feat(cli)!: hopon virtual instruction in the beautifier (#840)

AIR beautifier may output virtual `hopon` instruction based on specific pattern generated by the Aqua compiler.

The `air_beatifier::beatify` function has now an extra argument that determines if to perform the virtual instruction detection, giving more readable output.

The `air-beautify-wasm` crate has behavior of the `beautify` function changed: the functions now extracts virtual instructions, so it is a drop-in replacement for previous version with new functionality.  New exported function `beautify_raw` is added, that doesn't look for virtual instructions' patterns, formatting the code as is.

crates/beautifier/src/beautifier.rs

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+use super::r#virtual::try_hopon;
+
 use air_parser::ast;
 
 use std::fmt::Display;
@@ -82,25 +84,42 @@ pub enum BeautifyError {
 pub struct Beautifier<W: io::Write> {
     output: W,
     indent_step: usize,
+    try_hopon: bool,
 }
 
 impl<W: io::Write> Beautifier<W> {
     /// Beautifier for the output with default indentation step.
+    #[inline]
     pub fn new(output: W) -> Self {
         Self {
             output,
             indent_step: DEFAULT_INDENT_STEP,
+            try_hopon: false,
         }
     }
 
     /// Beautifier for the output with custom indentation step.
+    #[inline]
     pub fn new_with_indent(output: W, indent_step: usize) -> Self {
         Self {
             output,
             indent_step,
+            try_hopon: false,
         }
     }
 
+    #[inline]
+    /// Enable all patterns in the emited code.
+    pub fn enable_all_patterns(self) -> Self {
+        self.enable_try_hopon()
+    }
+
+    #[inline]
+    pub fn enable_try_hopon(mut self) -> Self {
+        self.try_hopon = true;
+        self
+    }
+
     /// Unwrap the Beautifier into the underlying writer.
     pub fn into_inner(self) -> W {
         self.output
@@ -253,6 +272,12 @@ impl<W: io::Write> Beautifier<W> {
     }
 
     fn beautify_new(&mut self, new: &ast::New<'_>, indent: usize) -> io::Result<()> {
+        if self.try_hopon {
+            if let Some(hop_on) = try_hopon(new) {
+                return self.beautify_simple(&hop_on, indent);
+            }
+        }
+        // else
         compound!(self, indent, new);
         Ok(())
     }

crates/beautifier/src/lib.rs

@@ -26,14 +26,22 @@
 )]
 
 mod beautifier;
+mod r#virtual;
 
 pub use crate::beautifier::{Beautifier, BeautifyError, DEFAULT_INDENT_STEP};
 
 use std::io;
 
 /// Beautify the `air_script` with default settings to the `output`.
-pub fn beautify(air_script: &str, output: &mut impl io::Write) -> Result<(), BeautifyError> {
+pub fn beautify(
+    air_script: &str,
+    output: &mut impl io::Write,
+    enable_patterns: bool,
+) -> Result<(), BeautifyError> {
     let mut beautifier = Beautifier::new(output);
+    if enable_patterns {
+        beautifier = beautifier.enable_all_patterns();
+    }
     beautifier.beautify(air_script)
 }
 

