python: support W presentation type

Problem: When outputting wide characters (e.g. emojis) in flux-jobs,
the alignment of output can be poor due to the characters having
different output widths.

Solution: Add a new W presentation type that can adjust formating
of the form "(<|>)N", e.g. {id.emoji:>12W}.  The output width will
be adjusted given the number of wide characters that exist in the
string.

Note that this presentation type does not help for all output scenarios,
as it depends on the width of the output and width of the alignment,
but it definitely helps in some scenarios.

Author: chu11

src/bindings/python/flux/util.py

@@ -29,6 +29,7 @@
 from typing import Mapping
 
 import yaml
+import unicodedata
 
 # tomllib added to standard library in Python 3.11
 # flux-core minimum is Python 3.6.
@@ -448,6 +449,24 @@ def format_field(self, value, spec):
             basecases = empty_outputs()
             value = "-" if str(value) in basecases else str(value)
             spec = spec[:-1] + "s"
+
+        if spec.endswith("W") and isinstance (value, str):
+            match = re.search(r"^([<>])(\d+)W", spec)
+            if match:
+                align = match[1]
+                width = int(match[2])
+                widecount = 0
+                for chr in value:
+                    if unicodedata.east_asian_width(chr) == 'W':
+                        widecount += 1
+                if width > widecount:
+                    width -= widecount;
+                    spec = f"{align}{width}s"
+        # if spec was not modified above, need to convert to "W"
+        # conversion to "s"
+        if spec.endswith("W"):
+            spec = spec[:-1] + "s"
+
         retval = super().format_field(value, spec)
 
         if denote_truncation and len(retval) < len(str(value)):