Add string map version ProcessWord to Lex

Signed-off-by: Yuichiro Kaneko <spiketeika@gmail.com>

frontend/dockerfile/shell/lex.go

@@ -44,6 +44,13 @@ func (s *Lex) ProcessWords(word string, env []string) ([]string, error) {
 	return words, err
 }
 
+// ProcessWordWithMap will use the 'env' list of environment variables,
+// and replace any env var references in 'word'.
+func (s *Lex) ProcessWordWithMap(word string, env map[string]string) (string, error) {
+	word, _, err := s.process(word, env)
+	return word, err
+}
+
 func (s *Lex) process(word string, env map[string]string) (string, []string, error) {
 	sw := &shellWord{
 		envs:        env,

frontend/dockerfile/shell/lex_test.go

@@ -22,6 +22,7 @@ func TestShellParser4EnvVars(t *testing.T) {
 	shlex := NewLex('\\')
 	scanner := bufio.NewScanner(file)
 	envs := []string{"PWD=/home", "SHELL=bash", "KOREAN=한국어"}
+	envsMap := buildEnvs(envs)
 	for scanner.Scan() {
 		line := scanner.Text()
 		lineCount++
@@ -56,6 +57,14 @@ func TestShellParser4EnvVars(t *testing.T) {
 				assert.Check(t, err, "at line %d of %s", lineCount, fn)
 				assert.Check(t, is.Equal(newWord, expected), "at line %d of %s", lineCount, fn)
 			}
+
+			newWord, err = shlex.ProcessWordWithMap(source, envsMap)
+			if expected == "error" {
+				assert.Check(t, is.ErrorContains(err, ""), "input: %q, result: %q", source, newWord)
+			} else {
+				assert.Check(t, err, "at line %d of %s", lineCount, fn)
+				assert.Check(t, is.Equal(newWord, expected), "at line %d of %s", lineCount, fn)
+			}
 		}
 	}
 }