Allow splitting string literals into multiple parts

test/libsolidity/SolidityScanner.cpp

@@ -505,7 +505,7 @@ BOOST_AUTO_TEST_CASE(valid_hex_literal)
 {
 	Scanner scanner(CharStream("{ hex\"00112233FF\"", ""));
 	BOOST_CHECK_EQUAL(scanner.currentToken(), Token::LBrace);
-	BOOST_CHECK_EQUAL(scanner.next(), Token::StringLiteral);
+	BOOST_CHECK_EQUAL(scanner.next(), Token::HexStringLiteral);
 	BOOST_CHECK_EQUAL(scanner.currentLiteral(), std::string("\x00\x11\x22\x33\xFF", 5));
 }
 

test/libsolidity/syntaxTests/string/string_multipart_hex_valid_parts.sol

@@ -0,0 +1,8 @@
+contract test {
+    function f() public pure returns (bytes32) {
+        bytes32 escapeCharacters = hex"aa" hex"b";
+        return escapeCharacters;
+    }
+}
+// ----
+// ParserError: (108-112): Expected even number of hex-nibbles within double-quotes.

test/libsolidity/syntaxTests/string/string_multipart_newline_with_hex_prefix.sol

@@ -0,0 +1,9 @@
+contract test {
+    function f() public pure returns (bytes32) {
+        bytes32 escapeCharacters = hex"0000"
+        hex"deaf"
+        hex"feed";
+        return escapeCharacters;
+    }
+}
+// ----

test/libsolidity/syntaxTests/string/string_multipart_newline_without_hex_prefix.sol

@@ -0,0 +1,10 @@
+contract test {
+    function f() public pure returns (bytes32) {
+        bytes32 escapeCharacters = hex"0000"
+        "deaf"
+        "feed";
+        return escapeCharacters;
+    }
+}
+// ----
+// ParserError: (118-124): Expected ';' but got 'StringLiteral'

test/libsolidity/syntaxTests/string/string_multipart_only_hex.sol

@@ -0,0 +1,8 @@
+contract test {
+    function f() public pure returns (bytes32) {
+        bytes32 escapeCharacters = hex"aa" hex"bb" "cc";
+        return escapeCharacters;
+    }
+}
+// ----
+// ParserError: (116-120): Expected ';' but got 'StringLiteral'

test/libsolidity/syntaxTests/string/string_multipart_only_regular.sol

@@ -0,0 +1,8 @@
+contract test {
+    function f() public pure returns (bytes32) {
+        bytes32 escapeCharacters = "foo" "bar" hex"aa";
+        return escapeCharacters;
+    }
+}
+// ----
+// ParserError: (112-119): Expected ';' but got 'HexStringLiteral'

test/libsolidity/syntaxTests/string/string_multipart_single_line.sol

@@ -0,0 +1,7 @@
+contract test {
+    function f() public pure returns (bytes32) {
+        bytes32 escapeCharacters = "first" "second" "third";
+        return escapeCharacters;
+    }
+}
+// ----