crates/beautifier/src/tests/beautifier.rs

@@ -388,3 +388,106 @@ fn fail_error() {
     let output = beautify_to_string(script).unwrap();
     assert_eq!(output, "fail :error:\n");
 }
+
+#[test]
+fn hopon_on() {
+    let script = r#"(new $ephemeral (new #ephemeral (canon "relay" $ephemeral #ephemeral)))"#;
+
+    let mut output = vec![];
+    let mut beautifier = Beautifier::new(&mut output).enable_all_patterns();
+    beautifier.beautify(script).unwrap();
+
+    assert_eq!(String::from_utf8(output).unwrap(), "hopon \"relay\"\n");
+}
+
+#[test]
+fn hopon_off() {
+    let script = r#"(new $ephemeral (new #ephemeral (canon "relay" $ephemeral #ephemeral)))"#;
+
+    let mut output = vec![];
+    let mut beautifier = Beautifier::new(&mut output);
+    beautifier.beautify(script).unwrap();
+
+    assert_eq!(
+        String::from_utf8(output).unwrap(),
+        concat!(
+            "new $ephemeral:\n",
+            "    new #ephemeral:\n",
+            "        canon \"relay\" $ephemeral #ephemeral\n"
+        ),
+    );
+}
+
+#[test]
+fn hopon_canon_mismatch() {
+    let script = r#"(new $ephemeral (new #can (canon "relay" $ephemeral #ephemeral)))"#;
+
+    let mut output = vec![];
+    let mut beautifier = Beautifier::new(&mut output).enable_all_patterns();
+    beautifier.beautify(script).unwrap();
+
+    assert_eq!(
+        String::from_utf8(output).unwrap(),
+        concat!(
+            "new $ephemeral:\n",
+            "    new #can:\n",
+            "        canon \"relay\" $ephemeral #ephemeral\n"
+        ),
+    );
+}
+
+#[test]
+fn hopon_stream_mismatch() {
+    let script = r#"(new $stream (new #ephemeral (canon "relay" $ephemeral #ephemeral)))"#;
+
+    let mut output = vec![];
+    let mut beautifier = Beautifier::new(&mut output).enable_all_patterns();
+    beautifier.beautify(script).unwrap();
+
+    assert_eq!(
+        String::from_utf8(output).unwrap(),
+        concat!(
+            "new $stream:\n",
+            "    new #ephemeral:\n",
+            "        canon \"relay\" $ephemeral #ephemeral\n"
+        ),
+    );
+}
+
+#[test]
+fn hopon_nested() {
+    let script =
+        r#"(new $other (new $ephemeral (new #ephemeral (canon "relay" $ephemeral #ephemeral))) )"#;
+
+    let mut output = vec![];
+    let mut beautifier = Beautifier::new(&mut output).enable_all_patterns();
+    beautifier.beautify(script).unwrap();
+
+    assert_eq!(
+        String::from_utf8(output).unwrap(),
+        "new $other:\n    hopon \"relay\"\n",
+    );
+}
+
+// this is bug that should be eventually fixed: it uses top-level #can
+// instead of the nested one which disappeared
+//
+// the compiler doesn't generate such code, but it can be crafted manually
+#[test]
+fn hopon_shadowing() {
+    let script = r#"(new #can (new $ephemeral (new #can (canon #can.$.[0] $ephemeral #can))) )"#;
+
+    let mut output = vec![];
+    let mut beautifier = Beautifier::new(&mut output).enable_all_patterns();
+    beautifier.beautify(script).unwrap();
+
+    assert_eq!(
+        String::from_utf8(output).unwrap(),
+        concat!(
+            "new #can:\n",
+            "    new $ephemeral:\n",
+            "        new #can:\n",
+            "            canon #can.$.[0] $ephemeral #can\n"
+        ),
+    );
+}

crates/beautifier/src/tests/mod.rs

@@ -32,8 +32,17 @@ use crate::{beautify, beautify_to_string, BeautifyError};
 fn beautify_valid() {
     let air_script = "(seq (null) (null))";
     let mut buffer = vec![];
-    let res = beautify(air_script, &mut buffer);
-    assert!(matches!(res, Ok(())));
+    let res = beautify(air_script, &mut buffer, false);
+    assert!(res.is_ok());
+    assert_eq!(std::str::from_utf8(&buffer).unwrap(), "null\nnull\n");
+}
+
+#[test]
+fn beautify_valid_with_patterns() {
+    let air_script = "(seq (null) (null))";
+    let mut buffer = vec![];
+    let res = beautify(air_script, &mut buffer, true);
+    assert!(res.is_ok());
     assert_eq!(std::str::from_utf8(&buffer).unwrap(), "null\nnull\n");
 }
 
@@ -41,7 +50,7 @@ fn beautify_valid() {
 fn beautify_invalid() {
     let air_script = "(seq (null))";
     let mut buffer = vec![];
-    let res = beautify(air_script, &mut buffer);
+    let res = beautify(air_script, &mut buffer, false);
     assert!(matches!(res, Err(BeautifyError::Parse(_))));
 }
 
