Dyn fields

compiler/ast/dag/expr.go

@@ -10,6 +10,9 @@ type (
 	VectorElem interface {
 		vectorElem()
 	}
+	PathElem interface {
+		pathElem()
+	}
 )
 
 // Exprs
@@ -27,7 +30,7 @@ type (
 	}
 	Assignment struct {
 		Kind string `json:"kind" unpack:""`
-		LHS  Expr   `json:"lhs"`
+		LHS  *Path  `json:"lhs"`
 		RHS  Expr   `json:"rhs"`
 	}
 	BinaryExpr struct {
@@ -72,6 +75,10 @@ type (
 		Exprs []Expr `json:"exprs"`
 		Body  Seq    `json:"body"`
 	}
+	Path struct {
+		Kind string     `json:"kind" unpack:""`
+		Path []PathElem `json:"path"`
+	}
 	RecordExpr struct {
 		Kind  string       `json:"kind" unpack:""`
 		Elems []RecordElem `json:"elems"`
@@ -123,6 +130,7 @@ func (*Func) ExprDAG()         {}
 func (*Literal) ExprDAG()      {}
 func (*MapExpr) ExprDAG()      {}
 func (*OverExpr) ExprDAG()     {}
+func (*Path) ExprDAG()         {}
 func (*RecordExpr) ExprDAG()   {}
 func (*RegexpMatch) ExprDAG()  {}
 func (*RegexpSearch) ExprDAG() {}
@@ -159,6 +167,34 @@ func (*Spread) recordAST()       {}
 func (*Spread) vectorElem()      {}
 func (*VectorValue) vectorElem() {}
 
+func (p *Path) StaticPath() *This {
+	this := &This{Kind: "This"}
+	for _, elem := range p.Path {
+		if p, ok := elem.(*StaticPathElem); ok {
+			this.Path = append(this.Path, p.Name)
+		} else {
+			return nil
+		}
+	}
+	return this
+}
+
+func NewStaticPath(path ...string) *Path {
+	p := &Path{Kind: "Path"}
+	for _, name := range path {
+		p.Path = append(p.Path, &StaticPathElem{Kind: "StaticPathElem", Name: name})
+	}
+	return p
+}
+
+type StaticPathElem struct {
+	Kind string `json:"kind" unpack:""`
+	Name string `json:"name"`
+}
+
+func (*This) pathElem()           {}
+func (*StaticPathElem) pathElem() {}
+
 func NewBinaryExpr(op string, lhs, rhs Expr) *BinaryExpr {
 	return &BinaryExpr{
 		Kind: "BinaryExpr",

compiler/ast/dag/op.go

@@ -95,8 +95,9 @@ type (
 		Args []Assignment `json:"args"`
 	}
 	Rename struct {
-		Kind string       `json:"kind" unpack:""`
-		Args []Assignment `json:"args"`
+		Kind string  `json:"kind" unpack:""`
+		Dsts []*This `json:"dsts"`
+		Srcs []*This `json:"srcs"`
 	}
 	Scatter struct {
 		Kind  string `json:"kind" unpack:""`

compiler/ast/dag/unpack.go

@@ -36,6 +36,8 @@ var unpacker = unpack.New(
 	Over{},
 	OverExpr{},
 	Pass{},
+	Path{},
+	StaticPathElem{},
 	PoolScan{},
 	Put{},
 	RecordExpr{},

compiler/kernel/expr.go

@@ -65,6 +65,12 @@ func (b *Builder) compileExpr(e dag.Expr) (expr.Evaluator, error) {
 		return expr.NewDottedExpr(b.zctx(), field.Path(e.Path)), nil
 	case *dag.Dot:
 		return b.compileDotExpr(e)
+	case *dag.Path:
+		// Path only works as a general expression if it is a static path.
+		if this := e.StaticPath(); this != nil {
+			return expr.NewDottedExpr(b.zctx(), field.Path(this.Path)), nil
+		}
+		return nil, fmt.Errorf("internal error: invalid path expression %s", e)
 	case *dag.UnaryExpr:
 		return b.compileUnary(*e)
 	case *dag.BinaryExpr:
@@ -263,15 +269,27 @@ func (b *Builder) compileDotExpr(dot *dag.Dot) (expr.Evaluator, error) {
 	return expr.NewDotExpr(b.zctx(), record, dot.RHS), nil
 }
 
