First steps of ConceptLexer. Need to update DefaultParser before continuing

core/ast/nodes.py

@@ -1,6 +1,7 @@
 from core.builtin_concepts import BuiltinConcepts, ListConcept
 from core.concept import Concept
 import ast
+import core.utils
 
 import logging
 
@@ -45,18 +46,18 @@ class NodeParent:
 
 
 class NodeConcept(Concept):
-    def __init__(self, key, parent: NodeParent):
+    def __init__(self, key, node_type, parent: NodeParent):
         super().__init__(key, True, False, key)
         self.parent = parent
+        self.node_type = node_type
 
     def get_node_type(self):
-        return self.key
+        return self.node_type
 
 
 class GenericNodeConcept(NodeConcept):
     def __init__(self, node_type, parent):
-        super().__init__(BuiltinConcepts.GENERIC_NODE, parent)
+        super().__init__(BuiltinConcepts.GENERIC_NODE, node_type, parent)
-        self.node_type = node_type
 
     def __repr__(self):
         return "Generic:" + self.node_type
@@ -74,17 +75,25 @@ class GenericNodeConcept(NodeConcept):
         return self.body
 
 
-class IdentifierConcept(NodeConcept):
+class IdentifierNodeConcept(NodeConcept):
     def __init__(self, parent, name):
-        super().__init__(BuiltinConcepts.IDENTIFIER_NODE, parent)
+        super().__init__(BuiltinConcepts.IDENTIFIER_NODE, "Name", parent)
         self.body = name
 
 
-def transform(node):
+class CallNodeConcept(NodeConcept):
+    def __init__(self, parent=None):
+        super().__init__(BuiltinConcepts.IDENTIFIER_NODE, "Call", parent)
+
+    def get_args_names(self, sheerka):
+        return sheerka.values(self.get_prop("args"))
+
+
+def python_to_concept(python_node):
     """
     Transform Python AST node into concept nodes
     for better usage
-    :param node:
+    :param python_node:
     :return:
     """
 
@@ -107,4 +116,34 @@ def transform(node):
                 concept.set_prop(field, value)
         return concept
 
-    return _transform(node, None)
+    return _transform(python_node, None)
+
+
+def concept_to_python(concept_node):
+    """
+    Transform back concept_node to Python AST node
+    :param concept_node:
+    :return:
+    """
+
+    def _transform(node):
+        node_type = node.get_node_type()
+        ast_object = core.utils.new_object("_ast." + node_type)
+        for field in node.props:
+            if field not in ast_object._fields:
+                continue
+
+            value = node.get_prop(field)
+            if isinstance(value, list) or isinstance(value, Concept) and value.key == str(BuiltinConcepts.LIST):
+                lst = []
+                for i in value:
+                    lst.append(_transform(i))
+                setattr(ast_object, field, lst)
+            elif isinstance(value, NodeConcept):
+                setattr(ast_object, field, _transform(value))
+            else:
+                setattr(ast_object, field, value)
+        return ast_object
+
+    res = _transform(concept_node)
+    return res

core/ast/visitors.py

@@ -57,13 +57,13 @@ class UnreferencedNamesVisitor(ConceptNodeVisitor):
 
     def visit_Name(self, node):
         parents = get_parents(node)
-        if ("For", "target") in parents: # variable used by the 'for' iteration
+        if ("For", "target") in parents:  # variable used by the 'for' iteration
             return
 
-        if ("Call", "func") in parents: # name of the function
+        if ("Call", "func") in parents:  # name of the function
             return
 
-        if ("Assign", "targets") in parents: # variable which is assigned
+        if ("Assign", "targets") in parents:  # variable which is assigned
             return
 
         if self.can_be_discarded(self.sheerka.value(node), parents):
@@ -91,6 +91,14 @@ class UnreferencedNamesVisitor(ConceptNodeVisitor):
         return False
 
 
+class ExtractPredicateVisitor(ConceptNodeVisitor):
+    def __init__(self, variable_name):
+        self.predicates = []
+        self.variable_name = variable_name
+
+
+
+
 def get_parents(node):
     if node.parent is None:
         return []

core/builtin_helpers.py

@@ -1,3 +1,8 @@
+import ast
+import core.ast.nodes
+from core.ast.nodes import CallNodeConcept, GenericNodeConcept
+from core.ast.visitors import UnreferencedNamesVisitor
+
 from core.builtin_concepts import BuiltinConcepts
 
 
@@ -81,3 +86,107 @@ def expect_one(context, return_values):
         False,
         sheerka.new(BuiltinConcepts.TOO_MANY_ERRORS, obj=return_values),
         parents=return_values)
+
+
+def get_names(sheerka, concept_node):
+    """
+    Finds all the names referenced by the concept_node
+    :param sheerka:
+    :param concept_node:
+    :return:
+    """
+    unreferenced_names_visitor = UnreferencedNamesVisitor(sheerka)
+    unreferenced_names_visitor.visit(concept_node)
+    return list(unreferenced_names_visitor.names)
+
+
+def extract_predicates(sheerka, expression, variables_to_include, variables_to_exclude):
+    """
+    from expression, tries to find all the predicates referencing a variable, and the variable only
+    for example
+    exp : isinstance(a, int) and isinstance(b, str)
+    will return 'isinstance(a, int)' if variable_name == 'a'
+    :param sheerka:
+    :param expression:
+    :param variables_to_include:
+    :param variables_to_exclude:
+    :return: list of predicates
+    """
+
+    if len(variables_to_include) == 0:
+        return []
+
+    def _get_predicates(_nodes):
+        _predicates = []
+        for _node in _nodes:
+            python_node = ast.Expression(body=core.ast.nodes.concept_to_python(_node))
+            python_node = ast.fix_missing_locations(python_node)
+            _predicates.append(python_node)
+        return _predicates
+
+    if isinstance(expression, str):
+        node = ast.parse(expression, mode="eval")
+    else:
+        return NotImplementedError()
+
+    concept_node = core.ast.nodes.python_to_concept(node)
+    main_op = concept_node.get_prop("body")
+
+    return _get_predicates(_extract_predicates(sheerka, main_op, variables_to_include, variables_to_exclude))
+
+
+def _extract_predicates(sheerka, node, variables_to_include, variables_to_exclude):
+    predicates = []
+
+    def _matches(_names, to_include, to_exclude):
+        _res = None
+        for n in _names:
+            if n in to_include and _res is None:
+                _res = True
+            if n in to_exclude:
+                _res = False
+        return _res
+
+    if node.node_type == "Compare":
+        if node.get_prop("left").node_type == "Name":
+            """Simple case of one comparison"""
+            comparison_name = sheerka.value(node.get_prop("left"))
+            if comparison_name in variables_to_include and comparison_name not in variables_to_exclude:
+                predicates.append(node)
+        else:
+            """The left part is an expression"""
+            res = _extract_predicates(sheerka, node.get_prop("left"), variables_to_include, variables_to_exclude)
+            if len(res) > 0:
+                predicates.append(node)
+    elif node.node_type == "Call":
+        """Simple case predicate"""
+        call_node = node if isinstance(node, CallNodeConcept) else CallNodeConcept().update_from(node)
+        args = list(call_node.get_args_names(sheerka))
+        if _matches(args, variables_to_include, variables_to_exclude):
+            predicates.append(node)
+    elif node.node_type == "UnaryOp" and node.get_prop("op").node_type == "Not":
+        """Simple case of negation"""
+        res = _extract_predicates(sheerka, node.get_prop("operand"), variables_to_include, variables_to_exclude)
+        if len(res) > 0:
+            predicates.append(node)
+    elif node.node_type == "BinOp":
+        names = get_names(sheerka, node)
+        if _matches(names, variables_to_include, variables_to_exclude):
+            predicates.append(node)
+    elif node.node_type == "BoolOp":
+        all_op = True
+        temp_res = []
+        for op in node.get_prop("values"):
+            res = _extract_predicates(sheerka, op, variables_to_include, variables_to_exclude)
+            if len(res) == 0:
+                all_op = False
+            else:
+                temp_res.extend(res)
+
+        if all_op:
+            predicates.append(node)
+        else:
+            for res in temp_res:
+                predicates.append(res)
+
+    return predicates

core/sheerka.py

@@ -23,7 +23,7 @@ class Sheerka(Concept):
     BUILTIN_CONCEPTS_KEYS = "Builtins_Concepts"
     USER_CONCEPTS_KEYS = "User_Concepts"
 
