Repository: ast-grep/ast-grep (language: rust)

Issue:
[refactor] have a semi-structured tracing output
Example

```
sg: summary|file: scannedCount=199
sg: entity|file|src/cli/scan.rs: skippedCount=47
sg: entity|rule|my-rule-id: finalSeverity=off
sg: entity|rule|my-rule-id: skipReason=ruleFilter
sg: entity|rule|my-rule-id: skipReason=severityOff
sg: detail|file*rule|src/cli/scan.rs,my-ast-grep-rule: hitResult=hitByInclude
sg: detail|file*rule|src/cli/scan.rs,my-ast-grep-rule: hitResult=hitByExclude
sg: detail|file*rule|src/cli/scan.rs,my-ast-grep-rule: hitResult=normalHit
```

[EBNF](https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form) notation, 

```ebnf
OUTPUT := "sg: ", GRANULARITY,  ENTITY_TYPE, ENTITY_IDENTIFIER_LIST , ": ", KEY_VAL_PAIRS;
GRANULARITY = "summary" | "entity" | "detail";
ENTITY_TYPE = "file" | "rule" | "file*rule";
ENTITY_IDENTIFER_LIST = "" | ( "|", IDENTIFIER, { ",", IDENTIFIER } );
KEY_VAL_PAIRS = KEY_VAL_PAIR, { ",", KEY_VAL_PAIR };
KEY_VAL_PAIR = KEY, "=", VAL;
```

Informal Notation

```
sg: <GRANULARITY>|<ENTITY_TYPE>|<ENTITY_IDENTIFIERS_SEPARATED_BY_COMMA>: KEY=VAL
```



Discussion / hints:

Fix patch:
diff --git a/crates/cli/src/utils/inspect.rs b/crates/cli/src/utils/inspect.rs
index a2ba3f9d86..f80a40e7d5 100644
--- a/crates/cli/src/utils/inspect.rs
+++ b/crates/cli/src/utils/inspect.rs
@@ -16,12 +16,13 @@ use ast_grep_config::RuleConfig;
 use anyhow::Result;
 use clap::ValueEnum;
 
+use std::fmt;
 use std::io::{Stderr, Write};
 use std::path::Path;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Mutex;
 
-#[derive(Clone, Copy, ValueEnum, Default, PartialEq, Debug)]
+#[derive(Clone, Copy, ValueEnum, Default, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Granularity {
   /// Do not show any tracing information
   #[default]
@@ -33,6 +34,16 @@ pub enum Granularity {
   // Detail,
 }
 
+impl fmt::Debug for Granularity {
+  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    match self {
+      Granularity::Nothing => write!(f, "nothing"),
+      Granularity::Summary => write!(f, "summary"),
+      Granularity::Entity => write!(f, "entity"),
+    }
+  }
+}
+
 impl Granularity {
   pub fn run_trace(&self) -> RunTrace {
     self.run_trace_impl(std::io::stderr())
@@ -74,19 +85,6 @@ impl FileTrace {
   pub fn add_skipped(&self) {
     self.files_skipped.fetch_add(1, Ordering::AcqRel);
   }
-  pub fn print<W: Write>(&self, w: &mut W) -> Result<()> {
-    write!(
-      w,
-      "Files scanned: {}, Files skipped: {}",
-      self.files_scanned.load(Ordering::Acquire),
-      self.files_skipped.load(Ordering::Acquire)
-    )?;
-    Ok(())
-  }
-  pub fn print_file<W: Write>(&self, w: &mut W, path: &Path, lang: SgLang) -> Result<()> {
-    write!(w, "Parse {} with {lang}", path.display())?;
-    Ok(())
-  }
 }
 
 pub struct TraceInfo<T, W: Write> {
@@ -96,57 +94,93 @@ pub struct TraceInfo<T, W: Write> {
   output: Mutex<W>,
 }
 
+impl<T, W: Write + Sync> TraceInfo<T, W> {
+  #[inline(always)]
+  fn semi_structured_print<F>(&self, level: Granularity, f: F) -> Result<()>
+  where
+    F: FnOnce(&mut W) -> Result<()>,
+  {
+    if self.level < level {
+      return Ok(());
+    }
+    let mut w = self.output.lock().expect("lock should not be poisoned");
+    write!(w, "sg: {level:?}")?;
+    f(&mut *w)?;
+    writeln!(&mut *w)?;
+    Ok(())
+  }
+
+  #[inline(always)]
+  fn print_summary<F>(&self, entity_type: &str, kv_write: F) -> Result<()>
+  where
+    F: FnOnce(&mut W) -> Result<()>,
+  {
+    self.semi_structured_print(Granularity::Summary, |w| {
+      write!(w, "|{entity_type}: ")?;
+      kv_write(w)
+    })
+  }
+
+  #[inline(always)]
+  fn print_entity<F, D>(&self, entity_type: &str, entity_path: D, kv_write: F) -> Result<()>
+  where
+    F: FnOnce(&mut W) -> Result<()>,
+    D: fmt::Display,
+  {
+    self.semi_structured_print(Granularity::Entity, |w| {
+      write!(w, "|{entity_type}|{entity_path}: ")?;
+      kv_write(w)
+    })
+  }
+
+  fn print_files(&self) -> Result<()> {
+    self.print_summary("file", |w| {
+      let scanned = self.file_trace.files_scanned.load(Ordering::Acquire);
+      let skipped = self.file_trace.files_skipped.load(Ordering::Acquire);
+      write!(w, "scannedFileCount={scanned},skippedFileCount={skipped}")?;
+      Ok(())
+    })?;
+    Ok(())
+  }
+}
+
 impl<W: Write + Sync> TraceInfo<(), W> {
-  // TODO: support more format?
   pub fn print(&self) -> Result<()> {
-    match self.level {
-      Granularity::Nothing => Ok(()),
-      Granularity::Summary | Granularity::Entity => {
-        let mut w = self.output.lock().expect("lock should not be poisoned");
-        self.file_trace.print(&mut *w)?;
-        writeln!(&mut *w)?;
-        Ok(())
-      }
-    }
+    self.print_files()
   }
 
