feat: add vesta viewer

.codespell/ignore_words.txt

@@ -22,3 +22,7 @@ CONECT
 ;; /src/diffpy/structure/parsers/p_xcfg.py:452
 ;; used in a function
 BU
+
+;; /src/diffpy/structure/parsers/p_vesta.py:452
+;; abbreviation for Structure in vesta
+STRUC

news/vesta_view.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* Added parser for vesta specific files and viewer for vesta
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

src/diffpy/structure/apps/vesta_viewer.py

@@ -0,0 +1,366 @@
+#!/usr/bin/env python
+##############################################################################
+#
+# diffpy.structure  by DANSE Diffraction group
+#                   Simon J. L. Billinge
+#                   (c) 2026 University of California, Santa Barbara.
+#                   All rights reserved.
+#
+# File coded by:    Simon J. L. Billinge, Rundong Hua
+#
+# See AUTHORS.txt for a list of people who contributed.
+# See LICENSE_DANSE.txt for license information.
+#
+##############################################################################
+"""View structure file in VESTA.
+
+Usage: ``vestaview [options] strufile``
+
+Vestaview understands more `Structure` formats than VESTA. It converts
+`strufile` to a temporary VESTA or CIF file which is opened in VESTA.
+See supported file formats: ``inputFormats``
+
+Options:
+  -f, --formula
+      Override chemical formula in `strufile`. The formula defines
+      elements in the same order as in `strufile`, e.g., ``Na4Cl4``.
+
+  -w, --watch
+      Watch input file for changes.
+
+  --viewer=VIEWER
+      The structure viewer program, by default "vesta".
+      The program will be executed as "VIEWER structurefile".
+
+  --formats=FORMATS
+      Comma-separated list of file formats that are understood
+      by the VIEWER, by default ``"vesta,cif"``. Files of other
+      formats will be converted to the first listed format.
+
+  -h, --help
+      Display this message and exit.
+
+  -V, --version
+      Show script version and exit.
+
+Notes
+-----
+VESTA is the actively maintained successor to AtomEye. Unlike AtomEye,
+VESTA natively reads CIF, its own ``.vesta`` format, and several other
+crystallographic file types, so format conversion is only required for
+formats not in that set.
+
+AtomEye XCFG format is no longer a default target format but the XCFG
+parser (``P_xcfg``) remains available in ``diffpy.structure.parsers``
+for backward compatibility.
+"""
+
+import os
+import re
+import signal
+import sys
+from pathlib import Path
+
+from diffpy.structure.structureerrors import StructureFormatError
+
+pd = {
+    "formula": None,
+    "watch": False,
+    "viewer": "vesta",
+    "formats": ["vesta", "cif"],
+}
+
+
+def usage(style=None):
+    """Show usage info. for ``style=="brief"`` show only first 2 lines.
+
+    Parameters
+    ----------
+    style : str, optional
+        The usage display style.
+    """
+    myname = Path(sys.argv[0]).name
+    msg = __doc__.replace("vestaview", myname)
+    if style == "brief":
+        msg = f"{msg.splitlines()[1]}\n" f"Try `{myname} --help' for more information."
+    else:
+        from diffpy.structure.parsers import input_formats
+
+        fmts = [fmt for fmt in input_formats() if fmt != "auto"]
+        msg = msg.replace("inputFormats", " ".join(fmts))
+    print(msg)
+
+
+def version():
+    """Print the script version."""
+    from diffpy.structure import __version__
+
+    print(f"vestaview {__version__}")
+
+
+def load_structure_file(filename, format="auto"):
+    """Load structure from the specified file.
+
+    Parameters
+    ----------
+    filename : str or Path
+        The path to the structure file.
+    format : str, optional
+        The file format, by default ``"auto"``.
+
+    Returns
+    -------
+    tuple
+        The loaded ``(Structure, fileformat)`` pair.
+    """
+    from diffpy.structure import Structure
+
