Move rtc_json code from API dir, enable unit test, unmark testonly

This change does three things:
 - Move rtc_json into rtc_base/strings/, a non-API directory more fitting to
   its purpose.
 - Make a target for the currently unused json_unittest.
 - Make the code available for use in non-test code again.

Bug: webrtc:9802
Change-Id: Id964a8a4b47b732a962a364894a4dbd3e7f4650f
Reviewed-on: https://webrtc-review.googlesource.com/103126
Commit-Queue: Sam Zackrisson <saza@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24932}
diff --git a/rtc_base/strings/json.cc b/rtc_base/strings/json.cc
new file mode 100644
index 0000000..efcb97a
--- /dev/null
+++ b/rtc_base/strings/json.cc
@@ -0,0 +1,294 @@
+/*
+ *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "rtc_base/strings/json.h"
+
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+
+#include "rtc_base/stringencode.h"
+
+namespace rtc {
+
+bool GetStringFromJson(const Json::Value& in, std::string* out) {
+  if (!in.isString()) {
+    if (in.isBool()) {
+      *out = rtc::ToString(in.asBool());
+    } else if (in.isInt()) {
+      *out = rtc::ToString(in.asInt());
+    } else if (in.isUInt()) {
+      *out = rtc::ToString(in.asUInt());
+    } else if (in.isDouble()) {
+      *out = rtc::ToString(in.asDouble());
+    } else {
+      return false;
+    }
+  } else {
+    *out = in.asString();
+  }
+  return true;
+}
+
+bool GetIntFromJson(const Json::Value& in, int* out) {
+  bool ret;
+  if (!in.isString()) {
+    ret = in.isConvertibleTo(Json::intValue);
+    if (ret) {
+      *out = in.asInt();
+    }
+  } else {
+    long val;  // NOLINT
+    const char* c_str = in.asCString();
+    char* end_ptr;
+    errno = 0;
+    val = strtol(c_str, &end_ptr, 10);  // NOLINT
+    ret = (end_ptr != c_str && *end_ptr == '\0' && !errno && val >= INT_MIN &&
+           val <= INT_MAX);
+    *out = val;
+  }
+  return ret;
+}
+
+bool GetUIntFromJson(const Json::Value& in, unsigned int* out) {
+  bool ret;
+  if (!in.isString()) {
+    ret = in.isConvertibleTo(Json::uintValue);
+    if (ret) {
+      *out = in.asUInt();
+    }
+  } else {
+    unsigned long val;  // NOLINT
+    const char* c_str = in.asCString();
+    char* end_ptr;
+    errno = 0;
+    val = strtoul(c_str, &end_ptr, 10);  // NOLINT
+    ret = (end_ptr != c_str && *end_ptr == '\0' && !errno && val <= UINT_MAX);
+    *out = val;
+  }
+  return ret;
+}
+
+bool GetBoolFromJson(const Json::Value& in, bool* out) {
+  bool ret;
+  if (!in.isString()) {
+    ret = in.isConvertibleTo(Json::booleanValue);
+    if (ret) {
+      *out = in.asBool();
+    }
+  } else {
+    if (in.asString() == "true") {
+      *out = true;
+      ret = true;
+    } else if (in.asString() == "false") {
+      *out = false;
+      ret = true;
+    } else {
+      ret = false;
+    }
+  }
+  return ret;
+}
+
+bool GetDoubleFromJson(const Json::Value& in, double* out) {
+  bool ret;
+  if (!in.isString()) {
+    ret = in.isConvertibleTo(Json::realValue);
+    if (ret) {
+      *out = in.asDouble();
+    }
+  } else {
+    double val;
+    const char* c_str = in.asCString();
+    char* end_ptr;
+    errno = 0;
+    val = strtod(c_str, &end_ptr);
+    ret = (end_ptr != c_str && *end_ptr == '\0' && !errno);
+    *out = val;
+  }
+  return ret;
+}
+
+namespace {
+template <typename T>
+bool JsonArrayToVector(const Json::Value& value,
+                       bool (*getter)(const Json::Value& in, T* out),
+                       std::vector<T>* vec) {
+  vec->clear();
+  if (!value.isArray()) {
+    return false;
+  }
+
+  for (Json::Value::ArrayIndex i = 0; i < value.size(); ++i) {
+    T val;
+    if (!getter(value[i], &val)) {
+      return false;
+    }
+    vec->push_back(val);
+  }
+
+  return true;
+}
+// Trivial getter helper
+bool GetValueFromJson(const Json::Value& in, Json::Value* out) {
+  *out = in;
+  return true;
+}
+}  // unnamed namespace
+
+bool JsonArrayToValueVector(const Json::Value& in,
+                            std::vector<Json::Value>* out) {
+  return JsonArrayToVector(in, GetValueFromJson, out);
+}
+
+bool JsonArrayToIntVector(const Json::Value& in, std::vector<int>* out) {
+  return JsonArrayToVector(in, GetIntFromJson, out);
+}
+
+bool JsonArrayToUIntVector(const Json::Value& in,
