Add better examples

Author: antonmedv

docs/examples/dates_test.go

@@ -0,0 +1,84 @@
+package examples
+
+import (
+	"testing"
+	"time"
+
+	"github.com/antonmedv/expr"
+	"github.com/stretchr/testify/require"
+)
+
+func TestExamples_dates(t *testing.T) {
+	code := `
+		Now() > Date("2020-01-01") &&
+		Now() - CreatedAt > Duration("24h")
+	`
+
+	options := []expr.Option{
+		expr.Env(Env{}),
+
+		// Operators override for date comprising.
+		expr.Operator("==", "Equal"),
+		expr.Operator("<", "Before"),
+		expr.Operator("<=", "BeforeOrEqual"),
+		expr.Operator(">", "After"),
+		expr.Operator(">=", "AfterOrEqual"),
+
+		// Time and duration manipulation.
+		expr.Operator("+", "Add"),
+		expr.Operator("-", "Sub"),
+
+		// Operators override for duration comprising.
+		expr.Operator("==", "EqualDuration"),
+		expr.Operator("<", "BeforeDuration"),
+		expr.Operator("<=", "BeforeOrEqualDuration"),
+		expr.Operator(">", "AfterDuration"),
+		expr.Operator(">=", "AfterOrEqualDuration"),
+	}
+
+	program, err := expr.Compile(code, options...)
+	require.NoError(t, err)
+
+	env := Env{
+		CreatedAt: Env{}.Date("2018-07-14"), // first commit date
+	}
+
+	output, err := expr.Run(program, env)
+	require.NoError(t, err)
+	require.Equal(t, true, output)
+}
+
+type Env struct {
+	datetime
+	CreatedAt time.Time
+}
+
+type datetime struct{}
+
+func (datetime) Date(s string) time.Time {
+	t, err := time.Parse("2006-01-02", s)
+	if err != nil {
+		panic(err)
+	}
+	return t
+}
+func (datetime) Duration(s string) time.Duration {
+	d, err := time.ParseDuration(s)
+	if err != nil {
+		panic(err)
+	}
+	return d
+}
+func (datetime) Now() time.Time                                { return time.Now() }
+func (datetime) Equal(a, b time.Time) bool                     { return a.Equal(b) }
+func (datetime) Before(a, b time.Time) bool                    { return a.Before(b) }
+func (datetime) BeforeOrEqual(a, b time.Time) bool             { return a.Before(b) || a.Equal(b) }
+func (datetime) After(a, b time.Time) bool                     { return a.After(b) }
+func (datetime) AfterOrEqual(a, b time.Time) bool              { return a.After(b) || a.Equal(b) }
+func (datetime) Add(a time.Time, b time.Duration) time.Time    { return a.Add(b) }
+func (datetime) Sub(a, b time.Time) time.Duration              { return a.Sub(b) }
+func (datetime) EqualDuration(a, b time.Duration) bool         { return a == b }
+func (datetime) BeforeDuration(a, b time.Duration) bool        { return a < b }
+func (datetime) BeforeOrEqualDuration(a, b time.Duration) bool { return a <= b }
+func (datetime) AfterDuration(a, b time.Duration) bool         { return a > b }
+func (datetime) AfterOrEqualDuration(a, b time.Duration) bool  { return a >= b }