1 files changed, 287 insertions, 0 deletions
diff --git a/Lib/_pyrepl/completing_reader.py b/Lib/_pyrepl/completing_reader.py
new file mode 100644
index 00000000000..19fc06feaf3
--- /dev/null
+++ b/Lib/_pyrepl/completing_reader.py
@@ -0,0 +1,287 @@
+#   Copyright 2000-2010 Michael Hudson-Doyle <micahel@gmail.com>
+#                       Antonio Cuni
+#
+#                        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.
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+
+import re
+from . import commands, console, reader
+from .reader import Reader
+
+
+# types
+Command = commands.Command
+if False:
+    from .types import Callback, SimpleContextManager, KeySpec, CommandName
+
+
+def prefix(wordlist: list[str], j: int = 0) -> str:
+    d = {}
+    i = j
+    try:
+        while 1:
+            for word in wordlist:
+                d[word[i]] = 1
+            if len(d) > 1:
+                return wordlist[0][j:i]
+            i += 1
+            d = {}
+    except IndexError:
+        return wordlist[0][j:i]
+    return ""
+
+
+STRIPCOLOR_REGEX = re.compile(r"\x1B\[([0-9]{1,3}(;[0-9]{1,2})?)?[m|K]")
+
+def stripcolor(s: str) -> str:
+    return STRIPCOLOR_REGEX.sub('', s)
+
+
+def real_len(s: str) -> int:
+    return len(stripcolor(s))
+
+
+def left_align(s: str, maxlen: int) -> str:
+    stripped = stripcolor(s)
+    if len(stripped) > maxlen:
+        # too bad, we remove the color
+        return stripped[:maxlen]
+    padding = maxlen - len(stripped)
+    return s + ' '*padding
+
+
+def build_menu(
+        cons: console.Console,
+        wordlist: list[str],
+        start: int,
+        use_brackets: bool,
+        sort_in_column: bool,
+) -> tuple[list[str], int]:
+    if use_brackets:
+        item = "[ %s ]"
+        padding = 4
+    else:
+        item = "%s  "
+        padding = 2
+    maxlen = min(max(map(real_len, wordlist)), cons.width - padding)
+    cols = int(cons.width / (maxlen + padding))
+    rows = int((len(wordlist) - 1)/cols + 1)
+
+    if sort_in_column:
+        # sort_in_column=False (default)     sort_in_column=True
+        #          A B C                       A D G
+        #          D E F                       B E
+        #          G                           C F
+        #
+        # "fill" the table with empty words, so we always have the same amout
+        # of rows for each column
+        missing = cols*rows - len(wordlist)
+        wordlist = wordlist + ['']*missing
+        indexes = [(i % cols) * rows + i // cols for i in range(len(wordlist))]
+        wordlist = [wordlist[i] for i in indexes]
+    menu = []
+    i = start
+    for r in range(rows):
+        row = []
+        for col in range(cols):
+            row.append(item % left_align(wordlist[i], maxlen))
+            i += 1
+            if i >= len(wordlist):
+                break
+        menu.append(''.join(row))
+        if i >= len(wordlist):
+            i = 0
+            break
+        if r + 5 > cons.height:
+            menu.append("   %d more... " % (len(wordlist) - i))
+            break
+    return menu, i
+
+# this gets somewhat user interface-y, and as a result the logic gets
+# very convoluted.
+#
+#  To summarise the summary of the summary:- people are a problem.
+#                  -- The Hitch-Hikers Guide to the Galaxy, Episode 12
+
+#### Desired behaviour of the completions commands.
+# the considerations are:
+# (1) how many completions are possible
+# (2) whether the last command was a completion
+# (3) if we can assume that the completer is going to return the same set of
+#     completions: this is controlled by the ``assume_immutable_completions``
+#     variable on the reader, which is True by default to match the historical
+#     behaviour of pyrepl, but e.g. False in the ReadlineAlikeReader to match
+#     more closely readline's semantics (this is needed e.g. by
+#     fancycompleter)
+#
+# if there's no possible completion, beep at the user and point this out.
+# this is easy.
+#
+# if there's only one possible completion, stick it in.  if the last thing
+# user did was a completion, point out that he isn't getting anywhere, but
+# only if the ``assume_immutable_completions`` is True.
+#
+# now it gets complicated.
+#
+# for the first press of a completion key:
+#  if there's a common prefix, stick it in.
+
+#  irrespective of whether anything got stuck in, if the word is now
+#  complete, show the "complete but not unique" message
+
+#  if there's no common prefix and if the word is not now complete,
+#  beep.