-    def __init__(self, debug=False):
+    def __init__(self, debug=False, skip_builtins_in_db=False):
         log.debug("Starting Sheerka.")
         super().__init__(BuiltinConcepts.SHEERKA, True, True, BuiltinConcepts.SHEERKA)
 
@@ -53,6 +53,7 @@ class Sheerka(Concept):
         self.parsers_prefix = None
 
         self.debug = debug
+        self.skip_builtins_in_db = skip_builtins_in_db
 
     def initialize(self, root_folder=None):
         """
@@ -109,14 +110,15 @@ class Sheerka(Concept):
             if not concept.is_unique and str(key) in builtins_classes:
                 self.builtin_cache[key] = builtins_classes[str(key)]
 
-            from_db = self.sdp.get_safe(self.CONCEPTS_ENTRY, concept.key)
+            if not self.skip_builtins_in_db:
-            if from_db is None:
+                from_db = self.sdp.get_safe(self.CONCEPTS_ENTRY, concept.key)
-                log.debug(f"'{concept.name}' concept is not found in db. Adding.")
+                if from_db is None:
-                self.set_id_if_needed(concept, True)
+                    log.debug(f"'{concept.name}' concept is not found in db. Adding.")
-                self.sdp.add("init", self.CONCEPTS_ENTRY, concept, use_ref=True)
+                    self.set_id_if_needed(concept, True)
-            else:
+                    self.sdp.add("init", self.CONCEPTS_ENTRY, concept, use_ref=True)
-                log.debug(f"Found concept '{from_db}' in db. Updating.")
+                else:
-                concept.update_from(from_db)
+                    log.debug(f"Found concept '{from_db}' in db. Updating.")
+                    concept.update_from(from_db)
 
             self.add_in_cache(concept)
 
@@ -125,7 +127,11 @@ class Sheerka(Concept):
         Init the parsers
         :return:
         """
-        for parser in core.utils.get_sub_classes("parsers", "parsers.BaseParser.BaseParser"):
+        base_class = core.utils.get_class("parsers.BaseParser.BaseParser")
+        for parser in core.utils.get_sub_classes("parsers", base_class):
+            if parser.__module__ == base_class.__module__:
+                continue
+
             log.debug(f"Adding builtin parser '{parser.__name__}'")
             self.parsers.append(parser)
 

core/tokenizer.py

@@ -54,12 +54,14 @@ class Token:
     column: int
 
     def __repr__(self):
-        if type == TokenKind.IDENTIFIER:
+        if self.type == TokenKind.IDENTIFIER:
-            value = "ident:" + str(self.value)
+            value = str(self.value)
-        elif type == TokenKind.WHITESPACE:
+        elif self.type == TokenKind.WHITESPACE:
-            value = " "
+            value = "<ws>"
-        elif type == TokenKind.NEWLINE:
+        elif self.type == TokenKind.NEWLINE:
             value = r"\n"
+        elif self.type == TokenKind.EOF:
+            value = "<EOF>"
         else:
             value = self.value
 

core/utils.py

@@ -105,27 +105,28 @@ def get_classes_from_package(package_name):
             yield c
 
 
-def get_sub_classes(package_name, base_class_name):
+def get_sub_classes(package_name, base_class):
     pkg = __import__(package_name)
     prefix = pkg.__name__ + "."
     for (module_loader, name, ispkg) in pkgutil.iter_modules(pkg.__path__, prefix):
         importlib.import_module(name)
 
-    base_class = get_class(base_class_name)
+    base_class = get_class(base_class) if isinstance(base_class, str) else base_class
-    return base_class.__subclasses__()
+    return set(base_class.__subclasses__()).union(
+        [s for c in base_class.__subclasses__() for s in get_sub_classes(package_name, c)])
 
 
-def remove_from_list(lst, to_remove):
+def remove_from_list(lst, to_remove_predicate):
     """
     Removes elements from a list if they exist
     :param lst:
-    :param to_remove:
+    :param to_remove_predicate:
     :return:
     """
 
     flagged = []
     for item in lst:
-        if to_remove(item):
+        if to_remove_predicate(item):
             flagged.append(item)
 
     for item in flagged:
@@ -134,3 +135,23 @@ def remove_from_list(lst, to_remove):
     return lst
 
 
+def product(a, b):
+    """
+    Kind of cartesian product between list a and b
+    knowing that a is also a list
+
+    So it's a cartesian product between a list of list and a list
+    """
+
+    if a is None or len(a) == 0:
+        return b
+    if b is None or len(b) == 0:
+        return a
+
+    res = []
+    for item_b in b:
+        for item_a in a:
+            items = item_a + [item_b]
+            res.append(items)
+
+    return res

evaluators/PythonEvaluator.py

@@ -47,7 +47,7 @@ class PythonEvaluator(OneReturnValueEvaluator):
             for prop_name, prop_value in context.obj.props.items():
                 my_locals[prop_name] = prop_value.value
 
-        node_concept = core.ast.nodes.transform(ast_)
+        node_concept = core.ast.nodes.python_to_concept(ast_)
         unreferenced_names_visitor = UnreferencedNamesVisitor(context.sheerka)
         unreferenced_names_visitor.visit(node_concept)
 

parsers/BaseParser.py

@@ -51,6 +51,10 @@ class BaseParser:
         if tokens is None:
             return ""
         res = ""
+
+        if not hasattr(tokens, "__iter__"):
+            tokens = [tokens]
+
         for token in tokens:
             value = Keywords(token.value).value if token.type == TokenKind.KEYWORD else token.value
             res += value

