gh-111201: A new Python REPL (GH-111567)

Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Marta Gómez Macías <mgmacias@google.com>
Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

1 files changed, 215 insertions, 0 deletions

diff --git a/Lib/_pyrepl/keymap.py b/Lib/_pyrepl/keymap.py
new file mode 100644
index 00000000000..31a02642ce8
--- /dev/null
+++ b/Lib/_pyrepl/keymap.py
@@ -0,0 +1,215 @@
+#   Copyright 2000-2008 Michael Hudson-Doyle <micahel@gmail.com>
+#                       Armin Rigo
+#
+#                        All Rights Reserved
+#
+#
+# Permission to use, copy, modify, and distribute this software and
+# its documentation for any purpose is hereby granted without fee,
+# provided that the above copyright notice appear in all copies and
+# that both that copyright notice and this permission notice appear in
+# supporting documentation.
+#
+# THE AUTHOR MICHAEL HUDSON DISCLAIMS ALL WARRANTIES WITH REGARD TO
+# THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS, IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL,
+# INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+# RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+# CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+"""
+functions for parsing keyspecs
+
+Support for turning keyspecs into appropriate sequences.
+
+pyrepl uses it's own bastardized keyspec format, which is meant to be
+a strict superset of readline's \"KEYSEQ\" format (which is to say
+that if you can come up with a spec readline accepts that this
+doesn't, you've found a bug and should tell me about it).
+
+Note that this is the `\\C-o' style of readline keyspec, not the
+`Control-o' sort.
+
+A keyspec is a string representing a sequence of keypresses that can
+be bound to a command.
+
+All characters other than the backslash represent themselves.  In the
+traditional manner, a backslash introduces a escape sequence.
+
+The extension to readline is that the sequence \\<KEY> denotes the
+sequence of charaters produced by hitting KEY.
+
+Examples:
+
+`a'     - what you get when you hit the `a' key
+`\\EOA'  - Escape - O - A (up, on my terminal)
+`\\<UP>' - the up arrow key
+`\\<up>' - ditto (keynames are case insensitive)
+`\\C-o', `\\c-o'  - control-o
+`\\M-.'  - meta-period
+`\\E.'   - ditto (that's how meta works for pyrepl)
+`\\<tab>', `\\<TAB>', `\\t', `\\011', '\\x09', '\\X09', '\\C-i', '\\C-I'
+   - all of these are the tab character.  Can you think of any more?
+"""
+
+_escapes = {
+    "\\": "\\",
+    "'": "'",
+    '"': '"',
+    "a": "\a",
+    "b": "\b",
+    "e": "\033",
+    "f": "\f",
+    "n": "\n",
+    "r": "\r",
+    "t": "\t",
+    "v": "\v",
+}
+
+_keynames = {
+    "backspace": "backspace",
+    "delete": "delete",
+    "down": "down",
+    "end": "end",
+    "enter": "\r",
+    "escape": "\033",
+    "f1": "f1",
+    "f2": "f2",
+    "f3": "f3",
+    "f4": "f4",
+    "f5": "f5",
+    "f6": "f6",
+    "f7": "f7",
+    "f8": "f8",
+    "f9": "f9",
+    "f10": "f10",
+    "f11": "f11",
+    "f12": "f12",
+    "f13": "f13",
+    "f14": "f14",
+    "f15": "f15",
+    "f16": "f16",
+    "f17": "f17",
+    "f18": "f18",
+    "f19": "f19",
+    "f20": "f20",
+    "home": "home",
+    "insert": "insert",
+    "left": "left",
+    "page down": "page down",
+    "page up": "page up",
+    "return": "\r",
+    "right": "right",
+    "space": " ",
+    "tab": "\t",
+    "up": "up",
+}
+
+
+class KeySpecError(Exception):
+    pass
+
+
+def _parse_key1(key, s):
+    ctrl = 0
+    meta = 0
+    ret = ""
+    while not ret and s < len(key):
+        if key[s] == "\\":
+            c = key[s + 1].lower()
+            if c in _escapes:
+                ret = _escapes[c]
+                s += 2
+            elif c == "c":
+                if key[s + 2] != "-":
+                    raise KeySpecError(
+                        "\\C must be followed by `-' (char %d of %s)"
+                        % (s + 2, repr(key))
+                    )
+                if ctrl:
+                    raise KeySpecError(
+                        "doubled \\C- (char %d of %s)" % (s + 1, repr(key))
+                    )
+                ctrl = 1
+                s += 3
+            elif c == "m":
+                if key[s + 2] != "-":
+                    raise KeySpecError(
+                        "\\M must be followed by `-' (char %d of %s)"
+                        % (s + 2, repr(key))
+                    )
+                if meta:
+                    raise KeySpecError(
+                        "doubled \\M- (char %d of %s)" % (s + 1, repr(key))
+                    )
+                meta = 1
+                s += 3
+            elif c.isdigit():
+                n = key[s + 1 : s + 4]
+                ret = chr(int(n, 8))
+                s += 4
+            elif c == "x":
+                n = key[s + 2 : s + 4]
+                ret = chr(int(n, 16))
+                s += 4
+            elif c == "<":
+                t = key.find(">", s)
+                if t == -1:
+                    raise KeySpecError(
+                        "unterminated \\< starting at char %d of %s"
+                        % (s + 1, repr(key))
+                    )
+                ret = key[s + 2 : t].lower()
+                if ret not in _keynames:
+                    raise KeySpecError(
+                        "unrecognised keyname `%s' at char %d of %s"
+                        % (ret, s + 2, repr(key))
+                    )
+                ret = _keynames[ret]
+                s = t + 1
+            else:
+                raise KeySpecError(
+                    "unknown backslash escape %s at char %d of %s"
+                    % (repr(c), s + 2, repr(key))
+                )
+        else:
+            ret = key[s]
+            s += 1
+    if ctrl:
+        if len(ret) > 1:
+            raise KeySpecError("\\C- must be followed by a character")
+        ret = chr(ord(ret) & 0x1F)  # curses.ascii.ctrl()
+    if meta:
+        ret = ["\033", ret]
+    else:
+        ret = [ret]
+    return ret, s
+
+
+def parse_keys(key):
+    s = 0
+    r = []
+    while s < len(key):
+        k, s = _parse_key1(key, s)
+        r.extend(k)
+    return r
+
+
+def compile_keymap(keymap, empty=b""):
+    r = {}
+    for key, value in keymap.items():
+        if isinstance(key, bytes):
+            first = key[:1]
+        else:
+            first = key[0]
+        r.setdefault(first, {})[key[1:]] = value
+    for key, value in r.items():
+        if empty in value:
+            if len(value) != 1:
+                raise KeySpecError("key definitions for %s clash" % (value.values(),))
+            else:
+                r[key] = value[empty]
+        else:
+            r[key] = compile_keymap(value, empty)
+    return r