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binaryexpr.go
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binaryexpr.go
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// Copyright 2017 Baliance. All rights reserved.
//
// Use of this source code is governed by the terms of the Affero GNU General
// Public License version 3.0 as published by the Free Software Foundation and
// appearing in the file LICENSE included in the packaging of this file. A
// commercial license can be purchased by contacting sales@baliance.com.
package formula
import (
"fmt"
"math"
)
// BinOpType is the binary operation operator type
//go:generate stringer -type=BinOpType
type BinOpType byte
// Operator type constants
const (
BinOpTypeUnknown BinOpType = iota
BinOpTypePlus
BinOpTypeMinus
BinOpTypeMult
BinOpTypeDiv
BinOpTypeExp
BinOpTypeLT
BinOpTypeGT
BinOpTypeEQ
BinOpTypeLEQ
BinOpTypeGEQ
BinOpTypeNE
BinOpTypeConcat // '&' in Excel
)
// BinaryExpr is a binary expression.
type BinaryExpr struct {
lhs, rhs Expression
op BinOpType
}
// NewBinaryExpr constructs a new binary expression with a given operator.
func NewBinaryExpr(lhs Expression, op BinOpType, rhs Expression) Expression {
return BinaryExpr{lhs, rhs, op}
}
// Eval evaluates the binary expression using the context given.
func (b BinaryExpr) Eval(ctx Context, ev Evaluator) Result {
lhs := b.lhs.Eval(ctx, ev)
rhs := b.rhs.Eval(ctx, ev)
// peel off array/list ops first
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeArray {
if !sameDim(lhs.ValueArray, rhs.ValueArray) {
return MakeErrorResult("lhs/rhs should have same dimensions")
}
return arrayOp(b.op, lhs.ValueArray, rhs.ValueArray)
} else if lhs.Type == ResultTypeList {
if len(lhs.ValueList) != len(rhs.ValueList) {
return MakeErrorResult("lhs/rhs should have same dimensions")
}
return listOp(b.op, lhs.ValueList, rhs.ValueList)
}
}
// TODO: check for and add support for binary operators on boolean values
switch b.op {
case BinOpTypePlus:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeNumberResult(lhs.ValueNumber + rhs.ValueNumber)
}
}
case BinOpTypeMinus:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeNumberResult(lhs.ValueNumber - rhs.ValueNumber)
}
}
case BinOpTypeMult:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeNumberResult(lhs.ValueNumber * rhs.ValueNumber)
}
}
case BinOpTypeDiv:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
if rhs.ValueNumber == 0 {
return MakeErrorResultType(ErrorTypeDivideByZero, "divide by zero")
}
return MakeNumberResult(lhs.ValueNumber / rhs.ValueNumber)
}
}
case BinOpTypeExp:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeNumberResult(math.Pow(lhs.ValueNumber, rhs.ValueNumber))
}
}
case BinOpTypeLT:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeBoolResult(lhs.ValueNumber < rhs.ValueNumber)
}
}
case BinOpTypeGT:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeBoolResult(lhs.ValueNumber > rhs.ValueNumber)
}
}
case BinOpTypeEQ:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
// TODO: see what Excel does regarding floating point comparison
return MakeBoolResult(lhs.ValueNumber == rhs.ValueNumber)
}
}
case BinOpTypeNE:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeBoolResult(lhs.ValueNumber != rhs.ValueNumber)
}
}
case BinOpTypeLEQ:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeBoolResult(lhs.ValueNumber <= rhs.ValueNumber)
}
}
case BinOpTypeGEQ:
if lhs.Type == rhs.Type {
if lhs.Type == ResultTypeNumber {
return MakeBoolResult(lhs.ValueNumber >= rhs.ValueNumber)
}
}
case BinOpTypeConcat:
return MakeStringResult(lhs.Value() + rhs.Value())
}
return MakeErrorResult("unsupported binary op")
}
func (b BinaryExpr) Reference(ctx Context, ev Evaluator) Reference {
return ReferenceInvalid
}
// sameDim returns true if the arrays have the same dimensions.
func sameDim(lhs, rhs [][]Result) bool {
if len(lhs) != len(rhs) {
return false
}
for i := range lhs {
if len(lhs[i]) != len(rhs[i]) {
return false
}
}
return true
}
func arrayOp(op BinOpType, lhs, rhs [][]Result) Result {
// we can assume the arrays are the same size here
res := [][]Result{}
for i := range lhs {
lst := listOp(op, lhs[i], rhs[i])
if lst.Type == ResultTypeError {
return lst
}
res = append(res, lst.ValueList)
}
return MakeArrayResult(res)
}
func listOp(op BinOpType, lhs, rhs []Result) Result {
res := []Result{}
// we can assume the arrays are the same size here
for i := range lhs {
l := lhs[i].AsNumber()
r := rhs[i].AsNumber()
if l.Type != ResultTypeNumber || r.Type != ResultTypeNumber {
return MakeErrorResult("non-nunmeric value in binary operation")
}
switch op {
case BinOpTypePlus:
res = append(res, MakeNumberResult(l.ValueNumber+r.ValueNumber))
case BinOpTypeMinus:
res = append(res, MakeNumberResult(l.ValueNumber-r.ValueNumber))
case BinOpTypeMult:
res = append(res, MakeNumberResult(l.ValueNumber*r.ValueNumber))
case BinOpTypeDiv:
if r.ValueNumber == 0 {
return MakeErrorResultType(ErrorTypeDivideByZero, "")
}
res = append(res, MakeNumberResult(l.ValueNumber/r.ValueNumber))
case BinOpTypeExp:
res = append(res, MakeNumberResult(math.Pow(l.ValueNumber, r.ValueNumber)))
case BinOpTypeLT:
res = append(res, MakeBoolResult(l.ValueNumber < r.ValueNumber))
case BinOpTypeGT:
res = append(res, MakeBoolResult(l.ValueNumber > r.ValueNumber))
case BinOpTypeEQ:
res = append(res, MakeBoolResult(l.ValueNumber == r.ValueNumber))
case BinOpTypeLEQ:
res = append(res, MakeBoolResult(l.ValueNumber <= r.ValueNumber))
case BinOpTypeGEQ:
res = append(res, MakeBoolResult(l.ValueNumber >= r.ValueNumber))
case BinOpTypeNE:
res = append(res, MakeBoolResult(l.ValueNumber != r.ValueNumber))
// TODO: support concat here
// case BinOpTypeConcat:
default:
return MakeErrorResult(fmt.Sprintf("unsupported list binary op %s", op))
}
}
return MakeListResult(res)
}