Merge: doc: fixed some typos and other misc. corrections

[nit.git] / src / neo.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Save and load a `Model` to/from a Neo4j graph.
#
# Nit models are composed by MEntities.
# This module creates NeoNode for each MEntity found in a `Model` and save them
# into Neo4j database.
#
# SEE: `Neo4jClient`
#
# NeoNodes can also be translated back to MEntities to rebuild a Nit `Model`.
#
# Structure of the nit `Model` in the graph:
#
# Note : Any null or empty attribute will not be saved in the database.
#
# For any `MEntity` (in addition to specific data):
#
# * labels: model name (`model_name`) and `MEntity`.
# * `name`: short (unqualified) name.
# * `mdoc`: JSON array representing the associated Markdown documentation
# (one item by line).
#
# Note : All nodes described here are MEntities.
#
# `MPackage`
#
# * labels: `MPackage`, `model_name` and `MEntity`.
# * `(:MPackage)-[:ROOT]->(:MGroup)`: root of the group tree.
#
# `MGroup`
#
# * labels: `MGroup`, `model_name` and `MEntity`.
# * `(:MGroup)-[:PROJECT]->(:MPackage)`: associated package.
# * `(:MGroup)-[:PARENT]->(:MGroup)`: parent group. Does not exist for the root
# group.
# * `(:MGroup)-[:DECLARES]->(:MModule)`: modules that are direct children of
# this group.
# * `(:MGroup)-[:NESTS]->(:MGroup)`: nested groups that are direct children of
# this group.
#
# `MModule`
#
# * labels: `MModule`, `model_name` and `MEntity`.
# * `location`: origin of the definition. SEE: `Location.to_s`
# * `(:MModule)-[:IMPORTS]->(:MModule)`: modules that are imported directly.
# * `(:MModule)-[:INTRODUCES]->(:MClass)`: all by classes introduced by this
# module.
# * `(:MModule)-[:DEFINES]->(:MClassDef)`: all class definitons contained in
# this module.
#
# `MClass`
#
# * labels: `MClass`, `model_name` and `MEntity`.
# * `kind`: kind of the class (`interface`, `abstract class`, etc.)
# * `visibility`: visibility of the class.
# * `parameter_names`: JSON array listing the name of each formal generic
# parameter (in order of declaration).
# * `(:MClass)-[:CLASSTYPE]->(:MClassType)`: SEE: `MClass.mclass_type`
#
# Arguments in the `CLASSTYPE` are named following the `parameter_names`
# attribute of the `MClassDef` that introduces the class. A class definition
# introduces a class if and only if it has this class as `MCLASS` and
# has `is_intro` set to `true`.
#
# `MClassDef`
#
# * labels: `MClassDef`, `model_name` and `MEntity`.
# * `location`: origin of the definition. SEE: `Location.to_s`
# * `(:MClassDef)-[:BOUNDTYPE]->(:MClassType)`: bounded type associated to the
# classdef.
# * `(:MClassDef)-[:MCLASS]->(:MClass)`: associated `MClass`.
# * `(:MClassDef)-[:INTRODUCES]->(:MProperty)`: all properties introduced by
# the classdef.
# * `(:MClassDef)-[:DECLARES]->(:MPropDef)`: all property definitions in the
# classdef (introductions and redefinitions).
# * `(:MClassDef)-[:INHERITS]->(:MClassType)`: all declared super-types
#
# `MProperty`
#
# * labels: `MProperty`, `model_name` and `MEntity`. Must also have `MMethod`,
# `MAttribute` `MVirtualTypeProp` or `MInnerClass`, depending on the class of
# the represented entity.
# * `visibility`: visibility of the property.
# * `is_init`: Indicates if the property is a constructor. Exists only if the
# node is a `MMethod`.
# * `(:MProperty)-[:INTRO_CLASSDEF]->(:MClassDef)`: classdef that introduces
# the property.
#
# Additional relationship for `MInnerClass`:
#
# * `(:MInnerClassDef)-[:NESTS]->(:MClass)`: actual inner class.
#
# `MPropDef`
#
# * labels: `MPropDef`, `model_name` and `MEntity`. Must also have `MMethodDef`,
# `MAttributeDef`, `MVirtualTypeDef` or `MInnerClassDef`, depending on the
# class of the represented entity.
