1 files changed, 63 insertions, 0 deletions

diff --git a/vendor/github.com/hashicorp/terraform/helper/schema/field_reader_multi.go b/vendor/github.com/hashicorp/terraform/helper/schema/field_reader_multi.go
new file mode 100644
index 0000000..89ad3a8
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/helper/schema/field_reader_multi.go
@@ -0,0 +1,63 @@
+package schema
+
+import (
+        "fmt"
+)
+
+// MultiLevelFieldReader reads from other field readers,
+// merging their results along the way in a specific order. You can specify
+// "levels" and name them in order to read only an exact level or up to
+// a specific level.
+//
+// This is useful for saying things such as "read the field from the state
+// and config and merge them" or "read the latest value of the field".
+type MultiLevelFieldReader struct {
+        Readers map[string]FieldReader
+        Levels  []string
+}
+
+func (r *MultiLevelFieldReader) ReadField(address []string) (FieldReadResult, error) {
+        return r.ReadFieldMerge(address, r.Levels[len(r.Levels)-1])
+}
+
+func (r *MultiLevelFieldReader) ReadFieldExact(
+        address []string, level string) (FieldReadResult, error) {
+        reader, ok := r.Readers[level]
+        if !ok {
+                return FieldReadResult{}, fmt.Errorf(
+                        "Unknown reader level: %s", level)
+        }
+
+        result, err := reader.ReadField(address)
+        if err != nil {
+                return FieldReadResult{}, fmt.Errorf(
+                        "Error reading level %s: %s", level, err)
+        }
+
+        return result, nil
+}
+
+func (r *MultiLevelFieldReader) ReadFieldMerge(
+        address []string, level string) (FieldReadResult, error) {
+        var result FieldReadResult
+        for _, l := range r.Levels {
+                if r, ok := r.Readers[l]; ok {
+                        out, err := r.ReadField(address)
+                        if err != nil {
+                                return FieldReadResult{}, fmt.Errorf(
+                                        "Error reading level %s: %s", l, err)
+                        }
+
+                        // TODO: computed
+                        if out.Exists {
+                                result = out
+                        }
+                }
+
+                if l == level {
+                        break
+                }
+        }
+
+        return result, nil
+}