+    stru = Structure()
+    parser = stru.read(str(filename), format)
+    return stru, parser.format
+
+
+def convert_structure_file(pd):
+    """Convert ``strufile`` to a temporary file understood by the
+    viewer.
+
+    On the first call, a temporary directory is created and stored in
+    ``pd``. Subsequent calls in watch mode reuse the directory.
+
+    The VESTA viewer natively reads ``.vesta`` and ``.cif`` files, so if
+    the source is already in one of the formats listed in
+    ``pd["formats"]`` and no formula override is requested, the file is
+    copied unchanged. Otherwise the structure is loaded and re-written in
+    the first format listed in ``pd["formats"]``.
+
+    Parameters
+    ----------
+    pd : dict
+        The parameter dictionary containing at minimum ``"strufile"``
+        and ``"formats"`` keys. It is modified in place to add
+        ``"tmpdir"`` and ``"tmpfile"`` on the first call.
+    """
+    if "tmpdir" not in pd:
+        from tempfile import mkdtemp
+
+        pd["tmpdir"] = Path(mkdtemp())
+    strufile = Path(pd["strufile"])
+    tmpfile = pd["tmpdir"] / strufile.name
+    tmpfile_tmp = Path(f"{tmpfile}.tmp")
+    pd["tmpfile"] = tmpfile
+    stru = None
+    fmt = pd.get("fmt", "auto")
+    if fmt == "auto":
+        stru, fmt = load_structure_file(strufile)
+        pd["fmt"] = fmt
+    if fmt in pd["formats"] and pd["formula"] is None:
+        import shutil
+
+        shutil.copyfile(strufile, tmpfile_tmp)
+        tmpfile_tmp.replace(tmpfile)
+        return
+    if stru is None:
+        stru = load_structure_file(strufile, fmt)[0]
+    if pd["formula"]:
+        formula = pd["formula"]
+        if len(formula) != len(stru):
+            emsg = f"Formula has {len(formula)} atoms while structure has " f"{len(stru)}"
+            raise RuntimeError(emsg)
+        for atom, element in zip(stru, formula):
+            atom.element = element
+    elif fmt == "rawxyz":
+        for atom in stru:
+            if atom.element == "":
+                atom.element = "C"
+    stru.write(str(tmpfile_tmp), pd["formats"][0])
+    tmpfile_tmp.replace(tmpfile)
+
+
+def watch_structure_file(pd):
+    """Watch ``strufile`` for modifications and reconvert when changed.
+
+    Polls the modification timestamps of ``pd["strufile"]`` and
+    ``pd["tmpfile"]`` once per second. When the source is newer, the
+    file is reconverted via :func:`convert_structure_file`.
+
+    Parameters
+    ----------
+    pd : dict
+        The parameter dictionary as used by
+        :func:`convert_structure_file`.
+    """
+    from time import sleep
+
+    strufile = Path(pd["strufile"])
+    tmpfile = Path(pd["tmpfile"])
+    while pd["watch"]:
+        if tmpfile.stat().st_mtime < strufile.stat().st_mtime:
+            convert_structure_file(pd)
+        sleep(1)
+
+
+def clean_up(pd):
+    """Remove temporary file and directory created during conversion.
+
+    Parameters
+    ----------
+    pd : dict
+        The parameter dictionary that may contain ``"tmpfile"`` and
+        ``"tmpdir"`` entries to be removed.
+    """
+    tmpfile = pd.pop("tmpfile", None)
+    if tmpfile is not None and Path(tmpfile).exists():
+        Path(tmpfile).unlink()
+    tmpdir = pd.pop("tmpdir", None)
+    if tmpdir is not None and Path(tmpdir).exists():
+        Path(tmpdir).rmdir()
+
+
+def parse_formula(formula):
+    """Parse chemical formula and return a list of elements.
+
+    Parameters
+    ----------
+    formula : str
+        The chemical formula string such as ``"Na4Cl4"`` or ``"H2O"``.
+
+    Returns
+    -------
+    list of str
+        The ordered list of element symbols with repetition matching the
+        formula.
+
+    Raises
+    ------
+    RuntimeError
+        Raised when ``formula`` does not start with an uppercase letter
+        or contains a non-integer count.
+    """
+    formula = re.sub(r"\s", "", formula)
