Started working on reduction system

experiments/reduction-scanner-1.mjs

@@ -0,0 +1,14 @@
+import { Reduction_Scanner, Reduction_Settings } from  '@efforting.tech/rule-processing/reduction-scanner';
+//import { Sub_Sequence_Rule } from  '@efforting.tech/rule-processing/rules';
+
+
+const rss = Reduction_Settings.load();
+
+const rs = new Reduction_Scanner(rss);
+
+rss.rules.push();
+
+
+const arr = [10, '+', 20, '*', 30];
+console.log(rs.perform_reduction(arr));
+console.log(arr);

planning/schema-vs-data.md

@@ -0,0 +1,6 @@
+# Rationale
+
+Schema is a quite low level feature that is used all over the place while the data package is more of a high level construct.
+It makes sense to move schemas into their own package.
+
+Schema uses a lot of informal conditions and will not depend on rule-processing/conditions but one could use those in higher levels if wanted.

source/data/field-configuration-factories.mjs

@@ -11,6 +11,11 @@ export function factory(factory_function, description) {
 	return new Field_Configuration(null, null, factory_function, description);
 }
 
+export function instance(type, description) {
+
+	return new Field_Configuration((i) => i instanceof type, null, () => new type(), description);
+}
+
 export function typed_value(coercion_function, default_value, description) {
 	return new Field_Configuration(null, coercion_function, () => default_value, description);
 }
@@ -33,6 +38,14 @@ export function typed_required(coercion_function, description) {
 	return new Field_Configuration((value) => value !== undefined, coercion_function, null, description);
 }
 
+export function schema(field_schema, default_value, description) {
+	return new Field_Configuration(null, (v) => field_schema.load(v), () => field_schema.load(default_value), description);
+}
+
+export function symbol(symbol_set, default_value, description) {
+	return new Field_Configuration(null, (v) => symbol_set.load(v), () => symbol_set.load(default_value), description);
+}
+
 export function symbol_set(description_to_name_mapping, description=null) {
 
 	const symbols_by_name = Object.fromEntries(Object.keys(description_to_name_mapping).map(k => [k, Symbol(k)]));

source/rule-processing/contracts.mjs

@@ -0,0 +1,74 @@
+import { FPR_State } from './state.mjs';
+
+export class Abstract_Reduction_Contract {
+	on_create_scanner(scanner) {}
+	on_start_transform(scanner, sequence) {}
+	on_end_transform(scanner, sequence) {}
+	on_reduction_attempted(scanner, sequence) {}
+	on_reduction_made(scanner, sequence) {}
+
+	check_if_done(scanner, sequence) {
+		return false;
+	}
+
+	assert_readiness(scanner, sequence) {}
+}
+
+export class Reduction_Contract extends Abstract_Reduction_Contract {
+	check_if_done(scanner, sequence) {
+		return scanner.last_reduction_status === false;
+	}
+}
+
+export class FPR_Contract extends Reduction_Contract {
+	constructor(end_condition=null) {
+		super();
+		Object.assign(this, { end_condition });
+	}
+
+	check_if_done(scanner, sequence) {
+		if (this.end_condition) {
+			return this.end_condition(scanner, sequence);
+		} else {
+			return super.check_if_done(scanner, sequence);
+		}
+	}
+
+	on_create_scanner(scanner) {
+		Object.assign(scanner, {
+			cycle_detected: false,
+			state_manager: new FPR_State(),
+		});
+	}
+
+	on_start_transform(scanner, sequence) {
+		super.on_start_transform(scanner, sequence);
+		const state_manager = scanner.state_manager;
+		state_manager.clear_journal();
+		const state = state_manager.gather_state(sequence);	//Log initial state
+		state_manager.log_state(state);
+
+		scanner.cycle_detected = false;
+	}
+
+	on_reduction_made(scanner, sequence) {
+		const state_manager = scanner.state_manager;
+		const state = state_manager.gather_state(sequence);
+
+		const pre_count = state_manager.length;
+		state_manager.log_state(state);
+		const post_count = state_manager.length;
+
+		if (pre_count === post_count) {
+			scanner.cycle_detected = true;
+		}
+
+	}
+
+	assert_readiness(scanner, sequence) {
+		if (scanner.cycle_detected) {
+			throw new Error('Cycle detected');
+		}
+	}
+
+}

