amber/lang/base/kernel-language.js

//jshint eqnull:true

define(function () {
    "use strict";

    function inherits (child, parent) {
        child.prototype = Object.create(parent.prototype, {
            constructor: {
                value: child,
                enumerable: false, configurable: true, writable: true
            }
        });
        return child;
    }

    function defineMethod (klass, name, method) {
        Object.defineProperty(klass.prototype, name, {
            value: method,
            enumerable: false, configurable: true, writable: true
        });
    }

    TraitsBrik.deps = ["event", "behaviors", "methods", "composition", "root"];
    function TraitsBrik (brikz, st) {
        var specialConstructors = brikz.commonSpecialConstructors;
        var SmalltalkObject = brikz.root.Object;
        var setupMethods = brikz.methods.setupMethods;
        var traitMethodChanged = brikz.composition.traitMethodChanged;
        var buildTraitOrClass = brikz.behaviors.buildTraitOrClass;
        var emit = brikz.commonEmit;
        var declareEvent = brikz.event.declareEvent;

        function SmalltalkTrait () {
        }

        specialConstructors.Trait = inherits(SmalltalkTrait, SmalltalkObject);

        SmalltalkTrait.prototype.trait = true;

        defineMethod(SmalltalkTrait, "toString", function () {
            return 'Smalltalk Trait ' + this.name;
        });
        declareEvent("traitAdded");
        defineMethod(SmalltalkTrait, "added", function () {
            emit.traitAdded(this);
        });
        declareEvent("traitRemoved");
        defineMethod(SmalltalkTrait, "removed", function () {
            emit.traitRemoved(this);
        });
        declareEvent("traitMethodAdded");
        defineMethod(SmalltalkTrait, "methodAdded", function (method) {
            var self = this;
            this.traitUsers.forEach(function (each) {
                traitMethodChanged(method.selector, method, self, each);
            });
            emit.traitMethodAdded(method, this);
        });
        declareEvent("traitMethodRemoved");
        defineMethod(SmalltalkTrait, "methodRemoved", function (method) {
            var self = this;
            this.traitUsers.forEach(function (each) {
                traitMethodChanged(method.selector, null, self, each);
            });
            emit.traitMethodRemoved(method, this);
        });

        function traitBuilder (traitName) {
            return {
                name: traitName,
                make: function () {
                    var that = new SmalltalkTrait();
                    that.name = traitName;
                    that.traitUsers = [];
                    setupMethods(that);
                    return that;
                },
                updateExisting: function (trait) {
                }
            };
        }

        st.addTrait = function (className, category) {
            return buildTraitOrClass(category, traitBuilder(className));
        };
    }

    MethodCompositionBrik.deps = ["methods", "arraySet"];
    function MethodCompositionBrik (brikz, st) {
        var updateMethod = brikz.methods.updateMethod;
        var addElement = brikz.arraySet.addElement;
        var removeElement = brikz.arraySet.removeElement;

        function aliased (selector, method) {
            var result = st.method(method, method.instantiateFn);
            if (method.selector !== selector) {
                result.selector = selector;
                result.source = '"Aliased as ' + selector + '"\n' + method.source;
            }
            result.owner = method.owner;
            return result;
        }

        function deleteKeysFrom (keys, obj) {
            keys.forEach(function (each) {
                delete obj[each];
            });
        }

        function fillTraitTransformation (traitTransformation, obj) {
            // assert(Object.getOwnProperties(obj).length === 0)
            var traitMethods = traitTransformation.trait.methods;
            Object.keys(traitMethods).forEach(function (selector) {
                obj[selector] = aliased(selector, traitMethods[selector]);
            });
            var traitAliases = traitTransformation.aliases;
            if (traitAliases) {
                Object.keys(traitAliases).forEach(function (aliasSelector) {
                    var aliasedMethod = traitMethods[traitAliases[aliasSelector]];
                    if (aliasedMethod) obj[aliasSelector] = aliased(aliasSelector, aliasedMethod);
                    // else delete obj[aliasSelector]; // semantically correct; optimized away
                });
            }
            var traitExclusions = traitTransformation.exclusions;
            if (traitExclusions) {
                deleteKeysFrom(traitExclusions, obj);
            }
            return obj;
        }

        function buildCompositionChain (traitComposition) {
            return traitComposition.reduce(function (soFar, each) {
                return fillTraitTransformation(each, Object.create(soFar));
            }, null);
        }

        st.setTraitComposition = function (traitComposition, traitOrBehavior) {
            var oldLocalMethods = traitOrBehavior.localMethods,
                newLocalMethods = Object.create(buildCompositionChain(traitComposition));
            Object.keys(oldLocalMethods).forEach(function (selector) {
                newLocalMethods[selector] = oldLocalMethods[selector];
            });
            var selector;
            traitOrBehavior.localMethods = newLocalMethods;
            for (selector in newLocalMethods) {
                updateMethod(selector, traitOrBehavior);
            }
            for (selector in oldLocalMethods) {
                updateMethod(selector, traitOrBehavior);
            }
            (traitOrBehavior.traitComposition || []).forEach(function (each) {
                removeElement(each.trait.traitUsers, traitOrBehavior);
            });
            traitOrBehavior.traitComposition = traitComposition && traitComposition.length ? traitComposition : null;
            (traitOrBehavior.traitComposition || []).forEach(function (each) {
                addElement(each.trait.traitUsers, traitOrBehavior);
            });
        };

