state machine examples

Author: stackdump

.gitignore

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+.DS_Store
+python/.DS_Store
+python/__pycache__/
+python/test/__pycache__/
+node_modules

Makefile

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+.PHONY: all run-rust run-bash run-python run-js run-ruby
+
+all: run-rust run-bash run-python run-js run-ruby
+
+run-rust:
+	@echo ---
+	@echo "Running Rust implementation..."
+	cargo run --manifest-path rust/Cargo.toml
+
+run-bash:
+	@echo ---
+	@echo "Running Bash implementation..."
+	bash bash/main.sh
+
+run-python:
+	@echo ---
+	@echo "Running Python implementation..."
+	python3 python/main.py
+
+run-js:
+	@echo ---
+	@echo "Running JavaScript implementation..."
+	node javascript/src/main.js
+
+run-ruby:
+	@echo ---
+	@echo "Running Ruby implementation..."
+	ruby ruby/main.rb

README.md

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+# Coffee Machine State Machine
+
+This project demonstrates the implementation of a coffee vending machine using state machines
+in different programming languages.
+
+[![pflow](https://pflow.dev/img/zb2rhjeJ8bKSGRDHYv1e4Ap6wZrXvF6hqQkGYW7B1hk1KBsWa.svg)](https://pflow.dev/p/zb2rhjeJ8bKSGRDHYv1e4Ap6wZrXvF6hqQkGYW7B1hk1KBsWa/)
+
+Click the image above to view the state machine in the [PFlow](https://pflow.dev) editor.
+
+## Contributing
+
+Contributions are welcome! Feel free to add new implementations in different languages or improve existing ones.
+
+## State Machine Implementation
+
+The state machine is implemented using the following components:
+- **States**: Represent the different states of the coffee machine (e.g., `BoiledWater`, `GroundCoffee`, `CoffeeInPot`).
+- **Transitions**: Represent the actions that cause state changes (e.g., `BrewCoffee`, `PourCoffee`).
+- **Arrows**: Define the allowed transitions between states.
+- **Guards**: Ensure that certain transitions only occur when specific conditions are met.
+
+## Languages
+
+The state machine is implemented in multiple programming languages to compare their behavior and ensure consistency.
+Each implementation follows the same Petri net model.
+
+### Other Languages
+
+Implementations in other languages (e.g., Python, Java, C++) will be added in their respective directories.
+Each implementation will follow the same structure and logic as the Rust implementation.
+
+## Running the State Machine
+
+To run all samples just use
+```
+make all
+```
+
+To run a specific language use
+```
+make run-bash
+```

bash/main.sh

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+#!/bin/bash
+
+states=(
+	"Water:1"
+	"BoiledWater:0"
+	"CoffeeBeans:1"
+	"GroundCoffee:0"
+	"Filter:1"
+	"CoffeeInPot:0"
+	"Pending:1"
+	"Sent:0"
+	"Payment:0"
+	"Cup:1"
+)
+
+actions=(
+	"BoilWater"
+	"GrindBeans"
+	"BrewCoffee"
+	"PourCoffee"
+	"Send"
+	"Credit"
+)
+
+arrows=(
+	"Water > BoilWater"
+	"BoilWater > BoiledWater"
+	"CoffeeBeans > GrindBeans"
+	"GrindBeans > GroundCoffee"
+	"BoiledWater > BrewCoffee"
+	"GroundCoffee > BrewCoffee"
+	"Filter > BrewCoffee"
+	"BrewCoffee > CoffeeInPot"
+	"CoffeeInPot > PourCoffee"
+	"Cup > PourCoffee"
+	"Pending > Send"
+	"Send > Sent"
+	"Sent > Credit"
+	"Credit > Payment"
+)
+
+guards=(
+	"Payment > PourCoffee"
+)
+
+# Print the current state as a set
+function print_state() {
+	local output="{"
+	for state in "${states[@]}"; do
+		IFS=":" read -r name value <<<"$state"
+		if [[ $value == "1" ]]; then
+			output+=" $name,"
+		fi
+	done
+	output="${output%,} }"
+	echo "$output"
+}
+
+# Check if the element is present in the current state
+function has_state() {
+	for state in "${states[@]}"; do
+		IFS=":" read -r name value <<<"$state"
+		if [[ $name == "$1" && $value == "1" ]]; then
+			return 0
+		fi
+	done
+	return 1
+}
+
+# Set the state of a given element
+function set_state() {
+	for i in "${!states[@]}"; do
+		IFS=":" read -r name value <<<"${states[$i]}"
+		if [[ $name == "$1" ]]; then
+			states[$i]="$name:$2"
+		fi
+	done
+	return 0
+}
+
+function guard_fails() {
+	for guard in "${guards[@]}"; do
+		local from to
+		IFS=" > " read -r from to <<<"$guard"
+		if [[ "$from" == "$1" ]]; then
+			if has_state "$to"; then
+				return 0
+			fi
+		fi
+		if [[ "$to" == "$1" ]]; then
+			if ! has_state "$from"; then
+				return 0
+			fi
+		fi
+
+	done
+	return 1
+}
+
+# Transform the state based on the action
+function transform() {
+	if guard_fails "$1"; then
+		return 1
+	fi
+
+	local arrow
+
+	for arrow in "${arrows[@]}"; do
+		IFS=" > " read -r from to <<<"$arrow"
+		if [[ "$from" == "$1" ]]; then # action -> state
+			if has_state "$to"; then
+				return 1 # Invalid output
+			else
+				set_state $to 1
+			fi
+		fi
+		if [[ $to == "$1" ]]; then # state -> action
+			if has_state "$from"; then
+				set_state "$from" 0
+			else
+				return 1 # Insufficient input
+			fi
+		fi
+	done
+	return 0
+}
+
+# Check if the action can be performed based on the current state
+function can_transform() {
+	if guard_fails "$1"; then
+		return 1
+	fi
+
+	local arrow
+	for arrow in "${arrows[@]}"; do
+		IFS=" > " read -r from to <<<"$arrow"
+		if [[ $from == "$1" ]]; then # action -> state
+			if has_state "$to"; then
+				return 1 # Invalid output
+			fi
+		fi
+		if [[ $to == "$1" ]]; then # state -> action
+			if ! has_state "$from"; then
+				return 1 # Insufficient input
+			fi
+		fi
+	done
+}
+
+# Main function - runs the process by executing the actions
+# for the current state until no more actions are possible
+function main() {
+	local step=1
+	echo "step #0: Initial state"
+	print_state
+	while true; do
+		local transformed=false
+		for action in "${actions[@]}"; do
+			if can_transform "$action"; then
+				transform "$action"
+				echo "step #$step: $($action)"
+				transformed=true
+				step=$((step + 1))
+				break
+			fi
+		done
+		if ! $transformed; then
+			break
+		else
+			print_state
+		fi
+	done
+}
+
+function BoilWater {
+	echo "Boiling Water"
+}
+
+function GrindBeans {
+	echo "Grinding Beans"
+}
+
+function BrewCoffee {
+	echo "Brewing Coffee"
+}
+
+function PourCoffee {
+	echo "Pouring Coffee"
+}
+
+function Send {
+	echo "Sending Payment"
+}
+
+function Credit {
+	echo "Crediting Payment"
+}
+
+main

golang/go.mod

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+module github.com/stackdump/pflow-polyglot/golang
+
+go 1.22.4