V2

1 files changed, 67 insertions, 0 deletions

diff --git a/internal/tokener/tokener.go b/internal/tokener/tokener.go
new file mode 100644
index 0000000..0886341
--- /dev/null
+++ b/internal/tokener/tokener.go
@@ -0,0 +1,67 @@
+package tokener
+
+type Tokener struct {
+	quotes  []byte
+	escaped bool
+	fixed   string
+	space   bool
+}
+
+// Visit visit a byte and update the state of the quotes.
+// It returns true if the byte was quotes or escape character.
+func (t *Tokener) Visit(b byte) {
+	// Check space.
+	if b == ' ' {
+		if !t.escaped && !t.Quoted() {
+			t.space = true
+		}
+	} else {
+		t.space = false
+	}
+
+	// Check escaping
+	if b == '\\' {
+		t.escaped = !t.escaped
+	} else {
+		defer func() { t.escaped = false }()
+	}
+
+	// Check quotes.
+	if !t.escaped && (b == '"' || b == '\'') {
+		if t.Quoted() && t.quotes[len(t.quotes)-1] == b {
+			t.quotes = t.quotes[:len(t.quotes)-1]
+		} else {
+			t.quotes = append(t.quotes, b)
+		}
+	}
+
+	// If not quoted, insert escape before inserting space.
+	if t.LastSpace() {
+		t.fixed += "\\"
+	}
+	t.fixed += string(b)
+}
+
+func (t *Tokener) Escaped() bool {
+	return t.escaped
+}
+
+func (t *Tokener) Quoted() bool {
+	return len(t.quotes) > 0
+}
+
+func (t *Tokener) Fixed() string {
+	return t.fixed
+}
+
+func (t *Tokener) Closed() string {
+	fixed := t.fixed
+	for i := len(t.quotes) - 1; i >= 0; i-- {
+		fixed += string(t.quotes[i])
+	}
+	return fixed
+}
+
+func (t *Tokener) LastSpace() bool {
+	return t.space
+}