+    if not re.match(r"^[A-Z]", formula):
+        raise RuntimeError(f"InvalidFormula '{formula}'")
+
+    elcnt = re.split(r"([A-Z][a-z]?)", formula)[1:]
+    ellst = []
+    try:
+        for i in range(0, len(elcnt), 2):
+            element = elcnt[i]
+            count = int(elcnt[i + 1]) if elcnt[i + 1] else 1
+            ellst.extend([element] * count)
+    except ValueError:
+        emsg = f"Invalid formula, {elcnt[i + 1]!r} is not valid count"
+        raise RuntimeError(emsg)
+    return ellst
+
+
+def die(exit_status=0, pd=None):
+    """Clean up temporary files and exit with ``exit_status``.
+
+    Parameters
+    ----------
+    exit_status : int, optional
+        The exit code passed to :func:`sys.exit`, by default 0.
+    pd : dict, optional
+        The parameter dictionary forwarded to :func:`clean_up`.
+    """
+    clean_up({} if pd is None else pd)
+    sys.exit(exit_status)
+
+
+def signal_handler(signum, stackframe):
+    """Handle OS signals by reverting to the default handler and
+    exiting.
+
+    On ``SIGCHLD`` the child exit status is harvested via
+    :func:`os.wait`; on all other signals :func:`die` is called with
+    exit status 1.
+
+    Parameters
+    ----------
+    signum : int
+        The signal number.
+    stackframe : frame
+        The current stack frame. Unused.
+    """
+    del stackframe
+    signal.signal(signum, signal.SIG_DFL)
+    if signum == signal.SIGCHLD:
+        _, exit_status = os.wait()
+        exit_status = (exit_status >> 8) + (exit_status & 0x00FF)
+        die(exit_status, pd)
+    else:
+        die(1, pd)
+
+
+def main():
+    """Entry point for the ``vestaview`` command-line tool."""
+    import getopt
+
+    pd["watch"] = False
+    try:
+        opts, args = getopt.getopt(
+            sys.argv[1:],
+            "f:whV",
+            ["formula=", "watch", "viewer=", "formats=", "help", "version"],
+        )
+    except getopt.GetoptError as errmsg:
+        print(errmsg, file=sys.stderr)
+        die(2)
+
+    for option, argument in opts:
+        if option in ("-f", "--formula"):
+            try:
+                pd["formula"] = parse_formula(argument)
+            except RuntimeError as err:
+                print(err, file=sys.stderr)
+                die(2)
+        elif option in ("-w", "--watch"):
+            pd["watch"] = True
+        elif option == "--viewer":
+            pd["viewer"] = argument
+        elif option == "--formats":
+            pd["formats"] = [word.strip() for word in argument.split(",")]
+        elif option in ("-h", "--help"):
+            usage()
+            die()
+        elif option in ("-V", "--version"):
+            version()
+            die()
+    if len(args) < 1:
+        usage("brief")
+        die()
+    if len(args) > 1:
+        print("too many structure files", file=sys.stderr)
+        die(2)
+    pd["strufile"] = Path(args[0])
+    signal.signal(signal.SIGHUP, signal_handler)
+    signal.signal(signal.SIGQUIT, signal_handler)
+    signal.signal(signal.SIGSEGV, signal_handler)
+    signal.signal(signal.SIGTERM, signal_handler)
+    signal.signal(signal.SIGINT, signal_handler)
+    env = os.environ.copy()
+    try:
+        convert_structure_file(pd)
+        spawnargs = (
+            pd["viewer"],
+            pd["viewer"],
+            str(pd["tmpfile"]),
+            env,
+        )
+        if pd["watch"]:
+            signal.signal(signal.SIGCHLD, signal_handler)
+            os.spawnlpe(os.P_NOWAIT, *spawnargs)
+            watch_structure_file(pd)
+        else:
+            status = os.spawnlpe(os.P_WAIT, *spawnargs)
+            die(status, pd)
+    except IOError as err:
+        print(f"{args[0]}: {err.strerror}", file=sys.stderr)
+        die(1, pd)
+    except StructureFormatError as err:
+        print(f"{args[0]}: {err}", file=sys.stderr)
+        die(1, pd)
+
+
+if __name__ == "__main__":
+    main()