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path: root/vendor/github.com/naoina/toml/util.go
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package toml

import (
    "fmt"
    "reflect"
    "strings"
)

const fieldTagName = "toml"

// fieldCache maps normalized field names to their position in a struct.
type fieldCache struct {
    named map[string]fieldInfo // fields with an explicit name in tag
    auto  map[string]fieldInfo // fields with auto-assigned normalized names
}

type fieldInfo struct {
    index   []int
    name    string
    ignored bool
}

func makeFieldCache(cfg *Config, rt reflect.Type) fieldCache {
    named, auto := make(map[string]fieldInfo), make(map[string]fieldInfo)
    for i := 0; i < rt.NumField(); i++ {
        ft := rt.Field(i)
        // skip unexported fields
        if ft.PkgPath != "" && !ft.Anonymous {
            continue
        }
        col, _ := extractTag(ft.Tag.Get(fieldTagName))
        info := fieldInfo{index: ft.Index, name: ft.Name, ignored: col == "-"}
        if col == "" || col == "-" {
            auto[cfg.NormFieldName(rt, ft.Name)] = info
        } else {
            named[col] = info
        }
    }
    return fieldCache{named, auto}
}

func (fc fieldCache) findField(cfg *Config, rv reflect.Value, name string) (reflect.Value, string, error) {
    info, found := fc.named[name]
    if !found {
        info, found = fc.auto[cfg.NormFieldName(rv.Type(), name)]
    }
    if !found {
        if cfg.MissingField == nil {
            return reflect.Value{}, "", fmt.Errorf("field corresponding to `%s' is not defined in %v", name, rv.Type())
        } else {
            return reflect.Value{}, "", cfg.MissingField(rv.Type(), name)
        }
    } else if info.ignored {
        return reflect.Value{}, "", fmt.Errorf("field corresponding to `%s' in %v cannot be set through TOML", name, rv.Type())
    }
    return rv.FieldByIndex(info.index), info.name, nil
}

func extractTag(tag string) (col, rest string) {
    tags := strings.SplitN(tag, ",", 2)
    if len(tags) == 2 {
        return strings.TrimSpace(tags[0]), strings.TrimSpace(tags[1])
    }
    return strings.TrimSpace(tags[0]), ""
}