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authorBoris Kolpackov <boris@codesynthesis.com>2023-03-29 09:16:59 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2023-03-29 09:16:59 +0200
commit0a93d97fdfb09a47e555c9990b4083f0b3eabce7 (patch)
tree564bbcc5ed726532102c153e9deb698a6fc4e0e4
parent96dfc87c05110c3d857fe6d1c6eaeb139e91826c (diff)
Add next_expect*() API to JSON parser
-rw-r--r--libbutl/json/parser.cxx143
-rw-r--r--libbutl/json/parser.hxx299
-rw-r--r--libbutl/json/parser.ixx336
-rw-r--r--libbutl/json/serializer.hxx8
4 files changed, 781 insertions, 5 deletions
diff --git a/libbutl/json/parser.cxx b/libbutl/json/parser.cxx
index fa8916b..8ef7422 100644
--- a/libbutl/json/parser.cxx
+++ b/libbutl/json/parser.cxx
@@ -171,6 +171,149 @@ namespace butl
return translate (*peeked_);
}
+ static inline const char*
+ event_name (event e)
+ {
+ switch (e)
+ {
+ case event::begin_object: return "beginning of object";
+ case event::end_object: return "end of object";
+ case event::begin_array: return "beginning of array";
+ case event::end_array: return "end of array";
+ case event::name: return "member name";
+ case event::string: return "string value";
+ case event::number: return "numeric value";
+ case event::boolean: return "boolean value";
+ case event::null: return "null value";
+ }
+
+ return "";
+ }
+
+ bool parser::
+ next_expect (event p, optional<event> s)
+ {
+ optional<event> e (next ());
+ bool r;
+ if (e && ((r = *e == p) || (s && *e == *s)))
+ return r;
+
+ string d ("expected ");
+ d += event_name (p);
+
+ if (s)
+ {
+ d += " or ";
+ d += event_name (*s);
+ }
+
+ if (e)
+ {
+ d += " instead of ";
+ d += event_name (*e);
+ }
+
+ throw invalid_json_input (input_name != nullptr ? input_name : "",
+ line (),
+ column (),
+ position (),
+ move (d));
+ }
+
+ void parser::
+ next_expect_name (const char* n, bool su)
+ {
+ for (;;)
+ {
+ next_expect (event::name);
+
+ if (name () == n)
+ return;
+
+ if (!su)
+ break;
+
+ next_expect_value_skip ();
+ }
+
+ string d ("expected object member name '");
+ d += n;
+ d += "' instead of '";
+ d += name ();
+ d += '\'';
+
+ throw invalid_json_input (input_name != nullptr ? input_name : "",
+ line (),
+ column (),
+ position (),
+ move (d));
+ }
+
+ void parser::
+ next_expect_value_skip ()
+ {
+ optional<event> e (next ());
+
+ if (e)
+ {
+ switch (*e)
+ {
+ case event::begin_object:
+ case event::begin_array:
+ {
+ // Skip until matching end_object/array keeping track of nesting.
+ // We are going to rely on the fact that we should either get such
+ // an event or next() should throw.
+ //
+ event be (*e);
+ event ee (be == event::begin_object
+ ? event::end_object
+ : event::end_array);
+
+ for (size_t n (0);; )
+ {
+ event e (*next ());
+
+ if (e == ee)
+ {
+ if (n == 0)
+ break;
+
+ --n;
+ }
+ else if (e == be)
+ ++n;
+ }
+
+ return;
+ }
+ case event::string:
+ case event::number:
+ case event::boolean:
+ case event::null:
+ return;
+ case event::name:
+ case event::end_object:
+ case event::end_array:
+ break;
+ }
+ }
+
+ string d ("expected value");
+
+ if (e)
+ {
+ d += " instead of ";
+ d += event_name (*e);
+ }
+
+ throw invalid_json_input (input_name != nullptr ? input_name : "",
+ line (),
+ column (),
+ position (),
+ move (d));
+ }
+
std::uint64_t parser::
line () const noexcept
{
diff --git a/libbutl/json/parser.hxx b/libbutl/json/parser.hxx
index 241ca46..95d9c4e 100644
--- a/libbutl/json/parser.hxx
+++ b/libbutl/json/parser.hxx
@@ -172,6 +172,9 @@ namespace butl
parser& operator= (parser&&) = delete;
parser& operator= (const parser&) = delete;
+ // Event iteration.