parsers/ConceptLexerParser.py

@@ -0,0 +1,495 @@
+#####################################################################################################
+# This part of code is highly inspired by the arpeggio project (https://github.com/textX/Arpeggio)
+# I don't directly use the project, but it helped me figure out
+# what to do.
+#       Dejanović I., Milosavljević G., Vaderna R.:
+#       Arpeggio: A flexible PEG parser for Python,
+#       Knowledge-Based Systems, 2016, 95, 71 - 74, doi:10.1016/j.knosys.2015.12.004
+#####################################################################################################
+from dataclasses import field, dataclass
+from collections import defaultdict
+from core.builtin_concepts import BuiltinConcepts
+from core.concept import Concept
+from core.tokenizer import TokenKind, Tokenizer, Token
+from parsers.BaseParser import BaseParser, Node, ErrorNode
+import core.utils
+import logging
+
+log = logging.getLogger(__name__)
+
+
+def flatten(iterable):
+    if iterable is None:
+        return []
+
+    result = []
+    for e in iterable:
+        if e.parsing_expression.rule_name is not None and e.parsing_expression.rule_name != "":
+            if hasattr(e, "children"):
+                e.children = flatten(e.children)
+            result.append(e)
+        elif hasattr(e, "children"):
+            result.extend(flatten(e.children))
+        else:
+            result.append(e)
+    return result
+
+
+@dataclass()
+class LexerNode(Node):
+    start: int
+    end: int
+
+
+class ConceptNode(LexerNode):
+    def __init__(self, concept, start, end, tokens=None, source=None, children=None):
+        super().__init__(start, end)
+        self.concept = concept
+        self.tokens = tokens
+        self.source = source
+        self.children = children
+
+        if self.source is None:
+            self.source = BaseParser.get_text_from_tokens(self.tokens)
+
+    def __eq__(self, other):
+        if not super().__eq__(other):
+            return False
+
+        if not isinstance(other, ConceptNode):
+            return False
+
+        return self.concept == other.concept and \
+               self.source == other.source
+
+    def __hash__(self):
+        return hash((self.concept, self.start, self.end, self.source))
+
+
+class NonTerminalNode(LexerNode):
+    def __init__(self, parsing_expression, start, end, children=None):
+        super().__init__(start, end)
+        self.parsing_expression = parsing_expression
+        self.children = children
+
+    def __repr__(self):
+        name = self.parsing_expression.rule_name or self.parsing_expression.__class__.__name__
+        if len(self.children) > 0:
+            sub_names = "(" + ",".join([repr(child) for child in self.children]) + ")"
+        else:
+            sub_names = ""
+        return name + sub_names
+
+
+class TerminalNode(LexerNode):
+    def __init__(self, parsing_expression, start, end, value):
+        super().__init__(start, end)
+        self.parsing_expression = parsing_expression
+        self.value = value
+
+    def __repr__(self):
+        name = self.parsing_expression.rule_name or ""
+        return name + f"'{self.value}'"
+
+
+@dataclass()
+class GrammarErrorNode(ErrorNode):
+    message: str
+
+
+class ParsingExpression:
+    def __init__(self, *args, **kwargs):
+        self.elements = args
+
+        nodes = kwargs.get('nodes', [])
+        if not hasattr(nodes, '__iter__'):
+            nodes = [nodes]
+        self.nodes = nodes
+
+        self.rule_name = kwargs.get('rule_name', '')
+
+    def parse(self, parser):
+        return self._parse(parser)
+
+
+class Sequence(ParsingExpression):
+    """
+    Will match sequence of parser expressions in exact order they are defined.
+    """
+
+    def _parse(self, parser):
+        init_pos = parser.pos
+        end_pos = parser.pos
+
+        children = []
+        for e in self.nodes:
+            node = e.parse(parser)
+            if node is None:
+                return None
+            else:
+                if node.end != -1:  # because Optional returns -1 when no match
+                    children.append(node)
+                    end_pos = node.end
+
+        return NonTerminalNode(self, init_pos, end_pos, children)
+
+
+class OrderedChoice(ParsingExpression):
+    """
+    Will match one among multiple
+    It will stop at the first match (so the order of definition is important)
+    """
+
+    def _parse(self, parser):
+        init_pos = parser.pos
+
+        for e in self.nodes:
+            node = e.parse(parser)
+            if node:
+                return NonTerminalNode(self, init_pos, node.end, [node])
+
+            parser.seek(init_pos)  # backtrack
+
+        return None
+
+
+class Optional(ParsingExpression):
+    """
+    Will match or not the elements
+    if many matches, will choose longest one
+    If you need order, use Optional(OrderedChoice)
+    """
+
+    def _parse(self, parser):
+        init_pos = parser.pos
+        selected_node = NonTerminalNode(self, parser.pos, -1, [])
+
+        for e in self.nodes:
+            node = e.parse(parser)
+            if node:
+                if node.end > selected_node.end:
+                    selected_node = node
+
+            parser.seek(init_pos)  # backtrack
+
+        if selected_node.end != -1:
+            parser.seek(selected_node.end)
+            parser.next_token()  # eat the tokens found
+
+        return selected_node
+
+
+class Match(ParsingExpression):
+    """
+    Base class for all classes that will try to match something from the input.
+    """
+
+    def __init__(self, rule_name, root=False):
+        super(Match, self).__init__(rule_name=rule_name, root=root)
+
+    def parse(self, parser):
+        result = self._parse(parser)
+        return result
+
+
+class StrMatch(Match):
+    """
+    Matches a literal
+    """
+
+    def __init__(self, to_match, rule_name="", root=False, ignore_case=None):
+        super(Match, self).__init__(rule_name=rule_name, root=root)
+        self.to_match = to_match
+        self.ignore_case = ignore_case
+
+    def __repr__(self):
+        return f"StrMatch('{self.to_match}')"
+
+    def _parse(self, parser):
+        token = parser.get_token()
+        m = str(token.value).lower() == self.to_match.lower() if self.ignore_case \
+            else token.value == self.to_match
+
+        if m:
+            node = TerminalNode(self, parser.pos, parser.pos, token.value)
+            parser.next_token()
+            return node
+
+        return None
+
+
+class CrossRef:
+    """
+    During the creation of the model,
+    Creates reference to a concept, as it may not be resolved yet
+    """
+
+    def __init__(self, concept):
+        self.concept = concept
+
+
+class ConceptLexerParser(BaseParser):
+    def __init__(self):
+        super().__init__("ConceptLexer")
+        self.concepts_dict = {}
+        self.ignore_case = True
+
+        self.token = None
+        self.pos = -1
+        self.tokens = None
+
+        self.context = None
+        self.text = None
+        self.sheerka = None
+
+    def add_error(self, error, next_token=True):
+        self.has_error = True
+        self.error_sink.append(error)
+        if next_token:
+            self.next_token()
+        return error
+
+    def reset_parser(self, context, text):
+        self.context = context
+        self.sheerka = context.sheerka
+        self.text = text
+
+        if isinstance(text, str):
+            self.tokens = list(Tokenizer(text))
+        else:
+            self.tokens = list(text)
+            self.tokens.append(Token(TokenKind.EOF, "", -1, -1, -1))  # make sure to finish with end of file token
+
+        self.token = None
+        self.pos = -1
+        self.next_token()
+
+    def get_token(self) -> Token:
+        return self.token
+
+    def next_token(self, skip_whitespace=True):
+        if self.token and self.token.type == TokenKind.EOF:
+            return False
+
+        self.pos += 1
+        self.token = self.tokens[self.pos]
+
+        if skip_whitespace:
+            while self.token.type == TokenKind.WHITESPACE or self.token.type == TokenKind.NEWLINE:
+                self.pos += 1
+                self.token = self.tokens[self.pos]
