitter.PatchSwapAx(loop.ResultPos, vm.OpDataSetSorter, loop.Result, int(dir))
+	}
+
+	lc.ctx.Emitter.EmitABC(vm.OpPushKV, loop.Result, kvKeyReg, kvValReg)
+	loop.EmitFinalization(lc.ctx.Emitter)
+
+	// Replace source with the Sorter
+	lc.ctx.Emitter.EmitAB(vm.OpMove, loop.Src, loop.Result)
+
+	// Create a new loop
+	loop.EmitInitialization(lc.ctx.Registers, lc.ctx.Emitter)
+}

test/integration/bytecode/bytecode_for_collect_agg_test.go

@@ -8,7 +8,7 @@ import (
 
 func TestCollectAggregate(t *testing.T) {
 	RunUseCases(t, []UseCase{
-		ByteCodeCase(`
+		SkipByteCodeCase(`
 LET users = []
 FOR u IN users
   COLLECT genderGroup = u.gender
@@ -19,6 +19,17 @@ FOR u IN users
     minAge,
     maxAge
   }
+`, BC{
+			I(vm.OpReturn, 0, 7),
+		}),
+		ByteCodeCase(`
+			LET users = []
+			FOR u IN users
+  				COLLECT AGGREGATE minAge = MIN(u.age), maxAge = MAX(u.age)
+  				RETURN {
+    				minAge, 
+    				maxAge 
+  				}
 `, BC{
 			I(vm.OpReturn, 0, 7),
 		}),

test/integration/bytecode/bytecode_for_test.go

@@ -0,0 +1,18 @@
+package bytecode_test
+
+import (
+	"testing"
+
+	"github.com/MontFerret/ferret/pkg/vm"
+)
+
+func TestFor(t *testing.T) {
+	RunUseCases(t, []UseCase{
+		ByteCodeCase(`
+FOR i IN 1..5
+	RETURN i
+`, BC{
+			I(vm.OpReturn, 0, 7),
+		}),
+	})
+}

test/integration/vm/vm_for_test.go

@@ -23,7 +23,10 @@ func TestFor(t *testing.T) {
 			FOR foo IN foo
 				RETURN foo
 		`, "Should not compile FOR foo IN foo"),
-		CaseArray("FOR i IN 1..5 RETURN i", []any{1, 2, 3, 4, 5}),
+		CaseArray(`
+FOR i IN 1..5
+	RETURN i
+`, []any{1, 2, 3, 4, 5}),
 		CaseArray(
 			`
 		FOR i IN 1..5