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// Routines for loading strings from files. Nominally for the put/filter verbs
// to load DSL strings from .mlr files.
package lib
import (
"os"
"strings"
csv "github.com/johnkerl/miller/v6/pkg/go-csv"
)
// LoadStringsFromFileOrDir calls LoadStringFromFile if path exists and is a
// file, or LoadStringsFromDir if path exists and is a directory. In the
// former case the extension is ignored; in the latter case it's used as a
// filter on the directory entries.
func LoadStringsFromFileOrDir(path string, extension string) ([]string, error) {
fileInfo, err := os.Stat(path)
if err != nil {
return nil, err
}
if fileInfo.IsDir() {
return LoadStringsFromDir(path, extension)
}
dslString, err := LoadStringFromFile(path)
if err != nil {
return nil, err
} else {
return []string{dslString}, nil
}
}
// LoadStringFromFile is just a wrapper around os.ReadFile,
// with a cast from []byte to string.
func LoadStringFromFile(filename string) (string, error) {
data, err := os.ReadFile(filename)
if err != nil {
return "", err
}
return string(data), nil
}
// LoadStringsFromDir loads all file contents for files in the given directory
// having the given extension. E.g. LoadStringsFromDir("/u/myfiles", ".mlr")
// will load /u/myfiles/foo.mlr and /u/myfiles/bar.mlr but will skip over
// /u/myfiles/data.csv and /u/myfiles/todo.txt.
func LoadStringsFromDir(dirname string, extension string) ([]string, error) {
dslStrings := []string{}
f, err := os.Open(dirname)
if err != nil {
return nil, err
}
defer f.Close()
names, err := f.Readdirnames(-1)
if err != nil {
return nil, err
}
for _, name := range names {
if !strings.HasSuffix(name, extension) {
continue
}
path := dirname + "/" + name
dslString, err := LoadStringFromFile(path)
if err != nil {
return nil, err
}
dslStrings = append(dslStrings, dslString)
}
return dslStrings, nil
}
func ReadCSVHeader(filename string) ([]string, error) {
handle, err := os.Open(filename)
if err != nil {
return nil, err
}
defer handle.Close()
csvReader := csv.NewReader(handle)
header, err := csvReader.Read()
if err != nil {
return nil, err
}
return header, nil
}
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