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package formula
import (
"io"
"io/ioutil"
"launchpad.net/ensemble/go/schema"
"launchpad.net/goyaml"
"os"
"strconv"
)
// Option represents a single configuration option that is declared
// as supported by a formula in its config.yaml file.
type Option struct {
Title string
Description string
Type string
Default interface{}
}
// Config represents the supported configuration options for a formula,
// as declared in its config.yaml file.
type Config struct {
Options map[string]Option
}
// ReadConfig reads a config.yaml file and returns its representation.
func ReadConfig(r io.Reader) (config *Config, err os.Error) {
data, err := ioutil.ReadAll(r)
if err != nil {
return
}
raw := make(map[interface{}]interface{})
err = goyaml.Unmarshal(data, raw)
if err != nil {
return
}
v, err := configSchema.Coerce(raw, nil)
if err != nil {
return nil, os.NewError("config: " + err.String())
}
config = &Config{}
config.Options = make(map[string]Option)
m := v.(schema.MapType)
for name, infov := range m["options"].(schema.MapType) {
opt := infov.(schema.MapType)
optTitle, _ := opt["title"].(string)
optType, _ := opt["type"].(string)
optDescr, _ := opt["description"].(string)
optDefault, _ := opt["default"]
config.Options[name.(string)] = Option{
Title: optTitle,
Type: optType,
Description: optDescr,
Default: optDefault,
}
}
return
}
// Validate processes the values in the input map according to the
// configuration in config, doing the following operations:
//
// - Values are converted from strings to the types defined
// - Options with default values are introduced for missing keys
// - Unknown keys and badly typed values are reported as errors
//
func (c *Config) Validate(values map[string]string) (processed map[string]interface{}, err os.Error) {
out := make(map[string]interface{})
for k, v := range values {
opt, ok := c.Options[k]
if !ok {
return nil, errorf("Unknown configuration option: %q", k)
}
switch opt.Type {
case "string":
out[k] = v
case "int":
i, err := strconv.Atoi64(v)
if err != nil {
return nil, errorf("Value for %q is not an int: %q", k, v)
}
out[k] = i
case "float":
f, err := strconv.Atof64(v)
if err != nil {
return nil, errorf("Value for %q is not a float: %q", k, v)
}
out[k] = f
default:
panic(errorf("Internal error: option type %q is unknown to Validate", opt.Type))
}
}
for k, opt := range c.Options {
if _, ok := out[k]; !ok && opt.Default != nil {
out[k] = opt.Default
}
}
return out, nil
}
var optionSchema = schema.FieldMap(
schema.Fields{
"type": schema.OneOf(schema.Const("string"), schema.Const("int"), schema.Const("float")),
"default": schema.OneOf(schema.String(), schema.Int(), schema.Float()),
"description": schema.String(),
},
schema.Optional{"default", "description"},
)
var configSchema = schema.FieldMap(
schema.Fields{
"options": schema.Map(schema.String(), optionSchema),
},
nil,
)
|