fix: preserve fixed boxes with None alignment

tabulate/__init__.py

@@ -1147,7 +1147,7 @@ def _choose_width_fn(has_invisible, enable_widechars, is_multiline):
     return width_fn
 
 
-def _align_column_choose_padfn(strings, alignment, has_invisible, preserve_whitespace):
+def _align_column_choose_padfn(strings, alignment, has_invisible, preserve_whitespace, pad_none):
     if alignment == "right":
         if not preserve_whitespace:
             strings = [s.strip() for s in strings]
@@ -1165,7 +1165,7 @@ def _align_column_choose_padfn(strings, alignment, has_invisible, preserve_white
         strings = [s + (maxdecimals - decs) * " " for s, decs in zip(strings, decimals)]
         padfn = _padleft
     elif not alignment:
-        padfn = _padnone
+        padfn = _padright if pad_none else _padnone
     else:
         if not preserve_whitespace:
             strings = [s.strip() for s in strings]
@@ -1212,10 +1212,11 @@ def _align_column(
     enable_widechars=False,
     is_multiline=False,
     preserve_whitespace=False,
+    pad_none=False,
 ):
     """[string] -> [padded_string]"""
     strings, padfn = _align_column_choose_padfn(
-        strings, alignment, has_invisible, preserve_whitespace
+        strings, alignment, has_invisible, preserve_whitespace, pad_none
     )
     width_fn = _align_column_choose_width_fn(has_invisible, enable_widechars, is_multiline)
 
@@ -1358,11 +1359,16 @@ def _format(val, valtype, floatfmt, intfmt, missingval="", has_invisible=True):
         return f"{val}"
 
 
-def _align_header(header, alignment, width, visible_width, is_multiline=False, width_fn=None):
+def _align_header(
+    header, alignment, width, visible_width, is_multiline=False, width_fn=None, pad_none=False
+):
     "Pad string header to width chars given known visible_width of the header."
     if is_multiline:
         header_lines = re.split(_multiline_codes, header)
-        padded_lines = [_align_header(h, alignment, width, width_fn(h)) for h in header_lines]
+        padded_lines = [
+            _align_header(h, alignment, width, width_fn(h), pad_none=pad_none)
+            for h in header_lines
+        ]
         return "\n".join(padded_lines)
     # else: not multiline
     ninvisible = len(header) - visible_width
@@ -1372,11 +1378,23 @@ def _align_header(header, alignment, width, visible_width, is_multiline=False, w
     elif alignment == "center":
         return _padboth(width, header)
     elif not alignment:
-        return f"{header}"
+        return _padright(width, header) if pad_none else f"{header}"
     else:
         return _padleft(width, header)
 
 
+def _is_fixed_width_table_format(fmt):
+    """Whether a format's row and line metadata describe a fixed text box."""
+    return (
+        isinstance(fmt.datarow, DataRow)
+        and bool(fmt.datarow.begin and fmt.datarow.end)
+        and any(
+            isinstance(line, Line) and bool(line.begin and line.end)
+            for line in (fmt.lineabove, fmt.linebetweenrows, fmt.linebelow)
+        )
+    )
+
+
 def _remove_separating_lines(rows):
     if isinstance(rows, list):
         separating_lines = []
@@ -2334,6 +2352,11 @@ def tabulate(
         is_multiline = True
     else:
         is_multiline = False
+    if isinstance(tablefmt, TableFormat):
+        format_metadata = tablefmt
+    else:
+        format_metadata = _table_formats.get(tablefmt, _table_formats["simple"])
+    pad_none = _is_fixed_width_table_format(format_metadata)
     width_fn = _choose_width_fn(has_invisible, enable_widechars, is_multiline)
 
     # format rows and columns, convert numeric values to strings
@@ -2400,6 +2423,7 @@ def tabulate(
             enable_widechars,
             is_multiline,
             preserve_whitespace,
+            pad_none,
         )
         for c, a, minw in zip(cols, aligns_copy, minwidths)
     ]
@@ -2435,16 +2459,15 @@ def tabulate(
             max(minw, max(width_fn(cl) for cl in c)) for minw, c in zip(minwidths, t_cols)
         ]
         headers = [
-            _align_header(h, a, minw, width_fn(h), is_multiline, width_fn)
+            _align_header(h, a, minw, width_fn(h), is_multiline, width_fn, pad_none)
             for h, a, minw in zip(headers, aligns_headers, minwidths)
         ]
         rows = list(zip(*cols))
     else:
         minwidths = [max(width_fn(cl) for cl in c) for c in cols]
         rows = list(zip(*cols))
 