+ //
+
// Return the next event or nullopt if end of input is reached.
//
// In the single-value parsing mode (default) the parsing code could
@@ -259,7 +262,8 @@ namespace butl
optional<event>
peek ();
- // Event data.
+
+ // Event data access.
//
// Return the object member name.
@@ -295,6 +299,299 @@ namespace butl
std::pair<const char*, std::size_t>
data () const {return std::make_pair (raw_s_, raw_n_);}
+
+ // Higher-level API suitable for parsing specific JSON vocabularies.
+ //
+ // The API summary:
+ //
+ // void next_expect (event);
+ // bool next_expect (event primary, event secondary);
+ //
+ // void next_expect_name (string name, bool skip_unknown = false);
+ //
+ // std::string& next_expect_string ();
+ // T next_expect_string<T> ();
+ // std::string& next_expect_number ();
+ // T next_expect_number<T> ();
+ // std::string& next_expect_boolean ();
+ // T next_expect_boolean<T>();
+ //
+ // std::string* next_expect_string_null ();
+ // optional<T> next_expect_string_null<T> ();
+ // std::string* next_expect_number_null ();
+ // optional<T> next_expect_number_null<T> ();
+ // std::string* next_expect_boolean_null ();
+ // optional<T> next_expect_boolean_null<T>();
+ //
+ // std::string& next_expect_member_string (string name, bool = false);
+ // T next_expect_member_string<T> (string name, bool = false);
+ // std::string& next_expect_member_number (string name, bool = false);
+ // T next_expect_member_number<T> (string name, bool = false);
+ // std::string& next_expect_member_boolean (string name, bool = false);
+ // T next_expect_member_boolean<T>(string name, bool = false);
+ //
+ // std::string* next_expect_member_string_null (string, bool = false);
+ // optional<T> next_expect_member_string_null<T> (string, bool = false);
+ // std::string* next_expect_member_number_null (string, bool = false);
+ // optional<T> next_expect_member_number_null<T> (string, bool = false);
+ // std::string* next_expect_member_boolean_null (string, bool = false);
+ // optional<T> next_expect_member_boolean_null<T>(string, bool = false);
+ //
+ // void next_expect_member_object (string name, bool = false);
+ // bool next_expect_member_object_null(string name, bool = false);
+ //
+ // void next_expect_member_array (string name, bool = false);
+ // bool next_expect_member_array_null(string name, bool = false);
+ //
+ // void next_expect_value_skip();
+
+ // Get the next event and make sure that it's what's expected: primary
+ // or, if specified, secondary event. If it is not either, then throw
+ // invalid_json_input with appropriate description. Return true if it is
+ // primary.
+ //
+ // The secondary expected event is primarily useful for handling
+ // optional members. For example:
+ //
+ // while (p.next_expect (event::name, event::end_object))
+ // {
+ // // Handle object member.
+ // }
+ //
+ // Or homogeneous arrays:
+ //
+ // while (p.next_expect (event::string, event::end_array))
+ // {
+ // // Handle array element.
+ // }
+ //
+ // Or values that can be null:
+ //
+ // if (p.next_expect (event::begin_object, event::null))
+ // {
+ // // Parse object.
+ // }
+ //
+ bool
+ next_expect (event primary, optional<event> secondary = nullopt);
+
+ // Get the next event and make sure it is event::name and the object
+ // member matches the specified name. If either is not, then throw
+ // invalid_json_input with appropriate description. If skip_unknown is
+ // true, then skip over unknown member names until a match is found.
+ //
+ void
+ next_expect_name (const char* name, bool skip_unknown = false);
+
+ void
+ next_expect_name (const std::string&, bool = false);
+
+ // Get the next event and make sure it is event::<type> returning its
+ // value similar to the value() functions. If it is not, then throw
+ // invalid_json_input with appropriate description.
