+import error
+private import json_parser
+private import json_lexer
+
+redef class Text
+
+ # Removes JSON-escaping if necessary in a JSON string
+ #
+ # assert "\\\"string\\uD83D\\uDE02\\\"".unescape_json == "\"string😂\""
+ fun unescape_json: Text do
+ if not json_need_escape then return self
+ return self.json_to_nit_string
+ end
+
+ # Does `self` need treatment from JSON to Nit ?
+ #
+ # i.e. is there at least one `\` character in it ?
+ #
+ # assert not "string".json_need_escape
+ # assert "\\\"string\\\"".json_need_escape
+ protected fun json_need_escape: Bool do return has('\\')
+
+ # Escapes `self` from a JSON string to a Nit string
+ #
+ # assert "\\\"string\\\"".json_to_nit_string == "\"string\""
+ # assert "\\nEscape\\t\\n".json_to_nit_string == "\nEscape\t\n"
+ # assert "\\u0041zu\\uD800\\uDFD3".json_to_nit_string == "Azu𐏓"
+ protected fun json_to_nit_string: String do
+ var res = new FlatBuffer.with_capacity(byte_length)
+ var i = 0
+ var ln = self.length
+ while i < ln do
+ var char = self[i]
+ if char == '\\' then
+ i += 1
+ char = self[i]
+ if char == 'b' then
+ char = 0x08.code_point
+ else if char == 'f' then
+ char = 0x0C.code_point
+ else if char == 'n' then
+ char = '\n'
+ else if char == 'r' then
+ char = '\r'
+ else if char == 't' then
+ char = '\t'
+ else if char == 'u' then
+ var u16_esc = from_utf16_digit(i + 1)
+ char = u16_esc.code_point
+ if char.is_surrogate and i + 10 < ln then
+ if self[i + 5] == '\\' and self[i + 6] == 'u' then
+ u16_esc <<= 16
+ u16_esc += from_utf16_digit(i + 7)
+ char = u16_esc.to_u32.from_utf16_surr.code_point
+ i += 6
+ else
+ char = 0xFFFD.code_point
+ end
+ end
+ i += 4
+ end
+ # `"`, `/` or `\` => Keep `char` as-is.
+ end
+ res.add char
+ i += 1
+ end
+ return res.to_s
+ end
+
+ # Parse `self` as JSON.
+ #
+ # If `self` is not a valid JSON document or contains an unsupported escape
+ # sequence, return a `JSONParseError`.
+ #
+ # Example with `JsonObject`:
+ #
+ # var obj = "\{\"foo\": \{\"bar\": true, \"goo\": [1, 2, 3]\}\}".parse_json
+ # assert obj isa JsonObject
+ # assert obj["foo"] isa JsonObject
+ # assert obj["foo"].as(JsonObject)["bar"] == true
+ #
+ # Example with `JsonArray`:
+ #
+ # var arr = "[1, 2, 3]".parse_json
+ # assert arr isa JsonArray
+ # assert arr.length == 3
+ # assert arr.first == 1
+ # assert arr.last == 3
+ #
+ # Example with `String`:
+ #
+ # var str = "\"foo, bar, baz\"".parse_json
+ # assert str isa String
+ # assert str == "foo, bar, baz"
+ #
+ # Example of a syntaxic error:
+ #
+ # var bad = "\{foo: \"bar\"\}".parse_json
+ # assert bad isa JsonParseError
+ # assert bad.position.col_start == 2
+ fun parse_json: nullable Serializable do
+ var lexer = new Lexer_json(to_s)
+ var parser = new Parser_json
+ var tokens = lexer.lex
+ parser.tokens.add_all(tokens)
+ var root_node = parser.parse
+ if root_node isa NStart then
+ return root_node.n_0.to_nit_object
+ else if root_node isa NError then
+ return new JsonParseError(root_node.message, root_node.position)
+ else abort
+ end
+end
+
+redef class FlatText
+ redef fun json_need_escape do
+ var its = items
+ for i in [first_byte .. last_byte] do
+ if its[i] == 0x5Cu8 then return true
+ end
+ return false
+ end
+end
+
+# A map that can be translated into a JSON object.
+interface JsonMapRead[K: String, V: nullable Serializable]
+ super MapRead[K, V]
+ super Serializable
+end
+
+# A JSON Object.
+class JsonObject
+ super JsonMapRead[String, nullable Serializable]
+ super HashMap[String, nullable Serializable]
+end
+
+# A sequence that can be translated into a JSON array.
+class JsonSequenceRead[E: nullable Serializable]
+ super Serializable
+ super SequenceRead[E]
+end
+
+# A JSON array.
+class JsonArray
+ super JsonSequenceRead[nullable Serializable]
+ super Array[nullable Serializable]
+end
+
+################################################################################
+# Redef parser