source/rule-processing/reduction-scanner.mjs

@@ -0,0 +1,103 @@
+import { Reduction_Contract, FPR_Contract } from './contracts.mjs';
+
+
+import * as CF from '@efforting.tech/data/field-configuration-factories';
+
+
+export const Reduction_Order = new CF.symbol_set({
+	RULE_MAJOR: 'For each rule, scan the full sequence',
+	POSITION_MAJOR: 'For each item in the sequence, try all rules',
+}, 'Reduction ordering');
+
+
+export const Reduction_Settings = new CF.Schema({
+	reduction_order: CF.symbol(Reduction_Order, 'RULE_MAJOR'),
+	reduction_contract: CF.instance(Reduction_Contract, 'The reduction contract defines the implementation of the reduction scanner'),
+	rules: CF.factory(() => []),
+}, 'Reduction settings');
+
+//TODO: Consider whether we can implement some hierarchical sub schema, like classes - we could of course reuse things by defining and object and spread it in here
+export const FP_Reduction_Settings = new CF.Schema({
+	reduction_order: CF.symbol(Reduction_Order, 'RULE_MAJOR'),
+	reduction_contract: CF.instance(FPR_Contract, 'The reduction contract defines the implementation of the reduction scanner'),
+	rules: CF.factory(() => []),
+}, 'Fixed point reduction settings');
+
+
+
+export class Reduction_Scanner {
+
+	static settings_schema = Reduction_Settings;
+
+	constructor(settings, use_lifecycle_cb=true) {
+		settings = this.constructor.settings_schema.load(settings);
+		Object.assign(this, { settings });
+		this.clear_transform_state();
+		if (use_lifecycle_cb) {
+			settings.reduction_contract.on_create_scanner(this);
+		}
+	}
+
+	perform_reduction(sequence) {
+		const { settings } = this;
+		switch (settings.reduction_order) {
+
+			case Reduction_Order.symbols.RULE_MAJOR:
+				for (const rule of settings.rules) {
+					for (let start_index=0; start_index < sequence.length; start_index++) {
+						const match = rule.match(sequence, start_index);
+						if (match) {
+							rule.action(this, sequence, match);
+							return true;
+						}
+					}
+				}
+				return false;
+
+			case Reduction_Order.symbols.POSITION_MAJOR:
+				for (let start_index=0; start_index < sequence.length; start_index++) {
+					for (const rule of settings.rules) {
+						const match = rule.match(sequence, start_index);
+						if (match) {
+							rule.action(this, sequence, match);
+							return true;
+						}
+					}
+				}
+				return false;
+			default:
+				throw new Error(`Unknown reduction order: ${this.reduction_order}`);	//TODO: Force invalid configuration  error
+
+		}
+
+	}
+
+	clear_transform_state() {
+		this.last_reduction_status = null;
+		this.reductions_attempted = 0;
+		this.reductions_made = 0;
+	}
+
+	transform(sequence) {
+		const { settings } = this;
+		const reduction_contract = settings.reduction_contract;
+		this.clear_transform_state();
+		reduction_contract.on_start_transform(this, sequence);
+
+		while (!reduction_contract.check_if_done(this, sequence)) {
+			reduction_contract.assert_readiness(this, sequence);
+			this.last_reduction_status = this.perform_reduction(sequence);
+			this.reductions_attempted++;
+			if (this.last_reduction_status) {
+				this.reductions_made++;
+				reduction_contract.on_reduction_made(this, sequence);
+			}
+			reduction_contract.on_reduction_attempted(this, sequence);
+		}
+
+		reduction_contract.on_end_transform(this, sequence);
+		return sequence;
+	}
+
+}
+

source/rule-processing/resolvers.mjs

@@ -2,7 +2,7 @@ import { Item_Unresolvable } from '@efforting.tech/errors';
 
 export class Abstract_Resolver {
 	resolve(item, extra_info={}) {
-		const result = this.resolve_handler(item);
+		const result = this.resolve_handler(item, extra_info);
 		if (!result?.handler) {
 			throw new Item_Unresolvable({ resolver: this, item });
 		}
@@ -17,10 +17,10 @@ export class Chained_Resolver extends Abstract_Resolver {
 		Object.assign(this, { chain_links });
 	}
 
