Implement 'ipython history show [opts]'

Includes: * a `-l` / `--limit` option which defaults to the last 1000 entries from the SQLite history database * a `-P` / `--pretty` option which pretty-prints the output with IPython.util.PyColorize * flags to specify a custom delimiter (defaults to tab) and add a header row (corresponding to the SQLite column names) * flags which control `--pretty`'s colorized output, defaulting to color only when stdout is a terminal
ipython · ernstki · Mar 3, 2022 · Mar 3, 2022 · Mar 3, 2022 · ce21888e59a69199b33982455b1f2368e5b41884
commit ce21888e59a69199b33982455b1f2368e5b41884
diff --git a/IPython/core/historyapp.py b/IPython/core/historyapp.py
@@ -10,9 +10,15 @@
 
 from traitlets.config.application import Application
 from .application import BaseIPythonApplication
-from traitlets import Bool, Int, Dict
+from traitlets import Bool, Int, Dict, Unicode, CaselessStrEnum
 from ..utils.io import ask_yes_no
 
+show_hist_help = """Show recent entries from the IPython history database.
+
+Limited to the last 1000 unless `--limit=N` is supplied; `--limit=0` or `-1`
+prints all entries in the database.
+"""
+
 trim_hist_help = """Trim the IPython history database to the last 1000 entries.
 
 This actually copies the last 1000 entries to a new database, and then replaces
@@ -29,6 +35,113 @@
 This is an handy alias to `ipython history trim --keep=0`
 """
 
+class HistoryShow(BaseIPythonApplication):
+    description = show_hist_help
+    limit = Int(1000,
+        help="Number of recent history entries to show."
+        ).tag(config=True)
+
+    delimiter = Unicode(u'\t',
+        help="Delimiter for separating the columns of history output."
+        ).tag(config=True)
+
+    header = Bool(False,
+        help="Include a header row in the output."
+        ).tag(config=True)
+
+    pretty = Bool(False,
+        help="Pretty-print the output using IPython.utils.PyColorize."
+        ).tag(config=True)
+
+    colors = CaselessStrEnum(('Neutral', 'NoColor','LightBG','Linux'),
+        default_value='Neutral',
+        help="Set the color scheme (NoColor, Neutral, Linux, or LightBG)."
+    ).tag(config=True)
+
+    color = CaselessStrEnum(('Never', 'Always', 'Auto'),
+        default_value='Auto',
+        help="Choose when to display color; requires `--pretty`."
+    ).tag(config=True)
+
+    flags = Dict({
+        'L': ({'HistoryShow': {'limit': -1}},
+            "No limit; show all history entries."),
+        'pretty': ({'HistoryShow': {'pretty': True}}, pretty.help),
+        'P': ({'HistoryShow': {'pretty': True}},
+            "An alias for `--pretty`."),
+        'header': ({'HistoryShow': {'header': True}}, header.help),
+        'headers': ({'HistoryShow': {'header': True}},
+            "An alias for `--header`."),
+        'H': ({'HistoryShow': {'header': True}},
+            "An alias for `--header`."),
+        'color-always':  ({'HistoryShow': {'color': 'Always'}},
+            "Always output in color (e.g., when piping into `less -R`)."),
+        'C':  ({'HistoryShow': {'color': 'Always'}},
+            "An alias for `--color-always`."),
+        'color-never':  ({'HistoryShow': {'color': 'Never'}},
+            "Never show color, even if the output is a terminal.")
+    })
+
+    aliases=Dict(dict(
+        l = 'HistoryShow.limit',
+        limit = 'HistoryShow.limit',
+        d = 'HistoryShow.delimiter',
+        delimiter = 'HistoryShow.delimiter',
+        header = 'HistoryShow.header',
+        pretty = 'HistoryShow.pretty',
+        colors = 'HistoryShow.colors',
+        color = 'HistoryShow.color',
+    ))
+
+    def start(self):
+        profile_dir = Path(self.profile_dir.location)
+        hist_file = profile_dir / "history.sqlite"
+        con = sqlite3.connect(hist_file)
+
+        if not self.limit:
+            self.limit = -1
+
+        # Grab the recent history from the current database.
+        entries = list(con.execute(
+            """SELECT session, line, source, source_raw FROM
+               history ORDER BY session DESC, line DESC LIMIT ?""",
+           (self.limit,)
+        ))
+
+        # Emulate shell `history` command; newest at bottom
+        entries.reverse()
+
+        if self.pretty:
+            import sys
+            from IPython.utils import PyColorize
+            pyformat = PyColorize.Parser(style=self.colors,
+                                         parent=self).format
+
+            for entry in entries:
+                header = f">>> # session {entry[0]}, line {entry[1]}\n"
+                entry = header + str(entry[3])
+
+                if (sys.stdout.isatty() or self.color == 'Always') \
+                        and self.color != 'Never':
+                    print(pyformat(entry, out='str'))
+                else:
+                    # could set self.colors='NoColor' and just use pyformat
+                    # here, too, but this is probably marginally faster
+                    print(entry, "\n")
+
+        else:
+            if self.header:
+                print(self.delimiter.join(['session', 'line', 'source',
+                                           'source_raw']))
+            for entry in entries:
+                # FIXME: even if you specify `-d,` this is not very
+                # CSV-friendly, since the outer quote character (single or
+                # double) depends on whether the history entry itself has
+                # embedded strings
+                print(self.delimiter.join([repr(x) for x in entry]))
+
+        con.close()
+
 
 class HistoryTrim(BaseIPythonApplication):
     description = trim_hist_help
@@ -145,6 +258,7 @@ class HistoryApp(Application):
     description = "Manage the IPython history database."
 
     subcommands = Dict(dict(
+        show = (HistoryShow, HistoryShow.description.splitlines()[0]),
         trim = (HistoryTrim, HistoryTrim.description.splitlines()[0]),
         clear = (HistoryClear, HistoryClear.description.splitlines()[0]),
     ))