Adds a JSON parser and a benchmark (json-bench) to catch performance regressions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146735 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/Support/JSONParserTest.cpp

@@ -0,0 +1,218 @@
+//===- unittest/Tooling/JSONParserTest ------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/JSONParser.h"
+#include "llvm/ADT/Twine.h"
+#include "gtest/gtest.h"
+
+namespace llvm {
+
+// Returns a buffer that contains the content of the given string without
+// the trailing zero, in order to get valgrind to catch out-of-bound reads.
+static std::vector<char> CutTrailingZero(StringRef String) {
+  std::vector<char> InputWithoutZero(String.size());
+  memcpy(&InputWithoutZero[0], String.data(), String.size());
+  return InputWithoutZero;
+}
+
+// Checks that the given input gives a parse error. Makes sure that an error
+// text is available and the parse fails.
+static void ExpectParseError(StringRef Message,
+                             const std::vector<char> &InputWithoutZero) {
+  StringRef Input = StringRef(&InputWithoutZero[0], InputWithoutZero.size());
+  JSONParser Parser(Input);
+  EXPECT_FALSE(Parser.validate()) << Message << ": " << Input;
+  EXPECT_TRUE(Parser.failed()) << Message << ": " << Input;
+  EXPECT_FALSE(Parser.getErrorMessage().empty()) << Message << ": " << Input;
+}
+
+// Overloads the above to allow using const char * as Input.
+static void ExpectParseError(StringRef Message, StringRef Input) {
+  return ExpectParseError(Message, CutTrailingZero(Input));
+}
+
+// Checks that the given input can be parsed without error.
+static void ExpectParseSuccess(StringRef Message,
+                               const std::vector<char> &InputWithoutZero) {
+  StringRef Input = StringRef(&InputWithoutZero[0], InputWithoutZero.size());
+  JSONParser Parser(Input);
+  EXPECT_TRUE(Parser.validate())
+    << Message << ": " << Input << " - " << Parser.getErrorMessage();
+}
+
+// Overloads the above to allow using const char * as Input.
+static void ExpectParseSuccess(StringRef Message, StringRef Input) {
+  return ExpectParseSuccess(Message, CutTrailingZero(Input));
+}
+
+TEST(JSONParser, FailsOnEmptyString) {
+  JSONParser Parser("");
+  EXPECT_EQ(NULL, Parser.parseRoot());
+}
+
+TEST(JSONParser, DoesNotReadAfterInput) {
+  JSONParser Parser(llvm::StringRef(NULL, 0));
+  EXPECT_EQ(NULL, Parser.parseRoot());
+}
+
+TEST(JSONParser, FailsIfStartsWithString) {
+  JSONParser Character("\"x\"");
+  EXPECT_EQ(NULL, Character.parseRoot());
+}
+
+TEST(JSONParser, ParsesEmptyArray) {
+  ExpectParseSuccess("Empty array", "[]");
+}
+
+TEST(JSONParser, FailsIfNotClosingArray) {
+  ExpectParseError("Not closing array", "[");
+  ExpectParseError("Not closing array", "  [  ");
+  ExpectParseError("Not closing array", "  [x");
+}
+
+TEST(JSONParser, ParsesEmptyArrayWithWhitespace) {
+  ExpectParseSuccess("Array with spaces", "  [  ]  ");
+  ExpectParseSuccess("All whitespaces", "\t\r\n[\t\n \t\r ]\t\r \n\n");
+}
+
+TEST(JSONParser, ParsesEmptyObject) {
+  ExpectParseSuccess("Empty object", "[{}]");
+}
+
+TEST(JSONParser, ParsesObject) {
+  ExpectParseSuccess("Object with an entry", "[{\"a\":\"/b\"}]");
+}
+
+TEST(JSONParser, ParsesMultipleKeyValuePairsInObject) {
+  ExpectParseSuccess("Multiple key, value pairs",
+                     "[{\"a\":\"/b\",\"c\":\"d\",\"e\":\"f\"}]");
+}
+
+TEST(JSONParser, FailsIfNotClosingObject) {
+  ExpectParseError("Missing close on empty", "[{]");
+  ExpectParseError("Missing close after pair", "[{\"a\":\"b\"]");
+}
+
+TEST(JSONParser, FailsIfMissingColon) {
+  ExpectParseError("Missing colon between key and value", "[{\"a\"\"/b\"}]");
+  ExpectParseError("Missing colon between key and value", "[{\"a\" \"b\"}]");
+}
+
+TEST(JSONParser, FailsOnMissingQuote) {
