Embed pyhocon into package, and extend parsing capabilities.

trains/backend_api/schema/service.py

@@ -4,8 +4,7 @@ import re
 import attr
 import six
 
-import pyhocon
-
+from ...utilities.pyhocon import ConfigTree
 from .action import Action
 
 
@@ -56,7 +55,7 @@ class Service(object):
 
     def parse(self, service_config):
         self._default = service_config.get(
-            "_default", pyhocon.ConfigTree()
+            "_default", ConfigTree()
         ).as_plain_ordered_dict()
 
         self._doc = '{} service'.format(self.name)
@@ -64,7 +63,7 @@ class Service(object):
         if description:
             self._doc += '\n\n{}'.format(description)
         self._definitions = service_config.get(
-            "_definitions", pyhocon.ConfigTree()
+            "_definitions", ConfigTree()
         ).as_plain_ordered_dict()
         self._definitions_refs = {
             k: self._get_schema_references(v) for k, v in self._definitions.items()

trains/backend_api/session/session.py

@@ -7,7 +7,7 @@ from six.moves.urllib.parse import urlparse, urlunparse
 import jwt
 import requests
 import six
-from pyhocon import ConfigTree
+from ...utilities.pyhocon import ConfigTree
 from requests.auth import HTTPBasicAuth
 
 from .callresult import CallResult

trains/backend_config/config.py

@@ -9,10 +9,9 @@ from fnmatch import fnmatch
 from os.path import expanduser
 from typing import Any
 
-import pyhocon
 import six
 from pathlib2 import Path
-from pyhocon import ConfigTree
+from ..utilities.pyhocon import ConfigTree, ConfigFactory
 from pyparsing import (
     ParseFatalException,
     ParseException,
@@ -310,7 +309,7 @@ class Config(object):
             print("Loading config from file %s" % file_path)
 
         try:
-            return pyhocon.ConfigFactory.parse_file(file_path)
+            return ConfigFactory.parse_file(file_path)
         except ParseSyntaxException as ex:
             msg = "Failed parsing {0} ({1.__class__.__name__}): (at char {1.loc}, line:{1.lineno}, col:{1.column})".format(
                 file_path, ex

trains/config/default/__main__.py

@@ -1,7 +1,7 @@
 from __future__ import print_function
 
 from six.moves import input
-from pyhocon import ConfigFactory
+from ...utilities.pyhocon import ConfigFactory
 from pathlib2 import Path
 from six.moves.urllib.parse import urlparse
 

trains/model.py

@@ -10,7 +10,7 @@ import six
 from .backend_api import Session
 from .backend_api.services import models
 from pathlib2 import Path
-from pyhocon import ConfigFactory, HOCONConverter
+from .utilities.pyhocon import ConfigFactory, HOCONConverter
 
 from .backend_interface.util import validate_dict, get_single_result, mutually_exclusive
 from .debugging.log import get_logger
@@ -288,14 +288,15 @@ class BaseModel(object):
         if not isinstance(config, dict):
             raise ValueError("Model configuration only supports dictionary objects")
         try:
-            # hack, pyhocon is not very good with dict conversion so we pass through json
             try:
+                text = HOCONConverter.to_hocon(ConfigFactory.from_dict(config))
+            except Exception:
+                # fallback json+pyhocon
+                # hack, pyhocon is not very good with dict conversion so we pass through json
                 import json
                 text = json.dumps(config)
-                text = HOCONConverter.convert(ConfigFactory.parse_string(text), 'hocon')
-            except Exception:
-                # fallback pyhocon
-                text = HOCONConverter.convert(ConfigFactory.from_dict(config), 'hocon')
+                text = HOCONConverter.to_hocon(ConfigFactory.parse_string(text))
+
         except Exception:
             raise ValueError("Could not serialize configuration dictionary:\n", config)
         return text

trains/utilities/pyhocon/__init__.py

@@ -0,0 +1,3 @@
+from .config_parser import ConfigParser, ConfigFactory
+from .config_tree import ConfigTree
+from .converter import HOCONConverter

