From 2c720b26abcd8ef757291f2baf1311a4aab58121 Mon Sep 17 00:00:00 2001
From: Niels <niels.lohmann@gmail.com>
Date: Fri, 5 Feb 2016 19:24:42 +0100
Subject: [PATCH] added a constructor from an input stream
---
doc/examples/basic_json__istream.cpp | 55 +++++++++++++++++++++++++
doc/examples/basic_json__istream.link | 1 +
doc/examples/basic_json__istream.output | 34 +++++++++++++++
src/json.hpp | 25 +++++++++++
src/json.hpp.re2c | 25 +++++++++++
test/unit.cpp | 36 ++++++++++++++++
6 files changed, 176 insertions(+)
create mode 100644 doc/examples/basic_json__istream.cpp
create mode 100644 doc/examples/basic_json__istream.link
create mode 100644 doc/examples/basic_json__istream.output
diff --git a/doc/examples/basic_json__istream.cpp b/doc/examples/basic_json__istream.cpp
new file mode 100644
index 00000000..71f16ed3
--- /dev/null
+++ b/doc/examples/basic_json__istream.cpp
@@ -0,0 +1,55 @@
+#include <json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+ // a JSON text
+ auto text = R"(
+ {
+ "Image": {
+ "Width": 800,
+ "Height": 600,
+ "Title": "View from 15th Floor",
+ "Thumbnail": {
+ "Url": "http://www.example.com/image/481989943",
+ "Height": 125,
+ "Width": 100
+ },
+ "Animated" : false,
+ "IDs": [116, 943, 234, 38793]
+ }
+ }
+ )";
+
+ // fill a stream with JSON text
+ std::stringstream ss;
+ ss << text;
+
+ // create JSON from stream
+ json j_complete(ss);
+ std::cout << std::setw(4) << j_complete << "\n\n";
+
+
+ // define parser callback
+ json::parser_callback_t cb = [](int depth, json::parse_event_t event, json & parsed)
+ {
+ // skip object elements with key "Thumbnail"
+ if (event == json::parse_event_t::key and parsed == json("Thumbnail"))
+ {
+ return false;
+ }
+ else
+ {
+ return true;
+ }
+ };
+
+ // fill a stream with JSON text
+ ss.clear();
+ ss << text;
+
+ // create JSON from stream (with callback)
+ json j_filtered(ss, cb);
+ std::cout << std::setw(4) << j_filtered << '\n';
+}
\ No newline at end of file
diff --git a/doc/examples/basic_json__istream.link b/doc/examples/basic_json__istream.link
new file mode 100644
index 00000000..e5475436
--- /dev/null
+++ b/doc/examples/basic_json__istream.link
@@ -0,0 +1 @@
+<a target="_blank" href="http://melpon.org/wandbox/permlink/lUltfC5TlmxeUq5X"><b>online</b></a>
\ No newline at end of file
diff --git a/doc/examples/basic_json__istream.output b/doc/examples/basic_json__istream.output
new file mode 100644
index 00000000..279a7ff7
--- /dev/null
+++ b/doc/examples/basic_json__istream.output
@@ -0,0 +1,34 @@
+{
+ "Image": {
+ "Animated": false,
+ "Height": 600,
+ "IDs": [
+ 116,
+ 943,
+ 234,
+ 38793
+ ],
+ "Thumbnail": {
+ "Height": 125,
+ "Url": "http://www.example.com/image/481989943",
+ "Width": 100
+ },
+ "Title": "View from 15th Floor",
+ "Width": 800
+ }
+}
+
+{
+ "Image": {
+ "Animated": false,
+ "Height": 600,
+ "IDs": [
+ 116,
+ 943,
+ 234,
+ 38793
+ ],
+ "Title": "View from 15th Floor",
+ "Width": 800
+ }
+}
diff --git a/src/json.hpp b/src/json.hpp
index 39ef1fe8..effdeb13 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -1806,6 +1806,31 @@ class basic_json
}
}
+ /*!
+ @brief construct a JSON value given an input stream
+
+ @param[in,out] i stream to read a serialized JSON value from
+ @param[in] cb a parser callback function of type @ref parser_callback_t
+ which is used to control the deserialization by filtering unwanted values
+ (optional)
+
+ @complexity Linear in the length of the input. The parser is a predictive
+ LL(1) parser. The complexity can be higher if the parser callback function
+ @a cb has a super-linear complexity.
+
+ @note A UTF-8 byte order mark is silently ignored.
+
+ @liveexample{The example below demonstrates constructing a JSON value from
+ a `std::stringstream` with and without callback
+ function.,basic_json__istream}
+
+ @since version 2.0.0
+ */
+ basic_json(std::istream& i, parser_callback_t cb = nullptr)
+ {
+ *this = parser(i, cb).parse();
+ }
+
///////////////////////////////////////
// other constructors and destructor //
///////////////////////////////////////
diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c
index f4909629..e0636ab3 100644
--- a/src/json.hpp.re2c
+++ b/src/json.hpp.re2c
@@ -1806,6 +1806,31 @@ class basic_json
}
}
+ /*!
+ @brief construct a JSON value given an input stream
+
+ @param[in,out] i stream to read a serialized JSON value from
+ @param[in] cb a parser callback function of type @ref parser_callback_t
+ which is used to control the deserialization by filtering unwanted values
+ (optional)
+
+ @complexity Linear in the length of the input. The parser is a predictive
+ LL(1) parser. The complexity can be higher if the parser callback function
+ @a cb has a super-linear complexity.
+
+ @note A UTF-8 byte order mark is silently ignored.
+
+ @liveexample{The example below demonstrates constructing a JSON value from
+ a `std::stringstream` with and without callback
+ function.,basic_json__istream}
+
+ @since version 2.0.0
+ */
+ basic_json(std::istream& i, parser_callback_t cb = nullptr)
+ {
+ *this = parser(i, cb).parse();
+ }
+
///////////////////////////////////////
// other constructors and destructor //
///////////////////////////////////////
diff --git a/test/unit.cpp b/test/unit.cpp
index 1c3957a4..fc77fe28 100644
--- a/test/unit.cpp
+++ b/test/unit.cpp
@@ -1264,6 +1264,42 @@ TEST_CASE("constructors")
}
}
}
+
+ SECTION("create a JSON value from an input stream")
+ {
+ SECTION("sts::stringstream")
+ {
+ std::stringstream ss;
+ ss << "[\"foo\",1,2,3,false,{\"one\":1}]";
+ json j(ss);
+ CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));
+ }
+
+ SECTION("with callback function")
+ {
+ std::stringstream ss;
+ ss << "[\"foo\",1,2,3,false,{\"one\":1}]";
+ json j(ss, [](int, json::parse_event_t, const json & val)
+ {
+ // filter all number(2) elements
+ if (val == json(2))
+ {
+ return false;
+ }
+ else
+ {
+ return true;
+ }
+ });
+ CHECK(j == json({"foo", 1, 3, false, {{"one", 1}}}));
+ }
+
+ SECTION("std::ifstream")
+ {
+ std::ifstream f("test/json_tests/pass1.json");
+ json j(f);
+ }
+ }
}
TEST_CASE("other constructors and destructor")