feat: connect to spicedb

1 files changed, 98 insertions, 0 deletions

diff --git a/vendor/github.com/dalzilio/rudd/replace.go b/vendor/github.com/dalzilio/rudd/replace.go
new file mode 100644
index 0000000..6a33658
--- /dev/null
+++ b/vendor/github.com/dalzilio/rudd/replace.go
@@ -0,0 +1,98 @@
+// Copyright (c) 2021 Silvano DAL ZILIO
+//
+// MIT License
+
+package rudd
+
+import (
+	"fmt"
+	"math"
+)
+
+var _REPLACEID = 1
+
+// Replacer is the types of substitution objects used in a Replace operation,
+// that substitutes variables in a BDD "function". The only method returning an
+// object of this type is the NewReplacer method. The result obtained when using
+// a replacer created from a BDD, in a Replace operation over a different BDD is
+// unspecified.
+type Replacer interface {
+	Replace(int32) (int32, bool)
+	Id() int
+}
+
+type replacer struct {
+	id    int     // unique identifier used for caching intermediate results
+	image []int32 // map the level of old variables to the level of new variables
+	last  int32   // last index in the Replacer, to speed up computations
+}
+
+func (r *replacer) String() string {
+	res := fmt.Sprintf("replacer(last: %d)[", r.last)
+	first := true
+	for k, v := range r.image {
+		if k != int(v) {
+			if !first {
+				res += ", "
+			}
+			first = false
+			res += fmt.Sprintf("%d<-%d", k, v)
+		}
+	}
+	return res + "]"
+}
+
+func (r *replacer) Replace(level int32) (int32, bool) {
+	if level > r.last {
+		return level, false
+	}
+	return r.image[level], true
+}
+
+func (r *replacer) Id() int {
+	return r.id
+}
+
+// NewReplacer returns a Replacer that can be used for substituting variable
+// oldvars[k] with newvars[k] in the BDD b. We return an error if the two slices
+// do not have the same length or if we find the same index twice in either of
+// them. All values must be in the interval [0..Varnum).
+func (b *BDD) NewReplacer(oldvars, newvars []int) (Replacer, error) {
+	res := &replacer{}
+	if len(oldvars) != len(newvars) {
+		return nil, fmt.Errorf("unmatched length of slices")
+	}
+	if _REPLACEID == (math.MaxInt32 >> 2) {
+		return nil, fmt.Errorf("too many replacers created")
+	}
+	res.id = (_REPLACEID << 2) | cacheidREPLACE
+	_REPLACEID++
+	varnum := b.Varnum()
+	support := make([]bool, varnum)
+	res.image = make([]int32, varnum)
+	for k := range res.image {
+		res.image[k] = int32(k)
+	}
+	for k, v := range oldvars {
+		if support[v] {
+			return nil, fmt.Errorf("duplicate variable (%d) in oldvars", v)
+		}
+		if v >= varnum {
+			return nil, fmt.Errorf("invalid variable in oldvars (%d)", v)
+		}
+		if newvars[k] >= varnum {
+			return nil, fmt.Errorf("invalid variable in newvars (%d)", v)
+		}
+		support[v] = true
+		res.image[v] = int32(newvars[k])
+		if int32(v) > res.last {
+			res.last = int32(v)
+		}
+	}
+	for _, v := range newvars {
+		if int(res.image[v]) != v {
+			return nil, fmt.Errorf("variable in newvars (%d) also occur in oldvars", v)
+		}
+	}
+	return res, nil
+}