-    if not isinstance(tablefmt, TableFormat):
-        tablefmt = _table_formats.get(tablefmt, _table_formats["simple"])
+    tablefmt = format_metadata
 
     ra_default = rowalign if isinstance(rowalign, str) else None
     rowaligns = _expand_iterable(rowalign, len(rows), ra_default)

test/test_output.py

@@ -4,7 +4,15 @@
 
 from pytest import mark
 
-from tabulate import SEPARATING_LINE, simple_separated_format, tabulate
+from tabulate import (
+    SEPARATING_LINE,
+    DataRow,
+    Line,
+    TableFormat,
+    _visible_width,
+    simple_separated_format,
+    tabulate,
+)
 
 from common import assert_equal, check_warnings, raises, skip
 
@@ -2288,6 +2296,106 @@ def test_pretty_headerless():
     assert_equal(expected, result)
 
 
+def test_none_alignment_preserves_content_and_box_geometry():
+    """None alignment keeps input whitespace while filling physical boxes."""
+    expected = "+---------+-------+\n| header  | title |\n+---------+-------+\n|     foo | title |\n| bar     | value |\n+---------+-------+"
+    result = tabulate(
+        [["    foo", "title"], ["bar", "value"]],
+        stralign=None,
+        headers=["header", "title"],
+        headersalign=[None, None],
+        tablefmt="pretty",
+    )
+    assert_equal(expected, result)
+    assert all(len(line) == 19 for line in result.splitlines())
+
+
+def test_none_alignment_uses_custom_box_metadata():
+    """A custom fixed format gets the same padding without a format-name check."""
+    fmt = TableFormat(
+        lineabove=Line("<", "=", "+", ">"),
+        linebelowheader=Line("<", "=", "+", ">"),
+        linebetweenrows=None,
+        linebelow=Line("<", "=", "+", ">"),
+        headerrow=DataRow("[", "][", "]"),
+        datarow=DataRow("[", "][", "]"),
+        padding=1,
+        with_header_hide=None,
+    )
+    result = tabulate([["    foo"], ["bar"]], stralign=None, tablefmt=fmt)
+    assert_equal("<=========>\n[     foo ]\n[ bar     ]\n<=========>", result)
+
+
+def test_none_alignment_orgtbl_remains_unpadded():
+    """A header separator alone does not turn a markup format into a box."""
+    assert_equal(
+        "|     foo |\n| bar |",
+        tabulate([["    foo"], ["bar"]], stralign=None, tablefmt="orgtbl"),
+    )
+    assert_equal(
+        "| h |\n|---------|\n|     foo |\n| bar |",
+        tabulate([["    foo"], ["bar"]], headers=["h"], stralign=None, tablefmt="orgtbl"),
+    )
+
+
+def test_none_alignment_custom_header_separator_is_not_a_box():
+    fmt = TableFormat(
+        lineabove=None,
+        linebelowheader=Line("", "-", "+", ""),
+        linebetweenrows=None,
+        linebelow=None,
+        headerrow=DataRow("|", "|", "|"),
+        datarow=DataRow("|", "|", "|"),
+        padding=1,
+        with_header_hide=None,
+    )
+    assert_equal(
+        "| h |\n---------\n|     foo |\n| bar |",
+        tabulate([["    foo"], ["bar"]], headers=["h"], stralign=None, tablefmt=fmt),
+    )
+
+
+def test_none_alignment_open_or_callable_frame_is_not_a_box():
+    open_frame = TableFormat(
+        lineabove=Line("<", "=", "+", ""),
+        linebelowheader=None,
+        linebetweenrows=None,
+        linebelow=None,
+        headerrow=DataRow("|", "|", "|"),
+        datarow=DataRow("|", "|", "|"),
+        padding=1,
+        with_header_hide=None,
+    )
+    callable_frame = TableFormat(
+        lineabove=lambda widths, aligns: "".join("-" for _ in widths),
+        linebelowheader=None,
+        linebetweenrows=None,
+        linebelow=None,
+        headerrow=DataRow("|", "|", "|"),
+        datarow=DataRow("|", "|", "|"),
+        padding=1,
+        with_header_hide=None,
+    )
+    for fmt, expected in (
+        (open_frame, "<=========\n|     foo |\n| bar |"),
+        (callable_frame, "-\n|     foo |\n| bar |"),
+    ):
+        assert_equal(
+            expected,
+            tabulate([["    foo"], ["bar"]], stralign=None, tablefmt=fmt),
+        )
+
+
+def test_none_alignment_box_handles_multiline_separator_and_index():
+    table = [["a\nb", "中"], SEPARATING_LINE, ["long", "x"]]
+    result = tabulate(
+        table, stralign=None, numalign=None, showindex=["i", "", "j"], tablefmt="grid"
+    )
+    lines = result.splitlines()
+    assert all(_visible_width(line) == _visible_width(lines[0]) for line in lines)
+    assert "a" in result and "b" in result and "中" in result
+
+
 def test_pretty_multiline_headerless():
     "Output: pretty with multiline cells without headers"
     table = [["foo bar\nbaz\nbau", "hello"], ["", "multiline\nworld"]]