64 lines
1.5 KiB
Go
64 lines
1.5 KiB
Go
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package schema
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import (
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"fmt"
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)
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// MultiLevelFieldReader reads from other field readers,
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// merging their results along the way in a specific order. You can specify
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// "levels" and name them in order to read only an exact level or up to
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// a specific level.
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//
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// This is useful for saying things such as "read the field from the state
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// and config and merge them" or "read the latest value of the field".
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type MultiLevelFieldReader struct {
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Readers map[string]FieldReader
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Levels []string
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}
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func (r *MultiLevelFieldReader) ReadField(address []string) (FieldReadResult, error) {
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return r.ReadFieldMerge(address, r.Levels[len(r.Levels)-1])
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}
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func (r *MultiLevelFieldReader) ReadFieldExact(
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address []string, level string) (FieldReadResult, error) {
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reader, ok := r.Readers[level]
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if !ok {
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return FieldReadResult{}, fmt.Errorf(
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"Unknown reader level: %s", level)
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}
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result, err := reader.ReadField(address)
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if err != nil {
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return FieldReadResult{}, fmt.Errorf(
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"Error reading level %s: %s", level, err)
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}
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return result, nil
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}
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func (r *MultiLevelFieldReader) ReadFieldMerge(
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address []string, level string) (FieldReadResult, error) {
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var result FieldReadResult
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for _, l := range r.Levels {
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if r, ok := r.Readers[l]; ok {
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out, err := r.ReadField(address)
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if err != nil {
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return FieldReadResult{}, fmt.Errorf(
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"Error reading level %s: %s", l, err)
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}
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// TODO: computed
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if out.Exists {
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result = out
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}
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}
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if l == level {
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break
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}
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}
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return result, nil
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}
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