-	resolve_handler(item) {
+	resolve_handler(item, extra_info={}) {
 		const { chain_links } = this;
 		for (const link of chain_links) {
-			const result = link.resolve_handler(item);
+			const result = link.resolve_handler(item, extra_info);
 			if (result?.handler) {
 				return result;
 			}
@@ -35,10 +35,10 @@ export class Predicate_Resolver extends Abstract_Resolver {
 		Object.assign(this, { rules });
 	}
 
-	resolve_handler(item) {
+	resolve_handler(item, extra_info={}) {
 		const { rules } = this;
 		for (const [predicate, handler] of rules) {
-			const predicate_result = predicate(item);
+			const predicate_result = predicate(item, extra_info);
 			// NOTE: to return a falsy predicate_result as a positive hit you must wrap it in something
 			if (predicate_result) {
 				return { handler, predicate_result };
@@ -52,7 +52,7 @@ export class RegExp_Resolver extends Predicate_Resolver {
 		// NOTE: Rules should be iterable as [predicate, handler] pairs
 		super();
 		Object.assign(this, {
-			rules: rules.map(([pattern, handler]) => [(str) => str.match(pattern), handler])
+			rules: rules.map(([pattern, handler]) => [(str, extra_info) => str.match(pattern), handler])
 		});
 	}
 
@@ -65,7 +65,7 @@ export class Mapping_Resolver extends Abstract_Resolver {
 		Object.assign(this, { rules, key_function });
 	}
 
-	resolve_handler(item) {
+	resolve_handler(item, extra_info={}) {
 		const { key_function, rules } = this;
 		const key = key_function ? key_function(item) : item;
 		return rules.get(key);
@@ -73,3 +73,26 @@ export class Mapping_Resolver extends Abstract_Resolver {
 
 }
 
+
+export class Sequential_Resolver extends Abstract_Resolver {
+	constructor(rules=[]) {
+		// NOTE: Rules should be iterable as [Abstract_Sequential_Condition, handler] pairs
+		super();
+		Object.assign(this, { rules });
+	}
+
+
+	resolve_handler(item, extra_info={}) {
+		const { rules } = this;
+
+		for (const [sequential_condition, handler] of rules) {
+			const sequential_condition_result = sequential_condition.match(item, extra_info);
+			// NOTE: to return a falsy predicate_result as a positive hit you must wrap it in something
+			if (sequential_condition_result) {
+				return { handler, sequential_condition_result };
+			}
+		}
+	}
+
+}
+

