Add more optimizations

Author: antonmedv

compiler/compiler.go

@@ -367,18 +367,6 @@ func (c *compiler) BinaryNode(node *ast.BinaryNode) {
 		c.emit(OpEndsWith)
 
 	case "..":
-		min, ok1 := node.Left.(*ast.IntegerNode)
-		max, ok2 := node.Right.(*ast.IntegerNode)
-		if ok1 && ok2 {
-			// Create range on compile time to avoid unnecessary work at runtime.
-			size := max.Value - min.Value + 1
-			rng := make([]interface{}, size)
-			for i := range rng {
-				rng[i] = min.Value + i
-			}
-			c.emitPush(rng)
-			return
-		}
 		c.compile(node.Left)
 		c.compile(node.Right)
 		c.emit(OpRange)

compiler/compiler_test.go

@@ -130,17 +130,6 @@ func TestCompile(t *testing.T) {
 				},
 			},
 		},
-		{
-			`1..2`,
-			vm.Program{
-				Constants: []interface{}{
-					[]interface{}{1, 2},
-				},
-				Bytecode: []byte{
-					vm.OpPush, 0, 0,
-				},
-			},
-		},
 	}
 
 	for _, test := range tests {

expr_test.go

@@ -583,6 +583,14 @@ func TestExpr(t *testing.T) {
 			`One in 0..1 && Two not in 0..1`,
 			true,
 		},
+		{
+			`1 + 2 + Three`,
+			6,
+		},
+		{
+			`2 ** 8`,
+			float64(256),
+		},
 	}
 
 	for _, tt := range tests {

optimizer/optimizer.go

@@ -2,14 +2,52 @@ package optimizer
 
 import (
 	. "github.com/antonmedv/expr/ast"
+	"math"
 )
 
 type fold struct{}
 type inRange struct{}
+type constRange struct{}
 
 func (*fold) Enter(node *Node) {}
 func (*fold) Exit(node *Node) {
 	switch n := (*node).(type) {
+	case *UnaryNode:
+		if n.Operator == "-" {
+			if i, ok := n.Node.(*IntegerNode); ok {
+				*node = &IntegerNode{
+					Value: -i.Value,
+				}
+			}
+		}
+
+	case *BinaryNode:
+		switch n.Operator {
+		case "+":
+			if a, ok := n.Left.(*IntegerNode); ok {
+				if b, ok := n.Right.(*IntegerNode); ok {
+					*node = &IntegerNode{
+						Value: a.Value + b.Value,
+					}
+				}
+			}
+			if a, ok := n.Left.(*StringNode); ok {
+				if b, ok := n.Right.(*StringNode); ok {
+					*node = &StringNode{
+						Value: a.Value + b.Value,
+					}
+				}
+			}
+		case "**":
+			if a, ok := n.Left.(*IntegerNode); ok {
+				if b, ok := n.Right.(*IntegerNode); ok {
+					*node = &FloatNode{
+						Value: math.Pow(float64(a.Value), float64(b.Value)),
+					}
+				}
+			}
+		}
+
 	case *ArrayNode:
 		if len(n.Nodes) > 0 {
 
@@ -54,8 +92,8 @@ func (*inRange) Exit(node *Node) {
 	case *BinaryNode:
 		if n.Operator == "in" || n.Operator == "not in" {
 			if rng, ok := n.Right.(*BinaryNode); ok && rng.Operator == ".." {
-				if from, ok := n.Left.(*IntegerNode); ok {
-					if to, ok := n.Right.(*IntegerNode); ok {
+				if from, ok := rng.Left.(*IntegerNode); ok {
+					if to, ok := rng.Right.(*IntegerNode); ok {
 						*node = &BinaryNode{
 							Operator: "and",
 							Left: &BinaryNode{
@@ -82,7 +120,29 @@ func (*inRange) Exit(node *Node) {
 	}
 }
 
+func (*constRange) Enter(node *Node) {}
+func (*constRange) Exit(node *Node) {
+	switch n := (*node).(type) {
+	case *BinaryNode:
+		if n.Operator == ".." {
+			if min, ok := n.Left.(*IntegerNode); ok {
+				if max, ok := n.Right.(*IntegerNode); ok {
+					size := max.Value - min.Value + 1
+					value := make([]int, size)
+					for i := range value {
+						value[i] = min.Value + i
+					}
+					*node = &ConstantNode{
+						Value: value,
+					}
+				}
+			}
+		}
+	}
+}
+
 func Optimize(node *Node) {
 	Walk(node, &fold{})
 	Walk(node, &inRange{})
+	Walk(node, &constRange{})
 }

optimizer/optimizer_test.go

@@ -31,16 +31,21 @@ func TestOptimize_in_range(t *testing.T) {
 
 	optimizer.Optimize(&tree.Node)
 
+	left := &ast.IdentifierNode{
+		Value: "age",
+	}
 	expected := &ast.BinaryNode{
-		Operator: "in",
-		Left: &ast.IdentifierNode{
-			Value: "age",
-		},
-		Right: &ast.BinaryNode{
-			Operator: "..",
-			Left: &ast.IntegerNode{
+		Operator: "and",
+		Left: &ast.BinaryNode{
+			Operator: ">=",
+			Left:     left,
+			Right: &ast.IntegerNode{
 				Value: 18,
 			},
+		},
+		Right: &ast.BinaryNode{
+			Operator: "<=",
+			Left:     left,
 			Right: &ast.IntegerNode{
 				Value: 31,
 			},
@@ -49,3 +54,16 @@ func TestOptimize_in_range(t *testing.T) {
 
 	assert.Equal(t, litter.Sdump(expected), litter.Sdump(tree.Node))
 }
+
+func TestOptimize_const_range(t *testing.T) {
+	tree, err := parser.Parse(`-1..1`)
+	require.NoError(t, err)
+
+	optimizer.Optimize(&tree.Node)
+
+	expected := &ast.ConstantNode{
+		Value: []int{-1, 0, 1},
+	}
+
+	assert.Equal(t, litter.Sdump(expected), litter.Sdump(tree.Node))
+}