@@ -56,5 +65,5 @@ fn beautify_to_string_valid() {
 fn beautify_to_string_invalid() {
     let air_script = "(seq (null))";
     let res = beautify_to_string(air_script);
-    assert!(matches!(res, Err(_)));
+    assert!(res.is_err());
 }

crates/beautifier/src/virtual.rs

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2024 Fluence DAO
+ *
+ * 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.
+ */
+
+use air_parser::ast;
+
+use core::fmt;
+use std::fmt::Display;
+
+/// A virtual `hopon` instruction.
+pub(crate) struct HopOn<'i> {
+    pub peer_id: ast::ResolvableToPeerIdVariable<'i>,
+}
+
+impl Display for HopOn<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "hopon {}", self.peer_id)
+    }
+}
+
+/// Try to parse the `new` instruction and its nested elements as a virtual `hopon` instruction.
+///
+/// For example:
+/// ```clojure
+/// (new #uniq1_name
+///    (new $uniq2_name
+///       (canon peer_id $uniq2_name #uniq1_name)))
+/// ```
+/// is parsed as a virtual instruction
+/// ```clojure
+/// (hopon peer_id)
+/// ```
+pub(crate) fn try_hopon<'i>(root_new: &ast::New<'i>) -> Option<HopOn<'i>> {
+    let expected_stream_name = &root_new.argument;
+
+    if let (ast::Instruction::New(nested_new), ast::NewArgument::Stream(stream_name)) =
+        (&root_new.instruction, expected_stream_name)
+    {
+        let expected_nested_canon_name = &nested_new.argument;
+
+        if let (ast::Instruction::Canon(canon), ast::NewArgument::CanonStream(nested_canon_name)) =
+            (&nested_new.instruction, expected_nested_canon_name)
+        {
+            if canon.canon_stream.name == nested_canon_name.name
+                && canon.stream.name == stream_name.name
+                // this condition handles case that is never generated by an Aqua compiler, but
+                // can be crafted manually
+                //
+                // see `hopon_shadowing` test for an example
+                && !canon_shadows_peer_id(nested_canon_name.name, &canon.peer_id)
+            {
+                return Some(HopOn {
+                    peer_id: canon.peer_id.clone(),
+                });
+            }
+        }
+    }
+
+    None
+}
+
+fn canon_shadows_peer_id(canon_name: &str, peer_id: &ast::ResolvableToPeerIdVariable<'_>) -> bool {
+    use ast::ResolvableToPeerIdVariable::*;
+    match peer_id {
+        InitPeerId => false,
+        Literal(_) => false,
+        Scalar(_) => false,
+        ScalarWithLambda(_) => false,
+        CanonStreamMapWithLambda(_) => false,
+        CanonStreamWithLambda(canon_with_lambda) => canon_with_lambda.name == canon_name,
+    }
+}

tools/cli/air/README.md

@@ -10,6 +10,8 @@ This subcommand reads an AIR script from standard input and prints it in human-r
 
 It outputs to standard output or a file.
 
+With `--patterns` options, it tries to recognize certain patterns that Aqua compiler emits and outputs it as more human readable Aqua-like syntax.  Currently only `hopon` syntax is recognized.
+
 ## `air run`
 
 Alias: `air r`.

tools/cli/air/src/beautify/mod.rs

@@ -25,6 +25,8 @@ use std::{io, path::PathBuf};
 pub(crate) struct Args {
     #[clap(short, long, default_value_t = air_beautifier::DEFAULT_INDENT_STEP)]
     indent_step: usize,
+    #[clap(short, long, help = "Recognize virtual instruction patterns")]
+    patterns: bool,
     #[clap(short, long)]
     output: Option<PathBuf>,
     input: Option<PathBuf>,
@@ -65,6 +67,12 @@ pub(crate) fn beautify(args: Args) -> Result<()> {
     let air_script = read_script(&args).context("failed to read the input")?;
     let output = build_output(&args).context("failed to open the output")?;
 
-    Beautifier::new_with_indent(output, args.indent_step).beautify(&air_script)?;
+    let mut beautifier = Beautifier::new_with_indent(output, args.indent_step);
+
+    if args.patterns {
+        beautifier = beautifier.enable_all_patterns();
+    }
+
+    beautifier.beautify(&air_script)?;
     Ok(())
 }

tools/wasm/air-beautify-wasm/src/lib.rs

@@ -19,6 +19,13 @@ use wasm_bindgen::prelude::*;
 #[wasm_bindgen]
 pub fn beautify(air_script: String) -> Result<String, JsError> {
     let mut output = vec![];
-    air_beautifier::beautify(&air_script, &mut output)?;
+    air_beautifier::beautify(&air_script, &mut output, true)?;
+    Ok(unsafe { String::from_utf8_unchecked(output) })
+}
+
+#[wasm_bindgen]
+pub fn beautify_raw(air_script: String) -> Result<String, JsError> {
+    let mut output = vec![];
+    air_beautifier::beautify(&air_script, &mut output, false)?;
     Ok(unsafe { String::from_utf8_unchecked(output) })
 }