Allow empty string as an arg value (#2027)

src/formatting/formatter.rs

@@ -1,3 +1,5 @@
+use unicode_segmentation::UnicodeSegmentation;
+
 use std::fmt::Debug;
 use std::time::Duration;
 

src/formatting/formatter/eng.rs

@@ -1,10 +1,14 @@
 use crate::formatting::prefix::Prefix;
 use crate::formatting::unit::Unit;
 
+use std::borrow::Cow;
+
 use super::*;
 
+type PadWith = Cow<'static, str>;
+
 const DEFAULT_NUMBER_WIDTH: usize = 2;
-const DEFAULT_NUMBER_PAD_WITH: char = ' ';
+const DEFAULT_NUMBER_PAD_WITH: PadWith = Cow::Borrowed(" ");
 
 // TODO: split those defaults
 pub const DEFAULT_NUMBER_FORMATTER: EngFormatter = EngFormatter {
@@ -29,7 +33,7 @@ pub struct EngFormatter {
     prefix_has_space: bool,
     prefix_hidden: bool,
     prefix_forced: bool,
-    pad_with: char,
+    pad_with: PadWith,
 }
 
 impl EngFormatter {
@@ -91,10 +95,13 @@ impl EngFormatter {
                         .error("force_prefix must be true or false")?;
                 }
                 "pad_with" => {
-                    pad_with = arg
-                        .val
-                        .parse()
-                        .error("pad_with must be a single character")?;
+                    if arg.val.graphemes(true).count() < 2 {
+                        pad_with = Cow::Owned(arg.val.into());
+                    } else {
+                        return Err(Error::new(
+                            "pad_with must be an empty string or a single character",
+                        ));
+                    }
                 }
                 other => {
                     return Err(Error::new(format!("Unknown argument for 'eng': '{other}'")));

src/formatting/formatter/str.rs

@@ -1,5 +1,3 @@
-use unicode_segmentation::UnicodeSegmentation;
-
 use std::iter::repeat;
 use std::time::Instant;
 

src/formatting/parse.rs

@@ -1,6 +1,6 @@
 use nom::{
     branch::alt,
-    bytes::complete::{escaped_transform, is_not, tag, take_while, take_while1},
+    bytes::complete::{escaped_transform, tag, take_while, take_while1},
     character::complete::{anychar, char},
     combinator::{cut, eof, map, not, opt},
     multi::{many0, separated_list0},
@@ -86,7 +86,10 @@ fn alphanum1(i: &str) -> IResult<&str, &str, PError> {
 fn arg1(i: &str) -> IResult<&str, &str, PError> {
     alt((
         take_while1(|x: char| x.is_alphanumeric() || x == '_' || x == '-' || x == '.' || x == '%'),
-        preceded(char('\''), cut(terminated(is_not("\'"), char('\'')))),
+        preceded(
+            char('\''),
+            cut(terminated(take_while(|x: char| x != '\''), char('\''))),
+        ),
     ))(i)
 }
 
@@ -222,6 +225,16 @@ mod tests {
                 }
             ))
         );
+        assert_eq!(
+            parse_arg("key:'',"),
+            Ok((
+                ",",
+                Arg {
+                    key: "key",
+                    val: ""
+                }
+            ))
+        );
         assert!(parse_arg("key:,").is_err());
     }