Use %v to print jf version

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "jf"
-version = "0.2.1"
+version = "0.2.2"
 edition = "2021"
 authors = ["Arijit Basu <[email protected]>"]
 description = 'jf: %q "JSON Formatted"'

README.md

@@ -36,6 +36,7 @@ And [VALUE]... [[NAME=]VALUE]... are the values for the placeholders.
 - Pass values for positional placeholders in the same order as in the template.
 - Pass values for named placeholders using `NAME=VALUE` syntax.
 - Do not declare or pass positional placeholders or values after named ones.
+- To get the `jf` version number, use `jf %v`.
 
 Example:
 

src/main.rs

@@ -2,6 +2,7 @@ use serde_json as json;
 use serde_yaml as yaml;
 use std::{collections::HashMap, env, fmt::Display};
 
+const VERSION: &str = env!("CARGO_PKG_VERSION");
 const USAGE: &str = r#"not enough arguments
 
 USAGE: jf TEMPLATE [VALUE]... [NAME=VALUE]...
@@ -19,6 +20,7 @@ USAGE: jf TEMPLATE [VALUE]... [NAME=VALUE]...
   Pass values for positional placeholders in the same order as in the template.
   Pass values for named placeholders using `NAME=VALUE` syntax.
   Do not declare or pass positional placeholders or values after named ones.
+  To get the `jf` version number, use `jf %v`.
 
 EXAMPLE:
 
@@ -176,6 +178,10 @@ where
                     val.push_str(&arg);
                     last_char = None;
                 }
+                ('v', Some('%')) => {
+                    val.push_str(&VERSION);
+                    last_char = None;
+                }
                 ('(', Some('%')) => {
                     if !is_reading_named_placeholders {
                         is_reading_named_placeholders = true;
@@ -418,3 +424,18 @@ fn test_invalid_named_placeholder_error() {
         format!("jf: invalid named placeholder '%(foo)x' at column 6, use '%(foo)q' for quoted strings and '%(foo)s' for other values")
     );
 }
+
+#[test]
+fn test_print_version() {
+    let arg = ["jf v%v"].into_iter().map(Into::into);
+    assert_eq!(format(arg).unwrap().to_string(), r#""jf v0.2.2""#);
+
+    let args = ["{foo: %q, bar: %(bar)q, version: %v}", "foo", "bar=bar"]
+        .into_iter()
+        .map(Into::into);
+
+    assert_eq!(
+        format(args).unwrap().to_string(),
+        r#"{"foo":"foo","bar":"bar","version":"0.2.2"}"#
+    );
+}