+
+        return self.token.type != TokenKind.EOF
+
+    def seek(self, pos):
+        self.pos = pos
+        self.token = self.tokens[self.pos]
+        return True
+
+    def rewind(self, offset, skip_whitespace=True):
+        self.pos += offset
+        self.token = self.tokens[self.pos]
+
+        if skip_whitespace:
+            while self.pos > 0 and (self.token.type == TokenKind.WHITESPACE or self.token.type == TokenKind.NEWLINE):
+                self.pos -= 1
+                self.token = self.tokens[self.pos]
+
+    def initialize(self, dict):
+        """
+        Adds a bunch of concepts, and how they can be recognized
+        :param dict: dictionary of concept; concept_definition
+        :return:
+        """
+
+        nodes_to_resolve = []
+        concepts_to_resolve = set()
+
+        # ## Gets the grammars
+        for concept, concept_def in dict.items():
+            concept.init_key()  # make sure that the key is initialized
+            grammar = self.get_model(concept, concept_def, nodes_to_resolve, concepts_to_resolve)
+            self.concepts_dict[concept] = grammar
+
+        # ## Removes concepts with infinite recursions
+        concepts_to_remove = self.detect_infinite_recursion(concepts_to_resolve)
+        for concept in concepts_to_remove:
+            concepts_to_resolve.remove(concept)
+            del self.concepts_dict[concept]
+
+        # ## Resolves cross references and remove grammar with unresolved references
+        self.resolve_cross_references(concepts_to_resolve, nodes_to_resolve)
+
+    def get_model(self, concept, concept_def, nodes_to_resolve, concepts_to_resolve):
+        def inner_get_model(expression):
+            if isinstance(expression, Concept):
+                ret = CrossRef(expression)
+                concepts_to_resolve.add(concept)
+                nodes_to_resolve.append(ret)
+            elif isinstance(expression, str):
+                ret = StrMatch(expression, ignore_case=self.ignore_case)
+            elif isinstance(expression, StrMatch):
+                ret = expression
+                if ret.ignore_case is None:
+                    ret.ignore_case = self.ignore_case
+            elif isinstance(expression, Sequence) or \
+                isinstance(expression, OrderedChoice) or \
+                isinstance(expression, Optional):
+                ret = expression
+                ret.nodes.extend([inner_get_model(e) for e in ret.elements])
+                if any((isinstance(x, CrossRef) for x in ret.nodes)):
+                    concepts_to_resolve.add(concept)
+                    nodes_to_resolve.append(ret)
+            else:
+                ret = self.add_error(GrammarErrorNode(f"Unrecognized grammar element '{expression}'."))
+            return ret
+
+        model = inner_get_model(concept_def)
+        if isinstance(model, CrossRef):
+            concepts_to_resolve.add(concept)
+
+        model.rule_name = concept.key
+        return model
+
+    def detect_infinite_recursion(self, concepts_to_resolve):
+
+        # infinite recursion matcher
+        def _is_infinite_recursion(ref_concept, node):
+            if isinstance(node, CrossRef):
+                if node.concept == ref_concept:
+                    return True
+                return _is_infinite_recursion(ref_concept, self.concepts_dict[node.concept])
+
+            if isinstance(node, OrderedChoice):
+                return _is_infinite_recursion(ref_concept, node.nodes[0])
+
+            if isinstance(node, Sequence):
+                for node in node.nodes:
+                    if _is_infinite_recursion(ref_concept, node):
+                        return True
+                return False
+
+            return False
+
+        removed_concepts = []
+        for e in concepts_to_resolve:
+            to_resolve = self.concepts_dict[e]
+            if _is_infinite_recursion(e, to_resolve):
+                removed_concepts.append(e)
+        return removed_concepts
+
+    # Cross-ref resolving
+    def resolve_cross_references(self, concepts_to_resolve, nodes_to_resolve):
+
+        repeat = True
+        while repeat:
+            repeat = False
+            for e in concepts_to_resolve:
+                to_resolve = self.concepts_dict[e]
+                if isinstance(to_resolve, CrossRef):
+                    repeat = True
+                    self.concepts_dict[e] = self.concepts_dict[to_resolve.concept]
+
+        for e in nodes_to_resolve:
+            if not isinstance(e, ParsingExpression):
+                continue  # cases when a concept directly references another concept
+
+            for i, node in enumerate(e.nodes):
+                if isinstance(node, CrossRef):
+                    if node.concept in self.concepts_dict:
+                        e.nodes[i] = self.concepts_dict[node.concept]
+
+    def parse(self, context, text):
+        if text == "":
+            return context.sheerka.ret(
+                self.name,
+                False,
+                context.sheerka.new(BuiltinConcepts.IS_EMPTY)
+            )
+
+        self.reset_parser(context, text)
+
+        concepts_found = [[]]
+        # actually list of list
+        # The first dimension is the number of possibilities found
+        # The second dimension is the number of concepts found, under one possibility
+        #
+        # Example 1
+        # concept foo : 'one' 'two'
+        # concept bar : 'one' 'two'
+        # input 'one two' -> will produce two possibilities (foo and bar).
+        #
+        # Example 2
+        # concept foo : 'one'
+        # concept bar : 'two'
+        # input 'one two' -> will produce one possibility which is (foo, bar) (foo then bar)
+
+        while True:
+            init_pos = self.pos
+            res = []
+            for concept, grammar in self.concepts_dict.items():
+                self.seek(init_pos)
+                node = grammar.parse(self)
+                if node is not None:
+                    concept_node = ConceptNode(concept, node.start, node.end, self.tokens[node.start: node.end + 1])
+                    if hasattr(node, "children"):
+                        concept_node.children = node.children
+                    res.append(concept_node)
+
+            if len(res) == 0:  # not recognized
+                self.seek(init_pos)
+                not_recognized = self.get_text_from_tokens(self.get_token())
+                self.add_error(self.sheerka.new(BuiltinConcepts.UNKNOWN_CONCEPT, body=not_recognized))
+                break
+
+            res = self.get_bests(res)  # only keep the concept that eat the more tokens
+            for r in res:
+                r.children = flatten(r.children)
+            concepts_found = core.utils.product(concepts_found, res)
+
+            # loop
+            self.seek(res[0].end)
+            if not self.next_token():
+                break
+
+        # manage when nothing is recognized (or other error)
+        if self.has_error:
+            return self.sheerka.ret(
+                self.name,
+                False,
+                self.sheerka.new(
+                    BuiltinConcepts.PARSER_RESULT,
+                    parser=self,
+                    source=text,
+                    body=self.error_sink,
+                    try_parsed=concepts_found[0] if len(concepts_found) == 1 else concepts_found))
+
+        # else
+        # returns as many ReturnValue than choices found
+        ret = []
+        for choice in concepts_found:
+            ret.append(
+                self.sheerka.ret(
+                    self.name,
+                    True,
+                    self.sheerka.new(
+                        BuiltinConcepts.PARSER_RESULT,
+                        parser=self,
+                        source=text,
+                        body=choice,
+                        try_parsed=choice)))
+
+        return ret[0] if len(ret) == 1 else ret
+
+    @staticmethod
+    def get_bests(results):
+        """
+        Returns the result that is the longest
+        :param results:
+        :return:
+        """
+        by_end_pos = defaultdict(list)
+        for result in results:
+            by_end_pos[result.end].append(result)
+
+        return by_end_pos[max(by_end_pos)]