-func compileLval(e dag.Expr) (field.Path, error) {
-	if this, ok := e.(*dag.This); ok {
-		return field.Path(this.Path), nil
+func (b *Builder) compilePath(e *dag.Path) (*expr.Path, error) {
+	elems := make([]expr.PathElem, 0, len(e.Path))
+	for _, elem := range e.Path {
+		switch e := elem.(type) {
+		case *dag.This:
+			eval, err := b.compileExpr(e)
+			if err != nil {
+				return nil, err
+			}
+			elems = append(elems, expr.NewPathElemExpr(b.octx.Zctx, eval))
+		case *dag.StaticPathElem:
+			elems = append(elems, &expr.StaticPathElem{Name: e.Name})
+		default:
+			return nil, fmt.Errorf("internal error: invalid lval type %T", e)
+		}
 	}
-	return nil, errors.New("invalid expression on lhs of assignment")
+	return expr.NewPath(elems), nil
 }
 
 func (b *Builder) compileAssignment(node *dag.Assignment) (expr.Assignment, error) {
-	lhs, err := compileLval(node.LHS)
+	lhs, err := b.compilePath(node.LHS)
 	if err != nil {
 		return expr.Assignment{}, err
 	}

compiler/kernel/groupby.go

@@ -2,18 +2,18 @@ package kernel
 
 import (
 	"errors"
-	"fmt"
 
 	"github.com/brimdata/zed/compiler/ast/dag"
 	"github.com/brimdata/zed/order"
 	"github.com/brimdata/zed/pkg/field"
 	"github.com/brimdata/zed/runtime/expr"
 	"github.com/brimdata/zed/runtime/op/groupby"
 	"github.com/brimdata/zed/zbuf"
+	"golang.org/x/exp/slices"
 )
 
 func (b *Builder) compileGroupBy(parent zbuf.Puller, summarize *dag.Summarize) (*groupby.Op, error) {
-	keys, err := b.compileAssignments(summarize.Keys)
+	keyPaths, keyVals, err := b.compileStaticAssignments(summarize.Keys)
 	if err != nil {
 		return nil, err
 	}
@@ -22,7 +22,7 @@ func (b *Builder) compileGroupBy(parent zbuf.Puller, summarize *dag.Summarize) (
 		return nil, err
 	}
 	dir := order.Direction(summarize.InputSortDir)
-	return groupby.New(b.octx, parent, keys, names, reducers, summarize.Limit, dir, summarize.PartialsIn, summarize.PartialsOut)
+	return groupby.New(b.octx, parent, keyPaths, keyVals, names, reducers, summarize.Limit, dir, summarize.PartialsIn, summarize.PartialsOut)
 }
 
 func (b *Builder) compileAggAssignments(assignments []dag.Assignment) (field.List, []*expr.Aggregator, error) {
@@ -44,12 +44,12 @@ func (b *Builder) compileAggAssignment(assignment dag.Assignment) (field.Path, *
 	if !ok {
 		return nil, nil, errors.New("aggregator is not an aggregation expression")
 	}
-	lhs, err := compileLval(assignment.LHS)
-	if err != nil {
-		return nil, nil, fmt.Errorf("lhs of aggregation: %w", err)
+	this := assignment.LHS.StaticPath()
+	if this == nil {
+		return nil, nil, errors.New("internal error: aggregator assignment must be a static path")
 	}
 	m, err := b.compileAgg(aggAST)
-	return lhs, m, err
+	return slices.Clone(this.Path), m, err
 }
 