+ //
+ std::string&
+ next_expect_string ();
+
+ template <typename T>
+ T
+ next_expect_string ();
+
+ std::string&
+ next_expect_number ();
+
+ template <typename T>
+ T
+ next_expect_number ();
+
+ std::string&
+ next_expect_boolean ();
+
+ template <typename T>
+ T
+ next_expect_boolean ();
+
+ // Similar to next_expect_<type>() but in addition to event::<type> also
+ // allow event::null, in which case returning no value.
+ //
+ std::string*
+ next_expect_string_null ();
+
+ template <typename T>
+ optional<T>
+ next_expect_string_null ();
+
+ std::string*
+ next_expect_number_null ();
+
+ template <typename T>
+ optional<T>
+ next_expect_number_null ();
+
+ std::string*
+ next_expect_boolean_null ();
+
+ template <typename T>
+ optional<T>
+ next_expect_boolean_null ();
+
+ // Call next_expect_name() followed by next_expect_<type>[_null]()
+ // returning its result. In other words, parse the entire object member
+ // with the specifed name and of type <type>, returning its value.
+
+ // next_expect_member_string()
+ //
+ std::string&
+ next_expect_member_string (const char* name, bool skip_unknown = false);
+
+ std::string&
+ next_expect_member_string (const std::string&, bool = false);
+
+ template <typename T>
+ T
+ next_expect_member_string (const char*, bool = false);
+
+ template <typename T>
+ T
+ next_expect_member_string (const std::string&, bool = false);
+
+ // next_expect_member_number()
+ //
+ std::string&
+ next_expect_member_number (const char* name, bool skip_unknown = false);
+
+ std::string&
+ next_expect_member_number (const std::string&, bool = false);
+
+ template <typename T>
+ T
+ next_expect_member_number (const char*, bool = false);
+
+ template <typename T>
+ T
+ next_expect_member_number (const std::string&, bool = false);
+
+ // next_expect_member_boolean()
+ //
+ std::string&
+ next_expect_member_boolean (const char* name, bool skip_unknown = false);
+
+ std::string&
+ next_expect_member_boolean (const std::string&, bool = false);
+
+ template <typename T>
+ T
+ next_expect_member_boolean (const char*, bool = false);
+
+ template <typename T>
+ T
+ next_expect_member_boolean (const std::string&, bool = false);
+
+ // next_expect_member_string_null()
+ //
+ std::string*
+ next_expect_member_string_null (const char*, bool = false);
+
+ std::string*
+ next_expect_member_string_null (const std::string&, bool = false);
+
+ template <typename T>
+ optional<T>
+ next_expect_member_string_null (const char*, bool = false);
+
+ template <typename T>
+ optional<T>
+ next_expect_member_string_null (const std::string&, bool = false);
+
+ // next_expect_member_number_null()
+ //
+ std::string*
+ next_expect_member_number_null (const char*, bool = false);
+
+ std::string*
+ next_expect_member_number_null (const std::string&, bool = false);
+
+ template <typename T>
+ optional<T>
+ next_expect_member_number_null (const char*, bool = false);
+
+ template <typename T>
+ optional<T>
+ next_expect_member_number_null (const std::string&, bool = false);
+
+ // next_expect_member_boolean_null()
+ //
+ std::string*
+ next_expect_member_boolean_null (const char*, bool = false);
+
+ std::string*
+ next_expect_member_boolean_null (const std::string&, bool = false);
+
+ template <typename T>
+ optional<T>
+ next_expect_member_boolean_null (const char*, bool = false);
+
+ template <typename T>
+ optional<T>
+ next_expect_member_boolean_null (const std::string&, bool = false);
+
+ // Call next_expect_name() followed by next_expect(event::begin_object).
+ // In the _null version also allow event::null, in which case return
+ // false.
+ //
+ void
+ next_expect_member_object (const char* name, bool skip_unknown = false);
+
+ void
+ next_expect_member_object (const std::string&, bool = false);
+
+ bool
+ next_expect_member_object_null (const char*, bool = false);
+
+ bool
+ next_expect_member_object_null (const std::string&, bool = false);
+
+ // Call next_expect_name() followed by next_expect(event::begin_array).
+ // In the _null version also allow event::null, in which case return
+ // false.