sdp/sheerkaDataProvider.py

@@ -129,7 +129,7 @@ class State:
         if digest is None:
             return
 
-        if not isinstance(items, list):
+        if not hasattr(items, "__iter__"):
             items = [items]
 
         for item in items:
@@ -575,9 +575,9 @@ class SheerkaDataProvider:
     def exists(self, entry, key=None, digest=None):
         """
         Returns true if the entry is defined
-        :param digest:
         :param key:
         :param entry:
+        :param digest: digest of the object, when several entries share the same key
         :return:
         """
         snapshot = self.get_snapshot()

tests/test_ConceptEvaluator.py

@@ -8,7 +8,7 @@ from parsers.BaseParser import BaseParser
 
 
 def get_context():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
     return ExecutionContext("test", "xxx", sheerka)
 

tests/test_ConceptLexerParser.py

@@ -0,0 +1,560 @@
+import pytest
+from core.builtin_concepts import BuiltinConcepts
+from core.concept import Concept
+from core.sheerka import Sheerka, ExecutionContext
+from parsers.ConceptLexerParser import ConceptLexerParser, ConceptNode, Sequence, StrMatch, OrderedChoice, Optional, \
+    CrossRef
+
+
+@pytest.mark.parametrize("match, text", [
+    ("foo", "foo"),
+    ("'foo'", "'foo'"),
+    ("1", "1"),
+    ("3.14", "3.14"),
+    ("+", "+"),
+    (StrMatch("foo"), "foo"),
+    (StrMatch("'foo'"), "'foo'"),
+    (StrMatch("1"), "1"),
+    (StrMatch("3.14"), "3.14"),
+    (StrMatch("+"), "+"),
+])
+def test_i_can_match_simple_tokens(match, text):
+    context = get_context()
+    foo = Concept(name="foo")
+    concepts = {foo: text}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, text)
+
+    assert res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.value == [ConceptNode(foo, 0, 0, source=text)]
+
+
+def test_i_can_match_multiple_concepts_in_one_input():
+    context = get_context()
+    one = Concept(name="one")
+    two = Concept(name="two")
+    concepts = {one: "one", two: "two"}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two one")
+
+    assert res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.value == [
+        ConceptNode(one, 0, 0, source="one"),
+        ConceptNode(two, 2, 2, source="two"),
+        ConceptNode(one, 4, 4, source="one"),
+    ]
+
+
+def test_i_cannot_match_an_unknown_input():
+    context = get_context()
+    parser = ConceptLexerParser()  # no grammar registered
+
+    res = parser.parse(context, "foo")
+
+    assert not res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert context.sheerka.isinstance(res.value.body[0], BuiltinConcepts.UNKNOWN_CONCEPT)
+    assert res.value.body[0].body == "foo"
+
+
+def test_i_cannot_match_when_part_of_the_input_is_unknown():
+    context = get_context()
+    one = Concept(name="one")
+    two = Concept(name="two")
+    concepts = {one: "one", two: "two"}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two three")
+    assert not res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.try_parsed == [
+        ConceptNode(one, 0, 0, source="one"),
+        ConceptNode(two, 2, 2, source="two")]  # these two were recognized
+    assert context.sheerka.isinstance(res.value.body[0], BuiltinConcepts.UNKNOWN_CONCEPT)
+    assert res.value.body[0].body == "three"
+
+
+def test_i_can_match_sequence():
+    context = get_context()
+    foo = Concept(name="foo")
+    concepts = {foo: Sequence("one", "two", "three")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two three")
+
+    assert res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.value == [ConceptNode(foo, 0, 4, source="one two three")]
+
+
+def test_wrong_sequence_is_not_matched():
+    context = get_context()
+    foo = Concept(name="foo")
+    concepts = {foo: Sequence("one", "two", "three")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two three one")
+
+    assert not res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.try_parsed == [ConceptNode(foo, 0, 4, source="one two three")]
+    assert context.sheerka.isinstance(res.value.body[0], BuiltinConcepts.UNKNOWN_CONCEPT)
+    assert res.value.body[0].body == "one"
+
+
+def test_i_cannot_match_sequence_if_end_of_file():
+    context = get_context()
+    foo = Concept(name="foo")
+    concepts = {foo: Sequence("one", "two", "three")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two")
+    assert not res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.try_parsed == []
+    assert context.sheerka.isinstance(res.value.body[0], BuiltinConcepts.UNKNOWN_CONCEPT)
+    assert res.value.body[0].body == "one"
+
+
+def test_i_always_choose_the_longest_match():
+    context = get_context()
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+    concepts = {bar: Sequence("one", "two"), foo: Sequence("one", "two", "three")}
+
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two three")
+
+    assert res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.value == [ConceptNode(foo, 0, 4, source="one two three")]
+
+
+def test_i_can_match_several_sequences():
+    context = get_context()
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+    concepts = {bar: Sequence("one", "two"), foo: Sequence("one", "two", "three")}
+
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two three one two")
+
+    assert res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.PARSER_RESULT)
+    assert res.value.value == [
+        ConceptNode(foo, 0, 4, source="one two three"),
+        ConceptNode(bar, 6, 8, source="one two"),
+    ]
+
+
+def test_i_can_match_ordered_choice():
+    context = get_context()
+    foo = Concept(name="foo")
+    concepts = {foo: OrderedChoice("one", "two")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res1 = parser.parse(context, "one")
+    assert res1.status
+    assert context.sheerka.isinstance(res1.value, BuiltinConcepts.PARSER_RESULT)
+    assert res1.value.body == [ConceptNode(foo, 0, 0, source="one")]
+
+    res2 = parser.parse(context, "two")
+    assert res2.status
+    assert context.sheerka.isinstance(res2.value, BuiltinConcepts.PARSER_RESULT)
+    assert res2.value.body == [ConceptNode(foo, 0, 0, source="two")]
+
+    res3 = parser.parse(context, "three")
+    assert not res3.status
+    assert context.sheerka.isinstance(res3.value.body[0], BuiltinConcepts.UNKNOWN_CONCEPT)
+    assert res3.value.body[0].body == "three"
+
+
+def test_i_cannot_match_ordered_choice_with_empty_alternative():
+    context = get_context()
+    foo = Concept(name="foo")
+    concepts = {foo: Sequence(OrderedChoice("one", ""), "two")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "ok")  # because token[0] is not "one" and not "" (it is 'two')
+    assert not res.status
+
+
+def test_i_can_mix_sequences_and_ordered_choices():
+    context = get_context()
+    foo = Concept(name="foo")
+
+    concepts = {foo: Sequence(OrderedChoice("twenty", "thirty"), "one", "ok")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res1 = parser.parse(context, "twenty one ok")
+    assert res1.status
+    assert context.sheerka.isinstance(res1.value, BuiltinConcepts.PARSER_RESULT)
+    assert res1.value.body == [ConceptNode(foo, 0, 4, source="twenty one ok")]
+
+    res2 = parser.parse(context, "thirty one ok")
+    assert res2.status
+    assert context.sheerka.isinstance(res2.value, BuiltinConcepts.PARSER_RESULT)
+    assert res2.value.body == [ConceptNode(foo, 0, 4, source="thirty one ok")]
+
+    res3 = parser.parse(context, "twenty one")
+    assert not res3.status
+    assert res3.value.body[0].body == "twenty"
+    assert res3.value.try_parsed == []
+
+
+def test_i_can_mix_ordered_choices_and_sequences():
+    context = get_context()
+    foo = Concept(name="foo")
+
+    concepts = {foo: OrderedChoice(Sequence("twenty", "thirty"), "one")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "twenty thirty")
+    assert res.status
+
+    res = parser.parse(context, "one")
+    assert res.status
+
+
+def test_i_cannot_parse_empty_optional():
+    context = get_context()
+    foo = Concept(name="foo")
+
+    concepts = {foo: Optional("one")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "")
+    assert not res.status
+    assert context.sheerka.isinstance(res.value, BuiltinConcepts.IS_EMPTY)
+
+
+def test_i_can_parse_optional():
+    context = get_context()
+    foo = Concept(name="foo")
+
+    concepts = {foo: Optional("one")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one")
+    assert res.status
+    assert res.value.value == [ConceptNode(foo, 0, 0, source="one")]
+
+
+def test_i_can_parse_sequence_starting_with_optional():
+    context = get_context()
+    foo = Concept(name="foo")
+
+    concepts = {foo: Sequence(Optional("twenty"), "one")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "twenty one")
+    assert res.status
+    assert res.value.body == [ConceptNode(foo, 0, 2, source="twenty one")]
+
+    res = parser.parse(context, "one")