# * `location`: origin of the definition. SEE: `Location.to_s`.
# * `(:MPropDef)-[:DEFINES]->(:MProperty)`: associated property.
#
# Additional attributes and relationship for `MMethodDef`:
#
# * `is_abstract`: Is the method definition abstract?
# * `is_intern`: Is the method definition intern?
# * `is_extern`: Is the method definition extern?
# * `(:MMethodDef)-[:SIGNATURE]->(:MSignature)`: signature attached to the
# property definition.
#
# Additional relationship for `MAttributeDef`:
#
# * `(:MAttributeDef)-[:TYPE]->(:MType)`: static type of the attribute,
# if specified.
#
# Additional relationship for `MVirtualTypeDef`:
#
# * `(:MVirtualTypeDef)-[:BOUND]->(:MType)`: type to which the virtual type
# is bound in this definition. Exists only if this definition bound the virtual
# type to an effective type.
#
# Additional relationship for `MInnerClassDef`:
#
# * `(:MInnerClassDef)-[:NESTS]->(:MClassDef)`: actual inner class'
# definition.
#
# `MType`
#
# * labels: `MType`, `model_name` and `MEntity`. Must also have `MClassType`,
# `MNullableType`, `MVirtualType`, `MRawType` or `MSignature`, depending on the
# class of the represented entity.
#
# Additional label and relationships for `MClassType`:
#
# * If it is a `MGenericType`, also has the `MGenericType` label.
# * `(:MClassType)-[:CLASS]->(:MClass)`: SEE: `MClassType.mclass`
# * `(:MClassType)-[:ARGUMENT]->(:MType)`: type arguments.
#
# Arguments are named following the `parameter_names` attribute of the
# `MClass` referred by `CLASS`.
#
# Additional relationship for `MVirtualType`:
#
# * `(:MVirtualType)-[:PROPERTY]->(:MProperty)`: associated property that
# determines the type (usually a `MVirtualTypeProp`).
#
# Additional attribute and relationship for `MParameterType`:
#
# * `rank`: position of the parameter (0 for the first parameter).
# * `(:MParameterType)-[:CLASS]->(:MClass)`: generic class where the parameter
# belong.
#
# Additional relationship for `MNullableType`:
#
# * `(:MNullableType)-[:TYPE]->(:MType)`: base type of the nullable type.
#
# Additional attribute and relationship for `MRawType`:
#
# * `text`: JSON array of the parts’ text.
# * `(:MRawType)-[:LINK]->(:MTypePart)`: the parts that link to another entity.
#
# Additional attribute and relationships for `MSignature`:
#
# * `parameter_names`: JSON array representing the list of the parameter names.
# * `(:MSignature)-[:PARAMETER]->(:MParameter)`: parameters.
# * `(:MSignature)-[:RETURNTYPE]->(:MType)`: return type. Does not exist for
# procedures.
#
# In order to maintain the correct parameters order, each `MSignature` node
# contains an array of parameter names corresponding to the parameter order in
# the signature.
#
# For example, if the source code contains:
#
# ~~~nitish
#     fun foo(a: A, b: B, c: C)
# ~~~
#
# The `MSignature` node will contain a property
# `parameter_names = ["a", "b", "c"]` so the MSignature can be reconstructed
# with the parameters in the correct order.
#
# `MParameter`
#
# * labels: `MParameter`, `model_name` and `MEntity`.
# * `is_vararg`: Is the parameter a vararg?
# * `rank`: position of the parameter (0 for the first parameter).
# * `(:MParameter)-[:TYPE]->(:MType)`: static type of the parameter.
#
# MParameters are also ranked by their position in the corresponding signature.
# Rank 0 for the first parameter, 1 for the next one and etc.
#
# `MTypePart`
#
# * labels: `MTypePart`, `model_name` and `MEntity`.
# * `rank`: position in the `MRawType`.
# * `(:MTypePart)-[:TARGET]->(:MEntity)`: the target of the link.
module neo