+ //
+ void
+ next_expect_member_array (const char* name, bool skip_unknown = false);
+
+ void
+ next_expect_member_array (const std::string&, bool = false);
+
+ bool
+ next_expect_member_array_null (const char*, bool = false);
+
+ bool
+ next_expect_member_array_null (const std::string&, bool = false);
+
+ // Get the next event and make sure it is the beginning of a value
+ // (begin_object, begin_array, string, number, boolean, null). If it is
+ // not, then throw invalid_json_input with appropriate description.
+ // Otherwise, skip until the end of the value, recursively in case of
+ // object and array.
+ //
+ // This function is primarily useful for skipping unknown object
+ // members, for example:
+ //
+ // while (p.next_expect (event::name, event::end_object))
+ // {
+ // if (p.name () == "known")
+ // {
+ // // Handle known member.
+ // }
+ // else
+ // p.next_expect_value_skip ();
+ // }
+ //
+ void
+ next_expect_value_skip ();
+
+ // Parsing location.
+ //
+
// Return the line number (1-based) corresponding to the most recently
// parsed event or 0 if nothing has been parsed yet.
//
diff --git a/libbutl/json/parser.ixx b/libbutl/json/parser.ixx
index 3f02a1e..cf6dca3 100644
--- a/libbutl/json/parser.ixx
+++ b/libbutl/json/parser.ixx
@@ -212,5 +212,341 @@ namespace butl
return parse_value<T> (value_.data (), value_.size (), *this);
}
+
+ inline void parser::
+ next_expect_name (const std::string& n, bool su)
+ {
+ next_expect_name (n.c_str (), su);
+ }
+
+ // next_expect_<type>()
+ //
+ inline std::string& parser::
+ next_expect_string ()
+ {
+ next_expect (event::string);
+ return value ();
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_string ()
+ {
+ next_expect (event::string);
+ return value<T> ();
+ }
+
+ inline std::string& parser::
+ next_expect_number ()
+ {
+ next_expect (event::number);
+ return value ();
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_number ()
+ {
+ next_expect (event::number);
+ return value<T> ();
+ }
+
+ inline std::string& parser::
+ next_expect_boolean ()
+ {
+ next_expect (event::boolean);
+ return value ();
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_boolean ()
+ {
+ next_expect (event::boolean);
+ return value<T> ();
+ }
+
+ // next_expect_<type>_null()
+ //
+ inline std::string* parser::
+ next_expect_string_null ()
+ {
+ return next_expect (event::string, event::null) ? &value () : nullptr;
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_string_null ()
+ {
+ return next_expect (event::string, event::null)
+ ? optional<T> (value<T> ())
+ : nullopt;
+ }
+
+ inline std::string* parser::
+ next_expect_number_null ()
+ {
+ return next_expect (event::number, event::null) ? &value () : nullptr;
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_number_null ()
+ {
+ return next_expect (event::number, event::null)
+ ? optional<T> (value<T> ())
+ : nullopt;
+ }
+
+ inline std::string* parser::
+ next_expect_boolean_null ()
+ {
+ return next_expect (event::boolean, event::null) ? &value () : nullptr;
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_boolean_null ()
+ {
+ return next_expect (event::boolean, event::null)
+ ? optional<T> (value<T> ())
+ : nullopt;
+ }
+
+ // next_expect_member_string()
+ //
+ inline std::string& parser::
+ next_expect_member_string (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_string ();
+ }
+
+ inline std::string& parser::
+ next_expect_member_string (const std::string& n, bool su)
+ {
+ return next_expect_member_string (n.c_str (), su);
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_member_string (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_string<T> ();
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_member_string (const std::string& n, bool su)
+ {
+ return next_expect_member_string<T> (n.c_str (), su);
+ }
+
+ // next_expect_member_number()
+ //
+ inline std::string& parser::
+ next_expect_member_number (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_number ();
+ }
+
+ inline std::string& parser::
+ next_expect_member_number (const std::string& n, bool su)
+ {
+ return next_expect_member_number (n.c_str (), su);
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_member_number (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_number<T> ();
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_member_number (const std::string& n, bool su)
+ {
+ return next_expect_member_number<T> (n.c_str (), su);
+ }
+
+ // next_expect_member_boolean()
+ //