+    assert res.status
+    assert res.value.body == [ConceptNode(foo, 0, 0, source="one")]
+
+
+def test_i_can_parse_sequence_ending_with_optional():
+    context = get_context()
+    foo = Concept(name="foo")
+
+    concepts = {foo: Sequence("one", "two", Optional("three"))}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two three")
+    assert res.status
+    assert res.value.body == [ConceptNode(foo, 0, 4, source="one two three")]
+
+    res = parser.parse(context, "one two")
+    assert res.status
+    assert res.value.body == [ConceptNode(foo, 0, 2, source="one two")]
+
+
+def test_i_can_parse_sequence_with_optional_in_between():
+    context = get_context()
+    foo = Concept(name="foo")
+
+    concepts = {foo: Sequence("one", Optional("two"), "three")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two three")
+    assert res.status
+    assert res.value.body == [ConceptNode(foo, 0, 4, source="one two three")]
+
+    res = parser.parse(context, "one three")
+    assert res.status
+    assert res.value.body == [ConceptNode(foo, 0, 2, source="one three")]
+
+
+def test_i_can_use_reference():
+    # The problem here is when there are multiple match for the same input
+    # The parsing result is a list of all concepts found
+    # So it's already a list that represents a sequence, not a choice
+    # So I need to create a choice concept
+    # create the return value for every possible graph
+    # --> The latter seems to be the best as we don't defer the resolution of the problem to someone else
+    context = get_context()
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {foo: Sequence("one", "two"), bar: foo}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two")
+    assert len(res) == 2
+
+    assert res[0].status
+    assert context.sheerka.isinstance(res[0].value, BuiltinConcepts.PARSER_RESULT)
+    assert res[0].value.body == [ConceptNode(foo, 0, 2, source="one two")]
+
+    assert res[1].status
+    assert context.sheerka.isinstance(res[1].value, BuiltinConcepts.PARSER_RESULT)
+    assert res[1].value.body == [ConceptNode(bar, 0, 2, source="one two")]
+
+
+def test_i_can_use_context_reference_with_multiple_levels():
+    """
+    Same than previous one, but with reference of reference
+    :return:
+    """
+    context = get_context()
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+    baz = Concept(name="baz")
+
+    concepts = {foo: Sequence("one", "two"), bar: foo, baz: bar}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two")
+    assert len(res) == 3
+
+    assert res[0].status
+    assert context.sheerka.isinstance(res[0].value, BuiltinConcepts.PARSER_RESULT)
+    assert res[0].value.body == [ConceptNode(foo, 0, 2, source="one two")]
+
+    assert res[1].status
+    assert context.sheerka.isinstance(res[1].value, BuiltinConcepts.PARSER_RESULT)
+    assert res[1].value.body == [ConceptNode(bar, 0, 2, source="one two")]
+
+    assert res[2].status
+    assert context.sheerka.isinstance(res[2].value, BuiltinConcepts.PARSER_RESULT)
+    assert res[2].value.body == [ConceptNode(baz, 0, 2, source="one two")]
+
+
+def test_order_is_not_important_when_using_references():
+    context = get_context()
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {bar: foo, foo: Sequence("one", "two")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "one two")
+    assert len(res) == 2
+    assert res[0].value.body == [ConceptNode(bar, 0, 2, source="one two")]
+    assert res[1].value.body == [ConceptNode(foo, 0, 2, source="one two")]
+
+
+def test_i_can_parse_when_reference():
+    context = get_context()
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {bar: Sequence(foo, OrderedChoice("one", "two")), foo: OrderedChoice("twenty", "thirty")}
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "twenty two")
+    assert res.status
+    assert res.value.body == [ConceptNode(bar, 0, 2, source="twenty two")]
+
+    res = parser.parse(context, "thirty one")
+    assert res.status
+    assert res.value.body == [ConceptNode(bar, 0, 2, source="thirty one")]
+
+    res = parser.parse(context, "twenty")
+    assert res.status
+    assert res.value.body == [ConceptNode(foo, 0, 0, source="twenty")]
+
+
+def test_i_can_detect_duplicates_when_reference():
+    context = get_context()
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {
+        bar: Sequence(foo, Optional(OrderedChoice("one", "two"))),
+        foo: OrderedChoice("twenty", "thirty")
+    }
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    res = parser.parse(context, "twenty")
+    assert len(res) == 2
+    assert res[0].status
+    assert context.sheerka.isinstance(res[0].value, BuiltinConcepts.PARSER_RESULT)
+    assert res[0].value.body == [ConceptNode(bar, 0, 0, source="twenty")]
+
+    assert res[1].status
+    assert context.sheerka.isinstance(res[1].value, BuiltinConcepts.PARSER_RESULT)
+    assert res[1].value.body == [ConceptNode(foo, 0, 0, source="twenty")]
+
+
+def test_i_can_detect_infinite_recursion():
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {
+        bar: foo,
+        foo: bar
+    }
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    assert bar not in parser.concepts_dict
+    assert foo not in parser.concepts_dict
+
+
+def test_i_can_detect_indirect_infinite_recursion_with_ordered_choice():
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {
+        bar: foo,
+        foo: OrderedChoice(bar, "foo")
+    }
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    assert foo not in parser.concepts_dict  # removed because of the infinite recursion
+    assert bar not in parser.concepts_dict  # removed because of the infinite recursion
+
+    # the other way around is possible
+    context = get_context()
+    concepts = {
+        bar: foo,
+        foo: OrderedChoice("foo", bar)
+    }
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+    assert foo in parser.concepts_dict
+    assert bar in parser.concepts_dict
+
+    res = parser.parse(context, "foo")
+    assert len(res) == 2
+    assert res[0].status
+    assert res[0].value.body == [ConceptNode(bar, 0, 0, source="foo")]
+    assert res[1].status
+    assert res[1].value.body == [ConceptNode(foo, 0, 0, source="foo")]
+
+
+def test_i_can_detect_indirect_infinite_recursion_with_sequence():
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {
+        bar: foo,
+        foo: Sequence("one", bar, "two")
+    }
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    assert foo not in parser.concepts_dict  # removed because of the infinite recursion
+    assert bar not in parser.concepts_dict  # removed because of the infinite recursion
+
+
+def test_i_can_detect_indirect_infinite_recursion_with_sequence_or_ordered_choice():
+    foo = Concept(name="foo")
+    bar = Concept(name="bar")
+
+    concepts = {
+        bar: foo,
+        foo: Sequence("one", OrderedChoice(bar, "other"), "two")
+    }
+    parser = ConceptLexerParser()
+    parser.initialize(concepts)
+
+    assert foo not in parser.concepts_dict  # removed because of the infinite recursion
+    assert bar not in parser.concepts_dict  # removed because of the infinite recursion
+
+
+def test_i_can_detect_indirect_infinite_recursion_with_optional():
+    # TODO infinite recursion with optional
+    pass
+
+#
+# def test_i_can_parse_basic_arithmetic_operations_and_resolve_properties():
+#     context = get_context()
+#     add = Concept(name="add")
+#     mult = Concept(name="mult")
+#     atom = Concept(name="atom")
+#
+#     concepts = {
+#         add: Sequence(mult, Optional(Sequence(OrderedChoice('+', '-', rule_name="sign"), add))),
+#         mult: Sequence(atom, Optional(Sequence(OrderedChoice('*', '/'), mult))),
+#         atom: OrderedChoice(OrderedChoice('1', '2', '3'), Sequence('(', add, ')')),
+#     }
+#
+#     parser = ConceptLexerParser()
+#     parser.register(concepts)
+#
+#     # res = parser.parse(context, "1")
+#     # assert len(res) == 3  # add, mult, atom
+#     #
+#     # res = parser.parse(context, "1 * 2")
+#     # assert len(res) == 2  # add and mult
+#     #
+#     # res = parser.parse(context, "1 + 2")
+#     # assert res.status
+#     # assert res.value.value == [ConceptNode(add, 0, 4, source="1 + 2")]
+#
+#     res = parser.parse(context, "1 * 2 + 3")
+#     assert res.status
+#     assert res.value.value == [ConceptNode(add, 0, 4, source="1 + 2 + 3")]
+
+
+def test_i_can_register_concepts_with_the_same_name():
+    # TODO : concepts are registered by name,
+    #  what when two concepts have the same name ?
+    pass
+
+
+def test_i_can_parse_very_very_long_input():
+    # TODO: In the current implementation, all the tokens are loaded in memory
+    # It's clearly not the good approach
+    pass
+
+
+def get_context():
+    sheerka = Sheerka(skip_builtins_in_db=True)
+    sheerka.initialize("mem://")
+
+    return ExecutionContext("sheerka", "xxxx", sheerka)