trains/utilities/pyhocon/config_parser.py

@@ -0,0 +1,743 @@
+import itertools
+import re
+import os
+import socket
+import contextlib
+import codecs
+from datetime import timedelta
+
+from pyparsing import Forward, Keyword, QuotedString, Word, Literal, Suppress, Regex, Optional, SkipTo, ZeroOrMore, \
+    Group, lineno, col, TokenConverter, replaceWith, alphanums, alphas8bit, ParseSyntaxException, StringEnd
+from pyparsing import ParserElement
+from .config_tree import ConfigTree, ConfigSubstitution, ConfigList, ConfigValues, ConfigUnquotedString, \
+    ConfigInclude, NoneValue, ConfigQuotedString
+from .exceptions import ConfigSubstitutionException, ConfigMissingException, ConfigException
+import logging
+import copy
+
+use_urllib2 = False
+try:
+    # For Python 3.0 and later
+    from urllib.request import urlopen
+    from urllib.error import HTTPError, URLError
+except ImportError:  # pragma: no cover
+    # Fall back to Python 2's urllib2
+    from urllib2 import urlopen, HTTPError, URLError
+
+    use_urllib2 = True
+try:
+    basestring
+except NameError:  # pragma: no cover
+    basestring = str
+    unicode = str
+
+logger = logging.getLogger(__name__)
+
+#
+# Substitution Defaults
+#
+
+
+class DEFAULT_SUBSTITUTION(object):
+    pass
+
+
+class MANDATORY_SUBSTITUTION(object):
+    pass
+
+
+class NO_SUBSTITUTION(object):
+    pass
+
+
+class STR_SUBSTITUTION(object):
+    pass
+
+
+def period(period_value, period_unit):
+    try:
+        from dateutil.relativedelta import relativedelta as period_impl
+    except Exception:
+        from datetime import timedelta as period_impl
+
+    if period_unit == 'nanoseconds':
+        period_unit = 'microseconds'
+        period_value = int(period_value / 1000)
+
+    arguments = dict(zip((period_unit,), (period_value,)))
+
+    if period_unit == 'milliseconds':
+        return timedelta(**arguments)
+
+    return period_impl(**arguments)
+
+
+class ConfigFactory(object):
+
+    @classmethod
+    def parse_file(cls, filename, encoding='utf-8', required=True, resolve=True, unresolved_value=DEFAULT_SUBSTITUTION):
+        """Parse file
+
+        :param filename: filename
+        :type filename: basestring
+        :param encoding: file encoding
+        :type encoding: basestring
+        :param required: If true, raises an exception if can't load file
+        :type required: boolean
+        :param resolve: if true, resolve substitutions
+        :type resolve: boolean
+        :param unresolved_value: assigned value value to unresolved substitution.
+        If overriden with a default value, it will replace all unresolved value to the default value.
+        If it is set to to pyhocon.STR_SUBSTITUTION then it will replace the value by its substitution expression (e.g., ${x})
+        :type unresolved_value: boolean
+        :return: Config object
+        :type return: Config
+        """
+        try:
+            with codecs.open(filename, 'r', encoding=encoding) as fd:
+                content = fd.read()
+                return cls.parse_string(content, os.path.dirname(filename), resolve, unresolved_value)
+        except IOError as e:
+            if required:
+                raise e
+            logger.warn('Cannot include file %s. File does not exist or cannot be read.', filename)
+            return []
+
+    @classmethod
+    def parse_URL(cls, url, timeout=None, resolve=True, required=False, unresolved_value=DEFAULT_SUBSTITUTION):
+        """Parse URL
+
+        :param url: url to parse
+        :type url: basestring
+        :param resolve: if true, resolve substitutions
+        :type resolve: boolean
+        :param unresolved_value: assigned value value to unresolved substitution.
+        If overriden with a default value, it will replace all unresolved value to the default value.
+        If it is set to to pyhocon.STR_SUBSTITUTION then it will replace the value by its substitution expression (e.g., ${x})
+        :type unresolved_value: boolean
+        :return: Config object or []
+        :type return: Config or list
+        """
+        socket_timeout = socket._GLOBAL_DEFAULT_TIMEOUT if timeout is None else timeout
+
+        try:
+            with contextlib.closing(urlopen(url, timeout=socket_timeout)) as fd:
+                content = fd.read() if use_urllib2 else fd.read().decode('utf-8')
+                return cls.parse_string(content, os.path.dirname(url), resolve, unresolved_value)
+        except (HTTPError, URLError) as e:
+            logger.warn('Cannot include url %s. Resource is inaccessible.', url)
+            if required:
+                raise e
+            else:
+                return []
+
+    @classmethod
+    def parse_string(cls, content, basedir=None, resolve=True, unresolved_value=DEFAULT_SUBSTITUTION):
+        """Parse URL
+
+        :param content: content to parse
+        :type content: basestring
+        :param resolve: If true, resolve substitutions
+        :param resolve: if true, resolve substitutions
+        :type resolve: boolean
+        :param unresolved_value: assigned value value to unresolved substitution.
+        If overriden with a default value, it will replace all unresolved value to the default value.
+        If it is set to to pyhocon.STR_SUBSTITUTION then it will replace the value by its substitution expression (e.g., ${x})
+        :type unresolved_value: boolean
+        :return: Config object
+        :type return: Config
+        """
+        return ConfigParser().parse(content, basedir, resolve, unresolved_value)
+
+    @classmethod
+    def from_dict(cls, dictionary, root=False):
+        """Convert dictionary (and ordered dictionary) into a ConfigTree
+        :param dictionary: dictionary to convert
+        :type dictionary: dict
+        :return: Config object
+        :type return: Config
+        """
+
+        def create_tree(value):
+            if isinstance(value, dict):
+                res = ConfigTree(root=root)
+                for key, child_value in value.items():
+                    res.put(key, create_tree(child_value))
+                return res
+            if isinstance(value, list):
+                return [create_tree(v) for v in value]
+            else:
+                return value
+
+        return create_tree(dictionary)
+
+
+class ConfigParser(object):
+    """
+    Parse HOCON files: https://github.com/typesafehub/config/blob/master/HOCON.md
+    """
+
+    REPLACEMENTS = {
+        '\\\\': '\\',
+        '\\\n': '\n',
+        '\\n': '\n',
+        '\\r': '\r',
+        '\\t': '\t',
+        '\\=': '=',
+        '\\#': '#',
+        '\\!': '!',
+        '\\"': '"',
+    }
+
+    period_type_map = {
+        'nanoseconds': ['ns', 'nano', 'nanos', 'nanosecond', 'nanoseconds'],
+
+        'microseconds': ['us', 'micro', 'micros', 'microsecond', 'microseconds'],
+        'milliseconds': ['ms', 'milli', 'millis', 'millisecond', 'milliseconds'],
+        'seconds': ['s', 'second', 'seconds'],
+        'minutes': ['m', 'minute', 'minutes'],
+        'hours': ['h', 'hour', 'hours'],
+        'weeks': ['w', 'week', 'weeks'],
+        'days': ['d', 'day', 'days'],
+
+    }
+
+    optional_period_type_map = {
+        'months': ['mo', 'month', 'months'],  # 'm' from hocon spec removed. conflicts with minutes syntax.
+        'years': ['y', 'year', 'years']
+    }
+
+    supported_period_map = None
+
+    @classmethod
+    def get_supported_period_type_map(cls):
+        if cls.supported_period_map is None:
+            cls.supported_period_map = {}
+            cls.supported_period_map.update(cls.period_type_map)
+
+            try:
+                from dateutil import relativedelta
+
+                if relativedelta is not None:
+                    cls.supported_period_map.update(cls.optional_period_type_map)
+            except Exception:
+                pass
+
+        return cls.supported_period_map
+
+    @classmethod
+    def parse(cls, content, basedir=None, resolve=True, unresolved_value=DEFAULT_SUBSTITUTION):
+        """parse a HOCON content
+
+        :param content: HOCON content to parse
+        :type content: basestring
+        :param resolve: if true, resolve substitutions
