123 lines
3.1 KiB
Go
123 lines
3.1 KiB
Go
package pointerstructure
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import (
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"fmt"
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"reflect"
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)
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// Set writes a value v to the pointer p in structure s.
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//
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// The structures s must have non-zero values set up to this pointer.
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// For example, if setting "/bob/0/name", then "/bob/0" must be set already.
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//
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// The returned value is potentially a new value if this pointer represents
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// the root document. Otherwise, the returned value will always be s.
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func (p *Pointer) Set(s, v interface{}) (interface{}, error) {
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// if we represent the root doc, return that
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if len(p.Parts) == 0 {
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return v, nil
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}
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// Save the original since this is going to be our return value
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originalS := s
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// Get the parent value
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var err error
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s, err = p.Parent().Get(s)
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if err != nil {
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return nil, err
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}
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// Map for lookup of getter to call for type
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funcMap := map[reflect.Kind]setFunc{
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reflect.Array: p.setSlice,
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reflect.Map: p.setMap,
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reflect.Slice: p.setSlice,
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}
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val := reflect.ValueOf(s)
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for val.Kind() == reflect.Interface {
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val = val.Elem()
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}
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for val.Kind() == reflect.Ptr {
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val = reflect.Indirect(val)
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}
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f, ok := funcMap[val.Kind()]
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if !ok {
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return nil, fmt.Errorf("set %s: invalid value kind: %s", p, val.Kind())
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}
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result, err := f(originalS, val, reflect.ValueOf(v))
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if err != nil {
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return nil, fmt.Errorf("set %s: %s", p, err)
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}
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return result, nil
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}
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type setFunc func(interface{}, reflect.Value, reflect.Value) (interface{}, error)
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func (p *Pointer) setMap(root interface{}, m, value reflect.Value) (interface{}, error) {
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part := p.Parts[len(p.Parts)-1]
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key, err := coerce(reflect.ValueOf(part), m.Type().Key())
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if err != nil {
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return root, err
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}
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elem, err := coerce(value, m.Type().Elem())
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if err != nil {
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return root, err
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}
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// Set the key
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m.SetMapIndex(key, elem)
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return root, nil
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}
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func (p *Pointer) setSlice(root interface{}, s, value reflect.Value) (interface{}, error) {
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// Coerce the value, we'll need that no matter what
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value, err := coerce(value, s.Type().Elem())
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if err != nil {
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return root, err
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}
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// If the part is the special "-", that means to append it (RFC6901 4.)
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part := p.Parts[len(p.Parts)-1]
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if part == "-" {
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return p.setSliceAppend(root, s, value)
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}
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// Coerce the key to an int
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idxVal, err := coerce(reflect.ValueOf(part), reflect.TypeOf(42))
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if err != nil {
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return root, err
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}
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idx := int(idxVal.Int())
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// Verify we're within bounds
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if idx < 0 || idx >= s.Len() {
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return root, fmt.Errorf(
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"index %d is out of range (length = %d)", idx, s.Len())
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}
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// Set the key
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s.Index(idx).Set(value)
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return root, nil
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}
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func (p *Pointer) setSliceAppend(root interface{}, s, value reflect.Value) (interface{}, error) {
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// Coerce the value, we'll need that no matter what. This should
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// be a no-op since we expect it to be done already, but there is
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// a fast-path check for that in coerce so do it anyways.
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value, err := coerce(value, s.Type().Elem())
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if err != nil {
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return root, err
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}
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// We can assume "s" is the parent of pointer value. We need to actually
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// write s back because Append can return a new slice.
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return p.Parent().Set(root, reflect.Append(s, value).Interface())
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}
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