 func (b *Builder) compileAgg(agg *dag.Agg) (*expr.Aggregator, error) {

compiler/kernel/op.go

@@ -174,36 +174,13 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 		if err != nil {
 			return nil, err
 		}
-		putter, err := expr.NewPutter(b.octx.Zctx, clauses)
-		if err != nil {
-			return nil, err
-		}
+		putter := expr.NewPutter(b.octx.Zctx, clauses)
 		return op.NewApplier(b.octx, parent, putter), nil
 	case *dag.Rename:
 		var srcs, dsts field.List
-		for _, fa := range v.Args {
-			dst, err := compileLval(fa.LHS)
-			if err != nil {
-				return nil, err
-			}
-			// We call CompileLval on the RHS because renames are
-			// restricted to dotted field name expressions.
-			src, err := compileLval(fa.RHS)
-			if err != nil {
-				return nil, err
-			}
-			if len(dst) != len(src) {
-				return nil, fmt.Errorf("cannot rename %s to %s", src, dst)
-			}
-			// Check that the prefixes match and, if not, report first place
-			// that they don't.
-			for i := 0; i <= len(src)-2; i++ {
-				if src[i] != dst[i] {
-					return nil, fmt.Errorf("cannot rename %s to %s (differ in %s vs %s)", src, dst, src[i], dst[i])
-				}
-			}
-			dsts = append(dsts, dst)
-			srcs = append(srcs, src)
+		for k := range v.Dsts {
+			srcs = append(srcs, v.Srcs[k].Path)
+			dsts = append(dsts, v.Dsts[k].Path)
 		}
 		renamer := expr.NewRenamer(b.octx.Zctx, srcs, dsts)
 		return op.NewApplier(b.octx, parent, renamer), nil
@@ -376,6 +353,24 @@ func (b *Builder) compileOver(parent zbuf.Puller, over *dag.Over) (zbuf.Puller,
 	return scope.NewExit(exit), nil
 }
 
+func (b *Builder) compileStaticAssignments(assignments []dag.Assignment) ([]field.Path, []expr.Evaluator, error) {
+	lhs := make([]field.Path, 0, len(assignments))
+	rhs := make([]expr.Evaluator, 0, len(assignments))
+	for _, a := range assignments {
+		this := a.LHS.StaticPath()
+		if this == nil {
+			return nil, nil, errors.New("internal error: dynamic lhs assignment when expecting a static path")
+		}
+		lhs = append(lhs, slices.Clone(this.Path))
+		r, err := b.compileExpr(a.RHS)
+		if err != nil {
+			return nil, nil, err
+		}
+		rhs = append(rhs, r)
+	}
+	return lhs, rhs, nil
+}
+
 func (b *Builder) compileAssignments(assignments []dag.Assignment) ([]expr.Assignment, error) {
 	keys := make([]expr.Assignment, 0, len(assignments))
 	for _, assignment := range assignments {
@@ -388,9 +383,9 @@ func (b *Builder) compileAssignments(assignments []dag.Assignment) ([]expr.Assig
 	return keys, nil
 }
 
-func splitAssignments(assignments []expr.Assignment) (field.List, []expr.Evaluator) {
+func splitAssignments(assignments []expr.Assignment) ([]*expr.Path, []expr.Evaluator) {
 	n := len(assignments)
-	lhs := make(field.List, 0, n)
+	lhs := make([]*expr.Path, 0, n)
 	rhs := make([]expr.Evaluator, 0, n)
 	for _, a := range assignments {
 		lhs = append(lhs, a.LHS)

compiler/optimizer/op.go

@@ -52,9 +52,9 @@ func (o *Optimizer) analyzeSortKey(op dag.Op, in order.SortKey) (order.SortKey,
 		return in, nil
 	case *dag.Rename:
 		out := in
-		for _, assignment := range op.Args {
-			if fieldOf(assignment.RHS).Equal(key) {
-				lhs := fieldOf(assignment.LHS)
+		for k := range op.Dsts {
+			if fieldOf(op.Srcs[k]).Equal(key) {
+				lhs := fieldOf(op.Dsts[k])
 				out = order.NewSortKey(in.Order, field.List{lhs})
 			}
 		}
@@ -211,6 +211,11 @@ func fieldOf(e dag.Expr) field.Path {
 	if this, ok := e.(*dag.This); ok {
 		return this.Path
 	}
+	if path, ok := e.(*dag.Path); ok {
+		if this := path.StaticPath(); this != nil {
+			return this.Path
+		}
+	}
 	return nil
 }