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ferret/pkg/runtime/expressions/condition.go
2018-10-28 01:45:26 -04:00

68 lines
1.2 KiB
Go

package expressions
import (
"context"
"github.com/MontFerret/ferret/pkg/runtime/core"
"github.com/MontFerret/ferret/pkg/runtime/values"
)
type ConditionExpression struct {
src core.SourceMap
test core.Expression
consequent core.Expression
alternate core.Expression
}
func NewConditionExpression(
src core.SourceMap,
test core.Expression,
consequent core.Expression,
alternate core.Expression,
) (*ConditionExpression, error) {
if test == nil {
return nil, core.Error(core.ErrMissedArgument, "test expression")
}
if alternate == nil {
return nil, core.Error(core.ErrMissedArgument, "alternate expression")
}
return &ConditionExpression{
src,
test,
consequent,
alternate,
}, nil
}
func (e *ConditionExpression) Exec(ctx context.Context, scope *core.Scope) (core.Value, error) {
out, err := e.test.Exec(ctx, scope)
if err != nil {
return values.None, core.SourceError(e.src, err)
}
cond := values.ToBoolean(out)
var next core.Expression
if cond == values.True {
next = e.consequent
// shortcut version
if next == nil {
return out, nil
}
} else {
next = e.alternate
}
res, err := next.Exec(ctx, scope)
if err != nil {
return values.None, core.SourceError(e.src, err)
}
return res, nil
}