1 files changed, 78 insertions, 0 deletions
diff --git a/region_cached.go b/region_cached.go
new file mode 100644
index 0000000..66cea16
--- /dev/null
+++ b/region_cached.go
@@ -0,0 +1,78 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"github.com/kch42/gomcmap/mcmap"
+)
+
+type CachedRegion struct {
+	Region      *mcmap.Region
+	cacheChunks []*mcmap.Chunk
+	cachePos    []XZPos
+	cachesize   int
+}
+
+func NewCachedRegion(reg *mcmap.Region, cachesize int) *CachedRegion {
+	if cachesize <= 0 {
+		panic(errors.New("Cachesize must be >0"))
+	}
+	return &CachedRegion{
+		Region:      reg,
+		cacheChunks: make([]*mcmap.Chunk, cachesize),
+		cachePos:    make([]XZPos, cachesize),
+		cachesize:   cachesize,
+	}
+}
+
+func (cr *CachedRegion) Chunk(x, z int) (*mcmap.Chunk, error) {
+	pos := XZPos{x, z}
+
+	for i, p := range cr.cachePos {
+		if p == pos {
+			if cr.cacheChunks[i] != nil {
+				chunk := cr.cacheChunks[i]
+				for j := i; j >= 1; j-- {
+					cr.cacheChunks[j] = cr.cacheChunks[j-1]
+					cr.cachePos[j] = cr.cachePos[j-1]
+				}
+				return chunk, nil
+			}
+		}
+	}
+
+	chunk, err := cr.Region.Chunk(x, z)
+	if err != nil {
+		return nil, err
+	}
+
+	if cr.cacheChunks[cr.cachesize-1] != nil {
+		if err := cr.cacheChunks[cr.cachesize-1].MarkUnused(); err != nil {
+			return nil, fmt.Errorf("Could not remove oldest cache element: %s", err)
+		}
+	}
+
+	for i := cr.cachesize - 1; i >= 1; i-- {
+		cr.cacheChunks[i] = cr.cacheChunks[i-1]
+		cr.cachePos[i] = cr.cachePos[i-1]
+	}
+	cr.cacheChunks[0] = chunk
+	cr.cachePos[0] = pos
+
+	return chunk, nil
+}
+
+func (cr *CachedRegion) Flush() error {
+	for i, chunk := range cr.cacheChunks {
+		if chunk == nil {
+			continue
+		}
+
+		if err := chunk.MarkUnused(); err != nil {
+			return err
+		}
+		cr.cacheChunks[i] = nil
+	}
+
+	return nil
+}