lexer: Unbreak support for dot-terminated multiline strings

lexer/lex.go

@@ -362,6 +362,7 @@ func multilineString(r *bufio.Reader, state *lexerState) (string, error) {
 				atLFHadDot = true
 			} else {
 				data.WriteByte('.')
+				atLFHadDot = false
 			}
 
 			atLF = false
@@ -381,6 +382,7 @@ func multilineString(r *bufio.Reader, state *lexerState) (string, error) {
 		default:
 			atLF = false
 			atLFHadDot = false
+			data.WriteByte(b)
 		}
 	}
 }

lexer/lex_test.go

@@ -66,4 +66,38 @@ whatever # aaaa
 		Number{Value: 123, Quantifier: Kilo, Position: LineCol(7, 20)},
 		BlockEnd{Position: LineCol(7, 25)},
 	})
+	testLexer(t, `set "message" text:
+From: [email protected]
+To: [email protected]
+Subject: Frop!
+
+Frop!
+.
+`, []Token{
+		Identifier{Text: "set", Position: LineCol(1, 1)},
+		String{Text: "message", Position: LineCol(1, 5)},
+		String{Text: "From: [email protected]\r\n" +
+			"To: [email protected]\r\n" +
+			"Subject: Frop!\r\n" +
+			"\r\n" +
+			"Frop!\r\n", Position: LineCol(1, 15)},
+	})
+	testLexer(t, `set "message" text:
+From: [email protected]
+To: [email protected]
+Subject: Frop!
+
+..
+Frop!
+.
+`, []Token{
+		Identifier{Text: "set", Position: LineCol(1, 1)},
+		String{Text: "message", Position: LineCol(1, 5)},
+		String{Text: "From: [email protected]\r\n" +
+			"To: [email protected]\r\n" +
+			"Subject: Frop!\r\n" +
+			"\r\n" +
+			".\r\n" +
+			"Frop!\r\n", Position: LineCol(1, 15)},
+	})
 }