source/rule-processing/state-serializer.mjs

@@ -0,0 +1,134 @@
+import * as CF from '@efforting.tech/data/field-configuration-factories';
+
+
+export const Object_Serialization_Strategy = new CF.Schema({
+	identity: CF.boolean(true, 'Serialize based on identity'),
+	type: CF.boolean(true, 'Serialize based on constructor'),
+	symbols: CF.boolean(true, 'Include symbol-keyed properties'),
+	keys: CF.boolean(true, 'Include property keys'),
+	values: CF.boolean(true, 'Include property values'),
+}, 'Object serialization strategy');
+
+
+
+export const State_Serialization_Strategy = new CF.Schema({
+	//BUG - there is currently no way (I think) to put defaults into a sub schema - this should be fixed
+	array: CF.schema(Object_Serialization_Strategy, {
+		identity: false,
+		type: true,
+		symbols: false,
+		keys: false,
+		values: true,
+	}, 'State serialization strategy for Array'),
+	object: CF.schema(Object_Serialization_Strategy, {
+		identity: true,
+		type: true,
+		symbols: true,
+		keys: true,
+		values: true,
+	}, 'State serialization strategy for Object'),
+}, 'State serialization strategy');
+
+
+
+
+export class State_Serializer {
+
+	static settings_schema = State_Serialization_Strategy;
+
+	constructor(symbols=new Map(), strategy) {
+		strategy = this.constructor.settings_schema.load(strategy);
+		Object.assign(this, { symbols, strategy });
+	}
+
+	serialize_symbols(...symbols) {
+		const result = [];
+		for (const symbol of symbols) {
+			const existing = this.symbols.get(symbol);
+			if (existing !== undefined) {
+				result.push(existing);
+			} else {
+				const new_symbol_index = this.symbols.size;
+				this.symbols.set(symbol, new_symbol_index);
+				result.push(new_symbol_index);
+			}
+		}
+		return result;
+	}
+
+
+	serialize_object(object) {
+		const state_strategy = this.strategy;
+		const result = [];
+
+		switch (typeof(object)) {
+			case 'object':
+				if (object === null) {
+					return ['N'];
+				}
+
+
+				const is_array = object.constructor === Array;
+				const strategy = is_array ? state_strategy.array : state_strategy.object;
+				result.push(is_array ? 'a' : 'o');
+
+
+				if (strategy.identity) {
+					const existing_instance = this.symbols.get(object);
+					if (existing_instance !== undefined) {
+						return existing_instance;
+					}
+
+					const [instance] = this.serialize_symbols(object);
+					result.push(instance);
+				}
+
+				if (strategy.type) {
+					const [type] = this.serialize_symbols(object.constructor);
+					result.push(type);
+				}
+
+				if (strategy.symbols) {
+					const symbols = this.serialize_symbols(...Object.getOwnPropertySymbols(object));
+					result.push(symbols);
+				}
+
+				if (strategy.keys) {
+					const keys = Object.keys(object).map(item => this.serialize_object(item));
+					result.push(keys);
+				}
+
+				if (strategy.values) {
+					const values = Object.values(object).map(item => this.serialize_object(item));
+					result.push(values);
+				}
+
+				return result;
+
+			case 'string':
+				return ['s', ...this.serialize_symbols(typeof(object)), object];
+
+			case 'number':
+				return ['n', ...this.serialize_symbols(typeof(object)), object];
+
+			case 'boolean':
+				return [object ? 'T' : 'F'];
+
+			case 'function':
+				const [reference_type, reference_id] = this.serialize_symbols(typeof(object), object);
+				return ['f', reference_type, reference_id];
+
+			case 'symbol':
+				return ['S', ...this.serialize_symbols(object)];
+
+
+			case 'undefined':
+				return ['u'];
+
+
+			default:
+				throw new Error(typeof(object));	//TODO - proper error
+		}
+	}
+};
+

source/rule-processing/state.mjs

@@ -0,0 +1,47 @@
+import { State_Serializer } from './state-serializer.mjs';
+import { createHash } from 'node:crypto';
+
+
+export class Abstract_State {
+	constructor(seen = new Set()) {
+		Object.assign(this, { seen });
+	}
+
+	gather_state(sequence) {
+		throw new Error(`gather_state(sequence) not implemented for ${this.constructor.name}`);
+	}
+
+	seen_state(state) {
+		return this.seen.has(state);
+	}
+
+	log_state(state) {
+		this.seen.add(state);
+	}
+
+	discard_state(state) {
+		this.seen.delete(state);
+	}
+
+	get length() {
+		return this.seen.size;
+	}
+
+	clear_journal() {
+		this.seen.clear();
+	}
+}
+
+export class FPR_State extends Abstract_State {
+	constructor(seen = new Set(), serializer = new State_Serializer()) {
+		super(seen);
+		Object.assign(this, { serializer });
+	}
+
+	gather_state(sequence) {
+		const str = JSON.stringify(this.serializer.serialize_object(sequence));
+		const hash = createHash('sha1').update(str).digest('hex');
+		return `${hash.slice(0, 8)}-${str}`;
+	}
+
+}