tests/test_DefaultParser.py

@@ -67,7 +67,7 @@ def get_concept(name, where=None, pre=None, post=None, body=None):
 
 
 def get_context():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
     return ExecutionContext("test", "xxx", sheerka)
 

tests/test_ExactConceptParser.py

@@ -125,7 +125,7 @@ def test_i_can_detect_concept_from_tokens():
 
 
 def get_context():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
 
     return ExecutionContext("sheerka", "xxxx", sheerka)

tests/test_MultipleSameSuccessEvaluator.py

@@ -7,7 +7,7 @@ from parsers.BaseParser import BaseParser
 
 
 def get_context():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
     return ExecutionContext("test", "xxx", sheerka)
 

tests/test_PyhtonEvaluator.py

@@ -8,7 +8,7 @@ from parsers.PythonParser import PythonNode, PythonParser
 
 
 def get_context():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
     return ExecutionContext("test", "xxx", sheerka)
 

tests/test_PythonParser.py

@@ -9,7 +9,7 @@ from parsers.PythonParser import PythonNode, PythonParser, PythonErrorNode
 
 
 def get_context():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
     return ExecutionContext("test", "xxx", sheerka)
 

tests/test_ast.py

@@ -8,7 +8,7 @@ from core.sheerka import Sheerka
 
 
 def get_sheerka():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
 
     return sheerka
@@ -34,7 +34,7 @@ def my_function(a,b):
     return a
 """
     tree = ast.parse(source)
-    tree_as_concept = core.ast.nodes.transform(tree)
+    tree_as_concept = core.ast.nodes.python_to_concept(tree)
     sheerka = get_sheerka()
 
     assert tree_as_concept.node_type == "Module"
@@ -87,7 +87,7 @@ def my_function(a,b):
     """
 
     node = ast.parse(source)
-    concept_node = core.ast.nodes.transform(node)
+    concept_node = core.ast.nodes.python_to_concept(node)
 
     visitor = TestNameVisitor()
     visitor.visit(concept_node)
@@ -115,7 +115,7 @@ my_function(x,y)
     sheerka = get_sheerka()
 
     node = ast.parse(source)
-    concept_node = core.ast.nodes.transform(node)
+    concept_node = core.ast.nodes.python_to_concept(node)
 
     visitor = UnreferencedNamesVisitor(sheerka)
     visitor.visit(concept_node)
@@ -129,3 +129,28 @@ my_function(x,y)
 def test_i_can_compare_NodeParent_with_tuple():
     node_parent = NodeParent(GenericNodeConcept("For", None), "target")
     assert node_parent == ("For", "target")
+
+
+def test_i_can_transform_back():
+    source = """
+def my_function(a,b):
+    for i in range(b):
+        a = a + b
+    return a
+
+
+my_function(x, y)
+    """
+
+    node = ast.parse(source)
+    concept_node = core.ast.nodes.python_to_concept(node)
+
+    transformed_back = core.ast.nodes.concept_to_python(concept_node)
+    assert dump_ast(transformed_back) == dump_ast(node)
+
+
+def dump_ast(node):
+    dump = ast.dump(node)
+    for to_remove in [", ctx=Load()", ", kind=None", ", type_ignores=[]"]:
+        dump = dump.replace(to_remove, "")
+    return dump

tests/test_builtin_helpers.py

@@ -1,3 +1,7 @@
+import ast
+
+import pytest
+
 from core.builtin_concepts import ReturnValueConcept, BuiltinConcepts
 from core.sheerka import Sheerka, ExecutionContext
 import core.builtin_helpers
@@ -110,8 +114,47 @@ def test_i_can_use_expect_one_when_not_a_list_false():
     assert res == item
 
 
+@pytest.mark.parametrize("expression, vars_to_include, vars_to_exclude, expected_expr", [
+    ("a == 1", [], [], []),
+    ("a == 1", ["a"], [], ["a == 1"]),
+    ("a == 1", [], ["a"], []),
+    ("predicate(a)", [], [], []),
+    ("predicate(a)", ["a"], [], ["predicate(a)"]),
+    ("predicate(a, b)", ["a"], [], ["predicate(a, b)"]),
+    ("predicate(a, b)", ["b"], [], ["predicate(a, b)"]),
+    ("predicate(a, b)", ["a", "b"], [], ["predicate(a, b)"]),
+    ("predicate(a, b)", ["a"], ["b"], []),
+    ("a + b == 1", [], [], []),
+    ("a + b == 1", ["a"], [], ["a + b == 1"]),
+    ("a + b == 1", ["a"], ["b"], []),
+    ("a + b == 1", ["b"], [], ["a + b == 1"]),
+    ("a + b == 1", ["a", "b"], [], ["a + b == 1"]),
+    ("a == 1 and b == 2", [], [], []),
+    ("a == 1 and b == 2", ["a"], [], ["a == 1"]),
+    ("a == 1 and b == 2", ["b"], [], ["b == 2"]),
+    ("a == 1 and b == 2", ["a"], ["b"], ["a == 1"]),
+    ("a == 1 and b == 2", ["a", "b"], [], ["a == 1 and b == 2"]),
+    ("predicate(a,c) and predicate(b,c)", ["a", "b"], [], ["predicate(a,c) and predicate(b,c)"]),
+    ("not(a == 1)", [], [], []),
+    ("not(a == 1)", ["a"], [], ["not(a==1)"]),
+    ("a == 1 or b == 2", [], [], []),
+    ("a == 1 or b == 2", ["a"], [], ["a == 1"]),
+    ("a == 1 or b == 2", ["b"], [], ["b == 2"]),
+    ("a == 1 or b == 2", ["a", "b"], [], ["a == 1 or b == 2"]),
+    ("predicate(a,c) or predicate(b,c)", ["a", "b"], [], ["predicate(a,c) or predicate(b,c)"]),
+])
+def test_i_can_extract_predicates(expression, vars_to_include, vars_to_exclude, expected_expr):
+    sheerka = get_sheerka()
+    expected = [ast.parse(expr, mode="eval") for expr in expected_expr]
+
+    actual = core.builtin_helpers.extract_predicates(sheerka, expression, vars_to_include, vars_to_exclude)
+    assert len(actual) == len(expected)
+    for i in range(len(actual)):
+        assert dump_ast(actual[i]) == dump_ast(expected[i])
+
+
 def get_sheerka():
-    sheerka = Sheerka()
+    sheerka = Sheerka(skip_builtins_in_db=True)
     sheerka.initialize("mem://")
 
