protoflow_blocks/blocks/core/
count.rs

1// This is free and unencumbered software released into the public domain.
2
3use crate::{StdioConfig, StdioError, StdioSystem, System};
4use protoflow_core::{
5    types::Any, Block, BlockResult, BlockRuntime, InputPort, Message, OutputPort, Port, PortError,
6};
7use protoflow_derive::Block;
8use simple_mermaid::mermaid;
9
10/// A block that counts the number of messages it receives, while optionally
11/// passing them through.
12///
13/// # Block Diagram
14#[doc = mermaid!("../../../doc/core/count.mmd")]
15///
16/// # Sequence Diagram
17#[doc = mermaid!("../../../doc/core/count.seq.mmd" framed)]
18///
19/// # Examples
20///
21/// ## Using the block in a system
22///
23/// ```rust
24/// # use protoflow_blocks::*;
25/// # fn main() {
26/// System::build(|s| {
27///     let stdin = s.read_stdin();
28///     let line_decoder = s.decode_lines();
29///     let counter = s.count::<String>();
30///     let count_encoder = s.encode_lines();
31///     let stdout = s.write_stdout();
32///     s.connect(&stdin.output, &line_decoder.input);
33///     s.connect(&line_decoder.output, &counter.input);
34///     s.connect(&counter.count, &count_encoder.input);
35///     s.connect(&count_encoder.output, &stdout.input);
36/// });
37/// # }
38/// ```
39///
40/// ## Running the block via the CLI
41///
42/// ```console
43/// $ protoflow execute Count
44/// ```
45///
46#[derive(Block, Clone)]
47pub struct Count<T: Message = Any> {
48    /// The input message stream.
49    #[input]
50    pub input: InputPort<T>,
51
52    /// The (optional) output target for the stream being passed through.
53    #[output]
54    pub output: OutputPort<T>,
55
56    /// The output port for the message count.
57    #[output]
58    pub count: OutputPort<u64>,
59
60    /// The internal state counting the number of messages received.
61    #[state]
62    counter: u64,
63}
64
65impl<T: Message> Count<T> {
66    pub fn new(input: InputPort<T>, output: OutputPort<T>, count: OutputPort<u64>) -> Self {
67        Self {
68            input,
69            output,
70            count,
71            counter: 0,
72        }
73    }
74}
75
76impl<T: Message + 'static> Count<T> {
77    pub fn with_system(system: &System) -> Self {
78        use crate::SystemBuilding;
79        Self::new(system.input(), system.output(), system.output())
80    }
81}
82
83impl<T: Message> Block for Count<T> {
84    fn execute(&mut self, runtime: &dyn BlockRuntime) -> BlockResult {
85        while let Some(message) = self.input.recv()? {
86            self.counter += 1;
87
88            if self.output.is_connected() {
89                self.output.send(&message)?;
90            } else {
91                drop(message);
92            }
93        }
94        self.output.close()?;
95
96        runtime.wait_for(&self.count)?;
97
98        match self.count.send(&self.counter) {
99            Ok(()) => {}
100            Err(PortError::Closed | PortError::Disconnected) => {
101                // TODO: log the error
102            }
103            Err(e) => return Err(e)?,
104        };
105
106        Ok(())
107    }
108}
109
110#[cfg(feature = "std")]
111impl<T: Message + crate::prelude::FromStr + crate::prelude::ToString + 'static> StdioSystem
112    for Count<T>
113{
114    fn build_system(config: StdioConfig) -> Result<System, StdioError> {
115        use crate::{CoreBlocks, IoBlocks, SystemBuilding};
116
117        config.reject_any()?;
118
119        Ok(System::build(|s| {
120            let stdin = config.read_stdin(s);
121            let message_decoder = s.decode_with::<T>(config.encoding);
122            let counter = s.count::<T>();
123            let count_encoder = s.encode_with::<u64>(config.encoding);
124            let stdout = config.write_stdout(s);
125            s.connect(&stdin.output, &message_decoder.input);
126            s.connect(&message_decoder.output, &counter.input);
127            s.connect(&counter.count, &count_encoder.input);
128            s.connect(&count_encoder.output, &stdout.input);
129        }))
130    }
131}
132
133#[cfg(test)]
134mod tests {
135    use super::Count;
136    use crate::{System, SystemBuilding};
137
138    #[test]
139    fn instantiate_block() {
140        // Check that the block is constructible:
141        let _ = System::build(|s| {
142            let _ = s.block(Count::<i32>::new(s.input(), s.output(), s.output()));
143        });
144    }
145}
protoflow_blocks/blocks/core/count.rs

protoflow_blocks/blocks/core/
count.rs