+        :type resolve: boolean
+        :param unresolved_value: assigned value value to unresolved substitution.
+        If overriden with a default value, it will replace all unresolved value to the default value.
+        If it is set to to pyhocon.STR_SUBSTITUTION then it will replace the value by its substitution expression (e.g., ${x})
+        :type unresolved_value: boolean
+        :return: a ConfigTree or a list
+        """
+
+        unescape_pattern = re.compile(r'\\.')
+
+        def replace_escape_sequence(match):
+            value = match.group(0)
+            return cls.REPLACEMENTS.get(value, value)
+
+        def norm_string(value):
+            return unescape_pattern.sub(replace_escape_sequence, value)
+
+        def unescape_string(tokens):
+            return ConfigUnquotedString(norm_string(tokens[0]))
+
+        def parse_multi_string(tokens):
+            # remove the first and last 3 "
+            return tokens[0][3: -3]
+
+        def convert_number(tokens):
+            n = tokens[0]
+            try:
+                return int(n, 10)
+            except ValueError:
+                return float(n)
+
+        def safe_convert_number(tokens):
+            n = tokens[0]
+            try:
+                return int(n, 10)
+            except ValueError:
+                try:
+                    return float(n)
+                except ValueError:
+                    return n
+
+        def convert_period(tokens):
+
+            period_value = int(tokens.value)
+            period_identifier = tokens.unit
+
+            period_unit = next((single_unit for single_unit, values
+                                in cls.get_supported_period_type_map().items()
+                                if period_identifier in values))
+
+            return period(period_value, period_unit)
+
+        # ${path} or ${?path} for optional substitution
+        SUBSTITUTION_PATTERN = r"\$\{(?P<optional>\?)?(?P<variable>[^}]+)\}(?P<ws>[ \t]*)"
+
+        def create_substitution(instring, loc, token):
+            # remove the ${ and }
+            match = re.match(SUBSTITUTION_PATTERN, token[0])
+            variable = match.group('variable')
+            ws = match.group('ws')
+            optional = match.group('optional') == '?'
+            substitution = ConfigSubstitution(variable, optional, ws, instring, loc)
+            return substitution
+
+        # ${path} or ${?path} for optional substitution
+        STRING_PATTERN = '"(?P<value>(?:[^"\\\\]|\\\\.)*)"(?P<ws>[ \t]*)'
+
+        def create_quoted_string(instring, loc, token):
+            # remove the ${ and }
+            match = re.match(STRING_PATTERN, token[0])
+            value = norm_string(match.group('value'))
+            ws = match.group('ws')
+            return ConfigQuotedString(value, ws, instring, loc)
+
+        def include_config(instring, loc, token):
+            url = None
+            file = None
+            required = False
+
+            if token[0] == 'required':
+                required = True
+                final_tokens = token[1:]
+            else:
+                final_tokens = token
+
+            if len(final_tokens) == 1:  # include "test"
+                value = final_tokens[0].value if isinstance(final_tokens[0], ConfigQuotedString) else final_tokens[0]
+                if value.startswith("http://") or value.startswith("https://") or value.startswith("file://"):
+                    url = value
+                else:
+                    file = value
+            elif len(final_tokens) == 2:  # include url("test") or file("test")
+                value = final_tokens[1].value if isinstance(token[1], ConfigQuotedString) else final_tokens[1]
+                if final_tokens[0] == 'url':
+                    url = value
+                else:
+                    file = value
+
+            if url is not None:
+                logger.debug('Loading config from url %s', url)
+                obj = ConfigFactory.parse_URL(
+                    url,
+                    resolve=False,
+                    required=required,
+                    unresolved_value=NO_SUBSTITUTION
+                )
+            elif file is not None:
+                path = file if basedir is None else os.path.join(basedir, file)
+                logger.debug('Loading config from file %s', path)
+                obj = ConfigFactory.parse_file(
+                    path,
+                    resolve=False,
+                    required=required,
+                    unresolved_value=NO_SUBSTITUTION
+                )
+            else:
+                raise ConfigException('No file or URL specified at: {loc}: {instring}', loc=loc, instring=instring)
+
+            return ConfigInclude(obj if isinstance(obj, list) else obj.items())
+
+        @contextlib.contextmanager
+        def set_default_white_spaces():
+            default = ParserElement.DEFAULT_WHITE_CHARS
+            ParserElement.setDefaultWhitespaceChars(' \t')
+            yield
+            ParserElement.setDefaultWhitespaceChars(default)
+
+        with set_default_white_spaces():
+            assign_expr = Forward()
+            true_expr = Keyword("true", caseless=True).setParseAction(replaceWith(True))
+            false_expr = Keyword("false", caseless=True).setParseAction(replaceWith(False))
+            null_expr = Keyword("null", caseless=True).setParseAction(replaceWith(NoneValue()))
+            # key = QuotedString('"', escChar='\\', unquoteResults=False) | Word(alphanums + alphas8bit + '._- /')
+            key = QuotedString('"', escChar='\\', unquoteResults=False) | \
+                  Word("0123456789.").setParseAction(safe_convert_number) | Word(alphanums + alphas8bit + '._- /')
+
+            eol = Word('\n\r').suppress()
+            eol_comma = Word('\n\r,').suppress()
+            comment = (Literal('#') | Literal('//')) - SkipTo(eol | StringEnd())
+            comment_eol = Suppress(Optional(eol_comma) + comment)
+            comment_no_comma_eol = (comment | eol).suppress()
+            number_expr = Regex(r'[+-]?(\d*\.\d+|\d+(\.\d+)?)([eE][+\-]?\d+)?(?=$|[ \t]*([\$\}\],#\n\r]|//))',
+                                re.DOTALL).setParseAction(convert_number)
+
+            period_types = itertools.chain.from_iterable(cls.get_supported_period_type_map().values())
+            period_expr = Regex(r'(?P<value>\d+)\s*(?P<unit>' + '|'.join(period_types) + ')$'
+                                ).setParseAction(convert_period)
+
+            # multi line string using """
+            # Using fix described in http://pyparsing.wikispaces.com/share/view/3778969
+            multiline_string = Regex('""".*?"*"""', re.DOTALL | re.UNICODE).setParseAction(parse_multi_string)
+            # single quoted line string
+            quoted_string = Regex(r'"(?:[^"\\\n]|\\.)*"[ \t]*', re.UNICODE).setParseAction(create_quoted_string)
+            # unquoted string that takes the rest of the line until an optional comment
+            # we support .properties multiline support which is like this:
+            # line1  \
+            # line2 \
+            # so a backslash precedes the \n
+            unquoted_string = Regex(r'(?:[^^`+?!@*&"\[\{\s\]\}#,=\$\\]|\\.)+[ \t]*', re.UNICODE).setParseAction(unescape_string)
+            substitution_expr = Regex(r'[ \t]*\$\{[^\}]+\}[ \t]*').setParseAction(create_substitution)
+            string_expr = multiline_string | quoted_string | unquoted_string
+
+            value_expr = period_expr | number_expr | true_expr | false_expr | null_expr | string_expr
+
+            include_content = (quoted_string | ((Keyword('url') | Keyword('file')) - Literal('(').suppress() - quoted_string - Literal(')').suppress()))
+            include_expr = (
+                Keyword("include", caseless=True).suppress() + (
+                    include_content | (
+                        Keyword("required") - Literal('(').suppress() - include_content - Literal(')').suppress()
+                    )
+                )
+            ).setParseAction(include_config)
+
+            root_dict_expr = Forward()
+            dict_expr = Forward()
+            list_expr = Forward()