     return sheerka
@@ -119,3 +162,10 @@ def get_sheerka():
 
 def get_context(sheerka):
     return ExecutionContext("test", "xxx", sheerka)
+
+
+def dump_ast(node):
+    dump = ast.dump(node)
+    for to_remove in [", ctx=Load()", ", kind=None", ", type_ignores=[]"]:
+        dump = dump.replace(to_remove, "")
+    return dump

tests/test_sheerka.py

@@ -50,7 +50,7 @@ def test_i_can_list_builtin_concepts():
 
 
 def test_builtin_concepts_are_initialized():
-    sheerka = get_sheerka()
+    sheerka = get_sheerka(skip_builtins_in_db=False)
     assert len(sheerka.concepts_cache) == len(BuiltinConcepts)
     for concept_name in BuiltinConcepts:
         assert str(concept_name) in sheerka.concepts_cache
@@ -61,7 +61,7 @@ def test_builtin_concepts_are_initialized():
 
 
 def test_builtin_concepts_can_be_updated():
-    sheerka = get_sheerka(root_folder)
+    sheerka = get_sheerka(root_folder, skip_builtins_in_db=False)
     loaded_sheerka = sheerka.get(BuiltinConcepts.SHEERKA)
     loaded_sheerka.desc = "I have a description"
     sheerka.sdp.modify("Test", sheerka.CONCEPTS_ENTRY, loaded_sheerka.key, loaded_sheerka)
@@ -89,7 +89,8 @@ def test_i_can_add_a_concept():
     assert concept_found.id == "1001"
 
     assert concept.key in sheerka.concepts_cache
-    assert sheerka.sdp.io.exists(sheerka.sdp.io.get_obj_path(SheerkaDataProvider.ObjectsFolder, concept_found.get_digest()))
+    assert sheerka.sdp.io.exists(
+        sheerka.sdp.io.get_obj_path(SheerkaDataProvider.ObjectsFolder, concept_found.get_digest()))
 
 
 def test_i_cannot_add_the_same_concept_twice():
@@ -414,7 +415,8 @@ as:
         assert getattr(concept_saved, prop) == getattr(expected, prop)
 
     assert concept_saved.key in sheerka.concepts_cache
-    assert sheerka.sdp.io.exists(sheerka.sdp.io.get_obj_path(SheerkaDataProvider.ObjectsFolder, concept_saved.get_digest()))
+    assert sheerka.sdp.io.exists(
+        sheerka.sdp.io.get_obj_path(SheerkaDataProvider.ObjectsFolder, concept_saved.get_digest()))
 
 
 def test_i_can_eval_def_concept_part_when_one_part_is_a_ref_of_another_concept():
@@ -443,7 +445,8 @@ def test_i_can_eval_def_concept_part_when_one_part_is_a_ref_of_another_concept()
         assert getattr(concept_saved, prop) == getattr(expected, prop)
 
     assert concept_saved.key in sheerka.concepts_cache
-    assert sheerka.sdp.io.exists(sheerka.sdp.io.get_obj_path(SheerkaDataProvider.ObjectsFolder, concept_saved.get_digest()))
+    assert sheerka.sdp.io.exists(
+        sheerka.sdp.io.get_obj_path(SheerkaDataProvider.ObjectsFolder, concept_saved.get_digest()))
 
 
 def test_i_cannot_eval_the_same_def_concept_twice():
@@ -551,12 +554,24 @@ def test_i_can_manage_concepts_with_the_same_key_when_values_are_the_same():
     res = sheerka.eval("hello 'foo'")
     assert len(res) == 1
     assert res[0].status
-    assert res[0].value, "hello foo"
+    assert res[0].value ==  "hello foo"
     assert res[0].who == sheerka.get_evaluator_name(MultipleSameSuccessEvaluator.NAME)
 
 
-def get_sheerka(root="mem://"):
+def test_i_can_create_concepts_on_python_codes():
-    sheerka = Sheerka()
+    sheerka = get_sheerka()
+    context = get_context(sheerka)
+
+    sheerka.create_new_concept(context, Concept(name="concepts", body="sheerka.concepts()"))
+    res = sheerka.eval("concepts")
+
+    assert len(res) == 1
+    assert res[0].status
+    assert isinstance(res[0].value, list)
+
+
+def get_sheerka(root="mem://", skip_builtins_in_db=True):
+    sheerka = Sheerka(skip_builtins_in_db)
     sheerka.initialize(root)
 
     return sheerka

tests/test_utils.py

@@ -51,8 +51,28 @@ def test_i_can_get_sub_classes():
     default_parser = core.utils.get_class("parsers.DefaultParser.DefaultParser")
     exact_concept_parser = core.utils.get_class("parsers.ExactConceptParser.ExactConceptParser")
     python_parser = core.utils.get_class("parsers.PythonParser.PythonParser")
+    concept_lexer_parser = core.utils.get_class("parsers.ConceptLexerParser.ConceptLexerParser")
 
     assert base_parser not in sub_classes
     assert default_parser in sub_classes
     assert exact_concept_parser in sub_classes
     assert python_parser in sub_classes
+    assert concept_lexer_parser in sub_classes
+
+
+@pytest.mark.parametrize("a,b, expected", [
+    ([], [], []),
+    ([], ['a'], ['a']),
+    ([[]], ['a'], [['a']]),
+    (['a'], [], ['a']),
+    ([['a']], [], [['a']]),
+
+    ([['a']], ['b'], [['a', 'b']]),
+    ([['a'], ['b']], ['c'], [['a', 'c'], ['b', 'c']]),
+    ([['a1', 'a2'], ['b1', 'b2', 'b3']], ['c'], [['a1', 'a2', 'c'], ['b1', 'b2', 'b3', 'c']]),
+    ([[]], ['a', 'b'], [['a'], ['b']]),
+    ([['a'], ['b']], ['c', 'd', 'e'], [['a', 'c'], ['b', 'c'], ['a', 'd'], ['b', 'd'], ['a', 'e'], ['b', 'e']]),
+])
+def test_i_can_product(a, b, expected):
+    res = core.utils.product(a, b)
+    assert res == expected