From 7aa6a8aefbb2013ef3dc87ecbdf5d947d4b413af Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Wed, 27 Feb 2019 13:41:41 -0800
Subject: Add ParseRange function to parse args of the form int/[int,int]

---
 src/rpc/util.cpp | 14 ++++++++++++++
 src/rpc/util.h   |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
index 86695bc1a5..7fb139f93c 100644
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -523,3 +523,17 @@ std::string RPCArg::ToString(const bool oneline) const
     }
     assert(false);
 }
+
+std::pair<int64_t, int64_t> ParseRange(const UniValue& value)
+{
+    if (value.isNum()) {
+        return {0, value.get_int64()};
+    }
+    if (value.isArray() && value.size() == 2 && value[0].isNum() && value[1].isNum()) {
+        int64_t low = value[0].get_int64();
+        int64_t high = value[1].get_int64();
+        if (low > high) throw JSONRPCError(RPC_INVALID_PARAMETER, "Range specified as [begin,end] must not have begin after end");
+        return {low, high};
+    }
+    throw JSONRPCError(RPC_INVALID_PARAMETER, "Range must be specified as end or as [begin,end]");
+}
diff --git a/src/rpc/util.h b/src/rpc/util.h
index 06800ad63c..f11998bafa 100644
--- a/src/rpc/util.h
+++ b/src/rpc/util.h
@@ -38,6 +38,9 @@ unsigned int ParseConfirmTarget(const UniValue& value);
 RPCErrorCode RPCErrorFromTransactionError(TransactionError terr);
 UniValue JSONRPCTransactionError(TransactionError terr, const std::string& err_string = "");
 
+//! Parse a JSON range specified as int64, or [int64, int64]
+std::pair<int64_t, int64_t> ParseRange(const UniValue& value);
+
 struct RPCArg {
     enum class Type {
         OBJ,
-- 
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