+            multi_value_expr = ZeroOrMore(comment_eol | include_expr | substitution_expr | dict_expr | list_expr | value_expr | (Literal(
+                '\\') - eol).suppress())
+            # for a dictionary : or = is optional
+            # last zeroOrMore is because we can have t = {a:4} {b: 6} {c: 7} which is dictionary concatenation
+            inside_dict_expr = ConfigTreeParser(ZeroOrMore(comment_eol | include_expr | assign_expr | eol_comma))
+            inside_root_dict_expr = ConfigTreeParser(ZeroOrMore(comment_eol | include_expr | assign_expr | eol_comma), root=True)
+            dict_expr << Suppress('{') - inside_dict_expr - Suppress('}')
+            root_dict_expr << Suppress('{') - inside_root_dict_expr - Suppress('}')
+            list_entry = ConcatenatedValueParser(multi_value_expr)
+            list_expr << Suppress('[') - ListParser(list_entry - ZeroOrMore(eol_comma - list_entry)) - Suppress(']')
+
+            # special case when we have a value assignment where the string can potentially be the remainder of the line
+            assign_expr << Group(
+                key - ZeroOrMore(comment_no_comma_eol) - (dict_expr | (Literal('=') | Literal(':') | Literal('+=')) - ZeroOrMore(
+                    comment_no_comma_eol) - ConcatenatedValueParser(multi_value_expr))
+            )
+
+            # the file can be { ... } where {} can be omitted or []
+            config_expr = ZeroOrMore(comment_eol | eol) + (list_expr | root_dict_expr | inside_root_dict_expr) + ZeroOrMore(
+                comment_eol | eol_comma)
+            config = config_expr.parseString(content, parseAll=True)[0]
+
+            if resolve:
+                allow_unresolved = resolve and unresolved_value is not DEFAULT_SUBSTITUTION and unresolved_value is not MANDATORY_SUBSTITUTION
+                has_unresolved = cls.resolve_substitutions(config, allow_unresolved)
+                if has_unresolved and unresolved_value is MANDATORY_SUBSTITUTION:
+                    raise ConfigSubstitutionException('resolve cannot be set to True and unresolved_value to MANDATORY_SUBSTITUTION')
+
+            if unresolved_value is not NO_SUBSTITUTION and unresolved_value is not DEFAULT_SUBSTITUTION:
+                cls.unresolve_substitutions_to_value(config, unresolved_value)
+        return config
+
+    @classmethod
+    def _resolve_variable(cls, config, substitution):
+        """
+        :param config:
+        :param substitution:
+        :return: (is_resolved, resolved_variable)
+        """
+        variable = substitution.variable
+        try:
+            return True, config.get(variable)
+        except ConfigMissingException:
+            # default to environment variable
+            value = os.environ.get(variable)
+
+            if value is None:
+                if substitution.optional:
+                    return False, None
+                else:
+                    raise ConfigSubstitutionException(
+                        "Cannot resolve variable ${{{variable}}} (line: {line}, col: {col})".format(
+                            variable=variable,
+                            line=lineno(substitution.loc, substitution.instring),
+                            col=col(substitution.loc, substitution.instring)))
+            elif isinstance(value, ConfigList) or isinstance(value, ConfigTree):
+                raise ConfigSubstitutionException(
+                    "Cannot substitute variable ${{{variable}}} because it does not point to a "
+                    "string, int, float, boolean or null {type} (line:{line}, col: {col})".format(
+                        variable=variable,
+                        type=value.__class__.__name__,
+                        line=lineno(substitution.loc, substitution.instring),
+                        col=col(substitution.loc, substitution.instring)))
+            return True, value
+
+    @classmethod
+    def _fixup_self_references(cls, config, accept_unresolved=False):
+        if isinstance(config, ConfigTree) and config.root:
+            for key in config:  # Traverse history of element
+                history = config.history[key]
+                previous_item = history[0]
+                for current_item in history[1:]:
+                    for substitution in cls._find_substitutions(current_item):
+                        prop_path = ConfigTree.parse_key(substitution.variable)
+                        if len(prop_path) > 1 and config.get(substitution.variable, None) is not None:
+                            continue  # If value is present in latest version, don't do anything
+                        if prop_path[0] == key:
+                            if isinstance(previous_item, ConfigValues) and not accept_unresolved:  # We hit a dead end, we cannot evaluate
+                                raise ConfigSubstitutionException(
+                                    "Property {variable} cannot be substituted. Check for cycles.".format(
+                                        variable=substitution.variable
+                                    )
+                                )
+                            else:
+                                value = previous_item if len(prop_path) == 1 else previous_item.get(".".join(prop_path[1:]))
+                                _, _, current_item = cls._do_substitute(substitution, value)
+                    previous_item = current_item
+
+                if len(history) == 1:  # special case, when self optional referencing without existing
+                    for substitution in cls._find_substitutions(previous_item):
+                        prop_path = ConfigTree.parse_key(substitution.variable)
+                        if len(prop_path) > 1 and config.get(substitution.variable, None) is not None:
+                            continue  # If value is present in latest version, don't do anything
+                        if prop_path[0] == key and substitution.optional:
+                            cls._do_substitute(substitution, None)
+
+    # traverse config to find all the substitutions
+    @classmethod
+    def _find_substitutions(cls, item):
+        """Convert HOCON input into a JSON output
+
+        :return: JSON string representation
+        :type return: basestring
+        """
+        if isinstance(item, ConfigValues):
+            return item.get_substitutions()
+
+        substitutions = []
+        elements = []
+        if isinstance(item, ConfigTree):
+            elements = item.values()
+        elif isinstance(item, list):
+            elements = item
+
+        for child in elements:
+            substitutions += cls._find_substitutions(child)
+        return substitutions
+
+    @classmethod
+    def _do_substitute(cls, substitution, resolved_value, is_optional_resolved=True):
+        unresolved = False
+        new_substitutions = []
+        if isinstance(resolved_value, ConfigValues):
+            resolved_value = resolved_value.transform()
+        if isinstance(resolved_value, ConfigValues):
+            unresolved = True
+            result = resolved_value
+        else:
+            # replace token by substitution
+            config_values = substitution.parent
+            # if it is a string, then add the extra ws that was present in the original string after the substitution
+            formatted_resolved_value = resolved_value \
+                if resolved_value is None \
+                or isinstance(resolved_value, (dict, list)) \
+                or substitution.index == len(config_values.tokens) - 1 \
+                else (str(resolved_value) + substitution.ws)
+            # use a deepcopy of resolved_value to avoid mutation
+            config_values.put(substitution.index, copy.deepcopy(formatted_resolved_value))
+            transformation = config_values.transform()
+            result = config_values.overriden_value \
+                if transformation is None and not is_optional_resolved \
+                else transformation
+
+            if result is None and config_values.key in config_values.parent:
+                del config_values.parent[config_values.key]
+            else:
+                config_values.parent[config_values.key] = result
