Initial QSfera import

Server/vendor/go-micro.dev/v4/metadata/metadata.go

@@ -0,0 +1,126 @@
+// Package metadata is a way of defining message headers
+package metadata
+
+import (
+	"context"
+	"strings"
+)
+
+type metadataKey struct{}
+
+// Metadata is our way of representing request headers internally.
+// They're used at the RPC level and translate back and forth
+// from Transport headers.
+type Metadata map[string]string
+
+func (md Metadata) Get(key string) (string, bool) {
+	// attempt to get as is
+	val, ok := md[key]
+	if ok {
+		return val, ok
+	}
+
+	// attempt to get lower case
+	val, ok = md[strings.Title(key)]
+	return val, ok
+}
+
+func (md Metadata) Set(key, val string) {
+	md[key] = val
+}
+
+func (md Metadata) Delete(key string) {
+	// delete key as-is
+	delete(md, key)
+	// delete also Title key
+	delete(md, strings.Title(key))
+}
+
+// Copy makes a copy of the metadata.
+func Copy(md Metadata) Metadata {
+	cmd := make(Metadata, len(md))
+	for k, v := range md {
+		cmd[k] = v
+	}
+	return cmd
+}
+
+// Delete key from metadata.
+func Delete(ctx context.Context, k string) context.Context {
+	return Set(ctx, k, "")
+}
+
+// Set add key with val to metadata.
+func Set(ctx context.Context, k, v string) context.Context {
+	md, ok := FromContext(ctx)
+	if !ok {
+		md = make(Metadata)
+	}
+	if v == "" {
+		delete(md, k)
+	} else {
+		md[k] = v
+	}
+	return context.WithValue(ctx, metadataKey{}, md)
+}
+
+// Get returns a single value from metadata in the context.
+func Get(ctx context.Context, key string) (string, bool) {
+	md, ok := FromContext(ctx)
+	if !ok {
+		return "", ok
+	}
+	// attempt to get as is
+	val, ok := md[key]
+	if ok {
+		return val, ok
+	}
+
+	// attempt to get lower case
+	val, ok = md[strings.Title(key)]
+
+	return val, ok
+}
+
+// FromContext returns metadata from the given context.
+func FromContext(ctx context.Context) (Metadata, bool) {
+	md, ok := ctx.Value(metadataKey{}).(Metadata)
+	if !ok {
+		return nil, ok
+	}
+
+	// capitalise all values
+	newMD := make(Metadata, len(md))
+	for k, v := range md {
+		newMD[strings.Title(k)] = v
+	}
+
+	return newMD, ok
+}
+
+// NewContext creates a new context with the given metadata.
+func NewContext(ctx context.Context, md Metadata) context.Context {
+	return context.WithValue(ctx, metadataKey{}, md)
+}
+
+// MergeContext merges metadata to existing metadata, overwriting if specified.
+func MergeContext(ctx context.Context, patchMd Metadata, overwrite bool) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	md, _ := ctx.Value(metadataKey{}).(Metadata)
+	cmd := make(Metadata, len(md))
+	for k, v := range md {
+		cmd[k] = v
+	}
+	for k, v := range patchMd {
+		if _, ok := cmd[k]; ok && !overwrite {
+			// skip
+		} else if v != "" {
+			cmd[k] = v
+		} else {
+			delete(cmd, k)
+		}
+	}
+	return context.WithValue(ctx, metadataKey{}, cmd)
+}