[common] Add ASCIITrim

common/string.go

@@ -72,3 +72,18 @@ func IsASCIIText(s string) bool {
 	}
 	return true
 }
+
+// NOTE: Assumes that s is ASCII as per IsASCIIText(), otherwise panics.
+func ASCIITrim(s string) string {
+	r := make([]byte, 0, len(s))
+	for _, b := range []byte(s) {
+		if b == 32 {
+			continue // skip space
+		} else if 32 < b && b <= 126 {
+			r = append(r, b)
+		} else {
+			panic(fmt.Sprintf("non-ASCII (non-tab) char 0x%X", b))
+		}
+	}
+	return string(r)
+}

common/string_test.go

@@ -64,3 +64,11 @@ func TestIsASCIIText(t *testing.T) {
 		assert.True(t, IsASCIIText(v), "%q is ascii-text", v)
 	}
 }
+
+func TestASCIITrim(t *testing.T) {
+	assert.Equal(t, ASCIITrim(" "), "")
+	assert.Equal(t, ASCIITrim(" a"), "a")
+	assert.Equal(t, ASCIITrim("a "), "a")
+	assert.Equal(t, ASCIITrim(" a "), "a")
+	assert.Panics(t, func() { ASCIITrim("\xC2\xA2") })
+}