        function aliasesOfSelector (selector, traitAliases) {
            if (!traitAliases) return [selector];
            var result = Object.keys(traitAliases).filter(function (aliasSelector) {
                return traitAliases[aliasSelector] === selector
            });
            if (!traitAliases[selector]) result.push(selector);
            return result;
        }

        function applyTraitMethodAddition (selector, method, traitTransformation, obj) {
            var changes = aliasesOfSelector(selector, traitTransformation.aliases);
            changes.forEach(function (aliasSelector) {
                obj[aliasSelector] = aliased(aliasSelector, method);
            });
            var traitExclusions = traitTransformation.exclusions;
            if (traitExclusions) {
                deleteKeysFrom(traitExclusions, obj);
            }
            return changes;
        }

        function applyTraitMethodDeletion (selector, traitTransformation, obj) {
            var changes = aliasesOfSelector(selector, traitTransformation.aliases);
            deleteKeysFrom(changes, obj);
            return changes;
        }

        function traitMethodChanged (selector, method, trait, traitOrBehavior) {
            var traitComposition = traitOrBehavior.traitComposition,
                chain = traitOrBehavior.localMethods,
                changes = [];
            for (var i = traitComposition.length - 1; i >= 0; --i) {
                chain = Object.getPrototypeOf(chain);
                var traitTransformation = traitComposition[i];
                if (traitTransformation.trait !== trait) continue;
                changes.push.apply(changes, method ?
                    applyTraitMethodAddition(selector, method, traitTransformation, chain) :
                    applyTraitMethodDeletion(selector, traitTransformation, chain));
            }
            // assert(chain === null);
            changes.forEach(function (each) {
                updateMethod(each, traitOrBehavior);
            });
        }

        this.traitMethodChanged = traitMethodChanged;
    }

    ClassesBrik.deps = ["root", "event", "behaviors", "methods", "arraySet", "nil"];
    function ClassesBrik (brikz, st) {
        var SmalltalkRoot = brikz.root.Root;
        var specialConstructors = brikz.commonSpecialConstructors;
        var globals = brikz.commonGlobals;
        var SmalltalkObject = brikz.root.Object;
        var buildTraitOrClass = brikz.behaviors.buildTraitOrClass;
        var setupMethods = brikz.methods.setupMethods;
        var removeTraitOrClass = brikz.behaviors.removeTraitOrClass;
        var addElement = brikz.arraySet.addElement;
        var removeElement = brikz.arraySet.removeElement;
        var emit = brikz.commonEmit;
        var declareEvent = brikz.event.declareEvent;
        var nilAsReceiver = brikz.nil.nilAsReceiver;

        function SmalltalkBehavior () {
        }

        function SmalltalkClass () {
        }

        function SmalltalkMetaclass () {
        }

        specialConstructors.Behavior = inherits(SmalltalkBehavior, SmalltalkObject);
        specialConstructors.Class = inherits(SmalltalkClass, SmalltalkBehavior);
        specialConstructors.Metaclass = inherits(SmalltalkMetaclass, SmalltalkBehavior);

        // Fake root class of the system.
        // Effective superclass of all classes created with `nil subclass: ...`.
        var nilAsClass = this.nilAsClass = {
            fn: SmalltalkRoot,
            subclasses: [],
            a$cls: {fn: SmalltalkClass}
        };

        SmalltalkMetaclass.prototype.meta = true;

        defineMethod(SmalltalkClass, "toString", function () {
            return 'Smalltalk ' + this.name;
        });
        defineMethod(SmalltalkMetaclass, "toString", function () {
            return 'Smalltalk Metaclass ' + this.instanceClass.name;
        });
        declareEvent("classAdded");
        defineMethod(SmalltalkClass, "added", function () {
            addSubclass(this);
            emit.classAdded(this);
        });
        declareEvent("classRemoved");
        defineMethod(SmalltalkClass, "removed", function () {
            emit.classRemoved(this);
            removeSubclass(this);
        });
        declareEvent("behaviorMethodAdded");
        defineMethod(SmalltalkBehavior, "methodAdded", function (method) {
            emit.behaviorMethodAdded(method, this);
        });
        declareEvent("behaviorMethodRemove");
        defineMethod(SmalltalkBehavior, "methodRemoved", function (method) {
            emit.behaviorMethodRemoved(method, this);
        });

