Add subpackage for expression string eval

cointop/portfolio.go

@@ -12,8 +12,8 @@ import (
 	"time"
 	"unicode/utf8"
 
-	"github.com/Knetic/govaluate"
 	"github.com/miguelmota/cointop/pkg/asciitable"
+	"github.com/miguelmota/cointop/pkg/eval"
 	"github.com/miguelmota/cointop/pkg/humanize"
 	"github.com/miguelmota/cointop/pkg/pad"
 	"github.com/miguelmota/cointop/pkg/table"
@@ -435,22 +435,11 @@ func (ct *Cointop) SetPortfolioHoldings() error {
 		return nil
 	}
 
-	var holdings float64 = 0
-	input := strings.TrimSpace(string(b[:n])) // remove trailing \0s
-	if input != "" {
-		expression, err := govaluate.NewEvaluableExpression(input)
-		if err != nil {
-			return nil // invalid expression - don't change anything
-		}
-		result, err := expression.Evaluate(nil)
-		if err != nil {
-			return nil // could not evaluate - don't change anything
-		}
-		var ok bool
-		holdings, ok = result.(float64)
-		if !ok {
-			return nil // not a float64 - don't change anything
-		}
+	input := string(b[:n])
+	holdings, err := eval.EvaluateExpressionToFloat64(input)
+	if err != nil {
+		// leave value as is if expression can't be evaluated
+		return nil
 	}
 	shouldDelete := holdings == 0
 

go.mod

@@ -2,7 +2,7 @@ module github.com/miguelmota/cointop
 
 require (
 	github.com/BurntSushi/toml v0.3.1
-	github.com/Knetic/govaluate v3.0.0+incompatible // indirect
+	github.com/Knetic/govaluate v3.0.0+incompatible
 	github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d
 	github.com/anaskhan96/soup v1.1.1 // indirect
 	github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be // indirect

pkg/eval/eval.go

@@ -0,0 +1,29 @@
+package eval
+
+import (
+	"errors"
+	"strings"
+
+	"github.com/Knetic/govaluate"
+)
+
+// EvaluateExpression ...
+func EvaluateExpressionToFloat64(expressionInput string) (float64, error) {
+	expressionInput = strings.TrimSpace(expressionInput) // remove trailing \0s
+	if expressionInput == "" {
+		return 0, nil
+	}
+	expression, err := govaluate.NewEvaluableExpression(expressionInput)
+	if err != nil {
+		return 0, err
+	}
+	result, err := expression.Evaluate(nil)
+	if err != nil {
+		return 0, err
+	}
+	f64, ok := result.(float64)
+	if !ok {
+		return 0, errors.New("could not type assert float64")
+	}
+	return f64, nil
+}