import doc::model_ext
import neo4j
import toolcontext

# Helper class that can save and load a `Model` into a Neo4j database.
class NeoModel

        # The model name.
        #
        # Because we use only one Neo4j instance to store all the models,
        # we need to mark their appartenance to a particular model and avoid loading all models.
        #
        # The name is used as a Neo label on each created nodes and used to load nodes from base.
        var model_name: String

        # The toolcontext used to init the `NeoModel` tool.
        var toolcontext: ToolContext

        # The Neo4j `client` used to communicate with the Neo4j instance.
        var client: Neo4jClient

        # Fill `model` using base pointed by `client`.
        fun load(model: Model): Model do
                var nodes: Array[NeoNode]

                toolcontext.info("Loading package node...", 1)
                nodes = client.nodes_with_labels([model_name, "MPackage"])
                for node in nodes do to_mpackage(model, node)
                toolcontext.info("Loading groups...", 1)
                nodes = client.nodes_with_labels([model_name, "MGroup"])
                for node in nodes do to_mgroup(model, node)
                toolcontext.info("Loading modules...", 1)
                nodes = client.nodes_with_labels([model_name, "MModule"])
                for node in nodes do to_mmodule(model, node)
                toolcontext.info("Loading classes...", 1)
                nodes = client.nodes_with_labels([model_name, "MClass"])
                for node in nodes do to_mclass(model, node)
                toolcontext.info("Loading class definitions...", 1)
                nodes = client.nodes_with_labels([model_name, "MClassDef"])
                for node in nodes do to_mclassdef(model, node)
                toolcontext.info("Loading properties...", 1)
                nodes = client.nodes_with_labels([model_name, "MProperty"])
                for node in nodes do to_mproperty(model, node)
                toolcontext.info("Loading property definitions...", 1)
                nodes = client.nodes_with_labels([model_name, "MPropDef"])
                for node in nodes do to_mpropdef(model, node)
                return model
        end

        # Save `model` in the base pointed by `client`.
        fun save(model: Model) do
                var nodes = collect_model_nodes(model)
                toolcontext.info("Save {nodes.length} nodes...", 1)
                push_all(nodes)
                var edges = collect_model_edges(model)
                toolcontext.info("Save {edges.length} edges...", 1)
                push_all(edges)
        end

        # Save `neo_entities` in base using batch mode.
        private fun push_all(neo_entities: Collection[NeoEntity]) do
                var batch = new NeoBatch(client)
                var len = neo_entities.length
                var sum = 0
                var i = 1
                for nentity in neo_entities do
                        batch.save_entity(nentity)
                        if i == batch_max_size then
                                do_batch(batch)
                                sum += batch_max_size
                                toolcontext.info(" {sum * 100 / len}% done", 1)
                                batch = new NeoBatch(client)
                                i = 1
                        else
                                i += 1
                        end
                end
                do_batch(batch)
        end

        # How many operation can be executed in one batch?
        private var batch_max_size = 1000

        # Execute `batch` and check for errors.
        #
        # Abort if `batch.execute` returns errors.
        private fun do_batch(batch: NeoBatch) do
                var errors = batch.execute
                if not errors.is_empty then
                        print errors
                        exit(1)
                end
        end

        # Collect all nodes from the current `model`.
        private fun collect_model_nodes(model: Model): Collection[NeoNode] do
                for mpackage in model.mpackages do
                        mpackage.to_node(nodes, model_name)
                        for mgroup in mpackage.mgroups do mgroup.to_node(nodes, model_name)
                end
                return nodes.values
        end

        # Collect all edges from the current `model`.
        #
        # Actually collect all out_edges from all nodes.
        private fun collect_model_edges(model: Model): Collection[NeoEdge] do
                var edges = new HashSet[NeoEdge]
                for node in nodes.values do edges.add_all(node.out_edges)
                return edges
        end

        # Mentities associated to nodes.
        #
        # The key is the node’s id.
        private var mentities = new HashMap[Int, MEntity]

        # Nodes associated with MEntities.
        private var nodes = new HashMap[MEntity, NeoNode]

        # Get the `MEntity` associated with `node`.
        fun to_mentity(model: Model, node: NeoNode): MEntity do
                if node.labels.has("MPackage") then return to_mpackage(model, node)
                if node.labels.has("MGroup") then return to_mgroup(model, node)
                if node.labels.has("MModule") then return to_mmodule(model, node)
                if node.labels.has("MClass") then return to_mclass(model, node)
                if node.labels.has("MClassDef") then return to_mclassdef(model, node)
                if node.labels.has("MProperty") then return to_mproperty(model, node)
                if node.labels.has("MPropDef") then return to_mpropdef(model, node)
                if node.labels.has("MType") then return to_mtype(model, node)
                if node.labels.has("MParameter") then return to_mparameter(model, node)
                abort
        end