+                s = cls._find_substitutions(result)
+                if s:
+                    new_substitutions = s
+                    unresolved = True
+
+        return (unresolved, new_substitutions, result)
+
+    @classmethod
+    def _final_fixup(cls, item):
+        if isinstance(item, ConfigValues):
+            return item.transform()
+        elif isinstance(item, list):
+            return list([cls._final_fixup(child) for child in item])
+        elif isinstance(item, ConfigTree):
+            items = list(item.items())
+            for key, child in items:
+                item[key] = cls._final_fixup(child)
+        return item
+
+    @classmethod
+    def unresolve_substitutions_to_value(cls, config, unresolved_value=STR_SUBSTITUTION):
+        for substitution in cls._find_substitutions(config):
+            if unresolved_value is STR_SUBSTITUTION:
+                value = substitution.raw_str()
+            elif unresolved_value is None:
+                value = NoneValue()
+            else:
+                value = unresolved_value
+            cls._do_substitute(substitution, value, False)
+        cls._final_fixup(config)
+
+    @classmethod
+    def resolve_substitutions(cls, config, accept_unresolved=False):
+        has_unresolved = False
+        cls._fixup_self_references(config, accept_unresolved)
+        substitutions = cls._find_substitutions(config)
+        if len(substitutions) > 0:
+            unresolved = True
+            any_unresolved = True
+            _substitutions = []
+            cache = {}
+            while any_unresolved and len(substitutions) > 0 and set(substitutions) != set(_substitutions):
+                unresolved = False
+                any_unresolved = True
+                _substitutions = substitutions[:]
+
+                for substitution in _substitutions:
+                    is_optional_resolved, resolved_value = cls._resolve_variable(config, substitution)
+
+                    # if the substitution is optional
+                    if not is_optional_resolved and substitution.optional:
+                        resolved_value = None
+                    if isinstance(resolved_value, ConfigValues):
+                        parents = cache.get(resolved_value)
+                        if parents is None:
+                            parents = []
+                            link = resolved_value
+                            while isinstance(link, ConfigValues):
+                                parents.append(link)
+                                link = link.overriden_value
+                            cache[resolved_value] = parents
+
+                    if isinstance(resolved_value, ConfigValues) \
+                       and substitution.parent in parents \
+                       and hasattr(substitution.parent, 'overriden_value') \
+                       and substitution.parent.overriden_value:
+
+                        # self resolution, backtrack
+                        resolved_value = substitution.parent.overriden_value
+
+                    unresolved, new_substitutions, result = cls._do_substitute(substitution, resolved_value, is_optional_resolved)
+                    any_unresolved = unresolved or any_unresolved
+                    substitutions.extend(new_substitutions)
+                    if not isinstance(result, ConfigValues):
+                        substitutions.remove(substitution)
+
+            cls._final_fixup(config)
+            if unresolved:
+                has_unresolved = True
+                if not accept_unresolved:
+                    raise ConfigSubstitutionException("Cannot resolve {variables}. Check for cycles.".format(
+                        variables=', '.join('${{{variable}}}: (line: {line}, col: {col})'.format(
+                            variable=substitution.variable,
+                            line=lineno(substitution.loc, substitution.instring),
+                            col=col(substitution.loc, substitution.instring)) for substitution in substitutions)))
+
+        cls._final_fixup(config)
+        return has_unresolved
+
+
+class ListParser(TokenConverter):
+    """Parse a list [elt1, etl2, ...]
+    """
+
+    def __init__(self, expr=None):
+        super(ListParser, self).__init__(expr)
+        self.saveAsList = True
+
+    def postParse(self, instring, loc, token_list):
+        """Create a list from the tokens
+
+        :param instring:
+        :param loc:
+        :param token_list:
+        :return:
+        """
+        cleaned_token_list = [token for tokens in (token.tokens if isinstance(token, ConfigInclude) else [token]
+                                                   for token in token_list if token != '')
+                              for token in tokens]
+        config_list = ConfigList(cleaned_token_list)
+        return [config_list]
+
+
+class ConcatenatedValueParser(TokenConverter):
+    def __init__(self, expr=None):
+        super(ConcatenatedValueParser, self).__init__(expr)
+        self.parent = None
+        self.key = None
+
+    def postParse(self, instring, loc, token_list):
+        config_values = ConfigValues(token_list, instring, loc)
+        return [config_values.transform()]
+
+
+class ConfigTreeParser(TokenConverter):
+    """
+    Parse a config tree from tokens
+    """
+
+    def __init__(self, expr=None, root=False):
+        super(ConfigTreeParser, self).__init__(expr)
+        self.root = root
+        self.saveAsList = True
+
+    def postParse(self, instring, loc, token_list):
+        """Create ConfigTree from tokens
+
+        :param instring:
+        :param loc:
+        :param token_list:
+        :return:
+        """
+        config_tree = ConfigTree(root=self.root)
+        for element in token_list:
+            expanded_tokens = element.tokens if isinstance(element, ConfigInclude) else [element]
+
+            for tokens in expanded_tokens:
+                # key, value1 (optional), ...
+                key = tokens[0].strip() if isinstance(tokens[0], (unicode, basestring)) else tokens[0]
+                operator = '='
+                if len(tokens) == 3 and tokens[1].strip() in [':', '=', '+=']:
+                    operator = tokens[1].strip()
+                    values = tokens[2:]
+                elif len(tokens) == 2:
+                    values = tokens[1:]
+                else:
+                    raise ParseSyntaxException("Unknown tokens {tokens} received".format(tokens=tokens))
+                # empty string
+                if len(values) == 0:
+                    config_tree.put(key, '')
+                else:
+                    value = values[0]
+                    if isinstance(value, list) and operator == "+=":
+                        value = ConfigValues([ConfigSubstitution(key, True, '', False, loc), value], False, loc)
+                        config_tree.put(key, value, False)
+                    elif isinstance(value, unicode) and operator == "+=":
+                        value = ConfigValues([ConfigSubstitution(key, True, '', True, loc), ' ' + value], True, loc)
+                        config_tree.put(key, value, False)
+                    elif isinstance(value, list):
+                        config_tree.put(key, value, False)
+                    else:
+                        existing_value = config_tree.get(key, None)
+                        if isinstance(value, ConfigTree) and not isinstance(existing_value, list):
+                            # Only Tree has to be merged with tree
+                            config_tree.put(key, value, True)
+                        elif isinstance(value, ConfigValues):
+                            conf_value = value
+                            value.parent = config_tree
+                            value.key = key
+                            if isinstance(existing_value, list) or isinstance(existing_value, ConfigTree):
+                                config_tree.put(key, conf_value, True)
+                            else:
+                                config_tree.put(key, conf_value, False)
+                        else:
+                            config_tree.put(key, value, False)
+        return config_tree