        // TODO remove, ["@foo"] backward compatibility
        function installIvarCompat (klass) {
            var ivars = klass.slots;
            ivars.forEach(function (ivar) {
                Object.defineProperty(klass.fn.prototype, "@" + ivar, {
                    get: function () {
                        return this[ivar];
                    },
                    set: function (value) {
                        return this[ivar] = value;
                    },
                    enumerable: false,
                    configurable: true
                });
            });
        }

        this.installIvarCompat = installIvarCompat;

        function setSlots (klass, slots) {
            slots.forEach(function (name) {
                if (!name.match(/^[a-zA-Z][a-zA-Z0-9]*$/))
                    throw new Error("Wrong identifier name: " + name);
            });

            klass.slots = slots;
            installIvarCompat(klass);
        }

        st.setSlots = setSlots;

        // TODO remove, .iVarNames backward compatibility
        Object.defineProperty(SmalltalkBehavior.prototype, "iVarNames", {
            enumerable: true,
            configurable: true,
            get: function () {
                return this.slots;
            },
            set: function (instanceVariableNames) {
                setSlots(this, instanceVariableNames);
            }
        });

        this.bootstrapHierarchy = function () {
            nilAsClass.a$cls = globals.Class;
            nilAsClass.subclasses.forEach(function (each) {
                each.a$cls.superclass = globals.Class;
                addSubclass(each.a$cls);
            });
        };

        /* Smalltalk class creation. A class is an instance of an automatically
         created metaclass object. Newly created classes (not their metaclass)
         should be added to the system, see smalltalk.addClass().
         Superclass linking is *not* handled here, see api.initialize()  */

        function classBuilder (className, superclass, fn) {
            var logicalSuperclass = superclass;
            if (superclass == null || superclass.a$nil) {
                superclass = nilAsClass;
                logicalSuperclass = null;
            }

            function klass () {
                var that = metaclass().instanceClass;

                that.superclass = logicalSuperclass;
                that.fn = fn || inherits(function () {
                    }, superclass.fn);
                that.slots = [];

                that.name = className;
                that.subclasses = [];

                setupMethods(that);
                return that;
            }

            function metaclass () {
                var that = new SmalltalkMetaclass();

                that.superclass = superclass.a$cls;
                that.fn = inherits(function () {
                }, that.superclass.fn);
                that.slots = [];

                that.instanceClass = new that.fn();

                wireKlass(that);
                setupMethods(that);
                return that;
            }

            return {
                name: className,
                make: klass,
                updateExisting: function (klass) {
                    if (klass.superclass != logicalSuperclass || fn && fn !== klass.fn)
                        throw new Error("Incompatible change of class: " + klass.name);
                }
            };
        }

        function wireKlass (klass) {
            Object.defineProperty(klass.fn.prototype, "a$cls", {
                value: klass,
                enumerable: false, configurable: true, writable: true
            });
        }

        this.wireKlass = wireKlass;

        /**
         * This function is used all over the compiled amber code.
         * It takes any value (JavaScript or Smalltalk)
         * and returns a proper Amber Smalltalk receiver.
         *
         * null or undefined -> nilAsReceiver,
         * object having Smalltalk signature -> unchanged,
         * otherwise wrapped foreign (JS) object
         */
        this.asReceiver = function (o) {
            if (o == null) return nilAsReceiver;
            else if (o.a$cls != null) return o;
            else return st.wrapJavaScript(o);
        };

        /* Add a class to the system, creating a new one if needed.
         A Package is lazily created if one with given name does not exist. */

        st.addClass = function (className, superclass, category) {
            // TODO remove, backward compatibility
            if (arguments[3]) {
                var added = st.addClass(className, superclass, arguments[3]);
                setSlots(added, category);
                return added;
            }

            // While subclassing nil is allowed, it might be an error, so
            // warn about it.
            if (typeof superclass === 'undefined' || superclass && superclass.a$nil) {
                console.warn('Compiling ' + className + ' as a subclass of `nil`. A dependency might be missing.');
            }
            return buildTraitOrClass(category, classBuilder(className, superclass, specialConstructors[className]));
        };

        st.removeClass = removeTraitOrClass;

        function addSubclass (klass) {
            addElement((klass.superclass || nilAsClass).subclasses, klass);
        }

        function removeSubclass (klass) {
            removeElement((klass.superclass || nilAsClass).subclasses, klass);
        }

        function metaSubclasses (metaclass) {
            return metaclass.instanceClass.subclasses
                .filter(function (each) {
                    return !each.meta;
                })
                .map(function (each) {
                    return each.a$cls;
                });
        }

        st.metaSubclasses = metaSubclasses;

        st.traverseClassTree = function (klass, fn) {
            var queue = [klass], sentinel = {};
            for (var i = 0; i < queue.length; ++i) {
                var item = queue[i];
                if (fn(item, sentinel) === sentinel) continue;
                var subclasses = item.meta ? metaSubclasses(item) : item.subclasses;
                queue.push.apply(queue, subclasses);
            }
        };
    }

    /* Making smalltalk that can load */

    function configureWithHierarchy (brikz) {
        brikz.traits = TraitsBrik;
        brikz.composition = MethodCompositionBrik;
        brikz.classes = ClassesBrik;

        brikz();
    }

    return configureWithHierarchy;
});