        # Build a new `MPackage` from a `node`.
        #
        # REQUIRE `node.labels.has("MPackage")`
        private fun to_mpackage(model: Model, node: NeoNode): MPackage do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MPackage then return m

                assert node.labels.has("MPackage")
                var location = to_location(node["location"].to_s)
                var mpackage = new MPackage(node["name"].to_s, model, location)
                mentities[node.id.as(Int)] = mpackage
                set_doc(node, mpackage)
                mpackage.root = to_mgroup(model, node.out_nodes("ROOT").first)
                return mpackage
        end

        # Build a new `MGroup` from a `node`.
        #
        # REQUIRE `node.labels.has("MGroup")`
        private fun to_mgroup(model: Model, node: NeoNode): MGroup do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MGroup then return m

                assert node.labels.has("MGroup")
                var location = to_location(node["location"].to_s)
                var mpackage = to_mpackage(model, node.out_nodes("PROJECT").first)
                var parent: nullable MGroup = null
                var out = node.out_nodes("PARENT")
                if not out.is_empty then
                        parent = to_mgroup(model, out.first)
                end
                var mgroup = new MGroup(node["name"].to_s, location, mpackage, parent)
                mentities[node.id.as(Int)] = mgroup
                set_doc(node, mgroup)
                return mgroup
        end

        # Build a new `MModule` from a `node`.
        #
        # REQUIRE `node.labels.has("MModule")`
        private fun to_mmodule(model: Model, node: NeoNode): MModule do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MModule then return m

                assert node.labels.has("MModule")
                var ins = node.in_nodes("DECLARES")
                var mgroup: nullable MGroup = null
                if not ins.is_empty then
                        mgroup = to_mgroup(model, ins.first)
                end
                var name = node["name"].to_s
                var location = to_location(node["location"].to_s)
                var mmodule = new MModule(model, mgroup, name, location)
                mentities[node.id.as(Int)] = mmodule
                set_doc(node, mmodule)
                var imported_mmodules = new Array[MModule]
                for smod in node.out_nodes("IMPORTS") do
                        imported_mmodules.add to_mmodule(model, smod)
                end
                mmodule.set_imported_mmodules(imported_mmodules)
                return mmodule
        end

        # Build a new `MClass` from a `node`.
        #
        # REQUIRE `node.labels.has("MClass")`
        private fun to_mclass(model: Model, node: NeoNode): MClass do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MClass then return m

                assert node.labels.has("MClass")
                var mmodule = to_mmodule(model, node.in_nodes("INTRODUCES").first)
                var name = node["name"].to_s
                var location = to_location(node["location"].to_s)
                var kind = to_kind(node["kind"].to_s)
                var visibility = to_visibility(node["visibility"].to_s)
                var parameter_names = new Array[String]
                if node.has_key("parameter_names") then
                        for e in node["parameter_names"].as(JsonArray) do
                                parameter_names.add e.to_s
                        end
                end
                var mclass = new MClass(mmodule, name, location, parameter_names, kind, visibility)
                mentities[node.id.as(Int)] = mclass
                set_doc(node, mclass)
                return mclass
        end

        # Build a new `MClassDef` from a `node`.
        #
        # REQUIRE `node.labels.has("MClassDef")`
        private fun to_mclassdef(model: Model, node: NeoNode): MClassDef do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MClassDef then return m

                assert node.labels.has("MClassDef")
                var mmodule = to_mmodule(model, node.in_nodes("DEFINES").first)
                var mtype = to_mtype(model, node.out_nodes("BOUNDTYPE").first).as(MClassType)
                var location = to_location(node["location"].to_s)
                var mclassdef = new MClassDef(mmodule, mtype, location)
                mentities[node.id.as(Int)] = mclassdef
                set_doc(node, mclassdef)
                var supertypes = new Array[MClassType]
                for sup in node.out_nodes("INHERITS") do
                        supertypes.add to_mtype(model, sup).as(MClassType)
                end
                mclassdef.set_supertypes(supertypes)
                mclassdef.add_in_hierarchy
                return mclassdef
        end