trains/utilities/pyhocon/config_tree.py

@@ -0,0 +1,604 @@
+from collections import OrderedDict
+from pyparsing import lineno
+from pyparsing import col
+try:
+    basestring
+except NameError:  # pragma: no cover
+    basestring = str
+    unicode = str
+
+import re
+import copy
+from .exceptions import ConfigException, ConfigWrongTypeException, ConfigMissingException
+
+
+class UndefinedKey(object):
+    pass
+
+
+class NonExistentKey(object):
+    pass
+
+
+class NoneValue(object):
+    pass
+
+
+class ConfigTree(OrderedDict):
+    KEY_SEP = '.'
+
+    def __init__(self, *args, **kwds):
+        self.root = kwds.pop('root') if 'root' in kwds else False
+        if self.root:
+            self.history = {}
+        super(ConfigTree, self).__init__(*args, **kwds)
+        for key, value in self.items():
+            if isinstance(value, ConfigValues):
+                value.parent = self
+                value.index = key
+
+    @staticmethod
+    def merge_configs(a, b, copy_trees=False):
+        """Merge config b into a
+
+        :param a: target config
+        :type a: ConfigTree
+        :param b: source config
+        :type b: ConfigTree
+        :return: merged config a
+        """
+        for key, value in b.items():
+            # if key is in both a and b and both values are dictionary then merge it otherwise override it
+            if key in a and isinstance(a[key], ConfigTree) and isinstance(b[key], ConfigTree):
+                if copy_trees:
+                    a[key] = a[key].copy()
+                ConfigTree.merge_configs(a[key], b[key], copy_trees=copy_trees)
+            else:
+                if isinstance(value, ConfigValues):
+                    value.parent = a
+                    value.key = key
+                    if key in a:
+                        value.overriden_value = a[key]
+                a[key] = value
+                if a.root:
+                    if b.root:
+                        a.history[key] = a.history.get(key, []) + b.history.get(key, [value])
+                    else:
+                        a.history[key] = a.history.get(key, []) + [value]
+
+        return a
+
+    def _put(self, key_path, value, append=False):
+        key_elt = key_path[0]
+        if len(key_path) == 1:
+            # if value to set does not exist, override
+            # if they are both configs then merge
+            # if not then override
+            if key_elt in self and isinstance(self[key_elt], ConfigTree) and isinstance(value, ConfigTree):
+                if self.root:
+                    new_value = ConfigTree.merge_configs(ConfigTree(), self[key_elt], copy_trees=True)
+                    new_value = ConfigTree.merge_configs(new_value, value, copy_trees=True)
+                    self._push_history(key_elt, new_value)
+                    self[key_elt] = new_value
+                else:
+                    ConfigTree.merge_configs(self[key_elt], value)
+            elif append:
+                # If we have t=1
+                # and we try to put t.a=5 then t is replaced by {a: 5}
+                l_value = self.get(key_elt, None)
+                if isinstance(l_value, ConfigValues):
+                    l_value.tokens.append(value)
+                    l_value.recompute()
+                elif isinstance(l_value, ConfigTree) and isinstance(value, ConfigValues):
+                    value.overriden_value = l_value
+                    value.tokens.insert(0, l_value)
+                    value.recompute()
+                    value.parent = self
+                    value.key = key_elt
+                    self._push_history(key_elt, value)
+                    self[key_elt] = value
+                elif isinstance(l_value, list) and isinstance(value, ConfigValues):
+                    self._push_history(key_elt, value)
+                    value.overriden_value = l_value
+                    value.parent = self
+                    value.key = key_elt
+                    self[key_elt] = value
+                elif isinstance(l_value, list):
+                    self[key_elt] = l_value + value
+                    self._push_history(key_elt, l_value)
+                elif l_value is None:
+                    self._push_history(key_elt, value)
+                    self[key_elt] = value
+
+                else:
+                    raise ConfigWrongTypeException(
+                        u"Cannot concatenate the list {key}: {value} to {prev_value} of {type}".format(
+                            key='.'.join(key_path),
+                            value=value,
+                            prev_value=l_value,
+                            type=l_value.__class__.__name__)
+                    )
+            else:
+                # if there was an override keep overide value
+                if isinstance(value, ConfigValues):
+                    value.parent = self
+                    value.key = key_elt
+                    value.overriden_value = self.get(key_elt, None)
+                self._push_history(key_elt, value)
+                self[key_elt] = value
+        else:
+            next_config_tree = super(ConfigTree, self).get(key_elt)
+            if not isinstance(next_config_tree, ConfigTree):
+                # create a new dictionary or overwrite a previous value
+                next_config_tree = ConfigTree()
+                self._push_history(key_elt, next_config_tree)
+                self[key_elt] = next_config_tree
+            next_config_tree._put(key_path[1:], value, append)
+
+    def _push_history(self, key, value):
+        if self.root:
+            hist = self.history.get(key)
+            if hist is None:
+                hist = self.history[key] = []
+            hist.append(value)
+
+    def _get(self, key_path, key_index=0, default=UndefinedKey):
+        key_elt = key_path[key_index]
+        elt = super(ConfigTree, self).get(key_elt, UndefinedKey)
+
+        if elt is UndefinedKey:
+            if default is UndefinedKey:
+                raise ConfigMissingException(u"No configuration setting found for key {key}".format(key='.'.join(key_path[:key_index + 1])))
+            else:
+                return default
+
+        if key_index == len(key_path) - 1:
+            if isinstance(elt, NoneValue):
+                return None
+            elif isinstance(elt, list):
+                return [None if isinstance(x, NoneValue) else x for x in elt]
+            else:
+                return elt
+        elif isinstance(elt, ConfigTree):
+            return elt._get(key_path, key_index + 1, default)
+        else:
+            if default is UndefinedKey:
+                raise ConfigWrongTypeException(
+                    u"{key} has type {type} rather than dict".format(key='.'.join(key_path[:key_index + 1]),
+                                                                     type=type(elt).__name__))
+            else:
+                return default
+
+    @staticmethod
+    def parse_key(string):
+        """
+        Split a key into path elements:
+        - a.b.c => a, b, c
+        - a."b.c" => a, QuotedKey("b.c") if . is any of the special characters: $}[]:=+#`^?!@*&.
+        - "a" => a
+        - a.b."c" => a, b, c (special case)
+        :param string: either string key (parse '.' as sub-key) or int / float as regular keys
+        :return:
+        """
+        if isinstance(string, (int, float)):
+            return [string]
+
+        special_characters = '$}[]:=+#`^?!@*&.'
+        tokens = re.findall(r'"[^"]+"|[^{special_characters}]+'.format(special_characters=re.escape(special_characters)), string)
+
+        def contains_special_character(token):
+            return any((c in special_characters) for c in token)
+
+        return [token if contains_special_character(token) else token.strip('"') for token in tokens]
+
+    def put(self, key, value, append=False):
+        """Put a value in the tree (dot separated)
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param value: value to put
+        """
+        self._put(ConfigTree.parse_key(key), value, append)
+
+    def get(self, key, default=UndefinedKey):
+        """Get a value from the tree
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: object
+        :return: value in the tree located at key
+        """
+        return self._get(ConfigTree.parse_key(key), 0, default)
+
+    def get_string(self, key, default=UndefinedKey):
+        """Return string representation of value found at key
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: basestring
+        :return: string value
+        :type return: basestring
+        """
+        value = self.get(key, default)
+        if value is None:
+            return None
+
+        string_value = unicode(value)
+        if isinstance(value, bool):
+            string_value = string_value.lower()
+        return string_value
+
+    def pop(self, key, default=UndefinedKey):
+        """Remove specified key and return the corresponding value.
+        If key is not found, default is returned if given, otherwise ConfigMissingException is raised
+
+        This method assumes the user wants to remove the last value in the chain so it parses via parse_key
+        and pops the last value out of the dict.
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: object
+        :param default: default value if key not found
+        :return: value in the tree located at key
+        """
+        if default != UndefinedKey and key not in self:
+            return default
+
+        value = self.get(key, UndefinedKey)
+        lst = ConfigTree.parse_key(key)
+        parent = self.KEY_SEP.join(lst[0:-1])
+        child = lst[-1]
+
+        if parent:
+            self.get(parent).__delitem__(child)
+        else:
+            self.__delitem__(child)
+        return value
+
+    def get_int(self, key, default=UndefinedKey):
+        """Return int representation of value found at key
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: int
+        :return: int value
+        :type return: int
+        """
+        value = self.get(key, default)
+        try:
+            return int(value) if value is not None else None
+        except (TypeError, ValueError):
+            raise ConfigException(
+                u"{key} has type '{type}' rather than 'int'".format(key=key, type=type(value).__name__))
+
+    def get_float(self, key, default=UndefinedKey):
+        """Return float representation of value found at key
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: float
+        :return: float value
+        :type return: float
+        """
+        value = self.get(key, default)
+        try:
+            return float(value) if value is not None else None
+        except (TypeError, ValueError):
+            raise ConfigException(
+                u"{key} has type '{type}' rather than 'float'".format(key=key, type=type(value).__name__))
+
+    def get_bool(self, key, default=UndefinedKey):
+        """Return boolean representation of value found at key
