JSONPath

A strict RFC 9535 JSONPath implementation. More...

Classes
class	sourcemeta::core::JSONPath
class	sourcemeta::core::JSONPathParseError

Detailed Description

A strict RFC 9535 JSONPath implementation.

This functionality is included as follows:

#include <sourcemeta/core/jsonpath.h>

---

Class Documentation

sourcemeta::core::JSONPath

class sourcemeta::core::JSONPath

A parsed RFC 9535 JSONPath query that can be evaluated many times.

Public Types
enum class	FilterFunctionName : std::uint8_t {   Length , Count , Match , Search ,   Value }
	The function extensions that filter expressions can invoke. More...
enum class	FilterComparisonOperator : std::uint8_t {   Equal , NotEqual , Less , LessEqual ,   Greater , GreaterEqual }
	The operators that filter comparisons can use. More...
enum class	SegmentKind : std::uint8_t { SingleName , SingleIndex , General }
	The precomputed shape of a query segment. More...
using	Callback
	The callback invoked for every query result node.
using	Selector
	A single selector within a query segment.
Public Member Functions
	JSONPath (const JSON::StringView expression)
auto	evaluate (const JSON &document, const Callback &callback) const -> void
auto	to_json () const -> JSON
Static Public Member Functions
static auto	normalize (const WeakPointer &location) -> JSON::String
static auto	from_json (const JSON &value) -> std::optional< JSONPath >

Member Typedef Documentation

Callback

using sourcemeta::core::JSONPath::Callback

Initial value:

 
std::function<void(const JSON &value, const WeakPointer &location)>

The callback invoked for every query result node.

Selector

using sourcemeta::core::JSONPath::Selector

Initial value:

std::variant<SelectorName, SelectorWildcard, SelectorIndex,
                               SelectorSlice, SelectorFilter>

A single selector within a query segment.

Member Enumeration Documentation

FilterComparisonOperator

enum class sourcemeta::core::JSONPath::FilterComparisonOperator : std::uint8_t

strong

The operators that filter comparisons can use.

Enumerator
Equal	Both sides are equal.
NotEqual	Both sides are not equal.
Less	The left side orders before the right side.
LessEqual	The left side orders before or equals the right side.
Greater	The right side orders before the left side.
GreaterEqual	The right side orders before or equals the left side.

FilterFunctionName

enum class sourcemeta::core::JSONPath::FilterFunctionName : std::uint8_t

strong

The function extensions that filter expressions can invoke.

Enumerator
Length	The length of a string, array, or object value.
Count	The number of nodes a query selects.
Match	Whether a string entirely matches a regular expression.
Search	Whether a string contains a match of a regular expression.
Value	The value of the single node a query selects.

SegmentKind

enum class sourcemeta::core::JSONPath::SegmentKind : std::uint8_t

strong

The precomputed shape of a query segment.

Enumerator
SingleName	A single name selector applied to children.
SingleIndex	A single index selector applied to children.
General	Any other combination of selectors.

Constructor & Destructor Documentation

JSONPath()

sourcemeta::core::JSONPath::JSONPath ( const JSON::StringView expression )

explicit

Parse a query expression, throwing on invalid input. For example:

#include <sourcemeta/core/jsonpath.h>
 
const sourcemeta::core::JSONPath path{"$.store.book[0].title"};

Member Function Documentation

evaluate()

auto sourcemeta::core::JSONPath::evaluate	(	const JSON &	document,
		const Callback &	callback ) const -> void

Evaluate the query against a document, invoking the callback once per result node. For example:

#include <sourcemeta/core/jsonpath.h>
#include <cassert>
 
const sourcemeta::core::JSON document{
  sourcemeta::core::parse_json("{ \"foo\": [ 1, 2 ] }")};
const sourcemeta::core::JSONPath path{"$.foo[0]"};
path.evaluate(document, [](const auto &value, const auto &location) {
  assert(value.is_integer());
  assert(location.size() == 2);
});

from_json()

auto sourcemeta::core::JSONPath::from_json ( const JSON & value ) -> std::optional< JSONPath >

staticnodiscard

Deserialize a query from its expression string as JSON, returning no result on invalid input. For example:

#include <sourcemeta/core/jsonpath.h>
#include <cassert>
 
const sourcemeta::core::JSON input{"$.foo[0]"};
const auto path{sourcemeta::core::JSONPath::from_json(input)};
assert(path.has_value());

normalize()

auto sourcemeta::core::JSONPath::normalize ( const WeakPointer & location ) -> JSON::String

staticnodiscard

Serialize a location into the RFC 9535 normalized path form. For example:

#include <sourcemeta/core/jsonpath.h>
#include <cassert>
 
const sourcemeta::core::JSON document{
  sourcemeta::core::parse_json("{ \"foo\": [ 1, 2 ] }")};
const sourcemeta::core::JSONPath path{"$.foo[0]"};
path.evaluate(document, [](const auto &value, const auto &location) {
  assert(sourcemeta::core::JSONPath::normalize(location) ==
    "$['foo'][0]");
});

to_json()

auto sourcemeta::core::JSONPath::to_json ( ) const -> JSON

nodiscard

Serialize the query into its expression string as JSON. For example:

#include <sourcemeta/core/jsonpath.h>
#include <cassert>
 
const sourcemeta::core::JSONPath path{"$.foo[0]"};
const sourcemeta::core::JSON result{path.to_json()};
assert(result.is_string());
assert(result.to_string() == "$.foo[0]");

sourcemeta::core::JSONPathParseError

class sourcemeta::core::JSONPathParseError

An error that represents a JSONPath parsing failure

Inheritance diagram for sourcemeta::core::JSONPathParseError:

Public Member Functions
	JSONPathParseError (const std::uint64_t column)
	Construct an error given the column number where parsing failed.
auto	column () const noexcept -> std::uint64_t
	Get the column number of the error.