        # Build a new `MProperty` from a `node`.
        #
        # REQUIRE `node.labels.has("MProperty")`
        private fun to_mproperty(model: Model, node: NeoNode): MProperty do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MProperty then return m

                assert node.labels.has("MProperty")
                var intro_mclassdef = to_mclassdef(model, node.out_nodes("INTRO_CLASSDEF").first)
                var name = node["name"].to_s
                var location = to_location(node["location"].to_s)
                var visibility = to_visibility(node["visibility"].to_s)
                var mprop: nullable MProperty = null
                if node.labels.has("MMethod") then
                        mprop = new MMethod(intro_mclassdef, name, location, visibility)
                        mprop.is_init = node["is_init"].as(Bool)
                else if node.labels.has("MAttribute") then
                        mprop = new MAttribute(intro_mclassdef, name, location, visibility)
                else if node.labels.has("MVirtualTypeProp") then
                        mprop = new MVirtualTypeProp(intro_mclassdef, name, location, visibility)
                else if node.labels.has("MInnerClass") then
                        var inner = to_mclass(model, node.out_nodes("NESTS").first)
                        mprop = new MInnerClass(intro_mclassdef, name, location, visibility, inner)
                end
                if mprop == null then
                        print "not yet implemented to_mproperty for {node.labels.join(",")}"
                        abort
                end
                mentities[node.id.as(Int)] = mprop
                set_doc(node, mprop)
                return mprop
        end

        # Build a new `MPropDef` from a `node`.
        #
        # REQUIRE `node.labels.has("MPropDef")`
        private fun to_mpropdef(model: Model, node: NeoNode): MPropDef do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MPropDef then return m

                assert node.labels.has("MPropDef")
                var mclassdef = to_mclassdef(model, node.in_nodes("DECLARES").first)
                var mproperty = to_mproperty(model, node.out_nodes("DEFINES").first)
                var location = to_location(node["location"].to_s)
                var mpropdef: nullable MPropDef = null
                if node.labels.has("MMethodDef") then
                        mpropdef = new MMethodDef(mclassdef, mproperty.as(MMethod), location)
                        mpropdef.is_abstract = node["is_abstract"].as(Bool)
                        mpropdef.is_intern = node["is_intern"].as(Bool)
                        mpropdef.is_extern = node["is_extern"].as(Bool)
                        mentities[node.id.as(Int)] = mpropdef
                        mpropdef.msignature = to_mtype(model, node.out_nodes("SIGNATURE").first).as(MSignature)
                else if node.labels.has("MAttributeDef") then
                        mpropdef = new MAttributeDef(mclassdef, mproperty.as(MAttribute), location)
                        mentities[node.id.as(Int)] = mpropdef
                        var static_mtype = node.out_nodes("TYPE")
                        if not static_mtype.is_empty then mpropdef.static_mtype = to_mtype(model, static_mtype.first)
                else if node.labels.has("MVirtualTypeDef") then
                        mpropdef = new MVirtualTypeDef(mclassdef, mproperty.as(MVirtualTypeProp), location)
                        mentities[node.id.as(Int)] = mpropdef
                        var bound = node.out_nodes("BOUND")
                        if not bound.is_empty then mpropdef.bound = to_mtype(model, bound.first)
                else if node.labels.has("MInnerClassDef") then
                        var inner = to_mclassdef(model, node.out_nodes("NESTS").first)
                        mpropdef = new MInnerClassDef(mclassdef,
                                        mproperty.as(MInnerClass), location, inner)
                        mentities[node.id.as(Int)] = mpropdef
                end
                if mpropdef == null then
                        print "not yet implemented to_mpropdef for {node.labels.join(",")}"
                        abort
                end
                set_doc(node, mpropdef)
                return mpropdef
        end