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: bool
+        :return: boolean value
+        :type return: bool
+        """
+
+        # String conversions as per API-recommendations:
+        # https://github.com/typesafehub/config/blob/master/HOCON.md#automatic-type-conversions
+        bool_conversions = {
+            None: None,
+            'true': True, 'yes': True, 'on': True,
+            'false': False, 'no': False, 'off': False
+        }
+        string_value = self.get_string(key, default)
+        if string_value is not None:
+            string_value = string_value.lower()
+        try:
+            return bool_conversions[string_value]
+        except KeyError:
+            raise ConfigException(
+                u"{key} does not translate to a Boolean value".format(key=key))
+
+    def get_list(self, key, default=UndefinedKey):
+        """Return list representation of value found at key
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: list
+        :return: list value
+        :type return: list
+        """
+        value = self.get(key, default)
+        if isinstance(value, list):
+            return value
+        elif isinstance(value, ConfigTree):
+            lst = []
+            for k, v in sorted(value.items(), key=lambda kv: kv[0]):
+                if re.match('^[1-9][0-9]*$|0', k):
+                    lst.append(v)
+                else:
+                    raise ConfigException(u"{key} does not translate to a list".format(key=key))
+            return lst
+        elif value is None:
+            return None
+        else:
+            raise ConfigException(
+                u"{key} has type '{type}' rather than 'list'".format(key=key, type=type(value).__name__))
+
+    def get_config(self, key, default=UndefinedKey):
+        """Return tree config representation of value found at key
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: config
+        :return: config value
+        :type return: ConfigTree
+        """
+        value = self.get(key, default)
+        if isinstance(value, dict):
+            return value
+        elif value is None:
+            return None
+        else:
+            raise ConfigException(
+                u"{key} has type '{type}' rather than 'config'".format(key=key, type=type(value).__name__))
+
+    def __getitem__(self, item):
+        val = self.get(item)
+        if val is UndefinedKey:
+            raise KeyError(item)
+        return val
+
+    try:
+        from collections import _OrderedDictItemsView
+    except ImportError:  # pragma: nocover
+        pass
+    else:
+        def items(self):  # pragma: nocover
+            return self._OrderedDictItemsView(self)
+
+    def __getattr__(self, item):
+        val = self.get(item, NonExistentKey)
+        if val is NonExistentKey:
+            return super(ConfigTree, self).__getattr__(item)
+        return val
+
+    def __contains__(self, item):
+        return self._get(self.parse_key(item), default=NoneValue) is not NoneValue
+
+    def with_fallback(self, config, resolve=True):
+        """
+        return a new config with fallback on config
+        :param config: config or filename of the config to fallback on
+        :param resolve: resolve substitutions
+        :return: new config with fallback on config
+        """
+        if isinstance(config, ConfigTree):
+            result = ConfigTree.merge_configs(copy.deepcopy(config), copy.deepcopy(self))
+        else:
+            from . import ConfigFactory
+            result = ConfigTree.merge_configs(ConfigFactory.parse_file(config, resolve=False), copy.deepcopy(self))
+
+        if resolve:
+            from . import ConfigParser
+            ConfigParser.resolve_substitutions(result)
+        return result
+
+    def as_plain_ordered_dict(self):
+        """return a deep copy of this config as a plain OrderedDict
+
+        The config tree should be fully resolved.
+
+        This is useful to get an object with no special semantics such as path expansion for the keys.
+        In particular this means that keys that contain dots are not surrounded with '"' in the plain OrderedDict.
+
+        :return: this config as an OrderedDict
+        :type return: OrderedDict
+        """
+        def plain_value(v):
+            if isinstance(v, list):
+                return [plain_value(e) for e in v]
+            elif isinstance(v, ConfigTree):
+                return v.as_plain_ordered_dict()
+            else:
+                if isinstance(v, ConfigValues):
+                    raise ConfigException("The config tree contains unresolved elements")
+                return v
+
+        return OrderedDict((key.strip('"') if isinstance(key, (unicode, basestring)) else key, plain_value(value))
+                           for key, value in self.items())
+
+
+class ConfigList(list):
+    def __init__(self, iterable=[]):
+        new_list = list(iterable)
+        super(ConfigList, self).__init__(new_list)
+        for index, value in enumerate(new_list):
+            if isinstance(value, ConfigValues):
+                value.parent = self
+                value.key = index
+
+
+class ConfigInclude(object):
+    def __init__(self, tokens):
+        self.tokens = tokens
+
+
+class ConfigValues(object):
+    def __init__(self, tokens, instring, loc):
+        self.tokens = tokens
+        self.parent = None
+        self.key = None
+        self._instring = instring
+        self._loc = loc
+        self.overriden_value = None
+        self.recompute()
+
+    def recompute(self):
+        for index, token in enumerate(self.tokens):
+            if isinstance(token, ConfigSubstitution):
+                token.parent = self
+                token.index = index
+
+        # no value return empty string
+        if len(self.tokens) == 0:
+            self.tokens = ['']
+
+        # if the last token is an unquoted string then right strip it
+        if isinstance(self.tokens[-1], ConfigUnquotedString):
+            # rstrip only whitespaces, not \n\r because they would have been used escaped
+            self.tokens[-1] = self.tokens[-1].rstrip(' \t')
+
+    def has_substitution(self):
+        return len(self.get_substitutions()) > 0
+
+    def get_substitutions(self):
+        lst = []
+        node = self
+        while node:
+            lst = [token for token in node.tokens if isinstance(token, ConfigSubstitution)] + lst
+            if hasattr(node, 'overriden_value'):
+                node = node.overriden_value
+                if not isinstance(node, ConfigValues):
+                    break
+            else:
+                break
+        return lst
+
+    def transform(self):
+        def determine_type(token):
+            return ConfigTree if isinstance(token, ConfigTree) else ConfigList if isinstance(token, list) else str
+
+        def format_str(v, last=False):
+            if isinstance(v, ConfigQuotedString):
+                return v.value + ('' if last else v.ws)
+            else:
+                return '' if v is None else unicode(v)
+
+        if self.has_substitution():
+            return self
+
+        # remove None tokens
+        tokens = [token for token in self.tokens if token is not None]
+
+        if not tokens:
+            return None
+
+        # check if all tokens are compatible
+        first_tok_type = determine_type(tokens[0])
+        for index, token in enumerate(tokens[1:]):
+            tok_type = determine_type(token)
+            if first_tok_type is not tok_type:
+                raise ConfigWrongTypeException(
+                    "Token '{token}' of type {tok_type} (index {index}) must be of type {req_tok_type} (line: {line}, col: {col})".format(
+                        token=token,
+                        index=index + 1,
+                        tok_type=tok_type.__name__,
+                        req_tok_type=first_tok_type.__name__,
+                        line=lineno(self._loc, self._instring),
+                        col=col(self._loc, self._instring)))
+
+        if first_tok_type is ConfigTree:
+            child = []
+            if hasattr(self, 'overriden_value'):
+                node = self.overriden_value
+                while node:
+                    if isinstance(node, ConfigValues):
+                        value = node.transform()
+                        if isinstance(value, ConfigTree):
+                            child.append(value)
+                        else:
+                            break
+                    elif isinstance(node, ConfigTree):
+                        child.append(node)
+                    else:
+                        break
+                    if hasattr(node, 'overriden_value'):
+                        node = node.overriden_value
+                    else:
+                        break
+
+            result = ConfigTree()
+            for conf in reversed(child):
+                ConfigTree.merge_configs(result, conf, copy_trees=True)
+            for token in tokens:
+                ConfigTree.merge_configs(result, token, copy_trees=True)
+            return result
+        elif first_tok_type is ConfigList:
+            result = []
+            main_index = 0
+            for sublist in tokens:
+                sublist_result = ConfigList()
+                for token in sublist:
+                    if isinstance(token, ConfigValues):
+                        token.parent = result
+                        token.key = main_index
+                    main_index += 1
+                    sublist_result.append(token)
+                result.extend(sublist_result)
+            return result
+        else:
+            if len(tokens) == 1:
+                if isinstance(tokens[0], ConfigQuotedString):
+                    return tokens[0].value
+                return tokens[0]
+            else:
+                return ''.join(format_str(token) for token in tokens[:-1]) + format_str(tokens[-1], True)
+
+    def put(self, index, value):
+        self.tokens[index] = value
+
+    def __repr__(self):  # pragma: no cover
+        return '[ConfigValues: ' + ','.join(str(o) for o in self.tokens) + ']'
+
+
+class ConfigSubstitution(object):
+    def __init__(self, variable, optional, ws, instring, loc):
+        self.variable = variable
+        self.optional = optional
+        self.ws = ws
+        self.index = None
+        self.parent = None
+        self.instring = instring
+        self.loc = loc
+
+    def __repr__(self):  # pragma: no cover
+        return '[ConfigSubstitution: ' + self.variable + ']'
+
+
+class ConfigUnquotedString(unicode):
+    def __new__(cls, value):
+        return super(ConfigUnquotedString, cls).__new__(cls, value)
+
+
+class ConfigQuotedString(object):
+    def __init__(self, value, ws, instring, loc):
+        self.value = value
+        self.ws = ws
+        self.instring = instring
+        self.loc = loc
+
+    def __repr__(self):  # pragma: no cover
+        return '[ConfigQuotedString: ' + self.value + ']'

