jsonwriter.py

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#  Copyright 2008-2015 Nokia Networks
#  Copyright 2016-     Robot Framework Foundation
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
 
class JsonWriter:
 
    def __init__(self, output, separator=''):
        self._writer_writer = JsonDumper(output)
        self._separator_separator = separator
 
    def write_json(self, prefix, data, postfix=';\n', mapping=None,
                   separator=True):
        self._writer_writer.write(prefix)
        self._writer_writer.dump(data, mapping)
        self._writer_writer.write(postfix)
        self._write_separator_write_separator(separator)
 
    def write(self, string, postfix=';\n', separator=True):
        self._writer_writer.write(string + postfix)
        self._write_separator_write_separator(separator)
 
    def _write_separator(self, separator):
        if separator and self._separator_separator:
            self._writer_writer.write(self._separator_separator)
 
 
class JsonDumper:
 
    def __init__(self, output):
        self.writewrite = output.write
        self._dumpers_dumpers = (MappingDumper(self),
                         IntegerDumper(self),
                         TupleListDumper(self),
                         StringDumper(self),
                         NoneDumper(self),
                         DictDumper(self))
 
    def dump(self, data, mapping=None):
        for dumper in self._dumpers_dumpers:
            if dumper.handles(data, mapping):
                dumper.dump(data, mapping)
                return
        raise ValueError('Dumping %s not supported.' % type(data))
 
 
class _Dumper:
    
    _handled_types = None
 
    def __init__(self, jsondumper):
        self._dump_dump = jsondumper.dump
        self._write_write = jsondumper.write
 
    def handles(self, data, mapping):
        return isinstance(data, self._handled_types_handled_types)
 
    def dump(self, data, mapping):
        raise NotImplementedError
 
 
class StringDumper(_Dumper):
    
    _handled_types = str
    
    _search_and_replace = [('\\', '\\\\'), ('"', '\\"'), ('\t', '\\t'),
                           ('\n', '\\n'), ('\r', '\\r'), ('</', '\\x3c/')]
 
    def dump(self, data, mapping):
        self._write_write('"%s"' % (self._escape_escape(data) if data else ''))
 
    def _escape(self, string):
        for search, replace in self._search_and_replace_search_and_replace:
            if search in string:
                string = string.replace(search, replace)
        return string
 
 
class IntegerDumper(_Dumper):
    # Handles also bool
    
    _handled_types = int
 
    def dump(self, data, mapping):
        self._write_write(str(data).lower())
 
 
class DictDumper(_Dumper):
    
    _handled_types = dict
 
    def dump(self, data, mapping):
        write = self._write_write
        dump = self._dump_dump
        write('{')
        last_index = len(data) - 1
        for index, key in enumerate(sorted(data)):
            dump(key, mapping)
            write(':')
            dump(data[key], mapping)
            if index < last_index:
                write(',')
        write('}')
 
 
class TupleListDumper(_Dumper):
    
    _handled_types = (tuple, list)
 
    def dump(self, data, mapping):
        write = self._write_write
        dump = self._dump_dump
        write('[')
        last_index = len(data) - 1
        for index, item in enumerate(data):
            dump(item, mapping)
            if index < last_index:
                write(',')
        write(']')
 
 
class MappingDumper(_Dumper):
 
    def handles(self, data, mapping):
        try:
            return mapping and data in mapping
        except TypeError:
            return False
 
    def dump(self, data, mapping):
        self._write_write(mapping[data])
 
 
class NoneDumper(_Dumper):
 
    def handles(self, data, mapping):
        return data is None
 
    def dump(self, data, mapping):
        self._write_write('null')