        # Build a new `MType` from a `node`.
        #
        # REQUIRE `node.labels.has("MType")`
        private fun to_mtype(model: Model, node: NeoNode): MType do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MType then return m

                assert node.labels.has("MType")
                if node.labels.has("MClassType") then
                        var mclass = to_mclass(model, node.out_nodes("CLASS").first)
                        var args = new Array[MType]
                        for narg in node.out_nodes("ARGUMENT") do
                                args.add to_mtype(model, narg)
                        end
                        var mtype = mclass.get_mtype(args)
                        mentities[node.id.as(Int)] = mtype
                        return mtype
                else if node.labels.has("MParameterType") then
                        var mclass = to_mclass(model, node.out_nodes("CLASS").first)
                        var rank = node["rank"].to_s.to_i
                        var mtype = mclass.mparameters[rank]
                        mentities[node.id.as(Int)] = mtype
                        return  mtype
                else if node.labels.has("MNullableType") then
                        var intype = to_mtype(model, node.out_nodes("TYPE").first)
                        var mtype = intype.as_nullable
                        mentities[node.id.as(Int)] = mtype
                        return mtype
                else if node.labels.has("MVirtualType") then
                        var mproperty = to_mproperty(model, node.out_nodes("PROPERTY").first)
                        assert mproperty isa MVirtualTypeProp
                        var mtype = mproperty.mvirtualtype
                        mentities[node.id.as(Int)] = mtype
                        return mtype
                else if node.labels.has("MSignature") then
                        # Get all param nodes
                        var mparam_nodes = new HashMap[String, MParameter]
                        for pnode in node.out_nodes("PARAMETER") do
                                var mparam = to_mparameter(model, pnode)
                                mparam_nodes[mparam.name] = mparam
                        end
                        # Load params in the good order
                        var mparam_names = node["parameter_names"]
                        var mparameters = new Array[MParameter]
                        if mparam_names isa JsonArray then
                                for mparam_name in mparam_names do
                                        var mparam = mparam_nodes[mparam_name.to_s]
                                        mparameters.add mparam
                                end
                        end
                        var return_mtype: nullable MType = null
                        var ret_nodes = node.out_nodes("RETURNTYPE")
                        if not ret_nodes.is_empty then
                                return_mtype = to_mtype(model, ret_nodes.first)
                        end
                        var mtype = new MSignature(mparameters, return_mtype)
                        mentities[node.id.as(Int)] = mtype
                        return mtype
                else if node.labels.has("MRawType") then
                        var mtype = new MRawType(model)
                        var parts = node["text"]
                        if parts isa JsonArray then
                                for p in parts do
                                        mtype.parts.add(new MTypePart(model, p.to_s, null))
                                end
                                for pnode in node.out_nodes("LINK") do
                                        assert pnode.labels.has("MTypePart")
                                        if not pnode.out_nodes("TARGET").is_empty then
                                                var rank = pnode["rank"]
                                                var target = to_mentity(model, pnode.out_nodes("TARGET").first)
                                                assert rank isa Int
                                                mtype.parts[rank] = mtype.parts[rank].link_to(target)
                                        end
                                end
                        end
                        mentities[node.id.as(Int)] = mtype
                        return mtype
                end
                print "not yet implemented to_mtype for {node.labels.join(",")}"
                abort
        end

        # Build a new `MParameter` from `node`.
        #
        # REQUIRE `node.labels.has("MParameter")`
        private fun to_mparameter(model: Model, node: NeoNode): MParameter do
                var m = mentities.get_or_null(node.id.as(Int))
                if m isa MParameter then return m

                assert node.labels.has("MParameter")
                var name = node["name"].to_s
                var mtype = to_mtype(model, node.out_nodes("TYPE").first)
                var is_vararg = node["is_vararg"].as(Bool)
                var mparameter = new MParameter(name, mtype, is_vararg)
                mentities[node.id.as(Int)] = mparameter
                return mparameter
        end

        # Get a `Location` from its string representation.
        private fun to_location(loc: String): nitc::Location do
                return new nitc::Location.from_string(loc)
        end

        # Get a `MVisibility` from its string representation.
        private fun to_visibility(vis: String): MVisibility do
                if vis == intrude_visibility.to_s then
                        return intrude_visibility
                else if vis == public_visibility.to_s then
                        return public_visibility
                else if vis == protected_visibility.to_s then
                        return protected_visibility
                else if vis == private_visibility.to_s then
                        return private_visibility
                else if vis == package_visibility.to_s then
                        return package_visibility
                else
                        return none_visibility
                end
        end

