Thomas Pelletier
21d3e85fcc
Idea would be to build a light AST as a first pass, then have the unmarshaler and Document parser do what they need with it.
95 lines
1.8 KiB
Go
95 lines
1.8 KiB
Go
package unmarshaler
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import (
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"fmt"
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"reflect"
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)
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type target interface {
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// Ensure the target's reflect value is not nil.
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ensure()
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// Store a string at the target.
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setString(v string) error
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// Appends an arbitrary value to the container.
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pushValue(v reflect.Value) error
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// Dereferences the target.
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get() reflect.Value
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}
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// struct target just contain the reflect.Value of the target field.
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type structTarget reflect.Value
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func (t structTarget) get() reflect.Value {
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return reflect.Value(t)
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}
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func (t structTarget) ensure() {
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f := t.get()
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if !f.IsNil() {
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return
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}
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switch f.Kind() {
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case reflect.Slice:
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f.Set(reflect.MakeSlice(f.Type(), 0, 0))
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default:
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panic(fmt.Errorf("don't know how to ensure %s", f.Kind()))
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}
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}
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func (t structTarget) setString(v string) error {
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f := t.get()
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if f.Kind() != reflect.String {
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return fmt.Errorf("cannot assign string to a %s", f.String())
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}
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f.SetString(v)
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return nil
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}
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func (t structTarget) pushValue(v reflect.Value) error {
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f := t.get()
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switch f.Kind() {
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case reflect.Slice:
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t.ensure()
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f.Set(reflect.Append(f, v))
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default:
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return fmt.Errorf("cannot push %s on a %s", v.Kind(), f.Kind())
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}
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return nil
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}
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func scope(v reflect.Value, name string) (target, error) {
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switch v.Kind() {
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case reflect.Struct:
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return scopeStruct(v, name)
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default:
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panic(fmt.Errorf("can't scope on a %s", v.Kind()))
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}
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}
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func scopeStruct(v reflect.Value, name string) (target, error) {
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// TODO: cache this
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t := v.Type()
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for i := 0; i < t.NumField(); i++ {
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f := t.Field(i)
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if f.PkgPath != "" {
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// only consider exported fields
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continue
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}
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if f.Anonymous {
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// TODO: handle embedded structs
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} else {
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// TODO: handle names variations
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if f.Name == name {
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return structTarget(v.Field(i)), nil
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}
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}
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}
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return nil, fmt.Errorf("field '%s' not found on %s", name, v.Type())
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}
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