add syntax highlighting

y2j/Cargo.toml

@@ -7,3 +7,4 @@ edition = "2021"
 atty = { version = "0.2" }
 serde_json = { version = "1.0", features = ["preserve_order"] }
 serde_yaml = { version = "0.9" }
+syntect = { version = "5.0", features = ["default-fancy"], default-features = false }

y2j/src/main.rs

@@ -1,5 +1,9 @@
 use atty::Stream;
 use std::{io::{self, Read}, process::exit};
+use syntect::easy::HighlightLines;
+use syntect::parsing::SyntaxSet;
+use syntect::highlighting::{ThemeSet, Style};
+use syntect::util::{as_24_bit_terminal_escaped, LinesWithEndings};
 
 const EXIT_SUCCESS: i32 = 0;
 const EXIT_INVALID_INPUT: i32 = 1;
@@ -40,6 +44,25 @@ fn main() {
         false => serde_json::to_string_pretty(&input).unwrap(),
     };
 
-    println!("{}", output);
+    // if stdout is not redirected, print with syntax highlighting
+    if atty::is(Stream::Stdout) {
+        let ps = SyntaxSet::load_defaults_newlines();
+        let ts = ThemeSet::load_defaults();
+        let syntax = match is_json {
+            true => ps.find_syntax_by_extension("json").unwrap(),
+            false => ps.find_syntax_by_extension("yaml").unwrap(),
+        };
+
+        let mut h = HighlightLines::new(syntax, &ts.themes["base16-ocean.dark"]);
+
+        for line in LinesWithEndings::from(output.as_str()) {
+            let ranges: Vec<(Style, &str)> = h.highlight_line(line, &ps).unwrap();
+            let escaped = as_24_bit_terminal_escaped(&ranges[..], true);
+            print!("{}", escaped);
+        }
+    } else {
+        println!("{}", output);
+    }
+
     exit(EXIT_SUCCESS);
 }