        # Get a `MKind` from its string representation.
        private fun to_kind(kind: String): MClassKind do
                if kind == abstract_kind.to_s then
                        return abstract_kind
                else if kind == concrete_kind.to_s then
                        return concrete_kind
                else if kind == interface_kind.to_s then
                        return interface_kind
                else if kind == enum_kind.to_s then
                        return enum_kind
                else if kind == extern_kind.to_s then
                        return extern_kind
                else
                        return raw_kind(kind)
                end
        end

        # Extract the `MDoc` from `node` and link it to `mentity`.
        private fun set_doc(node: NeoNode, mentity: MEntity) do
                if node.has_key("mdoc") then
                        var lines = new Array[String]
                        for e in node["mdoc"].as(JsonArray) do
                                lines.add e.to_s#.replace("\n", "\\n")
                        end
                        var location = to_location(node["mdoc_location"].to_s)
                        var mdoc = new MDoc(location)
                        mdoc.content.add_all(lines)
                        mdoc.original_mentity = mentity
                        mentity.mdoc = mdoc
                end
        end
end

redef class MPackage
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                var root = root
                if root != null then
                        node.out_edges.add(new NeoEdge(node, "ROOT", root.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MGroup
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                var parent = parent
                node.out_edges.add(new NeoEdge(node, "PROJECT", mpackage.to_node(nodes, model_name)))
                if parent != null then
                        node.out_edges.add(new NeoEdge(node, "PARENT", parent.to_node(nodes, model_name)))
                end
                for mmodule in mmodules do
                        node.out_edges.add(new NeoEdge(node, "DECLARES", mmodule.to_node(nodes, model_name)))
                end
                for subgroup in in_nesting.direct_smallers do
                        node.in_edges.add(new NeoEdge(node, "NESTS", subgroup.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MModule
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                for parent in in_importation.direct_greaters do
                        node.out_edges.add(new NeoEdge(node, "IMPORTS", parent.to_node(nodes, model_name)))
                end
                for mclass in intro_mclasses do
                        node.out_edges.add(new NeoEdge(node, "INTRODUCES", mclass.to_node(nodes, model_name)))
                end
                for mclassdef in mclassdefs do
                        node.out_edges.add(new NeoEdge(node, "DEFINES", mclassdef.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MClass
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node["kind"] = kind.to_s
                node["visibility"] = visibility.to_s
                if not mparameters.is_empty then
                        var parameter_names = new Array[String]
                        for p in mparameters do parameter_names.add(p.name)
                        node["parameter_names"] = new JsonArray.from(parameter_names)
                end
                node.out_edges.add(new NeoEdge(node, "CLASSTYPE", mclass_type.to_node(nodes, model_name)))
                return node
        end
end

redef class MClassDef
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.out_edges.add(new NeoEdge(node, "BOUNDTYPE", bound_mtype.to_node(nodes, model_name)))
                node.out_edges.add(new NeoEdge(node, "MCLASS", mclass.to_node(nodes, model_name)))
                for mproperty in intro_mproperties do
                        node.out_edges.add(new NeoEdge(node, "INTRODUCES", mproperty.to_node(nodes, model_name)))
                end
                for mpropdef in mpropdefs do
                        node.out_edges.add(new NeoEdge(node, "DECLARES", mpropdef.to_node(nodes, model_name)))
                end
                for sup in supertypes do
                        node.out_edges.add(new NeoEdge(node, "INHERITS", sup.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MProperty
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = make_node(nodes, model_name)
                node.labels.add "MProperty"
                node["visibility"] = visibility.to_s
                node.out_edges.add(new NeoEdge(node, "INTRO_CLASSDEF", intro_mclassdef.to_node(nodes, model_name)))
                node.labels.add self.class_name
                return node
        end
end

redef class MMethod
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node["is_init"] = is_init
                return node
        end
end

redef class MInnerClass
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.out_edges.add(new NeoEdge(node, "NESTS", inner.to_node(nodes, model_name)))
                return node
        end
end

redef class MPropDef
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = make_node(nodes, model_name)
                node.labels.add "MPropDef"
                node.out_edges.add(new NeoEdge(node, "DEFINES", mproperty.to_node(nodes, model_name)))
                node.labels.add self.class_name
                return node
        end
end

