1 files changed, 191 insertions, 0 deletions
diff --git a/pkg/jsonpath/funcs.go b/pkg/jsonpath/funcs.go
new file mode 100644
index 0000000..b745a33
--- /dev/null
+++ b/pkg/jsonpath/funcs.go
@@ -0,0 +1,191 @@
+package jsonpath
+
+// This file is copied from the Kubernetes jsonpath implementation and stripped of unused parts.
+
+//This file is copied from Go library text/template.
+//The original private functions eq, ge, gt, le, lt, and ne
+//are exported as public functions.
+
+import (
+	"errors"
+	"reflect"
+)
+
+var Equal = eq
+var GreaterEqual = ge
+var Greater = gt
+var LessEqual = le
+var Less = lt
+var NotEqual = ne
+
+// Comparison.
+
+// TODO: Perhaps allow comparison between signed and unsigned integers.
+
+var (
+	errBadComparisonType = errors.New("invalid type for comparison")
+	errBadComparison     = errors.New("incompatible types for comparison")
+	errNoComparison      = errors.New("missing argument for comparison")
+)
+
+type kind int
+
+const (
+	invalidKind kind = iota
+	boolKind
+	complexKind
+	intKind
+	floatKind
+	integerKind
+	stringKind
+	uintKind
+)
+
+func basicKind(v reflect.Value) (kind, error) {
+	switch v.Kind() {
+	case reflect.Bool:
+		return boolKind, nil
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return intKind, nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return uintKind, nil
+	case reflect.Float32, reflect.Float64:
+		return floatKind, nil
+	case reflect.Complex64, reflect.Complex128:
+		return complexKind, nil
+	case reflect.String:
+		return stringKind, nil
+	}
+	return invalidKind, errBadComparisonType
+}
+
+// eq evaluates the comparison a == b || a == c || ...
+func eq(arg1 interface{}, arg2 ...interface{}) (bool, error) {
+	v1 := reflect.ValueOf(arg1)
+	k1, err := basicKind(v1)
+	if err != nil {
+		return false, err
+	}
+	if len(arg2) == 0 {
+		return false, errNoComparison
+	}
+	for _, arg := range arg2 {
+		v2 := reflect.ValueOf(arg)
+		k2, err := basicKind(v2)
+		if err != nil {
+			return false, err
+		}
+		truth := false
+		if k1 != k2 {
+			// Special case: Can compare integer values regardless of type's sign.
+			switch {
+			case k1 == intKind && k2 == uintKind:
+				truth = v1.Int() >= 0 && uint64(v1.Int()) == v2.Uint()
+			case k1 == uintKind && k2 == intKind:
+				truth = v2.Int() >= 0 && v1.Uint() == uint64(v2.Int())
+			default:
+				return false, errBadComparison
+			}
+		} else {
+			switch k1 {
+			case boolKind:
+				truth = v1.Bool() == v2.Bool()
+			case complexKind:
+				truth = v1.Complex() == v2.Complex()
+			case floatKind:
+				truth = v1.Float() == v2.Float()
+			case intKind:
+				truth = v1.Int() == v2.Int()
+			case stringKind:
+				truth = v1.String() == v2.String()
+			case uintKind:
+				truth = v1.Uint() == v2.Uint()
+			default:
+				panic("invalid kind")
+			}
+		}
+		if truth {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+// ne evaluates the comparison a != b.
+func ne(arg1, arg2 interface{}) (bool, error) {
+	// != is the inverse of ==.
+	equal, err := eq(arg1, arg2)
+	return !equal, err
+}
+
+// lt evaluates the comparison a < b.
+func lt(arg1, arg2 interface{}) (bool, error) {
+	v1 := reflect.ValueOf(arg1)
+	k1, err := basicKind(v1)
+	if err != nil {
+		return false, err
+	}
+	v2 := reflect.ValueOf(arg2)
+	k2, err := basicKind(v2)
+	if err != nil {
+		return false, err
+	}
+	truth := false
+	if k1 != k2 {
+		// Special case: Can compare integer values regardless of type's sign.
+		switch {
+		case k1 == intKind && k2 == uintKind:
+			truth = v1.Int() < 0 || uint64(v1.Int()) < v2.Uint()
+		case k1 == uintKind && k2 == intKind:
+			truth = v2.Int() >= 0 && v1.Uint() < uint64(v2.Int())
+		default:
+			return false, errBadComparison
+		}
+	} else {
+		switch k1 {
+		case boolKind, complexKind:
+			return false, errBadComparisonType
+		case floatKind:
+			truth = v1.Float() < v2.Float()
+		case intKind:
+			truth = v1.Int() < v2.Int()
+		case stringKind:
+			truth = v1.String() < v2.String()
+		case uintKind:
+			truth = v1.Uint() < v2.Uint()
+		default:
+			panic("invalid kind")
+		}
+	}
+	return truth, nil
+}
+
+// le evaluates the comparison <= b.
+func le(arg1, arg2 interface{}) (bool, error) {
+	// <= is < or ==.
+	lessThan, err := lt(arg1, arg2)
+	if lessThan || err != nil {
+		return lessThan, err
+	}
+	return eq(arg1, arg2)
+}
+
+// gt evaluates the comparison a > b.
+func gt(arg1, arg2 interface{}) (bool, error) {
+	// > is the inverse of <=.
+	lessOrEqual, err := le(arg1, arg2)
+	if err != nil {
+		return false, err
+	}
+	return !lessOrEqual, nil
+}
+
+// ge evaluates the comparison a >= b.
+func ge(arg1, arg2 interface{}) (bool, error) {
+	// >= is the inverse of <.
+	lessThan, err := lt(arg1, arg2)
+	if err != nil {
+		return false, err
+	}
+	return !lessThan, nil
+}