+
+#        common prefix ->    yes          no
+#        word complete \/
+#            yes           "cbnu"      "cbnu"
+#            no              -          beep
+
+# for the second bang on the completion key
+#  there will necessarily be no common prefix
+#  show a menu of the choices.
+
+# for subsequent bangs, rotate the menu around (if there are sufficient
+# choices).
+
+
+class complete(commands.Command):
+    def do(self) -> None:
+        r: CompletingReader
+        r = self.reader  # type: ignore[assignment]
+        last_is_completer = r.last_command_is(self.__class__)
+        immutable_completions = r.assume_immutable_completions
+        completions_unchangable = last_is_completer and immutable_completions
+        stem = r.get_stem()
+        if not completions_unchangable:
+            r.cmpltn_menu_choices = r.get_completions(stem)
+
+        completions = r.cmpltn_menu_choices
+        if not completions:
+            r.error("no matches")
+        elif len(completions) == 1:
+            if completions_unchangable and len(completions[0]) == len(stem):
+                r.msg = "[ sole completion ]"
+                r.dirty = True
+            r.insert(completions[0][len(stem):])
+        else:
+            p = prefix(completions, len(stem))
+            if p:
+                r.insert(p)
+            if last_is_completer:
+                if not r.cmpltn_menu_vis:
+                    r.cmpltn_menu_vis = 1
+                r.cmpltn_menu, r.cmpltn_menu_end = build_menu(
+                    r.console, completions, r.cmpltn_menu_end,
+                    r.use_brackets, r.sort_in_column)
+                r.dirty = True
+            elif stem + p in completions:
+                r.msg = "[ complete but not unique ]"
+                r.dirty = True
+            else:
+                r.msg = "[ not unique ]"
+                r.dirty = True
+
+
+class self_insert(commands.self_insert):
+    def do(self) -> None:
+        r: CompletingReader
+        r = self.reader  # type: ignore[assignment]
+
+        commands.self_insert.do(self)
+
+        if r.cmpltn_menu_vis:
+            stem = r.get_stem()
+            if len(stem) < 1:
+                r.cmpltn_reset()
+            else:
+                completions = [w for w in r.cmpltn_menu_choices
+                               if w.startswith(stem)]
+                if completions:
+                    r.cmpltn_menu, r.cmpltn_menu_end = build_menu(
+                        r.console, completions, 0,
+                        r.use_brackets, r.sort_in_column)
+                else:
+                    r.cmpltn_reset()
+
+
+@dataclass
+class CompletingReader(Reader):
+    """Adds completion support"""
+
+    ### Class variables
+    # see the comment for the complete command
+    assume_immutable_completions = True
+    use_brackets = True  # display completions inside []
+    sort_in_column = False
+
+    ### Instance variables
+    cmpltn_menu: list[str] = field(init=False)
+    cmpltn_menu_vis: int = field(init=False)
+    cmpltn_menu_end: int = field(init=False)
+    cmpltn_menu_choices: list[str] = field(init=False)
+
+    def __post_init__(self) -> None:
+        super().__post_init__()
+        self.cmpltn_reset()
+        for c in (complete, self_insert):
+            self.commands[c.__name__] = c
+            self.commands[c.__name__.replace('_', '-')] = c
+
+    def collect_keymap(self) -> tuple[tuple[KeySpec, CommandName], ...]:
+        return super().collect_keymap() + (
+            (r'\t', 'complete'),)
+
+    def after_command(self, cmd: Command) -> None:
+        super().after_command(cmd)
+        if not isinstance(cmd, (complete, self_insert)):
+            self.cmpltn_reset()
+
+    def calc_screen(self) -> list[str]:
+        screen = super().calc_screen()
+        if self.cmpltn_menu_vis:
+            ly = self.lxy[1]
+            screen[ly:ly] = self.cmpltn_menu
+            self.screeninfo[ly:ly] = [(0, [])]*len(self.cmpltn_menu)
+            self.cxy = self.cxy[0], self.cxy[1] + len(self.cmpltn_menu)
+        return screen
+
+    def finish(self) -> None:
+        super().finish()
+        self.cmpltn_reset()
+
+    def cmpltn_reset(self) -> None:
+        self.cmpltn_menu = []
+        self.cmpltn_menu_vis = 0
+        self.cmpltn_menu_end = 0
+        self.cmpltn_menu_choices = []
+
+    def get_stem(self) -> str:
+        st = self.syntax_table
+        SW = reader.SYNTAX_WORD
+        b = self.buffer
+        p = self.pos - 1
+        while p >= 0 and st.get(b[p], SW) == SW:
+            p -= 1
+        return ''.join(b[p+1:self.pos])
+
+    def get_completions(self, stem: str) -> list[str]:
+        return []