redef class MMethodDef
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node["is_abstract"] = is_abstract
                node["is_intern"] = is_intern
                node["is_extern"] = is_extern
                var msignature = msignature
                if msignature != null then
                        node.out_edges.add(new NeoEdge(node, "SIGNATURE", msignature.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MAttributeDef
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                var static_mtype = static_mtype
                if static_mtype != null then
                        node.out_edges.add(new NeoEdge(node, "TYPE", static_mtype.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MVirtualTypeDef
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                var bound = bound
                if bound != null then
                        node.out_edges.add(new NeoEdge(node, "BOUND", bound.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MInnerClassDef
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.out_edges.add(new NeoEdge(node, "NESTS", inner.to_node(nodes, model_name)))
                return node
        end
end

redef class MTypePart
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                if self.target != null then
                        var target_node = self.target.as(not null).to_node(nodes, model_name)
                        node.out_edges.add(new NeoEdge(node, "TARGET", target_node))
                end
                return node
        end
end

redef class MParameter
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node["name"] = self.name
                node["is_vararg"] = self.is_vararg
                node.out_edges.add(new NeoEdge(node, "TYPE", self.mtype.to_node(nodes, model_name)))
                return node
        end
end

redef class MClassType
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.labels.add "MClassType"
                node.out_edges.add(new NeoEdge(node, "CLASS", mclass.to_node(nodes, model_name)))
                for arg in arguments do
                        node.out_edges.add(new NeoEdge(node, "ARGUMENT", arg.to_node(nodes, model_name)))
                end
                return node
        end
end


redef class MGenericType
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.labels.add "MGenericType"
                return node
        end
end

redef class MVirtualType
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.labels.add "MVirtualType"
                node.out_edges.add(new NeoEdge(node, "PROPERTY", mproperty.to_node(nodes, model_name)))
                return node
        end
end

redef class MParameterType
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.labels.add "MParameterType"
                node["rank"] = rank
                node.out_edges.add(new NeoEdge(node, "CLASS", mclass.to_node(nodes, model_name)))
                return node
        end
end

redef class MNullableType
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.labels.add "MNullableType"
                node.out_edges.add(new NeoEdge(node, "TYPE", mtype.to_node(nodes, model_name)))
                return node
        end
end

redef class MSignature
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.labels.add "MSignature"
                var names = new JsonArray
                var rank = 0
                for mparameter in mparameters do
                        names.add mparameter.name
                        var pnode = mparameter.to_node(nodes, model_name)
                        pnode["rank"] = rank
                        node.out_edges.add(new NeoEdge(node, "PARAMETER", pnode))
                        rank += 1
                end
                if not names.is_empty then node["parameter_names"] = names
                var return_mtype = return_mtype
                if return_mtype != null then
                        node.out_edges.add(new NeoEdge(node, "RETURNTYPE", return_mtype.to_node(nodes, model_name)))
                end
                return node
        end
end

redef class MRawType
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = super
                node.labels.add "MRawType"
                var text = new JsonArray
                var rank = 0
                for part in self.parts do
                        text.add part.text
                        if part.target != null then
                                var pnode = part.to_node(nodes, model_name)
                                pnode["rank"] = rank
                                node.out_edges.add(new NeoEdge(node, "LINK", pnode))
                        end
                        rank += 1
                end
                if not text.is_empty then node["text"] = text
                return node
        end
end

redef class MType
        redef fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = make_node(nodes, model_name)
                node.labels.add "MType"
                return node
        end
end

redef class MEntity
        # Build a `NeoNode` representing `self`.
        private fun to_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                if nodes.has_key(self) then return nodes[self]
                var node = make_node(nodes, model_name)
                node.labels.add self.class_name
                return node
        end

        # Make a new `NeoNode` based on `mentity`.
        private fun make_node(nodes: HashMap[MEntity, NeoNode], model_name: nullable String): NeoNode do
                var node = new NeoNode
                nodes[self] = node
                node.labels.add "MEntity"
                if model_name != null then node.labels.add model_name
                node["name"] = self.name
                if not self isa MSignature then
                        #FIXME: MSignature is a MEntity, but has no model :/
                        node["location"] = self.location.to_s
                end
                var mdoc = self.mdoc
                if mdoc != null then
                        node["mdoc"] = new JsonArray.from(mdoc.content)
                        node["mdoc_location"] = mdoc.location.to_s
                end
                return node
        end
end