+ inline std::string& parser::
+ next_expect_member_boolean (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_boolean ();
+ }
+
+ inline std::string& parser::
+ next_expect_member_boolean (const std::string& n, bool su)
+ {
+ return next_expect_member_boolean (n.c_str (), su);
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_member_boolean (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_boolean<T> ();
+ }
+
+ template <typename T>
+ inline T parser::
+ next_expect_member_boolean (const std::string& n, bool su)
+ {
+ return next_expect_member_boolean<T> (n.c_str (), su);
+ }
+
+ // next_expect_member_string_null()
+ //
+ inline std::string* parser::
+ next_expect_member_string_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_string_null ();
+ }
+
+ inline std::string* parser::
+ next_expect_member_string_null (const std::string& n, bool su)
+ {
+ return next_expect_member_string_null (n.c_str (), su);
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_member_string_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_string_null<T> ();
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_member_string_null (const std::string& n, bool su)
+ {
+ return next_expect_member_string_null<T> (n.c_str (), su);
+ }
+
+ // next_expect_member_number_null()
+ //
+ inline std::string* parser::
+ next_expect_member_number_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_number_null ();
+ }
+
+ inline std::string* parser::
+ next_expect_member_number_null (const std::string& n, bool su)
+ {
+ return next_expect_member_number_null (n.c_str (), su);
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_member_number_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_number_null<T> ();
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_member_number_null (const std::string& n, bool su)
+ {
+ return next_expect_member_number_null<T> (n.c_str (), su);
+ }
+
+ // next_expect_member_boolean_null()
+ //
+ inline std::string* parser::
+ next_expect_member_boolean_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_boolean_null ();
+ }
+
+ inline std::string* parser::
+ next_expect_member_boolean_null (const std::string& n, bool su)
+ {
+ return next_expect_member_boolean_null (n.c_str (), su);
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_member_boolean_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect_boolean_null<T> ();
+ }
+
+ template <typename T>
+ inline optional<T> parser::
+ next_expect_member_boolean_null (const std::string& n, bool su)
+ {
+ return next_expect_member_boolean_null<T> (n.c_str (), su);
+ }
+
+ // next_expect_member_object[_null]()
+ //
+ inline void parser::
+ next_expect_member_object (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ next_expect (event::begin_object);
+ }
+
+ inline void parser::
+ next_expect_member_object (const std::string& n, bool su)
+ {
+ next_expect_member_object (n.c_str (), su);
+ }
+
+ inline bool parser::
+ next_expect_member_object_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect (event::begin_object, event::null);
+ }
+
+ inline bool parser::
+ next_expect_member_object_null (const std::string& n, bool su)
+ {
+ return next_expect_member_object_null (n.c_str (), su);
+ }
+
+ // next_expect_member_array[_null]()
+ //
+ inline void parser::
+ next_expect_member_array (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ next_expect (event::begin_array);
+ }
+
+ inline void parser::
+ next_expect_member_array (const std::string& n, bool su)
+ {
+ next_expect_member_array (n.c_str (), su);
+ }
+
+ inline bool parser::
+ next_expect_member_array_null (const char* n, bool su)
+ {
+ next_expect_name (n, su);
+ return next_expect (event::begin_array, event::null);
+ }
+
+ inline bool parser::
+ next_expect_member_array_null (const std::string& n, bool su)
+ {
+ return next_expect_member_array_null (n.c_str (), su);
+ }
}
}
diff --git a/libbutl/json/serializer.hxx b/libbutl/json/serializer.hxx
index c143dab..5192cb4 100644
--- a/libbutl/json/serializer.hxx
+++ b/libbutl/json/serializer.hxx
@@ -169,8 +169,8 @@ namespace butl
//
// The member_begin_object() version is a shortcut for:
//
- // member_name (name, check);
- // begin_object ();
+ // member_name (name, check);
+ // begin_object ();
//
void
begin_object ();
@@ -212,8 +212,8 @@ namespace butl
//
// The member_begin_array() version is a shortcut for:
//
- // member_name (name, check);
- // begin_array ();
+ // member_name (name, check);
+ // begin_array ();
//
void
begin_array ();