+                           std::vector<unsigned int>* out) {
+  return JsonArrayToVector(in, GetUIntFromJson, out);
+}
+
+bool JsonArrayToStringVector(const Json::Value& in,
+                             std::vector<std::string>* out) {
+  return JsonArrayToVector(in, GetStringFromJson, out);
+}
+
+bool JsonArrayToBoolVector(const Json::Value& in, std::vector<bool>* out) {
+  return JsonArrayToVector(in, GetBoolFromJson, out);
+}
+
+bool JsonArrayToDoubleVector(const Json::Value& in, std::vector<double>* out) {
+  return JsonArrayToVector(in, GetDoubleFromJson, out);
+}
+
+namespace {
+template <typename T>
+Json::Value VectorToJsonArray(const std::vector<T>& vec) {
+  Json::Value result(Json::arrayValue);
+  for (size_t i = 0; i < vec.size(); ++i) {
+    result.append(Json::Value(vec[i]));
+  }
+  return result;
+}
+}  // unnamed namespace
+
+Json::Value ValueVectorToJsonArray(const std::vector<Json::Value>& in) {
+  return VectorToJsonArray(in);
+}
+
+Json::Value IntVectorToJsonArray(const std::vector<int>& in) {
+  return VectorToJsonArray(in);
+}
+
+Json::Value UIntVectorToJsonArray(const std::vector<unsigned int>& in) {
+  return VectorToJsonArray(in);
+}
+
+Json::Value StringVectorToJsonArray(const std::vector<std::string>& in) {
+  return VectorToJsonArray(in);
+}
+
+Json::Value BoolVectorToJsonArray(const std::vector<bool>& in) {
+  return VectorToJsonArray(in);
+}
+
+Json::Value DoubleVectorToJsonArray(const std::vector<double>& in) {
+  return VectorToJsonArray(in);
+}
+
+bool GetValueFromJsonArray(const Json::Value& in, size_t n, Json::Value* out) {
+  if (!in.isArray() || !in.isValidIndex(static_cast<int>(n))) {
+    return false;
+  }
+
+  *out = in[static_cast<Json::Value::ArrayIndex>(n)];
+  return true;
+}
+
+bool GetIntFromJsonArray(const Json::Value& in, size_t n, int* out) {
+  Json::Value x;
+  return GetValueFromJsonArray(in, n, &x) && GetIntFromJson(x, out);
+}
+
+bool GetUIntFromJsonArray(const Json::Value& in, size_t n, unsigned int* out) {
+  Json::Value x;
+  return GetValueFromJsonArray(in, n, &x) && GetUIntFromJson(x, out);
+}
+
+bool GetStringFromJsonArray(const Json::Value& in, size_t n, std::string* out) {
+  Json::Value x;
+  return GetValueFromJsonArray(in, n, &x) && GetStringFromJson(x, out);
+}
+
+bool GetBoolFromJsonArray(const Json::Value& in, size_t n, bool* out) {
+  Json::Value x;
+  return GetValueFromJsonArray(in, n, &x) && GetBoolFromJson(x, out);
+}
+
+bool GetDoubleFromJsonArray(const Json::Value& in, size_t n, double* out) {
+  Json::Value x;
+  return GetValueFromJsonArray(in, n, &x) && GetDoubleFromJson(x, out);
+}
+
+bool GetValueFromJsonObject(const Json::Value& in,
+                            const std::string& k,
+                            Json::Value* out) {
+  if (!in.isObject() || !in.isMember(k)) {
+    return false;
+  }
+
+  *out = in[k];
+  return true;
+}
+
+bool GetIntFromJsonObject(const Json::Value& in,
+                          const std::string& k,
+                          int* out) {
+  Json::Value x;
+  return GetValueFromJsonObject(in, k, &x) && GetIntFromJson(x, out);
+}
+
+bool GetUIntFromJsonObject(const Json::Value& in,
+                           const std::string& k,
+                           unsigned int* out) {
+  Json::Value x;
+  return GetValueFromJsonObject(in, k, &x) && GetUIntFromJson(x, out);
+}
+
+bool GetStringFromJsonObject(const Json::Value& in,
+                             const std::string& k,
+                             std::string* out) {
+  Json::Value x;
+  return GetValueFromJsonObject(in, k, &x) && GetStringFromJson(x, out);
+}
+
+bool GetBoolFromJsonObject(const Json::Value& in,
+                           const std::string& k,
+                           bool* out) {
+  Json::Value x;
+  return GetValueFromJsonObject(in, k, &x) && GetBoolFromJson(x, out);
+}
+
+bool GetDoubleFromJsonObject(const Json::Value& in,
+                             const std::string& k,
+                             double* out) {
+  Json::Value x;
+  return GetValueFromJsonObject(in, k, &x) && GetDoubleFromJson(x, out);
+}
+
+std::string JsonValueToString(const Json::Value& json) {
+  Json::FastWriter w;
+  std::string value = w.write(json);
+  return value.substr(0, value.size() - 1);  // trim trailing newline
+}
+
+}  // namespace rtc