trains/utilities/pyhocon/converter.py

@@ -0,0 +1,326 @@
+import json
+import re
+import sys
+
+from . import ConfigFactory
+from .config_tree import ConfigQuotedString
+from .config_tree import ConfigSubstitution
+from .config_tree import ConfigTree
+from .config_tree import ConfigValues
+from .config_tree import NoneValue
+
+
+try:
+    basestring
+except NameError:
+    basestring = str
+    unicode = str
+
+
+class HOCONConverter(object):
+    _number_re = r'[+-]?(\d*\.\d+|\d+(\.\d+)?)([eE][+\-]?\d+)?(?=$|[ \t]*([\$\}\],#\n\r]|//))'
+    _number_re_matcher = re.compile(_number_re)
+    
+    @classmethod
+    def to_json(cls, config, compact=False, indent=2, level=0):
+        """Convert HOCON input into a JSON output
+
+        :return: JSON string representation
+        :type return: basestring
+        """
+        lines = ""
+        if isinstance(config, ConfigTree):
+            if len(config) == 0:
+                lines += '{}'
+            else:
+                lines += '{\n'
+                bet_lines = []
+                for key, item in config.items():
+                    bet_lines.append('{indent}"{key}": {value}'.format(
+                        indent=''.rjust((level + 1) * indent, ' '),
+                        key=key.strip('"'),  # for dotted keys enclosed with "" to not be interpreted as nested key
+                        value=cls.to_json(item, compact, indent, level + 1))
+                    )
+                lines += ',\n'.join(bet_lines)
+                lines += '\n{indent}}}'.format(indent=''.rjust(level * indent, ' '))
+        elif isinstance(config, list):
+            if len(config) == 0:
+                lines += '[]'
+            else:
+                lines += '[\n'
+                bet_lines = []
+                for item in config:
+                    bet_lines.append('{indent}{value}'.format(
+                        indent=''.rjust((level + 1) * indent, ' '),
+                        value=cls.to_json(item, compact, indent, level + 1))
+                    )
+                lines += ',\n'.join(bet_lines)
+                lines += '\n{indent}]'.format(indent=''.rjust(level * indent, ' '))
+        elif isinstance(config, basestring):
+            lines = json.dumps(config)
+        elif config is None or isinstance(config, NoneValue):
+            lines = 'null'
+        elif config is True:
+            lines = 'true'
+        elif config is False:
+            lines = 'false'
+        else:
+            lines = str(config)
+        return lines
+
+    @staticmethod
+    def _auto_indent(lines, section):
+        try:
+            indent = len(lines) - lines.rindex('\n')
+        except:
+            indent = len(lines)
+        try:
+            section_indent = section.index('\n')
+        except:
+            section_indent = len(section)
+        if section_indent < 3:
+            return lines + section
+
+        indent = '\n' + ''.rjust(indent, ' ')
+        return lines + indent.join([l.strip() for l in section.split('\n')])
+        # indent = ''.rjust(indent, ' ')
+        # return lines + section.replace('\n', '\n'+indent)
+
+    @classmethod
+    def to_hocon(cls, config, compact=False, indent=2, level=0):
+        """Convert HOCON input into a HOCON output
+
+        :return: JSON string representation
+        :type return: basestring
+        """
+        lines = ""
+        if isinstance(config, ConfigTree):
+            if len(config) == 0:
+                lines += '{}'
+            else:
+                if level > 0:  # don't display { at root level
+                    lines += '{\n'
+                bet_lines = []
+
+                for key, item in config.items():
+                    if compact:
+                        full_key = key
+                        while isinstance(item, ConfigTree) and len(item) == 1:
+                            key, item = next(iter(item.items()))
+                            full_key += '.' + key
+                    else:
+                        full_key = key
+
+                    if isinstance(full_key, (basestring, unicode)) and cls._number_re_matcher.match(full_key):
+                        # if key can be casted to float, and it is a string, make sure we quote it
+                        full_key = '\"' + full_key + '\"'
+
+                    bet_line = ('{indent}{key}{assign_sign} '.format(
+                        indent=''.rjust(level * indent, ' '),
+                        key=full_key,
+                        assign_sign='' if isinstance(item, dict) else ' =',)
+                    )
+                    value_line = cls.to_hocon(item, compact, indent, level + 1)
+                    if isinstance(item, (list, tuple)):
+                        bet_lines.append(cls._auto_indent(bet_line, value_line))
+                    else:
+                        bet_lines.append(bet_line + value_line)
+                lines += '\n'.join(bet_lines)
+
+                if level > 0:  # don't display { at root level
+                    lines += '\n{indent}}}'.format(indent=''.rjust((level - 1) * indent, ' '))
+        elif isinstance(config, (list, tuple)):
+            if len(config) == 0:
+                lines += '[]'
+            else:
+                # lines += '[\n'
+                lines += '['
+                bet_lines = []
+                base_len = len(lines)
+                skip_comma = False
+                for i, item in enumerate(config):
+                    if 0 < i and not skip_comma:
+                        # if not isinstance(item, (str, int, float)):
+                        #     lines += ',\n{indent}'.format(indent=''.rjust(level * indent, ' '))
+                        # else:
+                        #     lines += ', '
+                        lines += ', '
+
+                    skip_comma = False
+                    new_line = cls.to_hocon(item, compact, indent, level + 1)
+                    lines += new_line
+                    if '\n' in new_line or len(lines) - base_len > 80:
+                        if i < len(config)-1:
+                            lines += ',\n{indent}'.format(indent=''.rjust(level * indent, ' '))
+                        base_len = len(lines)
+                        skip_comma = True
+                    # bet_lines.append('{value}'.format(value=cls.to_hocon(item, compact, indent, level + 1)))
+
+                # lines += '\n'.join(bet_lines)
+                # lines += ', '.join(bet_lines)
+
+                # lines += '\n{indent}]'.format(indent=''.rjust((level - 1) * indent, ' '))
+                lines += ']'
+        elif isinstance(config, basestring):
+            if '\n' in config and len(config) > 1:
+                lines = '"""{value}"""'.format(value=config)  # multilines
+            else:
+                lines = '"{value}"'.format(value=cls.__escape_string(config))
+        elif isinstance(config, ConfigValues):
+            lines = ''.join(cls.to_hocon(o, compact, indent, level) for o in config.tokens)
+        elif isinstance(config, ConfigSubstitution):
+            lines = '${'
+            if config.optional:
+                lines += '?'
+            lines += config.variable + '}' + config.ws
+        elif isinstance(config, ConfigQuotedString):
+            if '\n' in config.value and len(config.value) > 1:
+                lines = '"""{value}"""'.format(value=config.value)  # multilines
+            else:
+                lines = '"{value}"'.format(value=cls.__escape_string(config.value))
+        elif config is None or isinstance(config, NoneValue):
+            lines = 'null'
+        elif config is True:
+            lines = 'true'
+        elif config is False:
+            lines = 'false'
+        else:
+            lines = str(config)
+        return lines
+
+    @classmethod
+    def to_yaml(cls, config, compact=False, indent=2, level=0):
+        """Convert HOCON input into a YAML output
+
+        :return: YAML string representation
+        :type return: basestring
+        """
+        lines = ""
+        if isinstance(config, ConfigTree):
+            if len(config) > 0:
+                if level > 0:
+                    lines += '\n'
+                bet_lines = []
+                for key, item in config.items():
+                    bet_lines.append('{indent}{key}: {value}'.format(
+                        indent=''.rjust(level * indent, ' '),
+                        key=key.strip('"'),  # for dotted keys enclosed with "" to not be interpreted as nested key,
+                        value=cls.to_yaml(item, compact, indent, level + 1))
+                    )
+                lines += '\n'.join(bet_lines)
+        elif isinstance(config, list):
+            config_list = [line for line in config if line is not None]
+            if len(config_list) == 0:
+                lines += '[]'
+            else:
+                lines += '\n'
+                bet_lines = []
+                for item in config_list:
+                    bet_lines.append('{indent}- {value}'.format(indent=''.rjust(level * indent, ' '),
+                                                                value=cls.to_yaml(item, compact, indent, level + 1)))
+                lines += '\n'.join(bet_lines)
+        elif isinstance(config, basestring):
+            # if it contains a \n then it's multiline
+            lines = config.split('\n')
+            if len(lines) == 1:
+                lines = config
+            else:
+                lines = '|\n' + '\n'.join([line.rjust(level * indent, ' ') for line in lines])
+        elif config is None or isinstance(config, NoneValue):
+            lines = 'null'
+        elif config is True:
+            lines = 'true'
+        elif config is False:
+            lines = 'false'
+        else:
+            lines = str(config)
+        return lines
+
+    @classmethod
+    def to_properties(cls, config, compact=False, indent=2, key_stack=[]):
+        """Convert HOCON input into a .properties output
+
+        :return: .properties string representation
+        :type return: basestring
+        :return:
+        """
+
+        def escape_value(value):
+            return value.replace('=', '\\=').replace('!', '\\!').replace('#', '\\#').replace('\n', '\\\n')
+
+        stripped_key_stack = [key.strip('"') for key in key_stack]
+        lines = []
+        if isinstance(config, ConfigTree):
+            for key, item in config.items():
+                if item is not None:
+                    lines.append(cls.to_properties(item, compact, indent, stripped_key_stack + [key]))
+        elif isinstance(config, list):
+            for index, item in enumerate(config):
+                if item is not None:
+                    lines.append(cls.to_properties(item, compact, indent, stripped_key_stack + [str(index)]))
+        elif isinstance(config, basestring):
+            lines.append('.'.join(stripped_key_stack) + ' = ' + escape_value(config))
+        elif config is True:
+            lines.append('.'.join(stripped_key_stack) + ' = true')
+        elif config is False:
+            lines.append('.'.join(stripped_key_stack) + ' = false')
+        elif config is None or isinstance(config, NoneValue):
+            pass
+        else:
+            lines.append('.'.join(stripped_key_stack) + ' = ' + str(config))
+        return '\n'.join([line for line in lines if len(line) > 0])
+
+    @classmethod
+    def convert(cls, config, output_format='json', indent=2, compact=False):
+        converters = {
+            'json': cls.to_json,
+            'properties': cls.to_properties,
+            'yaml': cls.to_yaml,
+            'hocon': cls.to_hocon,
+        }
+
+        if output_format in converters:
+            return converters[output_format](config, compact, indent)
+        else:
+            raise Exception("Invalid format '{format}'. Format must be 'json', 'properties', 'yaml' or 'hocon'".format(
+                format=output_format))
+
+    @classmethod
+    def convert_from_file(cls, input_file=None, output_file=None, output_format='json', indent=2, compact=False):
+        """Convert to json, properties or yaml
+
+        :param input_file: input file, if not specified stdin
+        :param output_file: output file, if not specified stdout
+        :param output_format: json, properties or yaml
+        :return: json, properties or yaml string representation
+        """
+
+        if input_file is None:
+            content = sys.stdin.read()
+            config = ConfigFactory.parse_string(content)
+        else:
+            config = ConfigFactory.parse_file(input_file)
+
+        res = cls.convert(config, output_format, indent, compact)
+        if output_file is None:
+            print(res)
+        else:
+            with open(output_file, "w") as fd:
+                fd.write(res)
+
+    @classmethod
+    def __escape_match(cls, match):
+        char = match.group(0)
+        return {
+            '\b': r'\b',
+            '\t': r'\t',
+            '\n': r'\n',
+            '\f': r'\f',
+            '\r': r'\r',
+            '"': r'\"',
+            '\\': r'\\',
+        }.get(char) or (r'\u%04x' % ord(char))
+
+    @classmethod
+    def __escape_string(cls, string):
+        return re.sub(r'[\x00-\x1F"\\]', cls.__escape_match, string)

trains/utilities/pyhocon/exceptions.py

@@ -0,0 +1,17 @@
+class ConfigException(Exception):
+
+    def __init__(self, message, ex=None):
+        super(ConfigException, self).__init__(message)
+        self._exception = ex
+
+
+class ConfigMissingException(ConfigException, KeyError):
+    pass
+
+
+class ConfigSubstitutionException(ConfigException):
+    pass
+
+
+class ConfigWrongTypeException(ConfigException):
+    pass