Read a ledger: an instance's state, its history oldest first with sequence and author, a watch of its states, a declared index (issue 1966 T3)

node-tools/internal/ledger/memory.go

@@ -1,9 +1,12 @@
 package ledger
 
 import (
+	"encoding/json"
 	"sort"
 	"strings"
 	"sync"
+
+	"git.novox.be/novox/mesh-sdk/go/buscalls"
 )
 
 // The memory stores keep what the bus keeps, as the bus answers it, for a test of a ledger without a bus: a stream whose
@@ -156,3 +159,49 @@ func (s *MemorySnapshots) Put(key string, value []byte, expect uint64) error {
 	s.kv[key] = memoryValue{value, s.at}
 	return nil
 }
+
+// MemoryIndex is an index's bucket in memory.
+type MemoryIndex struct {
+	mu sync.Mutex
+	kv map[string][]byte
+}
+
+func (x *MemoryIndex) Entries(pattern string, limit int) ([]buscalls.IndexEntry, error) {
+	x.mu.Lock()
+	defer x.mu.Unlock()
+	if pattern == "" {
+		pattern = ">"
+	}
+	var keys []string
+	for k := range x.kv {
+		if Matches(pattern, k) {
+			keys = append(keys, k)
+		}
+	}
+	sort.Strings(keys)
+	var out []buscalls.IndexEntry
+	for _, k := range keys {
+		if limit > 0 && len(out) >= limit {
+			break
+		}
+		out = append(out, buscalls.IndexEntry{Key: k, Value: json.RawMessage(x.kv[k])})
+	}
+	return out, nil
+}
+
+func (x *MemoryIndex) Put(key string, value []byte) error {
+	x.mu.Lock()
+	defer x.mu.Unlock()
+	if x.kv == nil {
+		x.kv = map[string][]byte{}
+	}
+	x.kv[key] = value
+	return nil
+}
+
+func (x *MemoryIndex) Delete(key string) error {
+	x.mu.Lock()
+	defer x.mu.Unlock()
+	delete(x.kv, key)
+	return nil
+}