vam: Add abs function

runtime/sam/expr/function/math.go

@@ -14,7 +14,7 @@ type Abs struct {
 }
 
 func (a *Abs) Call(_ super.Allocator, args []super.Value) super.Value {
-	val := args[0]
+	val := args[0].Under()
 	switch id := val.Type().ID(); {
 	case super.IsUnsigned(id):
 		return val

runtime/vam/expr/function/function.go

@@ -16,6 +16,8 @@ func New(zctx *super.Context, name string, narg int) (expr.Function, field.Path,
 	var path field.Path
 	var f expr.Function
 	switch name {
+	case "abs":
+		f = &Abs{zctx}
 	case "base64":
 		f = &Base64{zctx}
 	case "bucket":

runtime/vam/expr/function/math.go

@@ -0,0 +1,62 @@
+package function
+
+import (
+	"math"
+
+	"github.com/brimdata/super"
+	"github.com/brimdata/super/vector"
+)
+
+// https://github.com/brimdata/super/blob/main/docs/language/functions.md#abs.md
+type Abs struct {
+	zctx *super.Context
+}
+
+func (a *Abs) Call(args ...vector.Any) vector.Any {
+	vec := vector.Under(args[0])
+	switch id := vec.Type().ID(); {
+	case super.IsUnsigned(id):
+		return vec
+	case super.IsSigned(id) || super.IsFloat(id):
+		return a.abs(vec)
+	}
+	return vector.NewWrappedError(a.zctx, "abs: not a number", vec)
+}
+
+func (a *Abs) abs(vec vector.Any) vector.Any {
+	switch vec := vec.(type) {
+	case *vector.Const:
+		var val super.Value
+		if super.IsFloat(vec.Type().ID()) {
+			val = super.NewFloat(vec.Type(), math.Abs(vec.Value().Float()))
+		} else {
+			v := vec.Value().Int()
+			if v < 0 {
+				v = -v
+			}
+			val = super.NewInt(vec.Type(), v)
+		}
+		return vector.NewConst(val, vec.Len(), vec.Nulls)
+	case *vector.View:
+		return vector.NewView(a.abs(vec.Any), vec.Index)
+	case *vector.Dict:
+		return vector.NewDict(a.abs(vec.Any), vec.Index, vec.Counts, vec.Nulls)
+	case *vector.Int:
+		var ints []int64
+		for _, v := range vec.Values {
+			if v < 0 {
+				v = -v
+			}
+			ints = append(ints, v)
+		}
+		return vector.NewInt(vec.Type(), ints, vec.Nulls)
+	case *vector.Float:
+		var floats []float64
+		for _, v := range vec.Values {
+			floats = append(floats, math.Abs(v))
+		}
+		return vector.NewFloat(vec.Type(), floats, vec.Nulls)
+	default:
+		panic(vec)
+	}
+}

runtime/ztests/expr/function/abs.yaml

@@ -0,0 +1,23 @@
+zed: abs(this)
+
+vector: true
+
+input: |
+  1
+  -1
+  0
+  1.0
+  -1.0
+  -1(int8)
+  1(uint8)
+  "foo"
+
+output: |
+  1
+  1
+  0
+  1.
+  1.
+  1(int8)
+  1(uint8)
+  error({message:"abs: not a number",on:"foo"})