   pub fn print_file(&self, path: &Path, lang: SgLang) -> Result<()> {
-    match self.level {
-      Granularity::Nothing | Granularity::Summary => Ok(()),
-      Granularity::Entity => {
-        let mut w = self.output.lock().expect("lock should not be poisoned");
-        self.file_trace.print_file(&mut *w, path, lang)?;
-        writeln!(&mut *w)?;
-        Ok(())
-      }
-    }
+    self.print_entity("file", path.display(), |w| {
+      write!(w, "language={lang}")?;
+      Ok(())
+    })
   }
 }
 
-impl<W: Write> TraceInfo<RuleTrace, W> {
+impl<W: Write + Sync> TraceInfo<RuleTrace, W> {
   // TODO: support more format?
   pub fn print(&self) -> Result<()> {
-    match self.level {
-      Granularity::Nothing => Ok(()),
-      Granularity::Summary | Granularity::Entity => {
-        let mut w = self.output.lock().expect("lock should not be poisoned");
-        self.file_trace.print(&mut *w)?;
-        writeln!(&mut *w, "\n{}", self.inner.print())?;
-        Ok(())
-      }
-    }
+    self.print_files()?;
+    self.print_summary("rule", |w| {
+      let (effective, skipped) = (
+        self.inner.effective_rule_count,
+        self.inner.skipped_rule_count,
+      );
+      write!(
+        w,
+        "effectiveRuleCount={effective},skippedRuleCount={skipped}"
+      )?;
+      Ok(())
+    })?;
+    Ok(())
   }
   pub fn print_file(&self, path: &Path, lang: SgLang, rules: &[&RuleConfig<SgLang>]) -> Result<()> {
-    let len = rules.len();
-    match self.level {
-      Granularity::Nothing | Granularity::Summary => Ok(()),
-      Granularity::Entity => {
-        let mut w = self.output.lock().expect("lock should not be poisoned");
-        self.file_trace.print_file(&mut *w, path, lang)?;
-        writeln!(&mut *w, ", applied {len} rule(s)")?;
-        Ok(())
-      }
-    }
+    self.print_entity("file", path.display(), |w| {
+      let len = rules.len();
+      write!(w, "language={lang},appliedRuleCount={len}")?;
+      Ok(())
+    })?;
+    Ok(())
   }
 }
 
@@ -155,14 +189,6 @@ pub struct RuleTrace {
   pub effective_rule_count: usize,
   pub skipped_rule_count: usize,
 }
-impl RuleTrace {
-  pub fn print(&self) -> String {
-    format!(
-      "Effective rules: {}, Skipped rules: {}",
-      self.effective_rule_count, self.skipped_rule_count
-    )
-  }
-}
 
 pub type RunTrace = TraceInfo<(), Stderr>;
 pub type ScanTrace = TraceInfo<RuleTrace, Stderr>;
@@ -186,7 +212,10 @@ mod test {
       0
     );
     assert!(run_trace.print().is_ok());
-    assert_eq!(ret, "Files scanned: 0, Files skipped: 0\n");
+    assert_eq!(
+      ret,
+      "sg: summary|file: scannedFileCount=0,skippedFileCount=0\n"
+    );
 
     let mut ret = String::new();
     let rule_stats = RuleTrace {
@@ -208,7 +237,9 @@ mod test {
     assert!(scan_trace.print().is_ok());
     assert_eq!(
       ret,
-      "Files scanned: 0, Files skipped: 0\nEffective rules: 10, Skipped rules: 2\n"
+      r"sg: summary|file: scannedFileCount=0,skippedFileCount=0
+sg: summary|rule: effectiveRuleCount=10,skippedRuleCount=2
+"
     );
   }
 


Test patch:
diff --git a/crates/cli/tests/run_test.rs b/crates/cli/tests/run_test.rs
index 826724e0e4..8fed91a002 100644
--- a/crates/cli/tests/run_test.rs
+++ b/crates/cli/tests/run_test.rs
@@ -57,6 +57,6 @@ fn test_inspect() -> Result<()> {
     .assert()
     .success()
     .stdout(contains("alert(1)"))
-    .stderr(contains("Files scanned: 2"));
+    .stderr(contains("scannedFileCount=2"));
   Ok(())
 }