+  ExpectParseError("Missing open quote", "[{a\":\"b\"}]");
+  ExpectParseError("Missing closing quote", "[{\"a\":\"b}]");
+}
+
+TEST(JSONParser, ParsesEscapedQuotes) {
+  ExpectParseSuccess("Parses escaped string in key and value",
+                     "[{\"a\":\"\\\"b\\\"  \\\" \\\"\"}]");
+}
+
+TEST(JSONParser, ParsesEmptyString) {
+  ExpectParseSuccess("Parses empty string in value", "[{\"a\":\"\"}]");
+}
+
+TEST(JSONParser, FailsOnMissingString) {
+  ExpectParseError("Missing value", "[{\"a\":}]");
+  ExpectParseError("Missing key", "[{:\"b\"}]");
+}
+
+TEST(JSONParser, ParsesMultipleObjects) {
+  ExpectParseSuccess(
+      "Multiple objects in array",
+      "["
+      " { \"a\" : \"b\" },"
+      " { \"a\" : \"b\" },"
+      " { \"a\" : \"b\" }"
+      "]");
+}
+
+TEST(JSONParser, FailsOnMissingComma) {
+  ExpectParseError(
+      "Missing comma",
+      "["
+      " { \"a\" : \"b\" }"
+      " { \"a\" : \"b\" }"
+      "]");
+}
+
+TEST(JSONParser, FailsOnSuperfluousComma) {
+  ExpectParseError("Superfluous comma in array", "[ { \"a\" : \"b\" }, ]");
+  ExpectParseError("Superfluous comma in object", "{ \"a\" : \"b\", }");
+}
+
+TEST(JSONParser, ParsesSpacesInBetweenTokens) {
+  ExpectParseSuccess(
+      "Various whitespace between tokens",
+      " \t \n\n \r [ \t \n\n \r"
+      " \t \n\n \r { \t \n\n \r\"a\"\t \n\n \r :"
+      " \t \n\n \r \"b\"\t \n\n \r } \t \n\n \r,\t \n\n \r"
+      " \t \n\n \r { \t \n\n \r\"a\"\t \n\n \r :"
+      " \t \n\n \r \"b\"\t \n\n \r } \t \n\n \r]\t \n\n \r");
+}
+
+TEST(JSONParser, ParsesArrayOfArrays) {
+  ExpectParseSuccess("Array of arrays", "[[]]");
+}
+
+TEST(JSONParser, HandlesEndOfFileGracefully) {
+  ExpectParseError("In string starting with EOF", "[\"");
+  ExpectParseError("In string hitting EOF", "[\"   ");
+  ExpectParseError("In string escaping EOF", "[\"  \\");
+  ExpectParseError("In array starting with EOF", "[");
+  ExpectParseError("In array element starting with EOF", "[[], ");
+  ExpectParseError("In array hitting EOF", "[[] ");
+  ExpectParseError("In array hitting EOF", "[[]");
+  ExpectParseError("In object hitting EOF", "{\"\"");
+}
+
+// Checks that the given string can be parsed into an identical string inside
+// of an array.
+static void ExpectCanParseString(StringRef String) {
+  std::string StringInArray = (llvm::Twine("[\"") + String + "\"]").str();
+  JSONParser Parser(StringInArray);
+  const JSONArray *ParsedArray = dyn_cast<JSONArray>(Parser.parseRoot());
+  StringRef ParsedString =
+      dyn_cast<JSONString>(*ParsedArray->begin())->getRawText();
+  EXPECT_EQ(String, ParsedString.str()) << Parser.getErrorMessage();
+}
+
+// Checks that parsing the given string inside an array fails.
+static void ExpectCannotParseString(StringRef String) {
+  std::string StringInArray = (llvm::Twine("[\"") + String + "\"]").str();
+  ExpectParseError((Twine("When parsing string \"") + String + "\"").str(),
+                   StringInArray);
+}
+
+TEST(JSONParser, ParsesStrings) {
+  ExpectCanParseString("");
+  ExpectCannotParseString("\\");
+  ExpectCannotParseString("\"");
+  ExpectCanParseString(" ");
+  ExpectCanParseString("\\ ");
+  ExpectCanParseString("\\\"");
+  ExpectCannotParseString("\"\\");
+  ExpectCannotParseString(" \\");
+  ExpectCanParseString("\\\\");
+  ExpectCannotParseString("\\\\\\");
+  ExpectCanParseString("\\\\\\\\");
+  ExpectCanParseString("\\\" ");
+  ExpectCannotParseString("\\\\\" ");
+  ExpectCanParseString("\\\\\\\" ");
+  ExpectCanParseString("    \\\\  \\\"  \\\\\\\"   ");
+}
+
+TEST(JSONParser, WorksWithIteratorAlgorithms) {
+  JSONParser Parser("[\"1\", \"2\", \"3\", \"4\", \"5\", \"6\"]");
+  const JSONArray *Array = dyn_cast<JSONArray>(Parser.parseRoot());
+  EXPECT_EQ(6, std::distance(Array->begin(), Array->end()));
+}
+
+} // end namespace llvm