Add --stats flag for reporting parse information.

cli/src/main.rs

@@ -64,6 +64,7 @@ fn run() -> error::Result<()> {
                 .arg(Arg::with_name("debug").long("debug").short("d"))
                 .arg(Arg::with_name("debug-graph").long("debug-graph").short("D"))
                 .arg(Arg::with_name("quiet").long("quiet").short("q"))
+                .arg(Arg::with_name("stat").long("stat").short("s"))
                 .arg(Arg::with_name("time").long("time").short("t"))
                 .arg(Arg::with_name("allow-cancellation").long("cancel"))
                 .arg(Arg::with_name("timeout").long("timeout").takes_value(true))
@@ -234,6 +235,9 @@ fn run() -> error::Result<()> {
         let max_path_length = paths.iter().map(|p| p.chars().count()).max().unwrap();
         let mut has_error = false;
         loader.find_all_languages(&config.parser_directories)?;
+
+        let mut stats : parse::Stats = Default::default();
+
         for path in paths {
             let path = Path::new(&path);
             let language =
@@ -249,8 +253,14 @@ fn run() -> error::Result<()> {
                 debug,
                 debug_graph,
                 allow_cancellation,
+                &mut stats,
             )?;
         }
+
+        if matches.is_present("stat") {
+            println!("{}", stats)
+        }
+
         if has_error {
             return Error::err(String::new());
         }

cli/src/parse.rs

@@ -4,7 +4,7 @@ use std::io::{self, Write};
 use std::path::Path;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::time::Instant;
-use std::{fs, thread, usize};
+use std::{fmt, fs, thread, usize};
 use tree_sitter::{InputEdit, Language, LogType, Parser, Point, Tree};
 
 #[derive(Debug)]
@@ -14,6 +14,22 @@ pub struct Edit {
     pub inserted_text: Vec<u8>,
 }
 
+#[derive(Debug, Default)]
+pub struct Stats {
+    successful_parses : usize,
+    total_parses : usize,
+}
+
+impl fmt::Display for Stats {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        return writeln!(f, "Total parses: {}; successful parses: {}; failed parses: {}; success percentage: {:.2}%",
+                 self.total_parses,
+                 self.successful_parses,
+                 self.total_parses - self.successful_parses,
+                 (self.successful_parses as f64) / (self.total_parses as f64) * 100.0);
+    }
+}
+
 pub fn parse_file_at_path(
     language: Language,
     path: &Path,
@@ -25,6 +41,7 @@ pub fn parse_file_at_path(
     debug: bool,
     debug_graph: bool,
     allow_cancellation: bool,
+    stats: &mut Stats,
 ) -> Result<bool> {
     let mut _log_session = None;
     let mut parser = Parser::new();
@@ -161,6 +178,11 @@ pub fn parse_file_at_path(
             }
         }
 
+        stats.total_parses += 1;
+        if first_error.is_none() {
+            stats.successful_parses += 1;
+        }
+
         if first_error.is_some() || print_time {
             write!(
                 &mut stdout,