buildkit/frontend/dockerfile/parser/split_command.go

119 lines
2.4 KiB
Go

package parser
import (
"strings"
"unicode"
)
// splitCommand takes a single line of text and parses out the cmd and args,
// which are used for dispatching to more exact parsing functions.
func splitCommand(line string) (string, []string, string, error) {
var args string
var flags []string
// Make sure we get the same results irrespective of leading/trailing spaces
cmdline := reWhitespace.Split(strings.TrimSpace(line), 2)
cmd := strings.ToLower(cmdline[0])
if len(cmdline) == 2 {
var err error
args, flags, err = extractBuilderFlags(cmdline[1])
if err != nil {
return "", nil, "", err
}
}
return cmd, flags, strings.TrimSpace(args), nil
}
func extractBuilderFlags(line string) (string, []string, error) {
// Parses the BuilderFlags and returns the remaining part of the line
const (
inSpaces = iota // looking for start of a word
inWord
inQuote
)
words := []string{}
phase := inSpaces
word := ""
quote := '\000'
blankOK := false
var ch rune
for pos := 0; pos <= len(line); pos++ {
if pos != len(line) {
ch = rune(line[pos])
}
if phase == inSpaces { // Looking for start of word
if pos == len(line) { // end of input
break
}
if unicode.IsSpace(ch) { // skip spaces
continue
}
// Only keep going if the next word starts with --
if ch != '-' || pos+1 == len(line) || rune(line[pos+1]) != '-' {
return line[pos:], words, nil
}
phase = inWord // found something with "--", fall through
}
if (phase == inWord || phase == inQuote) && (pos == len(line)) {
if word != "--" && (blankOK || len(word) > 0) {
words = append(words, word)
}
break
}
if phase == inWord {
if unicode.IsSpace(ch) {
phase = inSpaces
if word == "--" {
return line[pos:], words, nil
}
if blankOK || len(word) > 0 {
words = append(words, word)
}
word = ""
blankOK = false
continue
}
if ch == '\'' || ch == '"' {
quote = ch
blankOK = true
phase = inQuote
continue
}
if ch == '\\' {
if pos+1 == len(line) {
continue // just skip \ at end
}
pos++
ch = rune(line[pos])
}
word += string(ch)
continue
}
if phase == inQuote {
if ch == quote {
phase = inWord
continue
}
if ch == '\\' {
if pos+1 == len(line) {
phase = inWord
continue // just skip \ at end
}
pos++
ch = rune(line[pos])
}
word += string(ch)
}
}
return "", words, nil
}